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Discussion Starter #1 (Edited)
Hi:
I'm fiddling with my tbird again and I wanted to ask a question of some folks more educated than me on tweaking my tbird's setup. When we had a V6 in the tbird, the car was quite neutral handling. It was a pleasure to drive on the track (road course) but dog slow. We've since beat on it for 5 years now so the suspension is probably a bit more worn than it was when we started. Once we went to a 5.0V8 though, the handling has been a little "looser" feeling but the V8 now lets us throttle steer as necessary ("not turning in fast enough? give it a little more gas and the car rotates more")

Current Handling Setup
- Front Springs: 91 SC springs (349-403 lb./in) , used, 1.5 coils cut off, on our car since our first race in Oct 2011).
- Front struts: Monroe Sensatrac, left replaced in 2011 as new item, right one recently replaced before last race (pre Feb 2016) b/c it was blown
- From pillow top rubber strut assembly mount: doesnt' appear busted on driver's side, replaced with a new one on the passenger side when the blown strut was swapped out.
- Front Swaybar: 95 tbird 3.8 stock - 1.06" tubular IIRC. Not inclined to replace it.
- Front UCA: replaced w/ new Dorman (2011)
- Wheels: Direzza Star Specs 225/45-R16. We went to a 16" rim when we realized our V8 could overwhelm our 205/50-R15 tires with even just partial throttle (accidentally nearly went sideways when I goosed the throttle on the street)
- Approximately 150LB heavier at the nose with the V8 vs the V6.
- Rear swaybar: 90 SC stock - 1.04" solid vs 95 stock which was tubular
- Rear Springs: 1.5" drop Eibachs (514-714 lb/in)
- Rear shocks: Motorcraft OEM from 2011 ($10/ea closeout rockauto special)

* My race spares are a set (front and rear) of Suspension Techniques linear springs & matching shocks: 432LB linear front 631LB linear rear. I also have a set of KYB shocks that a TCCOA contributed to me for the cost of shipping (he says they were soft). Finally, I believe I have a paid of SC front struts that have a bit of rust on them from Dan I could use/cutup/whatever.

At our last race, the judge hopped on our fender and described our front end as "comfy"

WHAT I PLAN TO DO ALREADY
* Replace the front sway bar bushings - these also look pretty worn out. - DONE
* Replace the rear sway bar bushings: they didn't look as worn so this is just money/effort. - DONE
* Replace rear toe compensator links: DONE
* Replace the rear shocks with 99-04 Cobra bilsteins - DONE
* Replace front struts with Bilstein 3000GT inserts: IN PROGRESS. Requires:
- cut and gut two stoxk struts: DONE
- install insert
- fabricate shock top w/ 5/8" shaft hole
* Fabricate front strut braces (strut rod frame mount to LCA mount & LCA mount to frame rail) - IN PROCESS
* Replace the front LCAs - the bushings look a bit worn and new MOOG ones are cheap enough @ $30/ea. - IN PROCESS
* Replace the LCA rear bushings (inner) - SKIP FOR NOW


Questions
Q1: I know that if you "over-spring" a car, the result is a vehicle with squirrelly handling as the tire will bounce up and down and when doing so, the car will lose traction as you go over any hills (Sears point is very hilly). This is a big concern for me. What i don't know is what happens when you over-dampen a car so I'd like some advice here if anyone is knowledgable in this area. Would it be considered overdampening to leave my springs as-is and just replace the struts/shocks?

Q1b: I suspect if I go from an OEM quality ride (Monroe Sensatracs + Motorcraft) to Bilsteins up front, should I do the same out back? What if I just replaced the back shocks and left the front ones as is? How would that affect handling

Q2: If I do decide to replace the dampeners, I might as well consider replacing the front springs. My gut feeling is that with the added weight of the V8, I could use more spring up front but is going to the 650LB/in linear springs up front going to be too much?

Q2b: I know that too stiff a front end in relation to the rear will contribute to understeering. Will changing the ratio between front/rear springs cause an issue if I go with the QA1 springs up front?
Q2c: What do people with the QA1 springs up front use for the rears?
Q2d: Finally, will I notice a weird feeling by mixing and matching linear and progressive springs? If I go with the QA1 springs up front, my gut feeling is to keep the Eibachs in back. It'll be cheaper and they don't look broken.

Thanks in advice for your thoughts....
-g
 

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1) Over-dampening won't hurt handling, as long as it is evenly over-damped. It will hurt ride quality, but I don't think you are concerned about that. Honestly, SC springs with 1.5 coils cut off are plenty stiff for the chassis. Going too stiff can actually hurt handling because the chassis will flex rather than the suspension, which behaves unpredictably, and if the chassis is stiffened up enough with the cage, the car will start lifting the inside rear wheel in a turn, which means that tire won't have any traction.

1b) Bilsteins aren't made for the front of our cars. The stiffest aftermarket shock you will be able to get is the Tokico's. The Tokico Blues are pretty good, and will be way better than what you have, but if it is in the budget, the Tokico Illumina 2's are meant for the SC with the ARC setup, and if you set them to the firm setting and lock them there, that will be the stiffest bolt-in shock you can get for the front of this car. For the rear though, definitely go with the 03 Cobra Bilsteins.

2) As I said above, I think your front springs are plenty stiff. I suspect your Monroe Sensatracs are beyond shot after running even one race with those springs, let alone several. Keep in mind that when you cut a spring, you increase the stiffness of the spring by the ratio of coils you have now to coils you did have. In other words if a spring has a 400lb/in rating, and 10 coils, and you cut one coil off, that spring now has 444lb/in rate. If you cut 2 coils off that same spring, it is now 500lb/in. This gets a little more complicated for progressive springs, but the concept is the same, so regardless, right now up front you are horribly over-sprung. As for the rear, I think the Eibachs in the back are a weak link for you, and I would look to change them. There are varying degrees of progressiveness of a spring, and the eibachs are very progressive, meaning that they start very soft, and then get very stiff. This is great on a street car because you don't really sacrifice ride quality, but on a race-car, it makes the car less predictable. If possible, I would look for a set of SC springs to match the fronts, and then cut a coil off those. If those are not available, swapping to the suspension techniques springs all the way around should be an improvement.

As for other suggestions, I know you said you are not inclined to change the sway-bar, but running the stock 95 V6 bar, you are basically running the smallest factory bar ever made for these cars. Even stock SC sway bars front and rear would be a huge improvement in this area, as it would keep the car much flatter in the corners, but you have to match the stiffness of the front and rear sway bars. If you go too stiff in the rear without changing the front, it will induce oversteer. If you go the other way, it will induce understeer. I know it sucks having to pull the subframe down to replace the front bar, but I think it will help. If you are dead-set against changing the sway bars, then stiffening up the spring rate can also counter the lack of stiffness in the sway bar, but once again, it will have to be matched front and rear, or you will induce oversteer or understeer depending on whether the front or the rear is stiffer relative to the weight on that wheel. Another thing that is simple and cheap and will be a huge help with handing is front suspension bracing. A brace across the bottom of the front subframe from near where the LCA mounts to near where the front strut rod bushing mounts, and another brace from the bottom back of the rear subframe to the bottom of the frame rail will do wonders for your handling, and all is costs is some 1" square tubing from Home Depot, and some time with a MIG welder.

Also, I know it will hurt the budget, but if you want to be competitive, you need to step it up on the tires. This is a heavy car, and to keep up with those lightweight little Miatas and E30s in the corners, you need a lot of tire. A Mustang hub swap will open your door to tons of cheap 17" wheels. The Bullitt wheels for the SN95 Mustangs are a 17x8.5, which means you can run a 275/40/17 tire, which will let you throw that heavy car around the corners and actually hook. My final setup that I had on my car was 275/40/17 Nitto NT05s on 17x9 wheels, cut SC springs front and rear, SC sway bars, Tokico Blues up front with Bilsteins out back, and various suspension bracing pieces, and we could hang with or pass 90% of the other cars in the corners. I think the last time out, the only cars with faster lap times were a couple E30s, a very well done fox Mustang, and a super-cheaty 80s Volvo with a Ford 302 in it. I remember one particular time, another racer came up to me after the race. I had passed his Supra going into a banked turn, he was hard on the brakes and I was still full throttle, and he said the thought for sure as hot as I was going in, that he was going to watch me fly up and go straight into the wall, and couldn't believe how that big car just hooked the turn and went.
 

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Discussion Starter #3 (Edited)
Thanks so much for your feedback Mike.
Let's take these topics one at a time

Shocks/Struts and Springs
1) Over-dampening won't hurt handling, as long as it is evenly over-damped. It will hurt ride quality, but I don't think you are concerned about that. Honestly, SC springs with 1.5 coils cut off are plenty stiff for the chassis. Going too stiff can actually hurt handling because the chassis will flex rather than the suspension, which behaves unpredictably, and if the chassis is stiffened up enough with the cage, the car will start lifting the inside rear wheel in a turn, which means that tire won't have any traction.

1b) Bilsteins aren't made for the front of our cars. The stiffest aftermarket shock you will be able to get is the Tokico's. The Tokico Blues are pretty good, and will be way better than what you have, but if it is in the budget, the Tokico Illumina 2's are meant for the SC with the ARC setup, and if you set them to the firm setting and lock them there, that will be the stiffest bolt-in shock you can get for the front of this car. For the rear though, definitely go with the 03 Cobra Bilsteins.

2) As I said above, I think your front springs are plenty stiff. I suspect your Monroe Sensatracs are beyond shot after running even one race with those springs, let alone several. Keep in mind that when you cut a spring, you increase the stiffness of the spring by the ratio of coils you have now to coils you did have. In other words if a spring has a 400lb/in rating, and 10 coils, and you cut one coil off, that spring now has 444lb/in rate. If you cut 2 coils off that same spring, it is now 500lb/in. This gets a little more complicated for progressive springs, but the concept is the same, so regardless, right now up front you are horribly over-sprung. As for the rear, I think the Eibachs in the back are a weak link for you, and I would look to change them. There are varying degrees of progressiveness of a spring, and the eibachs are very progressive, meaning that they start very soft, and then get very stiff. This is great on a street car because you don't really sacrifice ride quality, but on a race-car, it makes the car less predictable. If possible, I would look for a set of SC springs to match the fronts, and then cut a coil off those. If those are not available, swapping to the suspension techniques springs all the way around should be an improvement.
As far as the shocks/springs go, I know Bilsteins are no longer available as a direct fit item but Paul and some others did come up with alternatives which insert available circle track shocks into the stock strut body.
http://forums.tccoa.com/44-suspension/140125-bilstein-racing-shocks-front-shock-custom-design.html
Bilstein 36mm inserts S7G-5555 aka F4-BE3-C239-H0 (pauls says too tall for lowered car)
Bilstein 36mm inserts S6G-5555 aka F4-BE3-A213-M6

Seeing as I have a blown out strut already available and some time, I prepped it for dropping in a Bilstein insert and I could easily do another one (esp since my driver's side strut is probably also worn out. At $75/ea, this seems a reasonable price for the Bilstein inserts. I know other people have used Koni Race inserts but at $350/pair, they are a bit more than I want to spend (I don't want to get bumped up to A class in the west coast races).
Koni 86111259RACE Road Racing/Autocross Double Adjustable Twin Tube Strut Insert | Autoplicity

Q: How well do you think these Bilsteins would last on the track, Mike? They have the added benefit of being DIY/shitty looking compared to the Tokicos.


In comparison, the Tokico Illumina EU3689 struts seem to run ~$150/ea which seem to be crankable to max stiffness with a Tokico adjuster tool (#TO00102) -- or a screwdriver.

Bottom Line: I really wish I knew someone near me with a shock dyno to tell me how crappy the shocks I have around are.
If I do upgrade the fronts, I'll go will bilsteins for the rear and grime them up.

It doesn't sound like keeping the existing spring setup would be detrimental if I replaced all four struts/springs with stiffer ones.
Q: How bad an idea would it be to replace the rears with Bilsteins shocks and leave the soft Monroe struts up front?

---
As far as the springs are concerned, I'm surprised that you would recommend going with softer SC springs in the rear. Even if the spring rate goes up with a coil being lopped off as you suggest, I'm skeptical that the SC would be any better
SC springs: 509-637 lb./in.
Eibach: 514-714 lb/in


None of my drivers have complained about unpredictability in handling with the progressive springs on the front/rear; it doesn't sound like you'd approve of going linear on the front and progressive in the rear though.

For giggles, we may just run with the ST suspension to see how linear springs on all four corners feels like.
. Curiously enough, they came off a donor 5.0 car owned by a grandpa who drove the car into a tree (broke the header panel that holds the headlights) and they pulled his license.


As for other suggestions, I know you said you are not inclined to change the sway-bar, but running the stock 95 V6 bar, you are basically running the smallest factory bar ever made for these cars. Even stock SC sway bars front and rear would be a huge improvement in this area, as it would keep the car much flatter in the corners, but you have to match the stiffness of the front and rear sway bars. If you go too stiff in the rear without changing the front, it will induce oversteer. If you go the other way, it will induce understeer. I know it sucks having to pull the subframe down to replace the front bar, but I think it will help. If you are dead-set against changing the sway bars, then stiffening up the spring rate can also counter the lack of stiffness in the sway bar, but once again, it will have to be matched front and rear, or you will induce oversteer or understeer depending on whether the front or the rear is stiffer relative to the weight on that wheel.
I did upgrade my swaybars -- the rear is from a 90SC which did seem to help a good deal since it's solid vs tubular. IMO, that helped the car really be neutral in the turns when we had a V6 up front. Now, I feel I have to goose the throttle more to get the car to turn in more quickly on sharp turns and going to a larger front swaybar (from 1.06" solid like I have now to the 1.1" solid bar I have onhand from a 93SC) is only going to induce more understeer.


Another thing that is simple and cheap and will be a huge help with handing is front suspension bracing. A brace across the bottom of the front subframe from near where the LCA mounts to near where the front strut rod bushing mounts, and another brace from the bottom back of the rear subframe to the bottom of the frame rail will do wonders for your handling, and all is costs is some 1" square tubing from Home Depot, and some time with a MIG welder.
Q: Do you have any pics of what those subframe braces might look like?

I took a look at my bushings and yeah, both the front and rear swaybar bushings are rotted out and need to be replaced. I'm skeptical about spending the time/effort to replace my rear LCAs inner bushings.

One easy one to replace would be the diff bushings as they look old but not necessary flattened out/rotted out.
At the same time, I would consider running a bolt through the rear diff brace and reinforcing the diff face so the bracket doesn't crack off the diff cover.
As seen in the last section of this first post
http://www.tccoa.com/forums/44-suspension/145031-recommended-suspension-bushings-mn12s-fn10s.html#post1569994
Q: Any thoughts on the value of stiffening the diff mount on the car?

Also, I know it will hurt the budget, but if you want to be competitive, you need to step it up on the tires. This is a heavy car, and to keep up with those lightweight little Miatas and E30s in the corners, you need a lot of tire. A Mustang hub swap will open your door to tons of cheap 17" wheels.
Yeah, I thought about doing a hub swap and getting two sets of 17" wheels but I just stepped up to 16" rims so I'm not terribly keen on abandoning them just yet. We have two sets of 16" rims in good condition with Direzza SS tires.
I don't anticipate quitting lemons racing anytime in the near future (having a kid hasn't changed my enjoyment of the project -- just the amount of time I can devote to it) so I will probably do a hub/wheel upgrade in conjunction with a 13" Cobra PBR swap upgrade once I decide that I need more braking.
 

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I forgot about the Bilstein insert deal. Yes, that should be a good way to go, since as you said, it will look like crappy old stock parts. For the rears, I made my Bilsteins look like rusted out crap by painting them flat black, then spray them with a light coating of undercoat, then while the undercoat was still tacky I rolled them around in the dirt a bit, and then misted them in random areas with a brown paint. I wish I had pictures of it, but the end result was a shock that looked like it had been in the car for 150K miles, and the judges never even questioned us on it.

For the springs, SC rear springs with one coil cut off will be stiffer than the Eibachs in stock form, and as you see, they are a less progressive spring. The advantage of a progressive spring is to soak up small bumps without transmitting them into the car. The disadvantage is it sacrifices a little bit of grip. If the track you run on is pretty smooth, then linear springs will be better. If the track is rough and bumpy, then progressive springs will help to not upset the car on those parts. With as progressive as they are, the Eibachs are a street spring, not a track spring, that is why I recommended replacing them.

I don't have any pics of the bracing, but if you search Johnny Langton's LECB, that is basically what you want to do, but his were made to be removable, so you can bypass that whole thing and just weld them directly in place, and if for some reason you need to drop the subframe, you will just have to cut them off.

As for the diff bushings, I did eventually wind up making solid ones out of roll bar tubing, not for handling but because my diff cooler pump was mounted to the subframe and driven off the diff flange, so it had to be solid mounted or it would kick the belt off under load. I didn't notice any improvement in handling from the solid mounted diff, probably partly because the subframe itself is rubber mounted. If you want to improve something with solid mounts, I would worry about stiffening up the subframe mounts themselves before worrying about the diff mounts.

Also for the tires, I only ever got one race out of a set of tires, regardless of what size or brand I was running. By the end of one race, they would still have some tread left, but they were definitely losing grip, so every race was another $700 for tires. The handling improvement, and the ability to run the 13" brakes were definitely worth it though.
 

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Discussion Starter #5
I forgot about the Bilstein insert deal. Yes, that should be a good way to go, since as you said, it will look like crappy old stock parts. For the rears, I made my Bilsteins look like rusted out crap by painting them flat black, then spray them with a light coating of undercoat, then while the undercoat was still tacky I rolled them around in the dirt a bit, and then misted them in random areas with a brown paint. I wish I had pictures of it, but the end result was a shock that looked like it had been in the car for 150K miles, and the judges never even questioned us on it.

For the springs, SC rear springs with one coil cut off will be stiffer than the Eibachs in stock form, and as you see, they are a less progressive spring. The advantage of a progressive spring is to soak up small bumps without transmitting them into the car. The disadvantage is it sacrifices a little bit of grip. If the track you run on is pretty smooth, then linear springs will be better. If the track is rough and bumpy, then progressive springs will help to not upset the car on those parts. With as progressive as they are, the Eibachs are a street spring, not a track spring, that is why I recommended replacing them.

I don't have any pics of the bracing, but if you search Johnny Langton's LECB, that is basically what you want to do, but his were made to be removable, so you can bypass that whole thing and just weld them directly in place, and if for some reason you need to drop the subframe, you will just have to cut them off.

As for the diff bushings, I did eventually wind up making solid ones out of roll bar tubing, not for handling but because my diff cooler pump was mounted to the subframe and driven off the diff flange, so it had to be solid mounted or it would kick the belt off under load. I didn't notice any improvement in handling from the solid mounted diff, probably partly because the subframe itself is rubber mounted. If you want to improve something with solid mounts, I would worry about stiffening up the subframe mounts themselves before worrying about the diff mounts.

Also for the tires, I only ever got one race out of a set of tires, regardless of what size or brand I was running. By the end of one race, they would still have some tread left, but they were definitely losing grip, so every race was another $700 for tires. The handling improvement, and the ability to run the 13" brakes were definitely worth it though.
I'll ponder what you said about the springs/shocks, and subframe bracing.
Your comment about tires is another reason why I'm hesistent to move to 17" tires and stuck with 15" tires so long. I think we are still under $500/race for 16" tires now.

I did find another issue last night: it turns out that my rear sway bar on the car was NOT the one I expected to be there. I suspect I must have gotten my "race parts" mixed with my "donor parts" and this probably explains why (I think it was Paul/tbirdtess) got the wrong sized SC when I shipped him one a few years ago.

Bottom Line:
I have a 0.90" or 0.91" rear bar (probably solid) and I believe I need more.
I could go with a 0.94" rear solid bar (from a 93 5.0 car) or find something bigger.

How much bigger do you think I should go, Mike?
-g
 

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If you have a 0.94" bar handy, that would probably be a good place to start. Like I said, you don't want to have a massive rear bar with the stock front bar, or the car will be very tail-happy. That's great for fun on the street, but can get you into trouble on a track. It is hard to say exactly what bar will be optimal for you, because things like spring rates, weight distribution, and tire size or pressure will all also affect how the car handles, and obviously you have drastically changed those things from factory, so you'll have to play with it a bit and see how it performs.
 

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Anything has to be better than the Monroe Sensa-Craps. They made my old 95 float up and down like a boat if I hit a dip in the road. Worst shock ever.

Al
 

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Discussion Starter #8 (Edited)
Summary of front shock insert options
For front strut inserts, I took a look at the few previously mentioned options other people have used to see if there's anything else out there.

Inner Diameter of stock body shock: 1.79" (at least in my Monroe Sensatrac)
Hole in stock shock top mount: 0.5"

Bilstein S7G-5555 aka F4-BE3-C239-H0 - $79/ea or $158/pair

36mm diameter
- 17.25" extended (assuming with the eyebolt you will remove), 11.75" collapsed
- Does NOT need a modified strut top mount
- need to bolt through body of strut assembly. While the spring is holding most of the weight, the bolt going through the cut strut assembly is taking all the force of the dampener) so use a Grade 8. I went with a 1/2"-13 x 2.5" long.
- Slides in (doesn't need press fitting)
- Proven by tbirdtess: http://forums.tccoa.com/44-suspension/140125-bilstein-racing-shocks-front-shock-custom-design.html
- POST TEST UPDATE: Unlike what Paul/tbirdtess suggested, the Bilstein S6G-5555 (#F4-BE3-A213-M6) are IMO too short to use even with a lowered card. I purchased these shocks and found that in order to make them work, I would have to place the bolt ABOVE the bottom most bracket (that mounts the strut to the LCA) instead of 1/2" below the top of the bracket. This would mean that the horizontal 1/2" bolt would only be supported by the thickness of the cut-down strut body vs the thickness of the cut-down strut body AND the brackets.
- I also noticed that removing the nut below the top eye-bolt will require you to hit the nut while holding the shaft with a sheet of rubber or something else non-marring. I can confirm though that the shaft diameter will fit through a stock strut assembly (once this nut is removed).



Bilstein 34-050224 / inserts from 91-99 Mitsubishi 3000GT / ~$131 price matched
- 36mm diameter: 1.41"
- Curiously enough MM says this also needs to be press fit
- Proven by Saturn5/MaddMartigan: http://forums.tccoa.com/44-suspension/145139-so-i-wanted-coil-overs-front.html
- Much beefier shaft and larger volume than the circle track shocks above.
- Good feedback from a guy with an S14 that autocrosses and has blown KONIs up multiple times already: http://www.nissanroadracing.com/showpost.php?p=84466&postcount=435
- NOTE: REQUIRES an enlarged top mount (5/8" hole vs 0.5" hole in stock top mount).

KONI 8611-1259RACE - $340/pair
- Double adjustable (Rebound on top, compression on bottom)
- 6.02 in. stroke, 13.07 in. body length
- Bolts straight to bottom of cut strut assembly (may require press fitting)
- CON: Will also require you to enlarge the shock top mount to 5/8" (insert a new 5/8" tube welded to a top mount washer)
- Not sure if an insert is needed to get it at the right height and how that will interfere with the bolting
- Also feedback from this autocrosser with an S14 nissan makes me wonder if they will last (S14 = 2700LB vs MN12 = ~3600LB)
http://www.nissanroadracing.com/showpost.php?p=84466&postcount=435

I found a another KONI with identical dimensions to the KONI above: KONI 8610-1437RACE - $240/pair
- Single adjustable (rebound on top)
- 1.71" diameter (press fit and bolt on bottom)
- 6.02 in. stroke, 13.07 in. body length
- Bolts straight to bottom of cut strut assembly (may require press fitting)
- Not sure if an insert is needed to get it at the right height


Bottom Line:
Since i don't care about adjustability, and the price is right, I'm leaning towards the Bilstein inserts that Paul used. Also, since it's not press fit, I could return them if needed.
 

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Discussion Starter #9
I installed new front and rear swaybar bushings and found they went in without any fuss. In the process though, I found some more issues I needed to address.

1) I think I realized why the car was understeering a bit on turn in: check out the top part of our rear swaybar endlink. Where there should have been a bushing these was just a big round ring with a bolt through it. Sure, the swaybar would eventually start transferring force from the inside wheel to the outside wheel but not until the bolt was pushed up against the ring. That' s no good. I replaced these with used spares but should probably buy two more endlinks in my next order.

2) I also found the rear outside driver's side pad was worn down (but not any of the other 3 pads in the rear). I'll replace them all as a set.

3) I'm a little concerned about the condition of my inner LCA bushings. Will some of you care to give me your opinion on their condition? If I need to replace them, I will (it's just work).

Regards,
-g
 

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Discussion Starter #10
Mike:
I took a look at SCP's braces and where they are installed and realized I can make this with square tubing as you have suggested.
4 x 16" square tubing.

I also realized i had some heavy duty 3/4" square tubing (seems thicker than normal stuff) in my scrap pile from one of the shopping cart donors.

Q: Do you think this stuff will be rigid enough? I have just enough to make each segment and could always add reinforcing bars later(like an additional bar or rod welded inside the tubes.

Q: How thick a plate should I be looking at for the ends? 1/8", 3/16?, 1/4"?
I suspect I could make all four plates with a 1'x1' or maybe 1'x2' max sheet?

-g
 

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3/16 Tubing and plates should be strong enough. But you'll need a cutting torch tip or a steel cutting table machine to cut it. I was thinking about doing this for my 89 Bird after I saw floor rust and cracks near rear shock tower. But my car runs fine the way it is and I was told it doesnt do much to help so I didnt try it. After driving my SC a bit I can feel a huge difference from the better sway bars, or maybe its the cut springs that gives it better handling.
 

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The plates at the end are only required if you want to make it removable. My thought was that if I needed to drop the subframe or the steering rack for any reason, it would be easier to just sawzall through the bars and re-weld them before the next race, so I welded the bars directly to the subframe and the lower rail. If you do want to use the plates though, I would suggest 3/16" plate. As far as what bar to use, I used 1" square tubing I bought at Home Depot, but it wasn't a very thick wall. The stresses on the tubing will mostly be tensile and compression forces, so very thick walls is not necessary. If you have the heavy duty 3/4" tubing already, I would go ahead and use it. The only concern with that is you said it came from a shopping cart, which are usually galvanized, so if they are, make sure to use a respirator when you are welding them since the burning galvanized coating creates some kind of poison gas.
 
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Discussion Starter #13
The plates at the end are only required if you want to make it removable. My thought was that if I needed to drop the subframe or the steering rack for any reason, it would be easier to just sawzall through the bars and re-weld them before the next race, so I welded the bars directly to the subframe and the lower rail. If you do want to use the plates though, I would suggest 3/16" plate. As far as what bar to use, I used 1" square tubing I bought at Home Depot, but it wasn't a very thick wall. The stresses on the tubing will mostly be tensile and compression forces, so very thick walls is not necessary. If you have the heavy duty 3/4" tubing already, I would go ahead and use it. The only concern with that is you said it came from a shopping cart, which are usually galvanized, so if they are, make sure to use a respirator when you are welding them since the burning galvanized coating creates some kind of poison gas.
I like the idea of making things removable. I visited my local steel shop and bought a decent sheet of 3/16" steel cut into six small sections with their metal shear for <$20. 1" square tube only cost $4 more so bought it as well.
 

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Bilstein 34-050224 / inserts from 91-99 Mitsubishi 3000GT
- 36mm diameter: 1.41"
- Curiously enough MM says this also needs to be press fit
- Proven by Saturn5/MaddMartigan: http://forums.tccoa.com/44-suspension/145139-so-i-wanted-coil-overs-front.html
- REQUIRES an enlarged top mount (5/8" hole vs 0.5" hole in stock top mount).
OK, so one of them had to be press fit. In hind sight, the reason for that is that I used a tubing cutter to get an even cut but the process left a "lip" on the inside of the old shock that I had no easy way to removed. If you don't have that they I suspect that you won't need a press. Also keep in mind that you'll need to press them to get the bottom bolt to protrude through. It would be cool to cut out the bottom completely and weld in a new bottom that conforms better but it's not really necessary.

The top mount wasn't all that big of a deal and if I had more fabrication skills the fancy top mounts I've seen for other cars would be the way to go. I'll cross that bridge if I have to.

Good luck with this.
 

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... the fancy top mounts I've seen for other cars would be the way to go.
Which mounts would you use as a base?

The double adjustable konis also require a large opening in the mount... :)

What I really want is a remote-reservoir double-adjustable shock, with ******* bluetooth adjustability I can run from the steering wheel.
But I digress from the original question. :)
 

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Discussion Starter #17
I was thinking something like this:
Silly question but do these porsche top mounts have the same positioning for the triangular holes in our front strut tower?

Also, back to the braces I just bought metal to fabricate:
Q: If I were to make them removable, is there any reason why I would make them in two pieces per side instead of one piece per side with THREE mount mounts (on tab welded to frame rail, underneath LCA attachment point, and finally underneath LCA strut support bar attachment point)? I can just use one sheet metal square for the plate underneath the LCA attachment point instead of fabricating two sheet metal tabs that will use the same bolt hole.

I can easily bolt a 3/8" grade 8 bolt underneath the LCA attachment point. Dince I have to enlarge the existing hole underneath the LCA strut support bar attachment point, I might as well go to 3/8")
 

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Silly question but do these porsche top mounts have the same positioning for the triangular holes in our front strut tower?
To be honest, I have no idea. I just Googled what I was talking about and this is one of the ones I found. I'm really more focused on the center mounting point in that design as well as the plate style than I am the specifics of it. Those seem to cost about $600 a pair so I wouldn't be interested in those anyway.

Also, back to the braces I just bought metal to fabricate:
Q: If I were to make them removable, is there any reason why I would make them in two pieces per side instead of one piece per side with THREE mount mounts (on tab welded to frame rail, underneath LCA attachment point, and finally underneath LCA strut support bar attachment point)? I can just use one sheet metal square for the plate underneath the LCA attachment point instead of fabricating two sheet metal tabs that will use the same bolt hole.
It took me a minute to understand what you meant. My opinion is that yes, you can do that. In fact, that's my plan exactly. I already made the bars under the K member, I just need to make the ones that attach the K member to the frame rails.

I can easily bolt a 3/8" grade 8 bolt underneath the LCA attachment point. Dince I have to enlarge the existing hole underneath the LCA strut support bar attachment point, I might as well go to 3/8")
I used 1/2" bolts. :wink2:
 

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If the are being held on by mounting tabs, I see no reason you can't make them one piece. I would just try to weld as much of it as you can with everything bolted to the car so it doesn't warp.
 

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If the are being held on by mounting tabs, I see no reason you can't make them one piece. I would just try to weld as much of it as you can with everything bolted to the car so it doesn't warp.
I agree with that. I just had my K member off the car when I made the front braces. The base principle in my design was that I was strengthening the front to rear mount points of the LCA with the first braces and then I will tie the K member to the frame rails with the second braces. The rear bolts of the front braces will be common with the front bolt of the rear braces under the front. It should tie everything together pretty nice.
 
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