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All:
While I've been busy with my new kid, I've finally gotten a chance to work on my tbird again to prep it for my next 24 Hours of Lemons race. Missing socket in the engine aside (I'll find it eventually even if I have to pull the stupid engine again), I'm trying to diagnose a handling issue.

It's hard to describe because we were only on the track for 18 laps last March (our last race) before alternator charging & cooling issues pulled us in but it seemed like my back end was quite loose and wanting to step out esp on left handed sweeping turns.

I'm 90% sure it's because something was wrong with my front right suspension. The other alternative cause would be because I had stupidly gone to a larger diameter tire when we stepped up to 16" wheels (225/50-R16s have a 4.43" sidewall compared to the 4.04" of our 205/50-R15 tires). We'll fix this with a credit card but back to my original questions.. which are in regards to the strut assembly I just pulled off my car.


The current plan is to replace the strut with an new one of identical make/model (Monroe Sensatrac - dont' laugh -- it's lemons). I also bought a new upper mount.

Q: What's going on with my upper mount?
Please see the first pic -- did the spring just get knocked off the mount or am I missing something here?

In Pic 2, I found that the metal tube and rubber mount that sits in the center popped right off. Is this normal or further indication that I need to toss this mount into the rubbish bin.
I'm pretty sure these are the original 1995 upper mounts that came with the car. That doesn't happen on my two "race spares" that I pulled off the 1993 Tbirds I scrapped, but it could be a design difference from the early to late MN12s.

In pic 3, you can see some tears that are absolutely a good reason to toss the mount.

As far as the old strut is concerned, it's only got a few hundred miles but those miles have been very, very hard on the car (2 full lemons races plus 3 track days plus 30 some laps in two crappy races). I'm not surprised if the strut is blown because there were some unexpected offroad trips that slammed this end of the car down hard -- one even caused the grease fitting in the upper control arm to punch a new hole in the top of the shock tower. FWIW, the strut itself still seems to rebound BUT you can smell some oil on the shaft and there seems some residue at the top of the shock body. Bottom Line: it's getting replaced.

FINALLY, I'm trying to understand if there are any other bits I might be missing on my front shock assembly -- and maybe need to beg Dan for :)

From top to bottom, here's what I currently have to reinstall:
1) Nut that screws onto the shaft.
2) 1-2" small Metal plate that distributes the spring's tension on the nut.
3) Rubber Upper Mount with this small metal shaft inside. This upper mount has 3 bolts that bot into my car's body.
4) Plastic cup that protects (maybe -- not sure what it exactly does) the upper part of the shock.
4) Spring (SC spring with one coil cut off - again lemons budget took precedence over what you'd do in a quality DD build).
5) Strut body

Q: I seem to recall a small rubber block that probably sat on the shaft of the strut underneath the cup item. It's not there now. Do I need it?

Thanks in advance for your advice here and best wishes to all of you for the New Years...
 

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S4gunn said:
Q: What's going on with my upper mount?
Please see the first pic -- did the spring just get knocked off the mount or am I missing something here?
Judging by the amount of dry rot I see on the bottom of the mount..I would say it's time to replace it..
S4gunn said:
In Pic 2, I found that the metal tube and rubber mount that sits in the center popped right off. Is this normal or further indication that I need to toss this mount into the rubbish bin.
That is an original Motorcraft upper mount you have pictured there..
They were designed differently than what's available aftermarket..

The aftermarket upper mount has a metal bushing that has been bonded to rubber in the center of the mount..

The original Motorcraft mount has a removable metal sleeve, and rubber bushings (which were not serviced separately)..

I would toss that upper mount out if I were you..
S4gunn said:
4) Plastic cup that protects (maybe -- not sure what it exactly does) the upper part of the shock.
That's just a dust shield..
S4gunn said:
Q: I seem to recall a small rubber block that probably sat on the shaft of the strut underneath the cup item. It's not there now. Do I need it?
That's a bump stop..It would probably be a good idea to keep that there.. ;)





Rayo..
 

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Yeah, that strut mount is done! As far as the mount sitting at an angle, that is due to the cut spring. Originally, the spring would have had a flat coil on the top. If you cut that coil off, then it won't sit right no matter what, but once it is installed in the car, the weight of the car will settle it out, so it won't make any difference.

As for the shocks, I strongly suggest some tokico blues since they are available again. Cut SC springs are very stiff, which is great for cornering, but you need a stiff shock to dampen it, and the monroes are just not up to that task. I run the blues in the front, and 03 cobra bilsteins in the rear. When I installed them, to avoid the bs inspection, I took brand new shocks, sprayed them with undercoating, rolled them around in the dirt while it was still tacky, then misted them with some brown paint. The upshot was that they look like 20 year old rusty old factory shocks.

Also for the tires, these are heavy cars and a wider tire really helps. If sticking with the SC 16" wheels, some 245/50/16s will help the car grip better.
 

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I didn't notice it until Mikey mentioned something about the cut spring..Then I took a closer look at your pics..

You have the coil spring installed upside down on the shock..



Still..Due to the condition of that mount I would replace it..







Rayo..
 

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The only thing I would add to the mix is that you need a good bump stop for the shock, especially for the off-road excursions.

Most shocks are done if you bottom them hard. :)


BTW, this mount is the big problem with using better front shocks; the hole in the middle isn't big enough.

As those have a separate sleeve, I'd mod those with some poly material, and use them. :)

I'd keep those bad mounts to use for future modification for Race Konis, or something.
Or I'll buy them off you. :)
 

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Discussion Starter #6
The only thing I would add to the mix is that you need a good bump stop for the shock, especially for the off-road excursions.

Most shocks are done if you bottom them hard. :)


BTW, this mount is the big problem with using better front shocks; the hole in the middle isn't big enough.

As those have a separate sleeve, I'd mod those with some poly material, and use them. :)

I'd keep those bad mounts to use for future modification for Race Konis, or something.
Or I'll buy them off you. :)
1) You're welcome to the bad one if you want it. If you are in no hurry, I'll probably be pulling the left front side off as well and if i replace it, its yours.

I have 4 more from parts cars I plan to keep as race spares so I'm good on spares.

2) I just went through all of my parts and do NOT seem to have any "bump stops".

Q: Do you have an OE or aftermarket part mfg/# for me to order?

I honestly don't know why I tossed it (would have been before my first race).

3) Thanks for the catch on the springs being installed upside down. Again, I blame myself from 4 years ago and will likely fix it on my front left side as well (will check at least).

-g
 

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Yeah, I can wait; those are different than I've seen, and get me closer to the Race Konis. (dream big, right?)

Here's a link to bump stops; IDK what fits, but this is where I always start for odd poly stuff:

energysuspension.com | Bump Stops- Shock and Strut
 

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Discussion Starter #8
BTW - if anyone has an extra pair of used stock bump stops, I'll be happy to take them off your hands as well.
-g
 

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*shrug* That's still where it is on my car.

RwP
 

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My Koni's came with poly ones that are apparently indestructible; the stock ones were gone.

:)
 

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Bump Stops

When you cut the front coil springs..You reduced the amount of travel in the front shocks..

This is where the bump stops come into play..

I'm only going to use these numbers as examples, just so you get it..I don't have exact figures handy..

Let's say for example you cut 2 coils off of the front of the coil springs..
If you started off with 4.3" of shock travel to begin with..Cutting the coil springs might knock that number in half..

So now you have 2.5" to 3" of available shock travel??

Car manufacturers take into account the total suspension package when they install the "bump stops"

What I mean is..With the original stock shocks, and stock coil springs..This allowed 4.3" of shock travel in the front....


This also allowed enough travel in the suspension..
So that the car would not hit the bump stops every time you drive over a bump in the road..

With less shock travel available the car will hit the "bump stops" sooner..

So in order to combat the car from hitting the "bump stops" so soon..The height of the "bump stops" needs to be reduced..
So the car isn't hitting the "bump stops" so soon, or literally riding on them..

You ask yourself "Why do I need bump stops"??

In short, they protect your shocks from bottoming out on themselves (causing them to fail prematurely)
They also work together with the rest of your suspension to provide a balanced suspension..


You need to find aftermarket "bump stops" that fit..I would start with a 1" tall bump stop..Since you already have limited shock travel..
Also it would be best to find a "bump stop" that has around a 1-3/4" OD..That way it fits inside the "Dust Sleeve"

Many manufacturers use a different size rod diameter in the shock..
So, you'll have to measure the piston rod diameter of the shocks you'll be using..
That way you know what ID you need on the "bump stops"

The piston rod diameter of the stock shocks is .63"

I looked, but I couldn't find a part number for the original "bump stops" used on our cars..
In your case, they wouldn't have worked well anyways..

Here's a few pics I took ok my Tokico's, so you could see where the bump stop is supposed to sit:






**With your car lowered as much as it is..
The only way you will really know how tall of " bump stop" to use is..By removing the "Dust Sleeve" from the shock..
Then assemble the spring/shock back together, and install it in the car with the weight of the car on it..
So you can actually see how much room you got in there..







Rayo..
 

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With the Tokico's shock and spring kit, I can't jack from the side anymore, and am now using the k-member, barely. :)

They are nice shocks, barely below the stock sport shocks; but I hate the progression on the springs; you really need to 'set' them into a corner.

The sport springs are better, but need to be cut slightly; I like Earl and CrystalPistol's 1-turn front, 5/8 turn rear solution. (they may or may not have invented it, but they posted pix, lol.)

One thing I hope to figure out in the long term Race-Koni dream I have is to position the shock as to keep as much travel as possible.

You can put an adjustable coil-over seat on the front, shorten the spring, then set the base mounting height of the shock vs. travel of the shock vs ride height to give ~3/4"-1" ground clearance at max compression of the shock. And it's still lowered, with a higher spring rate.
>:)

tbirdtess's bilstein mod would be amenable to this setup, and way cheaper than race konis... :)
 

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Discussion Starter #16
1) According to my notes, I cut 1.5 coils off the front and dropped the car overall approx 1" there. Your estimate Rayo is more conservative but targeting a 1" tall bump stop seems good enough advice.
1.5) My current Sensa Tracs have a shaft diameter of 0.792"

Q: Since the goal is to act as a bump STOP an not something that is supposed to resist the shaft going up and down (thereby causing heat and potentially more issues, how loose a fit do I want here? My thought would be that it should be loose, right? This way, the up/down movement of the shock doesn't heat up and start melting the bump stop and getting grunge on the shaft, right?
Given that this is a track car, I don't care about NVH.


2) These look to be reasonably priced poly bushings (from supercoupe perf -- a place I typically associate with higher pricd but "curated" product).
https://www.supercoupeperformance.com/front-polyurethane-shock-absorber-bump-stops-611

Q: Do yuo folks see any problems with cutting these bump stops down and/or drilling the center hole out?



3) At its smallest, I ran spec miata tires that dropped the car 1.89" vs stock and I never never had an issue jacking my car up. I did run into issues with clearance using a one piece exhaust that Dan traded me but I fixd that a while ago with my own custom 3" piping that was tucked up as far as I could.

New tires (225/45-R16) will only drop the car 1.44" lower than stock so I wont run into any issues here.


4) Longer term, I may try for the bilstein insert route but right now, I really just want to fix the front end so I can race next month.
 

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There's a generic moog part, MOOG-K90462, that has a bump stop and a cover.

For $20. For one side, lol.

Bill has a good price on these; I should probably get some.

I love his site; just wish I had more money for toys. :)

The bump stop usually ends up at the top of the shaft; that way it's not scrubbing the shaft each stroke.
The cover keeps the grit down some; I always put them in.

I would not have a problem cutting it to length, although you want to try to prevent the shock from bottoming out.

I'm not sure I'd "drill" it; it will pick up grit, and sand the shaft if it slips.

I'm not sure a real drill will work, you'll have to check. It might take a core tool. (sharp tube, various sizes; like you use for rubber)

Sharp razor blades will cut poly pretty easy.

I've been jacking from the transmission crossmember/mount area; it does both front and rear at the same time. :)
It's the thickest metal under there...

I can get the floor jack there on all the cars except the tbird with the tokico setup. :)
 

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You want it snug..Where it's not constantly moving up and down..

Here's some bushings that could work as bump stops:

9.8109

•3/4 Inch I.D.
•1 1/4 Inch Min O.D.
•1-3/8 Inch Max O.D.
•1 5/8 Inch Long
•2 Bushings Per Set

They look pretty sturdy compared to the bump stops SCP offers..

All you would have to do is just cut the height of it down..

You might have to open it up some too..Since your Sensa Tracs have a shaft diameter of 0.792"..

The nice thing about these is, you can get them at the parts store..

9.8109G Black
9.8109R Red






Rayo..
 

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Worst case with the bump stops, if they're snug, the car goes down once, it scrubs up, car goes back up, it's still on the piston shaft and rides clear of the piston body ...

So it's not as big a concern as you may thing, S4Gunn. Since once it's ridden up, it's OK.

(Matter of fact, if you want to, you COULD push it up to the top of the shaft before doing the shock/spring assembly ... )

RwP
 

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bind

Hello

You need to get away from this bump stop stuff.

You might have a bind.

I had a bind with the front sway bar & shock mount.
I had to down size the swaybar.
was caused by my front suspension settings.

Shock travel is important. but bump stop is not.
bouncing off of a bump stop feels like you hit something.
like a curb or a rut. that's a huge push!

The upper mount is an issue I am working on.

:zbench:
 
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