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Discussion Starter #1
I've been throwing parts at this issue for quite a while now and I'm getting sick of it.

When I hit the brakes, particularly at 50mph and up, but also at low speeds, the car immediately jerks violently to the right and the steering wheel turns by itself while this happens. It pulls hard enough that it will go off the road onto the shoulder if you're not holding on - it actually saved me from hitting a deer once when I slammed on the brakes - a Lincoln safety feature I guess LOL.

If I'm braking for more than a second or two the car will brake straight, but then when I release the brakes it pulls left.

I've had two mechanics look at it and an alignment shop, both of which I have been happy with their work. They both found nothing wrong - they did check the ball joints the proper way (jack up the lca and use a 2x4 to pry on the tire).

So far I've replaced the following:

Driver's side UCA and LCA;

Strut Rod Bushings at both LCA's (front strut rod bushings are solid and the wheel does not move when rocked with my foot and when watching the car brake).

Both rear calipers (one started leaking so I did it anyways);

Left front caliper and hose (alignment tech said he's seen that before and said it was probably a restrictive hose or sticking front left caliper).

Swapped pads from left to right to see if one is contaminated - no change;

Rotated tires left to right to see if there was a bad belt.

Bled the brakes numerous times just in case.

Otherwise the car drives beautifully. It tracks so straight on the highway that I can let the wheel go and it will stay straight.

If I downshift to 2nd on the highway (bad for the tranny I know) the car does nosedive a bit but stays straight on decel.

If I hit the e-brake on the highway it brakes straight.

WTF am I missing here? I'm going crazy trying to figure out why it won't brake straight
 

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Not to doubt your mechanic's ability, but that sounds exactly like worn out strut rod bushings. Did you replace the bushings to the subframe too, or just the ones at the control arm?
 

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Discussion Starter #3
Not to doubt your mechanic's ability, but that sounds exactly like worn out strut rod bushings. Did you replace the bushings to the subframe too, or just the ones at the control arm?
Strut rod at arms only. The frame side aren't cracked and are tight. When I had the LCA's off I reefed on the strut rod and there was zero movement back and forth at the frame side.
 

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Discussion Starter #5
Have someone move the car in the parking lot on and off the brakes while you watch the wheel in the wheel well. I think you'll be surprised.
Thanks, I'll try looking at it again. It's just weird because the strut rod bushings on my 96 tbird were totally shot, cracked and everything, but it never pulled under braking and yet the Mark's are in great shape.

What are the chances it could be the master cylinder? I've heard someone mention that because of the split circuits, but it just seems farfetched.
 

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Discussion Starter #6
Update: Upon a closer inspection and prying with a bigger prybar, I managed to find a slight bit of play in my passenger side uca and inner tie rod end.

Obviously I'll replace them, but could they cause the pulling under braking I'm describing?
 

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Possibly, but I'm still thinking strut rod bushings. The UCA is more there to keep the top of the wheel from falling in, and does not carry much load. When it moves, there will be very slight changes to caster and camber, but likely not enough to cause a pull. A loose inner tie rod will directly affect the toe, which would definitely could cause a pull, but it would be more dependent on steering input, not braking, since hitting the brakes wants to move the wheel forward or backward in the wheel well, not make it want to turn left or right. When the strut rod bushings are shot however, the wheel moves back in the wheel well drastically. This simultaneously makes a large change in the caster angle, as well as toe because when it pulls back, the tie rod is still connected so it turns the spindle slightly.
 

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Hard to say but I'll throw out this ancedotal experience.

I chased a "loose front end" for a long time. I had one of my Mark VIII's in the garage many times looking for physical 'play' in any of the bushings to no avail. After finally observing the front wheel(s) floating back/forth in the wheel well when an assistant moved the vehicle back and forth in the driveway pumping the brakes, I decided to R&R the strut rod bushings.

Not having the proper tools, I could not loosen the nut on the strut rod. So I bit the bullet and sent it to a local shop for repairs. Besides replacing the strut rod bushings the shop found one LCA suspect and the opposite side UCA as well. I had both sides, upper and lower replaced, basically rebuilding the entire front suspension.

After the obligatory alignment, the shop owner and I went for a test ride and the car drove literally like it was on rails, even under extreme braking.

I only surmise the previous multiple attempts to find play in any front end component could not replicate the forces on the front end components when under braking. Further, if you think how the front end components complement each other, a beginning failure in one component serves to amplify the stresses in any adjacent component causing a domino effect and a change in the front end geometry, particularly when braking.
 

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Discussion Starter #9
Makes sense. I guess I'll have to drop the LCA's and replace the front srb's and get it aligned for a third time this month :rolleyes:

I do have the OEM bushings sitting in my garage, which were actually cheaper at the dealer than Moog bushings. Weird.

Considering the car's 22 years old do you think the strut rod sleeves are going to be seized on the rod?

They're discontinued so does that mean I'm SOL and have to go w/aftermarket bushings if the sleeves are seized on?
 

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Good news - there's a guy who makes stainless ferrules for these! His name's Jay Richmond, and he's here as 98Mark8LSC - but is quicker found on Facebook and Lincolns vs Cadillacs ( http://www.lincolnvscadillac.com/ ) . I'd recommend Facebook myself.

Bad news - one of the rubber bushings has been discontinued from Ford, there's info in the bushing part number sticky.

Good news - there's still SOME stock last I heard out there.

But yes, it looks like we're going to have to bite the bullet and go for the "thermoplastic" crap. Which means you'll have to stick with the high end parts.

There's a thread here on the proper order to assemble the Moog parts - which isn't obvious from the parts! - and the pic is here: http://forums.tccoa.com/showpost.php?p=1503752&postcount=18

RwP
 

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Discussion Starter #11
So today I had my assistant (SWMBO) drive the car and brake hard repeatedly while I ran along side - guess what... both front wheels shift to the back of the car on hard braking, so I guess off to do the strut rod bushings I go!

Someone please educate me but wouldn't bad strut rod bushings cause the wheel to move forward on braking? I thought they mostly kept rearward tension on the LCA?

Man these cars are picky
 

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96BeaterBird - consider the physics.

When you apply the brakes, the wheels slow down. However, the body itself does not, until all the slack is taken out of the linkages.

So - the tires move back, the body moves forward on braking.

That's just basic physics, man.

RwP
 

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Discussion Starter #13
96BeaterBird - consider the physics.

When you apply the brakes, the wheels slow down. However, the body itself does not, until all the slack is taken out of the linkages.

So - the tires move back, the body moves forward on braking.

That's just basic physics, man.

RwP
Thanks for the lesson lol. I never thought it was an srb issue just because of the way it pulled violently under braking and how it drives so well at all other times.

In my mind I always pictured the LCA's being pushed forward under braking, I guess due to the caster angle (lca in front of the uca) it just seemed to make sense that the lca would be pushed forward.

Now I'm tempted to ride on the hood of the car and see how far back the wheel really goes :D
 

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The thing about why it pulls is that it alters the geometry of the tie rods vis the pivot angle, thereby ... steering the car.

For instance, as the wheel moves back, the tie rod is the same length (relatively) to the center of the car, so it pulls the front of the tire inwards (Inwards if in front - outwards if the tie rod is behind the spindle pivot line. I'd have to look,but I remember it being in front.)

That's why it steers so violently when you brake hard.

RwP
 

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Discussion Starter #15
It all makes sense now, but man do I feel dumb for starting ANOTHER srb thread :zbash:

Since it's supposed to be minus 20 here tomorrow and I'm getting kind of tired of wrenching on this car, I'm gonna drop it at a shop and let them deal with it.

The owner's pretty familiar with the ferrules and said he might even have extras laying around somewhere if they don't come off :thumbsup:

Now let's hope this actually is the issue! lol
 

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strut rod bushings aint no joke, I had one completely fail on my red 90 while I was making a loop from I-55 to I-12, I was doing about 70 when the front passenger wheel actually locked and I did a 360 down the enbankment off the side of the interstate, when the car finally stopped spinning I was just feet away from the tree line

thank god the stock locker wasnt burnt up in the rear dif, it had rained the day before and it was soo sloppy that with both wheels spinning my car was still sliding backwards down the hill while i was trying to get back on the interstate

I have yet to see a supercoupe with good strut rod bushings, all 9 of mine are shot
 

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Discussion Starter #17
strut rod bushings aint no joke, I had one completely fail on my red 90 while I was making a loop from I-55 to I-12, I was doing about 70 when the front passenger wheel actually locked and I did a 360 down the enbankment off the side of the interstate, when the car finally stopped spinning I was just feet away from the tree line

thank god the stock locker wasnt burnt up in the rear dif, it had rained the day before and it was soo sloppy that with both wheels spinning my car was still sliding backwards down the hill while i was trying to get back on the interstate

I have yet to see a supercoupe with good strut rod bushings, all 9 of mine are shot
:eek: Were those factory bushings or thermoplastic?
 

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Discussion Starter #18
Dammit! Just has the SRB's done and it still pulls!! It's a bit more manageable now though. The ferrules came out intact luckily, a bit rusty.

The pull's really similar, but if I hold onto the wheel I can keep it straight, so that's a plus.

So... where do I look now?
 

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Discussion Starter #20
Strange... I went back and read the original post and come away with a question... you replaced one front caliper?

Short of that, I can only suspect improper brake balance which means master cylinder maybe?
Yes, I replaced the left front caliper and flex hose. They both seemed fine, but they were cheap enough, I figured I should try it.

Both wheels rotate freely. I've taken measurements with an IR temp gun and the front wheels are within a few degrees of each other after some hard braking.

So how can I test the master cylinder? Or is there a way?
 
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