Front Suspension Mystery

[AhmadG]

I just spent sh*tloads of money replacing things. I bought Bing's TC rods, a Nismo subframe brace, and when I had them installed, I got the rusty rad support stiffened up with sheetmetal so everything in the front end was solid for mounting the brace.

It greatly improved turn-in and the car is smoother over bumps and all that , very noticeable difference, but the main reason I got these parts was because I suspected that it would fix my unstable braking. Worn TC rods are famous for causing front suspension play under braking, so I was sure that was it. This did improve the condition, but it still remains.

When I brake, the wheel gets turned clockwise about 10-30° depending on how hard I'm braking, and the car pulls to the left, the opposite direction to where it should go considering a clockwise steering wheel movment. It feels as if there is a bushing or something with play that "compresses" or moves after a certain amount of braking force is transmitted to the front suspension.

I have is a leaking tie rod boot on the driver's side of the steering rack. My mechanic is pretty sure I have a bad steering rack and that is the cause, judging from the ATF filled boot on the driver's side.

There is a wrong bolt holding the driver's side of the steering rack to the crossmember (where the bushing clamps), it allows about 1cm of potential movement for the steering rack, because only half of the bolt is threaded, and the rack is not clamped tightly in the bushing on that side. I will get this bolt changed asap. I'm thinking that the 1cm of play could cause the steering rack to move under enough braking force and cause the symptoms I described.

We were going to put several washers in the non-threaded area, but the washer's were too small in diameter to fit over the bolt.

Another thing that could cause the symptoms I described is a bad wheel bearing on one side, with huge axial play. I do get some noticeable humming noise that is speed related. It could also be bad tie rod ends......but I will check again after putting washers in that incorrect bolt.

When I'm turning hard, I also notice this "compression" happen somewhere in the front suspension, and the car wants to wander into a different lane. This "compression" is triggered after a certain amount of force, if I don't reach that amount it will not change the suspension geometry, after that magical point it will increase linearly with force, and then come to a point where it settles, and more force will not cause more play. As I back off the brakes, it feels like the front end of the car realigns itself, and the steering wheel goes back go center...........same with when I decrease the sharpness of a turn, it goes back to normal.

This is the best way I can describe this, lol, sorry for the huuuuuge post.

Any insight on this weird issue would be appreciated. Thanks.

[Eddiemac]

I would bring everything you mentioned back to OEM specs. Inspect the inner and outer tie rods and rack, replace the bad boots, and definately get the rack stable. The tie rods can be an issue, but the movement in the rack should be first in line. Fix those things and that will probably solve your problem. Even if it doesnt, your car will still be more stable than before. Good luck.

[liquid_cool]

one thing to look at above all others..........LCA's...Lower Controll Arms...

#1.) they are attached to the crossmember by a brass or steel bushing with rubber around it and a throu bolt....its oem rubber and probly 20 years old ..lol..#2.) on the spindle side..there attached by a BallJoint...after 20 odd years..those become worn out..you can even excellerate the condition by lowering the car improperly by cut springs and blown shocks...

if ither side of the LCA goes bye bye..your in deep *%[email protected] steering rack may have play..but thats fixable with a trip down to a hardware store and a replacement bolt/with locktight...if your lca's go out..you will be stranded with your oilpan on the ground and probly some serious damage..if not a major accident....

to help you...help us by posting up some pics of the front suspention and braking gear..with the wheels off..so us niccoheads can get a good look at what ya have going on..try to get close ups of the balljoints..and bushings..allso that steering rack too..what ever you think we need to see..post here...that will help alot.

[AhmadG]

I bought an OEM bolt for the steering rack, tightened it up to the best of my ability. The steering feels so much more direct now. The braking issue is however still apparent. When I get some time, I'll jack up the car again and take some pics.

I also purchased new inner and outer tie rods for when I do my next alignment. Above, the control arm is mentioned: the day after I had my spherical TC rods installed, I jacked up the car for an inspection, and the 2 nuts under the bolts attached to the FLCA were loose, so I tightened them up. When the TC rod was disconnected, I could move the control arm back and forth, and the bolt holdng it to the crossmember had visible movement (the bushing area). When the TC rod is bolted up tightly, there is no movement or clunking.

I tried to find a bad wheel bearing or any sort of play, there is none at the front. At the back, ZOMG my hicas is failing me, I can wiggle the wheels on both sides, and the tie rod just pushes into the rear steering rack, independently, this is why the back of the car feels so "mushy" and wobbly.

I also figured out the clunking sound that comes from engaging the clutch or on deceleration, my VLSD seems to have a lot more backlash than it should. Moving the wheels, the axles turn a bit, then a clunk is heard, which engages the transmission's output shaft, the same amount of play on both wheels, so I can conclude the play is in the diff.

I am very frustrated with this car, and I have a few days before I go off to university and my dad is going to be driving this car in the meantime. This is why I'm on such a pursuit to fix these things.

[the converted]

I'm going to assume that you set the caster properly after you installed the tension rods? Other than that, jack it up and start yanking on everything under there to see what is loose and needs to be fixed up.