Continued bounciness/shaking when braking - long list of things that have not worked

A

anon1000

Member
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United States
2004 Infiniti FX35 RWD with 144k miles. When coming to a red light and feathering the brakes, the car kinda jolts back and forth. Sometimes on HW speeds the steering wheel shakes and sometimes under braking you get similar feedback that you would get from warped rotors. Problem is, the brakes on both axles are ned (rotors/pads), tires are new and road force balanced (Yokohamas) and they have been checked several times. Shocks are new in the rear. Last time the dealer said steering rack needs to be tighten to eliminate the slight shimmy, they overtightened it and it no longer resets properly - no effect on the shaking/swaying under braking.

So, if it is not warped rotors, bad shock, unbalanced tires, loose steering rack - what is left? Infiniti says that the reason is hard compound Yokomaha tires, that I need soft Touring tire. I have always used the Yokos and this problem is about 5k mile old now. They also state that the wheel bearings are fine and all the suspension components are tight.

Anything more to check? Most noticeable right at 40->25mph soft braking.
 
Couple things come to my mind right away. MOTOR mounts! check this first, next inspect ball joint, then inspect caliper pistons. Change tire pressures and lastly check your alignment.
This has happened to me before too (overtightening the rack) pretty much messed up the rack and never worked the same again. I would try the things i listed. If it all doesnt work, it may most likely be related to your rack. Ive gone through this before

---------- Post added at 09:36 AM ---------- Previous post was at 09:35 AM ----------

and sad thing is we have the same model 04 rwd 35
 
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Hard to imagine dealer missing motor mounts. If you want to check that, just look for more than normal movement of engine as you gas it while in park
 
They're missing something. If it's only happening under braking, something is loose. The forces on the suspension under braking are more extreme than acceleration. So pretty much work your way out from the brakes. If it's not a warped rotor or stuck caliper, check the bearings. Then check the bushings, then check the arms, then check the shocks. Blaming the steering rack is sort of a cop out by the dealer since it's a known problem. But the loose steering rack doesn't cause problems, it just magnifies them.
 
also just came to my mind, incorrectly bedding in brakes leads to warpage. The dealer might of not done the bedding right, you can always try to rebed them.

---------- Post added at 03:48 PM ---------- Previous post was at 01:35 PM ----------

did you change the struts up front?? you only said you changed out the rears
 
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