Suspension feel

[unluky]

OK - I spent the weekend changing out my RTAB and rear sway bushings and now the car is at the shop being aligned. I will reserve judgment until after the alignment is done, but on the way in the feeling I was trying to fix still seemed to be there.

I have owned this car for 4 years and put 30K on it and this is a new feeling unless it is in my head.

I have added since I had it:

FCAB - powerflex purple
Front sway bushings - powerflex purple
got rid of run flats
H&R springs and Blistein shocks

After all this the car felt tight as a drum and drove perfect to me for years.

Now I have been experiencing a little high speed rear end wander - like driving on a windy day to a slight degree - which is 100% the description of RTAB. Also when you steer left and right quickly at speed (like avoiding a turtle in the road) the car used to feel like it moved as one solid unit, but now it seems (at least in my mind) like the front is dragging the rear a little. kind of like a whip.

Put in RTAB and rear sways this weekend and even they looked good when I took them out. I know there is a ton of other bushings back there, but everything I saw looked good.

Tire pressure is balls on.

Any other usual suspects I should be looking for? Something I am not thinking of?

[Huz-Z]

I'm assuming tires are good with no unusual wear pattern?

[unluky]

yes - brand new ones on the back, but this was there before. The rears were a little worn and the front are better than 2/3 there. Old rear tires were a little feathered, so I got new ones (Michelin pilot sports), replaced the RTAB, sway bushings and just got back from picking it up after a 4 wheel alignment - still exactly the same. Very frustrating.

Like something that connects the front and back, but I can't think what that would be. Veering back in forth in your lane on the hwy shows it the most, the rear just seems to "follow" the front instead of one solid movement like it was before. Just loose feeling for a lack of word. Not so much tilt like springs, but side to side like a whip. When I bounce each corner and not shock/spring bounce is there (tough to tell I know on cars like this) and with just doing it 1.5 years ago and less than 18K on them - I kinda doubt it is them. Also put in new front end links when I was done with the shocks and springs - they were the HD Meyle ones.

Front tires were rotated side to side and air pressure all around is exactly right.

[Huz-Z]

I'd want that fixed too. I'm far from an expert but as the car is at the shop right now, I'd definitely ask the tech there to see if he can spot anything that could be the cause. Is everything tight where it should be, without slop or play? Any toe / camber issues perhaps?

And fingers crossed that the alignment does the trick.

[unluky]

Alignment did not fix it. Got it picked up (AND steering wheel is a shade off center now - that drives me nuts) and same thing. I just can't pinpoint it. Hate to take it to a dealership, but might have to as I just can't find it.

Going on a trip this week, so might wait till I get back and get her in the air one more time and really look the front end over to make sure I did not miss something. I focused on the back more as I was pretty sure it was going to be the RTAB due to age and description of when they go out. They looked perfect though, so I was doubting it after they came out. Little dusty, but I have a long driveway, so that is normal. The whole underside of this car has always impressed me which how clean and well kept it seems to be. Nothing ever fights me.

[gas-can]

I've experience something like this before. It happened when I got a nail in one of the rear tires (maybe a year old). I tried changing just the rear pair and the car was...squirrely. It was really unsettled in turnins (like on a curve on the highway) and the car just felt unstable.

I noticed that the tire place had put one of the tires on backwards (wrong direction). Had them fix it, but the problem persisted.

Got an alignment (like you) - problem persisted.

Finally I replaced the fronts with new tires as well. Problem went away.

Not sure why, but these cars seem to despise having different aged tires in the front and back. I'm thinking rubber hardening/stickiness is the cause, but perhaps something to keep in mind?

-gc

[unluky]

That is very strange. The ones that came off were the exact same tires put on brand new on all 4 corners as the ones up front. The feeling started with them and has continued with everything I have done - including replacing the rear tires.

I may have to try that as nothing else can be found so far. Very strange it went from the most planted and tight car I have ever owned (after I did all the bushing work up front and new tires) to this and suddenly. Almost like something gave way, which is why I suspected the RTAB.

[Huz-Z]

Originally Posted by gas-can

I've experience something like this before. It happened when I got a nail in one of the rear tires (maybe a year old). I tried changing just the rear pair and the car was...squirrely. It was really unsettled in turnins (like on a curve on the highway) and the car just felt unstable.

I noticed that the tire place had put one of the tires on backwards (wrong direction). Had them fix it, but the problem persisted.

Got an alignment (like you) - problem persisted.

Finally I replaced the fronts with new tires as well. Problem went away.

Not sure why, but these cars seem to despise having different aged tires in the front and back. I'm thinking rubber hardening/stickiness is the cause, but perhaps something to keep in mind?

-gc

I recall others here with the same findings.

[gas-can]

Yup, my sentiments exactly.

I changed the rears to the exact same ones as before, just new. The fronts still had a LOT of tread left, hence why I didn't change them. I honestly thought I had broken something the first time I took a turn

m3griff had the same experience. See here http://www.zpost.com/forums/showthre...tires+rear+new

It does suck that you have to change all 4 tires anytime you get a bad nail though

[unluky]

That sounds so insane. I had a 300ZXTT for 13 years and I never replaced the tires at the same time as that beast chewed up tires constantly in the back even when trying not to.

What you are talking about in that thread is exactly what I am experiencing though. I also changed brands of tires. Just weird it was doing it before AND after the rear tire swap. Feels 100% in the rear though.

I have been thinking of going up a size in the front though to fill that wheel more, so maybe now is the time to try it. Hate to replace tires that still have lots of tread left, but be worth it to get my tight handling car back. I just don't 100% trust this car anymore and it was so tight and precise before. I love it.

[DanFromTucson]

Are the tires old (5+ years)? That may be a factor.

[unluky]

no, more like 3 years old maybe? the fronts anyway, rears are brand new of course.

[The HACK]

Subframe bushing.

[unluky]

OK - as crazy as it sounds - I put new treads up front and that did seem to fix the "windy" feeling at high speed. I took it on 2-3 hour long cruises and that feeling seems to have gone away - at least mostly. It may be gone and I am just hyper sensitive to it now that I am tuned into it. It definitely helped a bunch though.

I still feel like the side to side on quick changes is not what it used to be. I just don't trust it like I did - after the shocks and springs and front bushings and getting rid of the run flats it was planted and I would dive in on any corner with confidence. Now I am very hesitant. Might just need to learn to trust it again.

I'll give a bit more and then look into the subframe bushings harder if need be I guess. Everything looks good and clean under there - even the RTAB's that came out and are supposed to be smoked at this mileage looked great and solid.

Anyway - thanks for the tip on the tires - I would have never thought of that in a million years would make that feeling.

Appreciate it.

[ShakyDog]

How many miles on the tires since the change? You may still be wearing off the tire mold release agent. I know my Contis felt terrible for the first 200 to 400 miles. I was thinking I had made a horrible mistake.

Steve

[dre99gsx]

Same boat as you.. practically everything new (bushings, tires, suspension, you name it), and I get that 70mph 'whip' motion, and high speed (very high speed) tail-wandering. It is possible these babies are very sensitive to alignment, but perhaps softer bushings are the way to go for absorbing some of that motion. I upgraded almost everything to poly.

Funny thing - my Supra has the same issues, but it also was upgraded to all poly-type suspension bushings.

You're not the only one!

[unluky]

Tires are not even close to 500 miles yet, so I will let them break in more and see. I do remember when I went to the Conti's they got better with time, but I was coming from the run flats so they were "better" instantly.

Just sucks as the car felt perfect to me for several years until whatever this is started. after the tires, shocks, springs, FCAB's, and sway bushings, it was tight as a drum.

I'll keep looking for sure.

[elerner61]

Originally Posted by ShakyDog

How many miles on the tires since the change? You may still be wearing off the tire mold release agent. I know my Contis felt terrible for the first 200 to 400 miles. I was thinking I had made a horrible mistake.

Steve

+1. You should wait to get past the 500 mile mark before making any other changes.