Bad rear end sway

[92TTZ32]

Ok guys, so I'm new to the site, but I need some help solving an issue. I just bought another 92 NA to TT Swapped 300zx. It has full Megan racing fully adjustable suspension with tokico hp Blue struts, new energy suspension bushings (red), 2+2 sway bar in the rear, and just had alignment done yesterday.
Before the alignment, when I got on it, the rear end would slide to one side, and then hook, and the steering wheel would sometimes shake back and forth making me swerve inside the lane and have to let off of it.
Got an alignment done, set everything to factory spec besides the front camber because it was only 1 degree out on both sides. Now, any time I go around a somewhat sharp corner the back end just wants to slide out, and my steering wheel feels like it's being pushed against from the opposite side that I'm turning, and it's causing my front wheels to bump the opposite way in a corner.
If anybody else has run into these problems, and knows any tips or tricks to try, any help is greatly appreciated.

[raremotive]

Only things I am thinking that is causing your car to oversteer is you put a thicker sway bar in the rear. You can either go smaller or put a thicker front sway bar.

Negative Chamber at the front tires also promote oversteer as well.

And third, age of your tires. Anything around 4 years is trash, no matter how good it looks. RIP Paul Walker (9 year old tires).

Also you can lower the pressure of your front tires and raise the pressure of the rear. This helps with oversteer as well.

[92TTZ32]

i was told that the tires were only a year or so old. and after more driving today, i noticed that it really only happens in a curve to the right. the back end will try to slide out, and the front feels kind of like the power steering is trying to push it back to the left, causing it to bump the front wheels left in a right curve.

[raremotive]

For age of your tires check the DOT number:

front feels kind of like the power steering is trying to push it back to the left, causing it to bump the front wheels left in a right curve

Sounds very much like bump steer. Typically says your steering linkage are not following for the arc movement of the tire. I would attempt to fix the driver side to see if it improves. This might help with your rear sliding.

Bump steer is a common symptom for those who lower their car or play with the linkages.

[92TTZ32]

So what would I need to do to the linkage to correct the problem? And the number on the tires is 2711, so the 27th week of 2011. So they're old, but they still have plenty of tread.

[92TTZ32]

Just ordered new Megan racing bump steer correction tie rods from concept z. They'll be in next Thursday, so I'll have them in next weekend.

[92TTZ32]

Since the alignment, the bump steer is really the only issue now. I got on it quite a bit tonight. And it didn't try and break loose like it was before, I just can't drive it like it's meant to be when I come up on a corner lol.

[DCaff300ZX]

The TT Z32 really puts a lot of strain on the rear end when accelerating while turning, with mine I can really feel a difference when the turbos hit the top end as the whole rear shifts right about 2-3 inches sometimes (or feels like it's "bunching up") causing me to modulate the throttle or be oversteering, so I understand your situation as I am lowered as well. I also blame that feeling a lot on my worn rear tires, so I think we both are looking at basically the same things- lowered car geometry and worn rear tires.

[DCaff300ZX]

Double posting is frowned on here as it causes confusion, and doesn't help you as much as a single post in the correct forum such as here.
I will be deleting your post in General, as you should get more help here in addition to what you have gotten already.

[DCaff300ZX]

Re: Bad rear end sway
Postby raremotive » 23 Sep 2016 08:46

Only things I am thinking that is causing your car to oversteer is you put a thicker sway bar in the rear. You can either go smaller or put a thicker front sway bar.

Negative Chamber at the front tires also promote oversteer as well.

And third, age of your tires. Anything around 4 years is trash, no matter how good it looks. RIP Paul Walker (9 year old tires).

Also you can lower the pressure of your front tires and raise the pressure of the rear. This helps with oversteer as well.
All Work, No Play, Make Rare Dull Boy
Check out my blog, RareMotive.com


Re: Bad rear end sway
Postby 92TTZ32 » 23 Sep 2016 10:25

i was told that the tires were only a year or so old. and after more driving today, i noticed that it really only happens in a curve to the right. the back end will try to slide out, and the front feels kind of like the power steering is trying to push it back to the left, causing it to bump the front wheels left in a right curve.
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User avatarraremotive
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Re: Bad rear end sway
Postby raremotive » 23 Sep 2016 14:32

For age of your tires check the DOT number:

Image

front feels kind of like the power steering is trying to push it back to the left, causing it to bump the front wheels left in a right curve


Sounds very much like bump steer. Typically says your steering linkage are not following for the arc movement of the tire. I would attempt to fix the driver side to see if it improves. This might help with your rear sliding.

Bump steer is a common symptom for those who lower their car or play with the linkages.
All Work, No Play, Make Rare Dull Boy
Check out my blog, RareMotive.com


Re: Bad rear end sway
Postby 92TTZ32 » 23 Sep 2016 20:47

So what would I need to do to the linkage to correct the problem? And the number on the tires is 2711, so the 27th week of 2011. So they're old, but they still have plenty of tread.
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92TTZ32
Posts: 5
Joined: 23 Sep 2016 03:41
Car: 92 na to TT swapped 300ZX
Contact: Contact 92TTZ32
Re: Bad rear end sway
Postby 92TTZ32 » 23 Sep 2016 21:57

Just ordered new Megan racing bump steer correction tie rods from concept z. They'll be in next Thursday, so I'll have them in next weekend.


Re: Bad rear end sway
Postby 92TTZ32 » 23 Sep 2016 21:59

Since the alignment, the bump steer is really the only issue now. I got on it quite a bit tonight. And it didn't try and break loose like it was before, I just can't drive it like it's meant to be when I come up on a corner lol.


Re: Bad rear end sway
Postby DCaff300ZX » 24 Sep 2016 10:37

The TT Z32 really puts a lot of strain on the rear end when accelerating while turning, with mine I can really feel a difference when the turbos hit the top end as the whole rear shifts right about 2-3 inches sometimes (or feels like it's "bunching up") causing me to modulate the throttle or be oversteering, so I understand your situation as I am lowered as well. I also blame that feeling a lot on my worn rear tires, so I think we both are looking at basically the same things- lowered car geometry and worn rear tires.
Image

upgrading-my-tt-running-journal-t573379.html

[raremotive]

So what would I need to do to the linkage to correct the problem? And the number on the tires is 2711, so the 27th week of 2011. So they're old, but they still have plenty of tread.

Doesn't matter if they have plenty of thread. The composition of the tires break down. I would advise you to be careful in hard cornering or braking.

[92TTZ32]

i apologize for the double post, just wanted more people to see. i appreciate all the input, and advice. and mine does the same when i get on it, the rear end slide about a couple inches or so to one side, then hooks, and in the middle of a shift it will also kinda kick out, but the worst part is when i get up to about 110 mph or so in a pull, the steering wheel shakes back and forth, and causes the front wheels to shake, and i have to take corners at roughly 60 mph or lower, or else i almost have to switch lanes to keep the rear end from sliding out. tie rods are already ordered, so new tires, and a thicker front sway bar will be my next attempt to fix.

[92TTZ32]

what really confuses me though is that my first one was an n/a automatic, and i put just lowering springs on it, and it handled like a dream, and was lower than the one im having problems with. and every bit of suspension on the TT is megan racing, and fully adjustable, so it should handle like its on rails.

[raremotive]

Something doesn't seem right if your steering is shaking at high speed. Should dial in your alignment again. You replace your tension rod too? How is the wheel balance? Bad/old tires are also known to fall out of balance too.

[raremotive]

Since you practically replaced the entire suspension and bushings. Probably doesn't hurt to do a once over all bolts and hardware in the suspension to make sure nothing is loose. =)

[92TTZ32]

I've had the alignment done twice in the last week. Everything is set to factory spec except camber in the front. Both front wheels have 1 degree of camber, but other than that, everything else is perfect. And yes, I'm running Megan racing tension rods as well.
New bump steer tie rods are being delivered today, then I'm going to get another alignment, and as soon as I can afford a new set of tires, that will be next.

[evildky]

Set your rear shocks to full soft, put lower spring rates in the rear.

[DCaff300ZX]

Set your rear shocks to full soft, put lower spring rates in the rear.

Hmmm, that's a good call...I'm gonna try adjusting the rears less on mine and see what that does, thanks for sharing!

[92TTZ32]

I have the tokico hp blues, so unfortunately, that's the one thing that I can't adjust

[evildky]

I say "megan racing fully adjustable" and just assumed it was adjustable. so basically you have adjustable spring perches and that it right? what spring rates came wiht the kit? did you put the stiffer spring up front?

[92TTZ32]

I actually bought the car the way it sits. It has Megan racing springs, camber kits, upper and lower control arms, tie rods, tension rods, toe rods, rear traction rods, and the 2+2 sway bar in the rear.

[92TTZ32]

Everything is adjustable besides the struts, they're tokico hp blues, which are really good struts, I've used them on multiple cars, and never had a problem out of them.

[raremotive]

Seems the megans racing springs are 5.5 F and 4.5 R .. (kgf/mm) which is twice as much as factory. But not stiff like Swift springs (7F,5R)

[evildky]

Z32 uses shocks not struts, They terms get used in exchange with one another but there is a difference. My point was as I've seen on many older Z cars is when someone doesn't know what they are doing they often put the stiffer springs in the rear, i guess they think it's a truck? anyway, if they put the stiffer springs in the back that would make the car tail happy. Adding a stiffer rear bar without a stiffer front bar again makes the car more tail happy. You said you alignment checks out so how about the subframe bushings? if they go the whole rear subframe moves around making, you guessed it, tail happy.

[92TTZ32]

subframe bushings are all good too. i checked every single bushing under the car for play both times that it was on the alignment rack, and everything is super tight underneath. im gonna say that more than likely its probably a mix between old tires, and a thinner sway bar in the front. because all the suspension parts look fairly new, and everything is adjusted correctly, and all bushings are tight.