unstable rear end

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Ryan S
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unstable rear end

Post by Ryan S »

The car's rear end, not my own :lol:

Now, i have pretty stupid tyres, They are 45 profile and 235 wide in a 7inch rim. So it could just be that but when i turn hard(ish) the car feels wobbly at the rear, Like the body and tyres aren't connected. I've not investigated it at all yet but looking for some pointers as to what to look out for. Obviously i'll check the subframe etc but i'm sure i'd here it knocking if it wasn;t bolted on right. I'm currently not running the cross brace due to working on the engine etc but would that make the car feel that way?

Any input appreciated.

Ryan :thumleft:
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Re: unstable rear end

Post by rossonza »

Ryan S wrote:The car's rear end, not my own :lol:

Now, i have pretty stupid tyres, They are 45 profile and 235 wide in a 7inch rim. So it could just be that but when i turn hard(ish) the car feels wobbly at the rear, Like the body and tyres aren't connected. I've not investigated it at all yet but looking for some pointers as to what to look out for. Obviously i'll check the subframe etc but i'm sure i'd here it knocking if it wasn;t bolted on right. I'm currently not running the cross brace due to working on the engine etc but would that make the car feel that way?

Any input appreciated.

Ryan :thumleft:


Just for input. I'm not running my brace and I havnt experienced this.

Have all the bushes been replaced at the rear?
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Ryan S
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Re: unstable rear end

Post by Ryan S »

Yeah I've run without a brace before and not noticed anything. Not replaced the bushes but the longer of the driveshafts was out recently to change the driveshaft bearing. I'm gonna have to give the whole back end a once over.
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Re: unstable rear end

Post by Race Idiot »

If you've still got the 25 year old oem bushings I'd replace all of them.
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Re: unstable rear end

Post by SonicSW20 »

Upgrading the strut braces was noticeable on my t top, so I'd imagine removing them entirely would have an effect as well.

Those tyres are probably contributing to the issue too. 235/45R17 on a 7 inch wheel is outside the recommended fitment range for most manufacturers, you should check your specific brand. Most decent brands publish a technical data book that tells you the minimum / maximum / optimum wheel sizes for a given tyre size.

Continental for example: https://blobs.continental-tires.com/www ... k-data.pdf

As Race Idiot says, check your bushings for play, if they're original they'll be knackered.

Check the rear tie rod bearing too:

Image

This is often overlooked and excessive play here will let the rear wheel "turn" a small amount which will make the rear feel very nervous indeed.
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Re: unstable rear end

Post by Race Idiot »

Yeah if that rear toe-rod is xxxxx then you end up getting variable toe, which will cause 'unstable' handling.

Also aren't you running 9000mm spacers? Might be worth checking yer wheel bearings for play.

I don't think the tyre size is terrible, it's outside the fitment range but not hugely. You might wanna at least think about buying the correct width and offset wheels for that widebody tho :oldtongue:
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Re: unstable rear end

Post by Ryan S »

Haha, Yeah my spacers are rather large but the car handled great on them with 205/40 on the rear. Oddly enough the tie rod on the drivers side was loose a while back and that gave slightly different handling issues. Car would point itself right on acceleration and left on deceleration. I will obviously check them both though. I guess I'll just have to go over everything with a fine tooth comb. Now the car's getting used everything is loosening off and stuff! Having said that it is riding really nice now other than this issue. The tyres I actually ordered in error, I meant to order 235/40s. They rub on bumps etc so I'm gonna just order another pair for the rear but lower profile. Unfortunately i simply cannot afford the correct offset wheels. To fit the kit I'd need wheels around 12 inches wide :(
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Re: unstable rear end

Post by Ryan S »

Race Idiot wrote:If you've still got the 25 year old oem bushings I'd replace all of them.


Checked the bushes recently and they look like they have been replaced. Certainly not the originals thankfully!
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Re: unstable rear end

Post by SonicSW20 »

What tyres are they as well? Something like a Rainsport 3 (notoriously soft) will feel very different to an AD08R for example.

Even a low offset 9inch wheel with a smaller spacer would be a better situation, at least then you can fit a larger tyre like a 255/40R17.
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Re: unstable rear end

Post by Race Idiot »

Are you running 7inch all around with the same size spacers on all 4 corners? Like he said it would be better going with any wider staggered setup with smaller spacers as the suspension wasn't designed around a non square setup anyway.
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Re: unstable rear end

Post by Ryan S »

I have nankang ns2s all round. The wheels are 7 inch all round but it is a staggered setup. Spacers are staggered too as the rear arches are wider. I had michelins on it before and were 205 all round. It tramlined horribly with these on. I don't recall it doing this when i fitted the tyres so i feel like something's broke or come loose.

It's such a strange sensation to explain. Best way to describe it is the wheels not being connected to the body.
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Re: unstable rear end

Post by Race Idiot »

I've had that feeling where the rear definitely doesnt feel planted and kinda rolly compared to the front end. Most of the time it's been the rear toe is way out of spec.
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Re: unstable rear end

Post by Ryan S »

That's something I'll deffo have a look at then, Cheers bud.
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Ryan S
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Re: unstable rear end

Post by Ryan S »

SonicSW20 wrote:What tyres are they as well? Something like a Rainsport 3 (notoriously soft) will feel very different to an AD08R for example.

Even a low offset 9inch wheel with a smaller spacer would be a better situation, at least then you can fit a larger tyre like a 255/40R17.



I wouldn't be surprised if it was those two top bolts in your pic bud. I'm gonna give them a look at tonight if i can.
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Re: unstable rear end

Post by Race Idiot »

When was the last time you had it aligned?
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Re: unstable rear end

Post by Ryan S »

Long ago mate, It is on the to do list!! It's not been aligned since I put the spacers on. The short story is it went for painting 5 year ago, got it back from the painter then basically put it off the road. This is me just getting it all sorted now. So that deffo needs done.
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Re: unstable rear end

Post by SonicSW20 »

Ryan S wrote:Long ago mate, It is on the to do list!! It's not been aligned since I put the spacers on. The short story is it went for painting 5 year ago, got it back from the painter then basically put it off the road. This is me just getting it all sorted now. So that deffo needs done.


Has the subframe been off since then too? If so the rear alignment will be way out.
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Ryan S
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Re: unstable rear end

Post by Ryan S »

Yeah man, subframe's been off twice at least!
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Re: unstable rear end

Post by SonicSW20 »

Ryan S wrote:Yeah man, subframe's been off twice at least!


Alignment for sure is needed then. The subframe is not a perfect fit, the bores are a little larger than the bolts, so when removed its highly unlikely its reinstalled in exactly the same place. It's only a couple mm if that, but it all adds up when you combine that error with unbolting the struts from the hub knuckles which will also affect camber and toe.

Certainly can't make it any worse anyway... I'd just go through and check all your bolts / bushes / bearings first before spending money on an alignment.
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Re: unstable rear end

Post by Ryan S »

Yeah that's the plan I think. Front hubs have been off as well fitting big brake kit haha. I just feel like this symptom is a recent thing. I did quickly jack it up yesterday to feel for any play in the rear wheels and both were fine. But it really needs a proper inspection.
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