Front end raised up after reversing

[jayvoa]

On Friday I replaced my TCA's and ARB and fitted polybushes up front on my Mk3 Capri. Problem is, when I reverse the front raises up, naturally, but it doesn't settle back down.



The front stays up at this height until I drive forward again. I've driven the car for a couple of hours since fitting the new parts but it still does this. Is this normal and the new polybushes just need to settle in, or is it likely there's a problem? MOT is on Tuesday morning, so I'm hoping it does settle by then!

[Good Scrap]

Tracking is probably a good way out,

[nomad]

A common mistake is to fit and tighten the suspension while the car is jacked up but this preloads the bushes (this is a bad thing )

Best idea is to fit the bushes loosely with the car jacked up but don't tighten anything, then lower the car onto the wheels and bounce on the suspension a few times to let stuff find it's own happy place.
*Then* (without jacking it up) tighten everything and you're good to go play.

Have fun!

[jayvoa]

Jul 27, 2014 22:59:34 GMT nomad said:

A common mistake is to fit and tighten the suspension while the car is jacked up but this preloads the bushes (this is a bad thing )

Best idea is to fit the bushes loosely with the car jacked up but don't tighten anything, then lower the car onto the wheels and bounce on the suspension a few times to let stuff find it's own happy place.
*Then* (without jacking it up) tighten everything and you're good to go play.

Have fun!

Sounds like this could be the issue. Found a how-to guide online that suggested everything be torqued up before dropping the car back down on its wheels.

After work today I'll jack it up, loosen things off, lower it then tighten it all up again.

Cheers!

[Battles]

Jul 27, 2014 22:59:34 GMT nomad said:

A common mistake is to fit and tighten the suspension while the car is jacked up but this preloads the bushes (this is a bad thing )

An old school biker I know did this (maybe still does) when he tours on his seventies Honda with his wife and loads of luggage on the back.
It needed just a fraction more clearance to stop the suspension bottoming out. Modern touring bikes have separate pre-load adjustment on the suspension units.

[welshpug]

given its polybushes it wont be that, just soft springs and tight fresh bushes, which are actuslly acting as a bearing not a bush.

did you grease up the crush tubes before fitting?

[jayvoa]

Greased every bush, tube and bolt, making sure they were all generously coated. Used copper grease, which I guessed was ok?

[jayvoa]

Just having a think about how all the components move... Where the TCA bolts into the crossmember, do the crush tubes stay fixed within the bushes, with the only movement being the arm pivoting on the bolt itself? If this is the case I'll pop the bolts out tonight and make sure they're greased up enough. I've got copper grease and lm2 bearing grease to hand. Anybody advise one over the other?

Once this bolt is greased and back in, I'll loosen off the ARB to TCA nuts, drop it back down and torque it all up when the suspension is all sitting where it's meant to be. Sound about right?

[welshpug]

crush tubes don't move, the poly bush turns on them.

you only need to torque the bolts at rest with bonded rubber bushes, poly acts as a bearing so the first movement of the suspension will sort it.

all you are experiencing is sticktion which is normal with new poly bushes and nothing you can do but drive the dang thing

[rodney]

tracking,.

[nomad]

^
+1 to WelshPug
-1 to Me
( I didn't notice you had fitted Polybushes - you only get the preload problems with bonded bushes Note to self - read twice next time before commenting )

Hope you get it sorted, maybe just run it for a few days and see if the problem goes away...

[barty]

think you will find nomad is right

[RobinJI]

You're both right. It depends on the brand/location/use/stiffness of the bush. Certainly some poly-bushes do rotate around the crush tube, but equally a lot are designed to work as factory bushes do and purely flex without the mating surfaces rotating.

As for the issue the OP's having, I'm going to join the choir with 'Have you checked the tracking?' I'm betting it's toeing in quite a lot.

[jayvoa]

Currently trying to sort out the bits that failed on the MOT yesterday (knackered rear shocks, loose bump stop) but the tester was fine with the fact that it wasn't settling down correctly after reversing. He put it down to the polybushes needing to be settled in as they're brand new.

As soon as the MOT is sorted (if I get the rear shocks delivered in time!) I'll get the tracking checked and sorted. Last time I had it done was at a Kwikfit and the guy seemed a little confused working on an old car, saying he wasn't able to do much with the tracking (they were doing it for free as I was getting new air valves fitted into the wheels).

Could the new parts and stiffer bushes be highlighting a problem with the tracking where the old worn bushes were 'hiding' it?

Thanks for the advice, as always!

[RobinJI]

Fitting the new parts will more than likely have thrown out the tracking because everything won't quite be sat where it used to. Sadly it's pretty much the case with doing any work on the front suspension.

I say it's probably toeing in, because if it is then when you reverse the wheels are trying to tug outwards, away from each other. This will be pulling out on the lower control arm, and trying to pull it out straight, if the car's lowered (which is probably is, with this being retrorides ) then the arms are probably angled up towards the hubs, so pulling them out straight would raise the front end.

[optimusprime]

Jul 29, 2014 21:07:34 GMT RobinJI said:

You're both right. It depends on the brand/location/use/stiffness of the bush. Certainly some poly-bushes do rotate around the crush tube, but equally a lot are designed to work as factory bushes do and purely flex without the mating surfaces rotating.

Seconded.
All depends on where they are fitted,I found that the hard way........

[vitesseefi]

Tracking way out does this.

Nick

[jayvoa]

Jul 30, 2014 16:44:16 GMT RobinJI said:

Fitting the new parts will more than likely have thrown out the tracking because everything won't quite be sat where it used to. Sadly it's pretty much the case with doing any work on the front suspension.

I say it's probably toeing in, because if it is then when you reverse the wheels are trying to tug outwards, away from each other. This will be pulling out on the lower control arm, and trying to pull it out straight, if the car's lowered (which is probably is, with this being retrorides ) then the arms are probably angled up towards the hubs, so pulling them out straight would raise the front end.

This makes a lot of sense to me now... thanks for the explanation! I'll definitely be getting it sorted asap. I've got new tie rod ends and steering gaiters in a box somewhere so will take the chance to get these fitted at the same time.

Oh and my car is "naturally" lowered, as in the springs are a little bit old!

[jayvoa]

Just thought I'd put a proper ending to this thread, as I hate to read through a technical thread only to realise there's no conclusion!

Took the Capri to get the tracking done properly at my usual local tyre fitting shop with their fancy expensive alignment tech. It was so badly adjusted that one track rod end was wound as far on as it would go and the other was only about 4 or 5 threads on. I was told that the new parts and fresh bushes could have made some difference and put the alignment out, but there was no reason for the tracking to be adjusted the way it was.

Oh and I made a mistake in a previous post, it wasn't Kwik-Fit that did the tracking last, it was ATS (the signage outside is all blue and yellow... easy mistake!)

So, in conclusion, tracking was WAY out, got tracking done, problem gone.

Thanks again for all the advice!

[ChasR]

You will have also saved some premature tyre wear as well!