Slight change in direction off/on throttle?

[GoldCloverLeaf]

Recently driving down the highway i noticed when backing off the throttle the vehicle would pull to the right slightly and when getting back onto the throttle it would straighten out or even slightly pull to the left?

It isn't nearly as noticeable at slower speeds but it's still there, you can sometimes feel it when changing gears as the weight transfers. I think it was a gradual thing but it was really noticeable at higher speeds after some track work recently.

Any ideas? It feels like it might be coming from the rear... A-frame bushes or ball joint? I'm going to take a good look at it tonight but was after some ideas?

[Psimpson7]

trailing arm bushes most likely at the chassis end.

[GoldCloverLeaf]

I'll have a look but they are new superpro bushes... i'd say less than 1500kms on them... trailing arms are kinked so shouldn't prematurely wear out with the small lift i have.

All bushes are new at all 4 corners except for the A-frame bushes.

Most of the front ball joints are new-ish but i'll check those as well.

And yes i check tyre pressure... shocks are good too.

[PhilipA]

A frame bushes can cause this.
Regards Philip A

[djam1]

A Detroit locker with differing tyre pressures in the back will do it too.

[steveG]

If the bushes are just new, check that the bolts are all still tight. Particularly if there was any wear in the bracket holes.

Steve

[87County]

trailing arm bushes most likely at the chassis end.

agree - trailing arm bushes the most likely - use oem ones not poly ones

[n plus one]

agree - trailing arm bushes the most likely - use oem ones not poly ones

Care to elaborate around the OEM v poly issue?

[GoldCloverLeaf]

Thanks guys i'll have a good look tonight.

I already have a new a-frame ball joint ready to go in so i'll do the a-frame bushes while i'm at it.

I think the Superpro bushes have been proven... they are slotted at the chassis end to allow more flex as well. There is other rubbish stuff on the market though to steer clear of.

[JDNSW]

It will be one or more of the bushes locating either front or rear axle, so that the axle twists slightly going from drive to overrun or vice versa. There will be more free play on one side than the other.

It can be any of the bushes, but as suggested, the most likely is the rear lower link bush onto the axle housing. I think the A-frame bushes are unlikely to be at fault as they will only allow the rear axle to move sideways or rotate rather than twisting. I have experienced this from the lower link rear bushes, a loose lower link front bush, worn chassis bush on the front radius arm, and cracked chassis mount for the front radius arm.

Panhard rod bush wear will give wandering not throttle steering, but these can sometimes be confused.

John

[inside]

I had this when a trailing arm chassis bolt was loose. Especially noticeable when pulling out of roundabouts. Might be worth just seeing if they are loose as the bush could still be fine.

[Yorkshire_Jon]

I have just replaced all the bushes on my rear. A-frame ball joint and trailing arm bushes at both ends. The flogged trailing arm bushes gave me te same symptoms as you. If yours are new, did you use new lock-nuts also? It could be that you need to nip the nuts back up.

You said you have kinked trailing arms and also slotted bushes... Why?

I thought there was only one model of Super-Pro bush for the chassis - trailing arm, and that its straight through. I am aware of some other bushes that have an angled hole, but not Super-Pro.

Jon

[GoldCloverLeaf]

Perhaps slotted was the wrong term, they have a circular groove on one side of the bush to allow a bit more movement.

I had a crawl under there after work and one of the trailing arm nuts was a bit loose so tightened that and tightened everything else front and back including the mounting nuts but no luck, after a test drive it's still occurring.

I think it might be the trailing arm bushes at the diff end because i have Gwyn Lewis arms and they came with new standard rubber bushes so i left them in, i think there is some play there. I'll put in new super pro bushes as i already have them and i'll do the a-frame ones while i'm at it.

Will report back on my findings :)

[Yorkshire_Jon]

Ok, now I know what you mean.

I too have the Gwynn Lewis arms and SuperPro at both ends. I also no longer have any lateral movement.

Unless the A frame ball joint is seriously dead, it shouldn't induce any lateral movement, only fore/aft.

I'd suggest when you do the A-frame ball joint you also replace the two wishbone bushes at the chassis end of the A frame. I used SuperPro in there too.

R
Jon

Sent using Forum Runner

[GoldCloverLeaf]

Yep, you all called it, it was the trailing arm bushes to blame... it didn't even last 1000kms! I guess the extra articulation doesn't work so well with factory rubber bushes, hopefully the super-pro ones i put in will last longer.

https://www.aulro.com/afvb/

[jazzaD1]

did you tighten the bolts when all 4 wheels were back on the ground? I neglected to do that with my commodore years ago and the bushes tore themselves up pretty quick

[JDNSW]

Yep, you all called it, it was the trailing arm bushes to blame... it didn't even last 1000kms!

Thanks for letting us know the problem. It really helps others coming in and looking for answers to their own problems when someone posts what was eventually found.

And the picture makes it clear.

The early failure may not have been from the extra articulation, but possibly from incorrect installation - it is important to tighten the bolt after the suspension is loaded and at normal height, and sometimes people forget this. (This means the rubber is unstressed in the centre of the movement, so there is the smallest amount of distortion in each direction.)

John

[GoldCloverLeaf]

To be honest, i didnt bother jacking it up to remove or replace the trailing arms, i just did one at a time.

Before tightening i did bounce the suspension a couple of times to settle so should be ok.

Ideally you would do up all the bushes loosely then drive up and down the driveway then tighten but we'll see how it goes :)

[steveG]

That's another good thing about the Superpro bushes. Because the steel bush in the middle is a separate item and free to rotate, you don't have to worry about vehicle height when tightening up the bolts.

Steve

[Yorkshire_Jon]

Yep, you all called it, it was the trailing arm bushes to blame... it didn't even last 1000kms! I guess the extra articulation doesn't work so well with factory rubber bushes, hopefully the super-pro ones i put in will last longer.

http://img542.imageshack.us/img542/9473/4fkq.jpg

This is interesting... Those bushes are normally not affected by suspension lift and as such are not affected by articulation.

How much lift do you have? I can't recall with certainty the way the arms fit but to me, it looks as though the top most part of the trailing arm immediately forward of the bush has been fouling on the axle mounts under maximum articulation - notice how the centre point of the bush is not along the centreline of the arm. That being the case, the weakest point of failure will be the bush itself as the point of rotation will move to the two fowling surfaces (above and forward of the bolt), which would then lead to premature bush failure as it pulls itself apart.

As I mentioned earlier I have those arms with King Spring KLRR-05 springs and SuperPro bushes and have no problems in this regard. Though maybe I should have a play with the trolley jack and high lift this weekend to double check!!

hth
J

[LowRanger]

I have those arms and have done over 10,000km and the bushes are like new:D

It is just every other suspension bush that I wear out in under 1000km:p

[GoldCloverLeaf]

This is interesting... Those bushes are normally not affected by suspension lift and as such are not affected by articulation.

How much lift do you have? I can't recall with certainty the way the arms fit but to me, it looks as though the top most part of the trailing arm immediately forward of the bush has been fouling on the axle mounts under maximum articulation - notice how the centre point of the bush is not along the centreline of the arm. That being the case, the weakest point of failure will be the bush itself as the point of rotation will move to the two fowling surfaces (above and forward of the bolt), which would then lead to premature bush failure as it pulls itself apart.

As I mentioned earlier I have those arms with King Spring KLRR-05 springs and SuperPro bushes and have no problems in this regard. Though maybe I should have a play with the trolley jack and high lift this weekend to double check!!

hth
J

Minimal lift, perhaps 30-40mm max... it was the only the one side that was knackered, the drivers side was OK. So perhaps it was an installation issue or just a bad bush, who knows.

[Yorkshire_Jon]

Minimal lift, perhaps 30-40mm max... it was the only the one side that was knackered, the drivers side was OK. So perhaps it was an installation issue or just a bad bush, who knows.

OK, doesn't sound like anything to be worried about then. Replace and see how you go.