Will your car rock you to sleep?

I've mentioned before that my car doesn't seem happy when driving out of town. It doesn't feel all that stable in a straight line / seems to react quite badly to surface changes - but sometimes also "rocks" me from side to side for 5 or 10s.

I had the rear shocks replaced by Phoenix which made no difference, and I took the car back there yesterday afternoon for further diagnosis (it will be there all week). However - during the previous test drive (when they diagnosed the rear shocks as the problem) Mark simulated the "rocking" problem by making the car change direction very quickly - i.e. at 30-40mph, he quickly turned the steering left / right / left / right / left / right. Although this was artificially induced - it did cause me to be rocking from side to side in the passenger seat - even for a few seconds after the car had straightened up. At the time, I assumed this was normal - although he had reproduced the same behaviour, I thought any car would probably rock like that if you changed direction the way he had.

However - I tried the same thing this morning in my 964 - and there is absolutely no rocking at all. The car changes direction very quickly, but is stable and as soon as you stop changing direction the car is immediately settled.

Am I making an unfair comparison? I have fairly new lowered suspension on the 964 and stock on the Supra. If you replicate what Mark did to my car - does it cause you to rock from side to side?

Phoenix haven't experienced the car doing this on it's own yet (i.e. without this artificial provocation). But I'm thinking that it shouldn't have behaved like this when he forces it either and that this is in fact showing the same problem. I guess it's not something people do in their normal driving (I hope) - but how stable is your car if you weave from side to side like Mark did in mine?

My TT is solid, the NA I have at the moment does the same as yours, mainly over 50mph - a few others on here report the same issue.

So far the NA has had several alignments, different wheels, different suspension and new upper suspension arms, this behaviour still exists.

I had a Fiesta that did the same thing once but that was down to the panard rod snapping, not something a Supra needs to worry about.

http://www.mkivsupra.net/vbb/showthread.php?t=90514&

http://www.mkivsupra.net/vbb/showthread.php?t=89069&

Sod the allignment, is that your missus in your avatar??

Sod the allignment, is that your missus in your avatar??

lol

But seriously, that doesnt sound good. The suspension in my TT is rock solid. And although the wheel balance is a little out top end, around 80-90mph my car never rocks or anything like that.

Its your shocks..

dont care if you have replaced them recently the new ones must be faulty as well

Its your shocks..

 

dont care if you have replaced them recently the new ones must be faulty as well

The car I've got has had 3 sets on now, standard > aftermarket > different standard - I find it hard to believe that all are faulty.

The car I've got has had 3 sets on now, standard > aftermarket > different standard - I find it hard to believe that all are faulty.

I did only replace the rears though - I do wonder if I should replace the fronts just to rule them out. I'm not convinced it is them though - if I hit a bump the car seems to behave OK.

Oh - and yes, it is my g/f in the avatar.

I had a similar problem on my old Pug but it was more constant, rather than every now and then for about 15s. It turned out to be a flaw in the tyre. One of them had a slight bulge which gradually increased in size. MIght just be worth checking all your tyres just in case.

I had a Fiesta that did the same thing once but that was down to the panard rod snapping, not something a Supra needs to worry about.

That happened to me in an old fiesta of mine... It was quite an interesting drive

That happened to me in an old fiesta of mine... It was quite an interesting drive

Isn't it just! Mine snapped at 70 on a country road, not nice

I upgraded to the MK3 XR2i rod though, much kudos was gained

I had a similar problem on my old Pug but it was more constant, rather than every now and then for about 15s. It turned out to be a flaw in the tyre. One of them had a slight bulge which gradually increased in size. MIght just be worth checking all your tyres just in case.

Fronts are new (and it did it before I changed them). I am considering chaging the rears just in case. Although Phoenix said they would probably swap wheels with another car for a test drive to rule that out.

Could be the brand of tyres. Certain tyre have tendency to tramline and wander following the contours of the road. Also check tyre pressures. Can be something as basic as that.

Could be the brand of tyres. Certain tyre have tendency to tramline and wander following the contours of the road. Also check tyre pressures. Can be something as basic as that.

Have checked tyre pressures (and tried different pressures) but it makes no difference.

It's not tramlining - the 964 will do that. Following the contours in the road would be OK - it's the rocking from side to side that's the problem. I've searched before and seen other threads on this - and the best description I saw was :

The snaking effect that can happen when cars tow caravans. I guess it feels like that would.

Spoke to Phoenix this morning. Mark's conclusion is that it's the Diff mounts.

He says that he's checked all the bushes (again), knows the rear shocks are OK because he replaced them, is sure the front shocks are OK (which I also agree with), tried it with different wheels / tyres (he said it was a little better but still unhappy) and the only place he can find any play at all is the bushes for the diff mount. There are 3 in total apparently, so he is currently getting prices.

I don't know whether it will cure it or not - but it seems that it could explain the swaying / rocking as the diff moves relative to the rest of the car. And - I know this is a problem that quite a few people seem to experience, and many have replaced bushes / shocks / tyres / wishbones etc. and still not cured the problem. I'm guessing they probably haven't replaced the diff mounts - so maybe it's the only thing left it can be!

Oh - and my damn front brakes were binding again so I also owe for a set of used front calipers (I've got some in my garage but he wouldn't have known that). However - even including that - the bill was practically nothing. Wonder if he'll start servicing my 964!

I hope the problem is sorted Dave.

I'm sure Mark will be able to service your Porsche too.

Ro

Interesting stuff, can you post the prices up here when you get them please

Might be worth getting Nic to do us a group buy so those of us without the problem can get the bits replaced before it happens

my n/a never used to do it, but my tt used to "rock" on the motorway

Interesting stuff, can you post the prices up here when you get them please

 

Might be worth getting Nic to do us a group buy so those of us without the problem can get the bits replaced before it happens

I should have the price for parts tomorrow and will post them then. I am going to have to collect the car tomorrow because I need to drive to France next weekend - so it will have to go back to have them fitted.

Labour might be interesting. He said that they should be quite easy to replace unless something is stuck / jammed (can't remember what) and if that's the case he would have to unbolt the subframe - which will no doubt affect the price.

If by any chance he gets the parts early next week I might try to get it back to him - but more likely it will be done in a couple of weeks time.

Did the prices come through?

Finally, yes they did (took a while though!).

The diff mounts total about £150. He says that worst case labour will be 2.5 hours, because he may have to unbolt the subframe to get access to the rear mounts properly. So - worst case £100 labour - total £250.

He will order the parts and once they turn up I will book it in as soon as possible. It's tempting to wait until March since it needs a service / MOT then anyway - but since it's a drive in / drive out job I will get it done as soon as I can.

Will let you know the results.

I'm watching this thread eagerly, along with the others. Anybody have the PNs for the diff mounts (TT please)? Please keep us informed, as this greatly effects how I'll be able to drive the Ring this year. I can assure you, it's definitely not tires. I've experimented with 4 brands.

I can't help with part numbers, since I left it all to Phoenix.

I am dropping my car off on 31st March. I suspect it will be ready by the middle of the following week but I doubt I will take time off work to collect it so will only find out if it's cured the following weekend.

Did you get this sorted? was it the diff mounts? There's other threads about this topic as well. I've been told it's the rear lower control arms so that's what I'm replacing.

Did you get this sorted? was it the diff mounts? There's other threads about this topic as well. I've been told it's the rear lower control arms so that's what I'm replacing.

It was sorted. I can't be 100% sure - because the diff mounts were done at the same time - but one of the control arms was replaced. Since then, the car has been absolutely fine - so I suspect the control arm was my problem.