Understeer

Mon Feb 13, 2006 8:38 am

Hi,

I will to keep this short but there is a big history behind my problems(s), I garaged car for year and a half and when I went to put it back on road the steering was terrible.

After changing everything (power rack / pump / bearings / track rod ends / springs / strut top bearings it was a lot better but I still feel the steering is heavy and i get huge amounds of understeer

I believe these cars are bad for understeer anyway but does anyone have any ideas what would help this ?

Car is 89 325i Motorsport Cab , I have a feeling that the strut top bearings should have a diff camber on this car from standard and think standard may have been fitted.

Also does anyone know correct wheel alinment details as I also think this has been set as standard 325i and am sure this is slightly diff on the cab.

Cheers , I live in Stenhousemuir (near Falkirk and wish I had see meet at wheel as I would have come down)

Mon Feb 13, 2006 12:00 pm

I have a 1989 325 cab, and the one thing it NEVER does is understeer.

I'm afraid I don't know if the strut mounts are different on your particular model, but I didn't think they were....

just take it to a tyre-fitters and get them to check all the camber/castor/tracking; as long as they are reputable you should get a comprehensive and cheap answer to any alignment problem

Mon Feb 13, 2006 7:27 pm

It never used to understeer anything like it does now and I have had the wheels aligned at least 3 times but I am not sure if the strut tops are at the wrong cambre if that will make the wheel alingment wrong.

I did get the wheels done one years ago and it was perfect and I remember the guy looking up the correct settings and saying that it was diff from standard.

I may try get this done again but I dont want to keep getting this redone if the struts are at wrong angle.

Cheers anyway any info is helpful.

Mon Feb 13, 2006 7:37 pm

Have you changed the tyres since you got it out of the garage?

Mon Feb 13, 2006 7:42 pm

sorry, i'm not attempting to make anyone sound silly here, but there isn't any chance the bloke in the tyre place who is doing the 4 wheel alignment isn't looking at M3 settings or anything like that if you are telling him "motorsport". It may be that there is little or no difference, i don't know.
It is just a silly mistake I suppose could be made?

Mon Feb 13, 2006 7:47 pm

nice idea Widge, but I would have thought the symptoms of tyrewalls being deformed by sitting for a year would be vibration rather than understeer

I'm sure if anyone knows of a difference in strut set-up for the motorsport, if you raise a thread on 'cab motorsport' you might get some of the owners replying

I know the 325 strut is a different size from the smaller (lighter!) engines, and I assume it is M-tec suspension on a motorsport(?), but I doubt if BMW spent any money developing anything different for that specific model - it's just a 'look' rather than anything radically different

Mon Feb 13, 2006 7:48 pm

E30Beemerlad stop talking such sense

(wish I'd thought of that one!)

Mon Feb 13, 2006 9:05 pm

As everyone is having a go

Have you checked / changed the rear axle bushes - might sound daft, but it will steer like crap if these are shot.

Mon Feb 13, 2006 10:27 pm

I was thining more along the lines of tyre pressures, to fine tune oversteer and underteer charcteristics on IRL cars they change the tyre pressures, it changes the flex in the side walls. Or the tyres could have just gone hard.

Mon Feb 13, 2006 11:05 pm

gotcha

I kinda assumed the owner would have checked pressures, and if kept cool and out of the light, tyres should last 5 years..... but you could be spot-on - are there any cracks in the sidewalls of the tyres?

Mon Feb 13, 2006 11:11 pm

I just thought with everything else he has replaced then it would by sods law be the most simple thing. And they are the most important component of any vehicle, it's those little bits of rubber that do everything.

Tue Feb 14, 2006 9:36 am

Tyres are all new although they they aint a great brand but I have used same tyres before and not had this problem.

I may try contact BMW on this as no one seems to know if they are same or diff top bearings.

cheers anyway

Tue Feb 14, 2006 7:54 pm

According to the ETK, '89 cab and '89 4 door saloon (as an example) have the same strut top mounts.
Two alternatives are shown - a standard one, and one for correcting camber.
Understeering E30 suggests something very wrong in the suspension or alignment.
Suspension angles are easy enough to check if you can get the car on dead level ground.

Tue Feb 14, 2006 8:38 pm

Just a thought (eek!), if you didn't drive the car for over a year then you'll be used to driving something else and the steering may feel heavier just because you're used to something else and can't quite remember the exact feel of the e30. Or at least that's what I found.

Wed Feb 15, 2006 8:21 am

I will go get this checked again , I do drive other car (brand new A3) and it is smooth, But I used to be able to turn steering with one finger in the BM and I cant do that anymore.

Maybe I didnt have my weetabix

I will go get it checked again as I dont think it is returning to centre after a corner properly either.

cheers all for your advice / thoughts.