THSCC Forums

Turns out there is about 1/4" rear toe OUT on my 325es RallyBMW, no doubt due to one of the seven or so fender benders that it appears the car has been in prior to my owning it

It's supposed to be about 1/16" toe in and I'd like to get it there if possible.

I'm trying to figure out what options I may have for achieving this. Toe is non-adjustable in the rear. The car has curved semi-trailing arms which connect through 2 rubber bushings per side to a horizontal subframe. The subframe is attached to the body through 2 big coke-can sized rubber bushings at the sides of the car in front of the rear wheels.

Offset bushing would work but that is more effort than I'm willing to spend on it. That's a 12 hour job on this car (for me at least) and the parts are $$$$.

I'm not sure exactly what is out of whack -- the body, the subframe, the trailing arms, or the bushings -- and I don't really care. I'm just trying to figure out if I can bend *something* to get the toe back to about 0.

So anyone with experience with this? Or know of a shop that will do it?

I have a very, very small budget for working on this car, so any option that costs more than $100 isn't an option.

Ideas that involve jacks, chain, a tree, and a 4x4 are welcome

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

No experience myself in this whatsoever, but as part of my research on my 914 build up, I have seen people doing this type of DIY to their 914s to repair previous damage hidden under previous repairs.

For the 914 there is complete measurements available as to what makes up a "square" body. I suspect you could find the same for the BMW. Using this, you should be able to tell you what is out of wack. In one 914 example I saw where someone had welded in place some pull points (where there was no place to hook a chain) to pull something back into place via hydraulic jack. You then pull, measure, repeat until it is where you want.

Then when done, you could cut off the pull points with angle grinder. I suspect that this is much like pulling out dents via the weld on tabs as used by body shops, but just scaled up and using jacks instead of slide hammers.

Problem is, I doubt I have told you anything you didn't already know.

_________________
Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

Is that just a total toe measurement, or is that 1/8 out per side (do you have 1/4 toe out on only one side?).

Just trying to figure out what's not straight and where.

Three letters:

BFH

_________________
02 Focus SVT
STF 9

Do you have standard cup bearings or sealed units that bolt to the arms? If they're the sealed bolt-in kind, you might could shim it.

_________________
1988 Plymouth Reliant

Well I just started a string measurement. It looks like it is about 2mm out on the left and 4mm on the right.

The main reason the car was abandoned was because of a "bad transmission" which actually turned out to be that the differential was not properly bolted to the rear subframe -- the front two bolts were in place but the rear 2 were missing. Under acceleration the diff would violently rotate down and toward the front, twisting the rear subframe. (The driveshaft was rubbing the d/s hole in the subframe, which is what caused the PO and his mechanic to think the trans was bad...).

Anyways I think that these years of subframe twisting has caused it to straighten out a little bit which would cause toe out.

Here's a pic of an E30 rear subframe. This is what it would look like looking up from under the car. Front is to the right, rear is to the left. The trailing arm mounting points are on the top and not visible. this is the piece that I am theorizing may have "straigtened" a bit and needs to get bent a little more.



Here's a picture of the semi-trailing arms that attach to it:



I still can't conjure up a good picture in my head about how to tweak that subframe a few mm while still on the car. Need to grab onto where the diff is attached and pull it backwards relative to the mounting points.

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

How would that work? Pull the bearings/hubs off and put something in the hole off to one side that will keep the bearing from seating completely on one side?

I believe they are big cartridge bearings -- not sure what kind or shape of material I could use as a shim on a circular mounting surface...

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

I know you're half-joking. If there was a way to wail on it I'd do it. Problem is everything is isolated with rubber bushings, and the metal is quite stout. There isn't a BFH that could do this job!

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Some cars have a sealed unit (containing the bearing assembly and hub) that bolts onto the trailing arm or steering knuckle.

_________________
1988 Plymouth Reliant

Tow strap and a tree?


Edit: You could probably sell tickets and make a few $$$ while trying it.

Scott

I would buy a ticket to see that!

_________________
02 Focus SVT
STF 9

Mike is the diff also mounted to the unibody at the back end? If it is like my old Datsun 510 then the tow strap would end up trying to move the diff mounts and the bushings on the crossmember would have too much give to put any force on the crossmember itself. Poor 510 guys used to slot the mounting holes for the trailing arms. You could try this and put washers under the mounting nuts. when you get the alignment right weld the washers in place.

_________________
George Bright Member # 141
One of the youngest of the old farts.
Yes I voted against you joining the club.

What George said.

It's cheap (FREE! washers and about 5 seconds of welding).

It does cost some time though, but it's probably the best option for your particular situation. If you want to get really fancy, MOOG chassis parts sells some "standard" eccentric bolts that I am 99% sure would work- you'd still have to slot the subframe holes a bit, and weld some small tabs perpendicular to the existing metal to help the eccentrics work, but it would be slick. I would also recommend welding the washers once you get the alignment set.

If you're thinking the toe in is really hurting your rallyx handling, I seriously doubt it.


Bret.

A semi trailing rear car with toe out defines squirrelly. My 510 was a handful with rear toe out. And If I remember corectly it has roll oversteer too. ie with body roll the rear end turns outward. And braking also makes it toe out too. When set up right it is a gas to drive because you can steer quite a bit with the throttle even on a low power car such as a 510.

_________________
George Bright Member # 141
One of the youngest of the old farts.
Yes I voted against you joining the club.

Jack and chains...but what is in the way? I saw an article about using a steel beam, two chains and a bottle jack to bend a solid rear axel on a front wheel drive car. Based on a need to pull the outboard ends forward to increase rear tow in, the jack would need to "mount" at the center of the subframe. The steel beam would attach by chain to the ends of the subframe and the jack would push the beam forward bending the frame as it went. The problem with all of this is that the jack would need to be horizontal and intersect the steel beam at the exact center. I think that the subframe is slightly above the floorpan which makes it impossible to pull straight forward. Now if you can tolerate a little forward and downward then you might get away with it.
Regarding a little toe-out at the rear: The E30 naturally toes out under suspension compression so that adding throttle in a turn causes rear steering to the outside. That is why E30's look like they are tail-out when in corners. They are not actually sliding, they just have rear steer. It is exaggerated if the car has been lowered without adding offset bushings to correct the geometry changes (like in my black car with lots of rear steer).
On the other hand, Mike if you cure the oversteering, will the car have a name change to "Unter" Steering?
Charlie Guthrie

_________________
1998 BMW Z3
1987 BMW 325is
2000 BMW
1996 F250 Turbo Diesel