I am working on a 1994 940 with 195K miles. I replaced the strut cartridges, rear shocks, tie rod ends, ball joints, and the cone bushings (can't remember proper name). The car drives nicely but there was a steering wheel vibration at 65-72 MPH. I started trying to get at the cause by checking the run-out of the front rims (alloy rims). The lt. frt. was .020", lt. rear was .035", rt. frt. was .050, and the rt. rear was .015".
I rotated the rt. side and I think the problem is pretty much gone, but test drive was short. Is .050" out of spec.?
I also have a 1995 940 with 91K miles on it with almost the same problem. The rims are also alloy. The front end has never been changed/nothing replaced.
We also have a few other 940s (6) in the family. I have never had this problem with steel rims regardless of how worn the front ends were.
Question is, what is the maximum run-out of the rims on the 940s?
--
Mine:4-940s running, 2-740, 1-940 parts, dtrs:4-940s

Hi,

This from blue Pocketbook for 700, 850, 900 series (in mm):




Your tight front-end (after replacing front suspension parts) would expose more rim/tyre imperfections. Choose your best spec rims to fit on the fronts. Usually out of spec rims don't cause steering vibration at more than 100kmh (62mph) - thats more of tyre balancing fault. Check for evenness of tyre wear too. For out of spec rims I'd look for good used ones in the yards.

As an anecdote I've seen how a tyre specialist balance a 7 series BMW wheels while waiting for my turn at the shop years ago. He couldn't get the right amount of balancing the first time around for the alloy wheels. He then deflates the tyre, spins the tyre around the rims to redistribute overall weight, inflates it back and test it again on the balancing machine. Must have done this about 3 to 4 times for each wheel. Total time taken nearly two hours for all wheels. I'm glad my Volvo tyre job was much easier.

Regards,
Amarin.

Thanks Amarin, the .8mm or .031" lateral runout makes a lot of sense! I exchanged the rt. side, puting the .050 lateral runout rim (out of spec.) in back and the .015 lateral runout rim in front and the vibration went away on a 100 mile trip yesterday.
So, I think the specs. you provided in your response are good.
I think runout checking will be a part of tire rotation in the future as well as checking rims before getting new tires.
--
Mine:4-940s running, 2-740, 1-940 parts, dtrs:4-940s

I've honestly never encountered this problem. I have seen a steel rim get bent by hitting a curb, etc. Usually, In my experience, most vibration in the front end has been caused by a tire out of balance or a sticking Brake caliper that caused the brake to drag and get hot, thus warping the Rotor.

Hope this helps

I think I will get the tires balance as a next step if the vibration shows up. I'll know more after tomorrow's 100 mile trip, mainly freeway.
Thanks
--
Mine:4-940s running, 2-740, 1-940 parts, dtrs:4-940s