Driveshaft is rubbing gas tank

[ron1999]

car is 40mm lowered,
rear sub frame rebuilt about 400 mils ago (new sub frame bushings, new RTAB, new diff mounts, new CSB, new guibo)
what have i done wrong?
could it be that i over toruqed the rear sub frame nuts?

i noticed that if i lower the CSB in about 2-3mm the rubbing stops, but i dont think that this is the wat the CSB should be installed.

any ideas?

[jlevie]

I'd be wondering about the subframe bushings as they would be the most likely reason for this. In particular whether the large washer is between the bushing and car.

[ron1999]

subframe mounts are AKG polly, grade 70
the washer is there - on top of the upper bushing.
actually - thinking about it - im kind of afraid that i closed the nuts that hold the subframe too much.
i'll add pictured later on - i hope it will explain things better.


Q: in case nuts were closed too much - is a simple open, lift the car, lower the car and re torque them will do the trick?

[jlevie]

You can't over tighten the subframe bolts. The inner sleeve of the bushing is what the bolt tightens down onto. But you can put the bushings in upside down, which will raise the subframe and thus the drive shaft. Is the thick rim of the bushing on top? It should be.

[ron1999]

are you sire about the sub frame bolts?
im not sure that they go into the bushing - they have ridges that hold them in place inside the car's chasis aint it?
im afraid that i may have bent their position while torquing....

[jw 325ic]

pics?

[jlevie]

are you sire about the sub frame bolts?
im not sure that they go into the bushing - they have ridges that hold them in place inside the car's chasis aint it?
im afraid that i may have bent their position while torquing....

Yes I'm sure. The subframe bolts have knurled portions under the head of the bolt to lock them in the frame when driven home. When you tighten the subframe bolts you are bringing the inner sleeve of the bushing up against the frame. So when tight there is metal to metal contact from the nut to the head of the bolt.

Go look at the flanges of the bushings and make sure that the thick flange is on top.

[ron1999]

ok,
i didnt have time to take pictures, but last weekend i did the following:
i checked the boshings and it seemed like they kind of smashed (is this the correct word?) between the car's body and the subframe.. so

i opened the secure tab bolts (two torx screws)
i released the subframe main bolts - didnt take them off, but had them closed only bolt-long, with no extra threads
i raised the car off the grounds on both sides -to loose the subframe from its position.
i let it sit for a while, than i lowered the car and closed the subframe bolts untill i had about 4-5 threads sticking down from the bolts.
than i secured the locking plates.

went for a ride -the car feels better now. and rubbing of the diff with the gas tank has stopped.
or at least - i think it has stopped.

[jlevie]

That is just wrong. The subframe bolt must be tight. If the nuts aren't torqued to spec there is a risk of the nuts coming off. Something about your assembly is wrong and the subframe is going to have to come back down to fix it. My suspicion is that you have the bushings in upside down.