Shortened Drive Shaft?

[markseven]

My '87 325is is lowered on H&Rs. I just found out that I may need a new drive shaft. Is a stock ds okay or do I need a shortened one due to the fact that my car is lowered? If a stock ds is okay, where's the best place to get one and what should I expect to pay? How about for a shortened ds?

TIA,
Mark

[euroshark]

You do not need to modify the driveshaft after lowering the car.

Is your car driveable at this very moment?

Most good driveline shops can modify your current shaft to accept standard Circlips and normal U Joints. This makes rebuilding them super easy and cheap. Expect to pay nearly $500 for a rebuilt one from Bavauto or BMP.

[AlpineIS]

The length of your driveshaft has no relation to the height of your car. The ds connects the tranny to the diff. So...if you get anything shorter than what you have now you will be left with a gap.

If you must change it make sure you get an exact replacement. Automatic driveshafts are shorter than manual tranny driveshafts.

[ivo316]

If you had a solid rear axle you (maybe) would have to shorten the driveshaft, usually in Camaros and mustangs the slip joint at the end of the tranny had clearance enough to slide through the difference and avoid cutting the driveshaft.

You have independent rear suspension, so when you lower your car, the distance from your differential to the tranny remains equal, and all that varies is the camber of the rear wheels (goes to negative) - please someone correct me if i'm wrong.

You do not need to shorten the driveshaft, but if you had to, a good machinist would cut it, weld or thread the Ujoint supports and re- blance the assembly, but it's not necessary. ;)

[318isbmw]

if I remember right, the BMP ones are modified to use the normal u joints and circlips.

and even if you had a straight axle, I've laid out chevy trucks and mazda's on the ground and they only then run into clearance issues w/ the stock driveshaft, they make those to have a full inch at the tranny to move inward so you gotta be going way way low or high to run out of clearance on driveshafts.

[Garageaholic]

go to www.wholesaleimportparts.com and you'll find re-manufactured driveshafts for about $330. I got mine from there, Not only can it handle the 300rwhp my car hands out, but it is balanced and shipping is refunded! To add icing to the cake, there's a 1 year warrantee to boot!

[markseven]

Thanks guys! :D

M3fan4eva, good link, my man ;)

[markseven]

Um, how hard is it to install a new drive shaft, on a scale of 1 - 10 with 10 being extremely difficult? Is it worth it to pay a shop to do it?

[Jscotty]

You have independent rear suspension, so when you lower your car, the distance from your differential to the tranny remains equal, and all that varies is the camber of the rear wheels (goes to negative) - please someone correct me if i'm wrong.
;)

You are absolutely right.. the differential remains in a fixed position regardless of how far you lower the car. On the other hand, the axle shafts may have to be modified (depending on how low you make the car) because the diagonal distance from the differential to the hub may change.

[euroshark]

Its a 3 out of 10 if you don't count moving the exhaust. I'd say the exhaust removal is harder than doing the driveshaft.

[318isbmw]

Its a 3 out of 10 if you don't count moving the exhaust. I'd say the exhaust removal is harder than doing the driveshaft.

I'd agree, super easy to do.

[markseven]

Is there a DIY for this? I checked bimmerdiy.com, and even though there is a section titled 'Transmission / Drive Shaft', there isn't a diy for drive shaft replacement. :o Thanks again for the help, amigos!

[PiercedE30]

the hardest part is removing everything to get to the driveshaft.

[markseven]

the hardest part is removing everything to get to the driveshaft.

Are there any special tools required for replacing the CSB? :borg:

[euroshark]

The DIY instructions would go something like this:

1. Remove the exhaust hangers and unbolt the downpipes from the flanges at the manifolds. Remove exhaust system. -OR- Just loosen the downpipes and let the exhaust drop down enough to access the front and rear of the driveshaft.

2. With the transmission in any gear, start loosening the bolts that hold the driveshaft / guibo to the transmission output flange. There will be 3 bolts, so taking the car out of gear to rotate the driveshaft might be necessary. Having the tranny in gear isn't necessary, but it might help if the bolts are really tight. Don't remove the bolts yet, just get them loose.

3. You will need to be able to jack up the rear end to loosen all of the bolts at on the differential flange. There are 4 of these, so I just jack up one wheel and rotate the driveshaft until I can get at 2 bolts at a time, then hold everything in place with the parking brake. Loosen then repeat till they are all loose.

4. Unbolt the center support bearing (csb) from the chassis. There may be a large heat shield in the way once you remove the exhaust, this will have to be removed to access the driveshaft. The csb should have two bolts and is very easy to remove. Once the csb is off the car, the driveshaft should hang lose. If it does not come out at this point, you may have to loosen the big gland nut that keeps the two halves of the shaft together. Do this with a large pair of channel locks, it shouldn't be super tight. Either remove the shaft as one piece by bending it in the middle, or by separating the halves and removing them separately.

5. Installation will be the same as removal. If you split the halves to remove it, you probably need to put them in separately and connect them afterwards.