Project 39: Replacing the Driveshaft Flex Disc / Guibo

[Wayne 962]

Got any questions on Project 39 for your E36 or E30? Ask them here!

-Wayne

[bmaurer]

I am replacing the flex disc in my '95 318 ti and I have come across two little problems. First, the 12 mm bolts are two different grades and I am not positive which came from where. I think the 8.8 came from the drive shaft flange and the 10.8 came from the transmission flange. Second, the 101 projects book has the bolts following the arrows (the arrow always pointing to the nut and not the bolt head) while the Bentley manual has all the bolt heads on the south side of the flex disc, same as the way mine was before disassembly. Well come to think of it I have five questions. Third, the golden colored 8.8 bolts have some white stuff on the threads; what might that be and does it need freshening up? Fourth, the flex disc replacement has the valleys 60 degrees off compared to the original when focusing on the arrow alignment. And fifth, I can see preloading the mid bearing on the drive shaft when replacing the bearing, but shouldn't the bracket go back in the original location (I marked it well) if using the old bearing assembly? Bentley calls for 4-6 mm. The car has manual gearbox, and I doubt the flex disc has been replaced before. The odometer reads 81k. Much thanks in advance. Bruce

[Jeron]

1) I doubt it matters where you put the 8.8 and 10.8 bolts. The part number is the same for all 6.
2) E36 Bentley and 101 Projects but state the arrow points to the nut.
3) Clean the bolts and use a little blue Loctite, especially if you arent replacing the lock nuts.
4) dunno
5) I would compare the specified preload location to your markings and go from there.

Other than using Loctite and getting the bearing preload close, your other issues are of little consequence.

[bmaurer]

Thanks for your help, Jeron. Just finished the project, but while the car is up on blocks I think I'll flush some new brake fluid through. One thing that is a little unnerving is the clearance between the end of the bolt going through the transmission output flange and the transmission case. It is only 1 to 1 1/2 mm max. I thought about putting a washer behind the head of the bolts, but didn't want to wait for 3 new nuts. Again thanks for your time

[Jeron]

I don't think it matters which way the bolts go through the Guibo. If they were originally in there pointing rear-ward and you are worried about clearance I would probably have put them all in pointing rear-ward.

However, there shouldn't be any relative movement on those bolts. The guibo and axle should absorb all of the deflection needed.

This guy posted that very problem yesterday. It a bit different because his is an Xi and the axle where his problem is to the front diff but the concept is exactly the same. It appears to be the bolt tips on the axle side of the guibo are touching the output flange.

e30 325ix front end noise

[martin944]

do you really need to remove the exhaust to get to the flex disc?

[Jeron]

I "think" I've heard of people prying the driveshaft rearwards and getting the guibo in there without dropping the exhaust. I cant say for sure though.

[bmaurer]

I tried to slide the driveshaft on its spline midway, but there is just not enough travel. Taking the exhaust out is not hard, you'll need a flexible coupling on the 14mm socket to get to 2 of the nuts holding the front exhaust pipe to the header. I did it alone, supporting the cat converter on a milk crate as I cut loose the rubber supports toward the rear. The front flange will rest on the stiffening bar across the chassis under the transmission then you can let down the rear and then the front. Watch out for the o2 sensor wiring. The forward support for the exhaust mounted to the transmission must be for noise suppression because it is just too frail on its little rubber isolaters to hold much weight. All the driveshaft components are straight forward too, it just takes a little time. I found removing the transmission support a must. The hardest parts were the bolts on the guibo and jacking up the car in stages and making it VERY secure. I have 14 inches from the floor to the underside of the rocker panel, but don't have a creeper. The guibo bolts need two 18 mm wrenches - I could not get a socket on either side. As mentioned in a previous post, the bolts are different grades on mine. I cut the box end off one wrench and fit the handle in a 3/4 inch pipe 16 inches long to get enough leverage. New exhaust nuts, rubber hanger parts, guibo nuts and exhaust flange gasket are a must. Transmission mounts while you're there is cheap enough. Penetrating oil on the exhaust flange nuts soaking for a few hours is a good thing. Overall it was not too hard, just time consuming. The 101 projects book explains it well.

[bmaurer]

Thank you Jeron for the link to the thread about the driveshaft bolts hitting the differential. Yes it is a similar problem, but I agree it should not be an issue as long as any thrust bearings in the gearbox behave. It is interesting to note that in the picture of the differential, the orientation of the flanges to the "valleys" of the flex disc are the same as the one I had asked you about. They are 30 degrees clockwise to the flange bolt, whereas in the 101 book and Bentley the valleys are 30 degrees counter clockwise, or 60 degrees different between the two flex discs. It makes me wonder if I got the right part. Also on my installation the bolts can only go one way through the transmission output flange due to clearance. The flex disc can be bolted to the driveshaft before fitting to the transmission and point the bolts the other way, but those already have lots of clearance.

[bmaurer]

Hey martin944, When my son bought this '95 318 ti, he had it inspected at an independent shop. They came up with a list of things to fix including engine mounts and the guibo as well as several other items. Point being the estimate for labor for the mounts was 2 1/2 hours and the guibo was 2 hours even. I did the mounts in 2 hours (never did it before and they were a pain) and the guibo took me at least 6. If the mechanic can do the guibo in 2 hours, then there must be a short cut.

[Jeron]

The engine mounts shouldn't take more than an hour with the right tools.

I can have my transmission out in 6 hours. The guibo is about a 2-3 hours job tops.