differential installation

[ajf]

I'm installing the differential, which seems as if it should be easy ("reverse of removal" as they say). It has not been.

There are 8 bolts on the bracket (4 top, 2 on each side; 4 side, 2 on each side) and 1 bolt into the rear mount. The car is on jack stands and I'm working alone. I'm using a floor jack to support and maneuver the diff, with a secondary bottle jack on one end. I'm having a hard time lining things up, no matter what method I attempt or strategy I use.

Any tips from those who have done this would be appreciated. There must be some trick I have not yet discovered. Thanks.

 

[Stevehose]

I used a tranny jack

 

[lloyd]

I'm installing the differential, which seems as if it should be easy ("reverse of removal" as they say). It has not been.

There are 8 bolts on the bracket (4 top, 2 on each side; 4 side, 2 on each side) and 1 bolt into the rear mount. The car is on jack stands and I'm working alone. I'm using a floor jack to support and maneuver the diff, with a secondary bottle jack on one end. I'm having a hard time lining things up, no matter what method I attempt or strategy I use.

Any tips from those who have done this would be appreciated. There must be some trick I have not yet discovered. Thanks.

This is probably not a direct answer to your conundrum. Difficulty might be encountered depending upon how your floor jack actually cradles the carrier. Note the illustrations using what appears to be scrap lumber.

I have not had to do this by my lonesome for quite some time. Last time I used a specialized transmission jack (similar to below), although I would imagine jacks designed to hoist motorcycles or lawn/farm equipment could be equally handy.

 

[E911]

A simple, cheap,wooden miter box works well- makes it easy to balance it on the jack pad- will work on a tranny also.

 

[ajf]

Thanks -- I'm using wooden planks, chocks, shims, and wedges to set things up as best I can. Not solving the core problem, though.

 

[Gazz]

I suspect that you are talking about is the difficulty in getting all the bolts holes to line up in order to get the bolts in. Firstly you need to acknowledge that although it is German, and a BMW, it may not be a perfect fit.
I got the diff in by first partially installing what bolts would go in, including the main rubber housing bolt. Then manipulated the diff into place using various jacking points and jiggling it by hand to get the remaining bolts in to the housing. Be sure to use your favourite swear words during the process, this enables you call on your anger energy when jiggling that sucker.

 

[aearch]

i used punches to align all the holes
hold it in place
and while setting all the bolts loose

 

[sfdon]

Gazz is right- start each bolt by a few threads ....

 

[ajf]

Thanks, folks. I've been trying to do exactly this...I seem to be able to get 1, maybe 2, bolts in a small amount and then I jiggle/persuade/shim/tilt the massive hulk of metal about in an attempt to get the rest to fall in line but they never do. Honestly, if I hadn't taken the damn thing off I would not believe it actually fits in there at all. I will not admit how long I've spent at this so far, so I was hoping there was a trick I was unaware of.

 

[MatthewCervi]

On my Bavaria I think I was able to get 5 of the 8 bolts in pretty easily and then had to work at the last 3 (with the final one requiring the most amount of shoving, lifting, etc.). Are all the bolts and holes clean? Dirt would not be your friend here.

I installed mine about 6 weeks ago, but I've already forgotten whether I started with the big rear bolt or left it for last. I *think* I loosely installed it first so that the weight of the diff was partially supported, but I'm not sure now.

 

[Tony.dreamer]

 

[sfdon]

Fresh hardware and a quick thread chase is suggested.

 

[Tony.dreamer]

Thank you SF Don , I always love your short and sweet answers ... I would love to meet you some day... That is exactly what we did. You need to get a good set of metric thread chasers and clean the threads first. If you don't use fresh bolts you would also need to run them through thread chasers. More often than not You would be pleasantly surprised why you should do that.
I also assume that since you have lifted the back of the car the car is not level . I imagine that you bolted the rear piece with rubber first (since it is easiest) to help you hold it in place... if so I think I can see more difficulty you would encounter with the moment the weight of the Diff creats and unlevel car since the rubber flexes..

 

[sfdon]

I work under the car on my back with a tranny jack and a big lever to pry the diff into position to bolt up. A 2 foot pry bar is your friend. One hand levers into position and one threads the bolt. Working with a stable base is important.
My tranny jack is adjustable for tilt.
McMaster sells those bolts for 75 cents
New is cheap especially after you cross thread your first bolt hole.

 

[ajf]

I did get new bolts, even a bit longer so they could bridge the distance better when mating up, and I pre-threaded them to be sure they would fit first. And I have become friends with my long pry bar. The only thing I don't have is the tranny jack, which will be my next move.

Thanks again everyone for the help and input, much appreciated.

 

[bavbob]

I just did this a week ago. found that the rear subframe will twist a bit and alter alignment for the diff. I removed the nuts from the underside of the subframe bushings which added flexibility (assuming your wheels are not touching the ground), then started each diff bolt and rotated tightening. When done, torque subframe bushing nuts back. Logic has little place here, ie removal under static conditions should=replacement and it does not.