Driveshaft / Prop shaft centre support bearing query

AndyNZ

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Hi folks,

Feels like I've been asking a few questions here lately. A result of having purchased an E9 already disassembled and with previous owners having begun rust removal repairs to a very low standard.

One of the driveshaft support bearing brackets is missing from inside the tunnel - a result of a previous patch repair and the bracket never re-fitted. As part of figuring out the correct location for the missing bracket we're lining up the support bearing as it should be located.

It seems clear from images on Real OEM, W&N sites and other posts on this forum that the open side of this support bearing backs onto the universal joint in the centre of the driveshaft and therefore faces toward the front of the car. The closed side of this bearing faces the spline shaft - i.e. to the rear of the car.

Given the asymmetrical design of the bearing mounting bracket, it should only be able to be fitted one way (due to the shape of the transmission tunnel).

When we fit the support bearing in place and correct orientation, it is off-centre and on an unusual angle. When we rotate it 180 degrees so that the closed face is toward the front of the car (the wrong way around) it lines up beautifully, as the photos show (taken from the front of the car looking rearward).

I'd be grateful if anyone can solve this mystery please. (Top W&N image inserted for reference).

Driveshaft support bearing.JPG
IMG_4432.jpg
IMG_4433.jpg
 

sfdon

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sfdon

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It’s not supposed to be centered- look closely
 

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AndyNZ

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Thank you for taking the time to take these photos & share them. So in your view the middle photo of mine above doesn't look too unusual? From your photos, the left side of the bearing mount hangs lower than the right, which is consistent with mine.
 

Stevehose

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It's all about getting the guibo and the tranny flange mating surfaces to rotate without wobble, the CSB can be adjusted up/down and side to side to accomplish this.
 

eriknetherlands

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I think a few measurement of the brackets and their relative location is what you need.
I know the for-aft position of the brackets differs between automatic and stick shift. Not sure about it, but i think it was 20mm.
I have an automatic, what do you have? Let me know if I can measure something for you.
 

sfdon

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Thank you for taking the time to take these photos & share them. So in your view the middle photo of mine above doesn't look too unusual? From your photos, the left side of the bearing mount hangs lower than the right, which is consistent with mine.
Mind your one photo that shows you holding the CB on the wrong side of the bracket. As noted - the open side does indeed face the front of the car and
is notably not centered in the tunnel. I would guess this would insure the bearings in the u-joint don‘t brinnell.
if you want a pic and drawing of the correct location and shape of your missing bracket- let me know. I do not think the mounts have different heights.
 

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AndyNZ

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I think a few measurement of the brackets and their relative location is what you need.
I know the for-aft position of the brackets differs between automatic and stick shift. Not sure about it, but i think it was 20mm.
I have an automatic, what do you have? Let me know if I can measure something for you.
Thank you, I have a manual with 4-speed gearbox. I am confident of the for-aft position (thank you for your kind offer) - just figuring out the correct mounting position of the CSB seems to be the challenge at the moment.
 

AndyNZ

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Mind your one photo that shows you holding the CB on the wrong side of the bracket. As noted - the open side does indeed face the front of the car and
is notably not centered in the tunnel. I would guess this would insure the bearings in the u-joint don‘t brinnell.
if you want a pic and drawing of the correct location and shape of your missing bracket- let me know. I do not think the mounts have different heights.
That would be most helpful and greatly appreciated if you have the time.
 

sfdon

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Andy- we have 20 cars in our shops for restoration- we can provide whatever pics and measure you need.
 

deQuincey

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Mind your one photo that shows you holding the CB on the wrong side of the bracket. As noted - the open side does indeed face the front of the car and
is notably not centered in the tunnel. I would guess this would insure the bearings in the u-joint don‘t brinnell.
if you want a pic and drawing of the correct location and shape of your missing bracket- let me know. I do not think the mounts have different heights.

Is this the bearing that needs to be pushed 2mm frontwards during assembly to give pressure towards the gearbox ?
thanks
 

Ohmess

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I had always thought that the reason that the bearing is not centered in our cars is that our engines are canted 15 degrees to allow for a lower hood height. Thus, my theory goes, the crankshaft is not perfectly centered in the engine bay.
 

sfdon

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