Rear drum to disc conversion

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hb02
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Tue Dec 05, 2023 9:23 pm

Hi there ,

I have a 1985 2 door 320i manual and i want to convert the rear drums to discs. I have the 325i rear arms and driveshafts. My question is can i re use my standard 320i driveshafts or do i have to use the 325i driveshafts? I have a small case diff (6 bolts) not sure what the ratio is.

Thanks ,
Hamza beig
hb02
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Wed Dec 06, 2023 4:58 pm

hb02 wrote:
Tue Dec 05, 2023 9:23 pm
Hi there ,

I have a 1985 2 door 320i manual and i want to convert the rear drums to discs. I have the 325i rear arms and driveshafts. My question is can i re use my standard 320i driveshafts or do i have to use the 325i driveshafts? I have a small case diff (6 bolts) not sure what the ratio is.

Thanks ,
Hamza beig
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BenHar
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Wed Dec 06, 2023 6:15 pm

I think if you have a small case diff you need to use the 320i shafts.

But check if the 325i ones fit. If they do then use whichever are in better condition.

Ben
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flybynite
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Wed Dec 06, 2023 7:27 pm

I think its going to depend on what size wheel bearings it has, '85 could have had either. You need to use the drive shafts that fit the size of wheel bearing you have in the hubs.
hb02
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Thu Dec 07, 2023 7:42 am

If i have rear 325j arms and if i get 325i wheel bearings the 325i driveshafts shoulf fit fine correct? I am going to replace tbe bearings anyway. I was just wondering if where the driveshaft meets tbe diff would be any different?
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flybynite
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Thu Dec 07, 2023 7:59 am

hb02 wrote:
Thu Dec 07, 2023 7:42 am
If i have rear 325j arms and if i get 325i wheel bearings the 325i driveshafts shoulf fit fine correct? I am going to replace tbe bearings anyway. I was just wondering if where the driveshaft meets tbe diff would be any different?
325 hubs will have the bigger wheel bearing, Early 320 may not. Replacing them makes no difference, small-bearing hubs cannot take the larger bearing and vice-versa.

325 arms hubs and driveshafts will fit but if you have a small case 168mm diff you may need to change your diff output flanges to suit the arms.

If your 320 has the larger bearing everything should fit.
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