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Differentials Limit Slip, gear ratio discussions.

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Old 01-14-2021, 11:45 PM   #121
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Thumbs up Differential Dummy

Thanks Living Legend for that summary on your install. Helps alot. I'm researching info to do the same.

Do you (or anyone else) know of anyway to tell the difference between the medium and small case just by seeing the case itself. I know its easily known if you know the model and engine size and possibly cover shape etc... but what about when just seeing the gear case itself? Is the ring gear actually larger in diameter?

Thanks to a CoolJess76 post from wayback I know I need the following;
E24 3.46LSD from a 5 speed 6 cylinder car. (Possibly a bit lower 3.25 from a E24 for a but more top end)
E30 cover, half shafts, output flanges, speed sensor. Any other suggestions?

AND I'm looking to buy all this right now.
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Old 01-15-2021, 12:24 AM   #122
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Default Differential Dummy

Anyone know if I can swap my small case 188mm 3.46 gear set and LSD carrier into a 6 cylinder case? I know whats involved gear wise, just need to know of its possible.

Is there really a large case? I see posts on other sites saying large case and medium case. I suspect they mean the same...
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Old 01-15-2021, 02:34 AM   #123
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Call Dan at diffsonline.com.......he is a highly regarded specialist in rebuilding bmw differentials. Got my E30 3.23 lsd from him. He would be great source of info to answer your questions.
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Old 01-15-2021, 03:38 PM   #124
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Small case - 168MM
Medium case - 188MM
Large case -210MM

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98 318Ti S52
84 318i M10 Zender
93 325is Parker
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Old 01-16-2021, 02:14 AM   #125
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Default Differential Dummy

Thanks folks. My bad, it is a 168mm. ZEK, I know mounts and covers are different by model etc... but how can I quickly tell size (small, med, large) from just looking at the gear case casting itself? People advertise a medium rear but its hard to discern from a picture as its close in shape to the small. I had swapped in an LSD spool/carrier from a '92 coupe we stripped and junked and was hoping (wishing) I could just swap the guts to a Z32.8 or E24 case. Looks like not. The spool went right in. No changes needed for proper backlash and pattern. It was perfect. Doing gear work for quite a while and I never experienced that before. FYI- CoolJess76 (spell) has an all inclusive post from a few years back listing all the swap options for the Ti diff. I can't search by user name or I'd share it here again. P.S. I'd prefer to bite the bullet and source a complete rear subframe and all parts from a ZM. Know of any?
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Old 04-10-2021, 09:28 PM   #126
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Originally Posted by Alivinglegend View Post
With it all bolted up the tabs that grab the rear mount appear to be in constant contact with the rear cover. I am getting more diff noise in the cabin than before, but I made some other changes at the same time so it might not be just the diff. Exhaust and suspension were replaced too. At some point I'll probably drop the diff again and grind those tabs back so that they have more clearance.
I just finished a medium case diff swap and ran into the same issue. The steel diff bushing tab towards the front of the car will rub against the side of the wider medium case diff. What I did was just bend the tab with a crescent wrench, rather than grind it. You don't have to bend it much to get it to clear, and this keeps the coating more or less intact. No issues so far.

The diff I used was a 3.64 Torsen LSD from a Z3. Speed sensor is identical to the 318ti so I used the Z3 one.

I used shafts from a 1989 E30 6 cylinder. They fit perfectly, but you have to shim the ABS sensors as has been mentioned previously. I initially used a 5/8" washer ground to fit but it was too thick and gave me ABS issues at low speeds. What worked better was stacking some stainless steel round shims. You will need 18mm I.D. for the sensor and 6mm I.D. for the little hex bolt. I used 4x 0.5mm thick shims, so 2mm thick overall. This was about half the thickness of the 5/8" washer I used at first.

As a side note, I have the standard 3.45 small case open diff and shafts sitting around now if anyone needs them for a project. Located in Northern CA.

Last edited by mb0686; 04-10-2021 at 09:40 PM.
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Old 07-09-2021, 03:21 PM   #127
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Default Diff and Prop dimensions for a 318i Bond Bug

Hi Guys,

I have a Bond Bug special with a BMW 318i LSD fitted, BMW prop coverted into a Quaife reversing gearbox.

BMW E36 318i LSD 2.93

I have to get a ABS ring made up to fit between the prop and diff but cannot find the drilling pattern drawings on the net for the 4 prop bolts.

Does anyone have a mechanical drawing of the flange and bolts please to save me taking it all apart to measure.

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