What's left of my diff.
Time to go for an e28 rear subframe so I can take advantage of a greater selection of LSD's. Currently, In Aus, I can only find two sideloader LSD's, with the wrong ratio's and at $2.5k each.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Now secured a good e28 rear subframe and a new race (60% lock, steel shims etc) LSD, hopefully 3.45 but confirming. These should be at the mechanics within the next two weeks. Photos to come.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
New race LSD and rear sub-frame are here. Needs a new wheel bearing so will get both done.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
If you can find the rear cover from an early E28 ( with the mount centered on the cover ) it will bolt right in using the stock holes.
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Aware of this but the racing diff at 60% lock as a different rear plate, longer. Appreciate the suggestion but tried and failed on that one. So I'll get a specialist welder I know to modify the subframe.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Nearly there with the diff swap. We are cutting off the section of e28 rear subframe that bolts to the e28 diff, and welding to the e3 subframe. We will then set the diff mounting to accept rear plates with either the offset bolt mount or the bolt mount in the centre.
I've got a stock 25% locked 3.45 LSD to go in and the race LSD with the 60% lock. The two LSD's are pictured besides each other. Note the beefed up steel flanges on the race LSD.
We will strengthen the floor mounting prior to fitting the LSD's.
Post completion I'll be able to swap e28 medium case diff's in and out so a replacement will be a 30 min swap and not a 5 day fabrication.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
excellent.. I didn't think that E3 could look so sporty. only one question to you, exhaust headers it is still with coated or aluminium alloy?
ceramic coated. Car should be back ont he track in a month or two. fitting the e28 rear subframe is taking time. The race diff is forcing additional works and we need to weld the e28 subframe. We also need to shorten the propshaft as we cannot push the race diff any further to the rear as it is just a few mm's from the fuel tank.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
I'm accidentally got to your post when searched here E3 S38B38 with weber carbs, it is also a racing car. If you haven't seen this then I recommend you, i think it will be interesting for you.
As I said, I couldn't have imagine that the E3 could look so sporty before as I saw your car. I noticed that it is coupe and went to search more pics and found that E3 from factory only sedans. after found where you told you that your E3 is shortened by 33 centimeters.. It's amazing custom really
good luck to swap subframe of e28. it will be interesting to see it on the track in work.
Last edited by bmw emw; 02-06-2020 at 03:46 AM.
This lovely gift from China has slowed me down on the rear subframe swap. I need to get the car on a hoist and measure up (which is a pain as the car currently has no rear subframe) the hold-down bolt locations for the e28 subframe so we can weld it up. I also need to get the drive shaft to a machinist and get it shortened.
That said, I have an S38B38 in my 633Csi, that is a brand new engine build with zero kms and built to race endurance performance level. We are currently working on that car so this has slowed a little. I'll get back in and get everything measured up next week. Should be ready next month but with the lockdowns (thanks CCP you lying marfioso bastards) racing in Australia is shut down and will be for a minimum of a few months to go, so I have time.
I've seen the E3 with the S38B38, it is a fantastic car and a credit to the owner.
Stay safe.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
I am looking for new parts for my roadster. Maybe you can help me, because I just can’t find the steering knuckle that suits me. I want to make a big eversion of the wheels in order to start learning to ride in a drift. I have been enjoying this sport for a long time, but I could not afford this grove.
Last edited by bimmerfaje; 06-19-2020 at 06:24 AM.
We progress with the rear subframe swap. We are now going to strengthen the boot (see fatigue cracking) and the chassis under the current diff mounting location. The previous diff mount was meant to be flexible but the bolt running through this diff mount nearly pulled through the chassis floor. All to be fixed.
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You can see the prying (bend in the floor) where the diff mount bolt was pulling through. You can also see the fatigue cracking.
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The old diff mount. For an e3/e12 chassis, not the new e28 rear subframe and e28 diff.
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All the load was on the diff bolt. The flexible coupling did nothing.
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Paper thin sheet metal was holding the diff in place! Seriously!!
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
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The two diffs. The diff on the left is the brand new 60% lock race diff. Notice the big metal flanges. The diff on the right is the 3.45 LSD, stock 25% lock. We are re-fabricating the rear plate on the race diff to centralise the fixing cleat. This will let me swap diff in and out without needing a secondary fixing point under the chassis.
We could not just swap plates as the racing diff has a rear plate about 25mm shorter than the stock diff.
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The two diffs.
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The E3 batwing is very keen to get racing again! Tracks open next month.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Diff has been modified and is ready to go back in.
We had to shorten the prop shaft. See photo, now back from the fabricator.
We made our own diff mounts to go in that circular hole where the diff bolt is seen in previous posts.
Next week it all comes back together.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
I am having trouble messageing you, could you send me your email? I was hoping to get some advise for my m30 build
Message sent E28NZ. Let e know if you got it.
Josh
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Thanks Josh, I have emailed you
The diff rear cover plate is now done. Rather than destroying the current offset rear cover plate they made a new one. The car is now strengthened and the diff should go in early next week. The shortened prop shaft is no back in.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
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Boot with fuel equipment out. Note the buckled floor where the old diff mount pulled the floor down.
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You can see the floor deflected and the boot fatigue cracked.
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This plate was pulled into the boot floor by the diff. That is the diff mounting bolt.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
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6mm by 75mm flat plates welded together and, the top horizontal plate welded to the bottom of the wheel arches.
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We welded this 5mm by 30mm flat plate under it to remove the lip in the boot floor fold.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
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2 blank diff mount blocks we made.
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prop shaft in.
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Fueling system out
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Car almost back together. New race diff in and bolted up.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
As you can see we painted the internals of the boot (trunk) and have now returned the fuel system. The diff mount bolt comes through the floor and bolts through a poly block. This poly block can compress ever so slightly so takes the shock out of hard acceleration.
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The boot before.
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The boot painted internally with anti-rust paint.
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We are now ready for out test day. New diff oil, new fuel, all checked out.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
Went racing on the weekend. SMP Amaroo Circuit which is a little twisty thing with no straights. Really a hill-climb course.
Not suited to the car at all. Gearing all wrong. Was always needing to change up 100m before a corner and then had to heal-toe down two gears to hit the apex. Not easy when the peddles are still original E3 and you need to dislocate your right ankle to get enough accelerator pedal power and braking pressure.
I usually do 6 sessions but shared my car with a good friend. He did 3 and I did 3.
First session was damp and cold. Second I was pushing too hard and had to do a safe final lap to get a time, 1.08.38. My last session I thought I might save time by holding 7200 rpm to the corner and not changing up but it was in fact 2 seconds slower. So if I had more session I would have gone back to selecting another gear 100m out from my braking zone.
Next event October 31 is the SMP Gardner circuit that better suits my gearing. More to come.
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1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
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