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Getting started on my E28 rear axle swap

Mike Goble

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It dried up enough to go out and take things apart and test fit the E28 rear axle. Surprisingly, it lined up on all three stock mounting positions.
 

afeustel

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Hi Mike.
In what ways does it not fit? In other words, why shouldn't we (Bav owners) all swap to E28 rear sub and diff, etc.?

Also, we're those front and rear seats a bolt in swap as well?
 

Mike Goble

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Things that don't fit right away:

The sway bar needs to be mounted. If you choose to use the E28 bar, you need to weld some attaching points to the frame. If you keep the E3 bar, you have to weld some tabs on the trailing arms and carrier. I'm keeping the E3 bar.

The e-brake cables are slightly different, so you need to extend the cable tubes about 10".

I have E28 differentials with differing covers, you need the one that has the mount centered on the diff.

You need to rework the brake lines and weld a bracket to the trailing arm to line up with the existing flex lines.

You can use any E30 differential and change the flanges and cover to fit the E28 mount. I have a 3.25 LSD and a 3.73 LSD, so I'll be experimenting there. E30 LSD's are fairly easy to acquire, about $90 at P-n-P.
 

Mike Goble

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Got the rear axle all back together yesterday and it works very well. I actually gained a bit of tire clearance, probably because my Bav rear axle was really thrashed. I guess it's I'll be putting some 255's on the rear in a while. I'm liking the longer legs of the 3.25 gears, first gear is actually worth something now. Now on to the headers and front struts.
 

e30strube

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Outside of the brackets for brake lines and sway bar, does everything bolt in? No issues with the diff itself? I have a 3.25 diff sitting in my garage that would be a nice addition to the car.
 

Mike Goble

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As you know, it's never quite as easy as it first appears.
You can actually use the stock E28 hard brake lines if you get some longer flex lines that go all the way out to the original bracket.
The e-brake tubes have to be moved up into the tunnel because the E28 cables come over the top of the carrier, and the tubes have to be extended 7". I used some 12mm tubing from a tranny cooler line to get the job done.
The differential yoke protrudes a little bit farther than stock, but I have enough room in the driveshaft slip joint to accommodate this.
The diff itself is a bit larger than stock, so if your exhaust pipe is presently real close to it you may have to massage it a little. Since my exhaust system is on its last legs and I've got a set of Stahl headers going in I'm not too worried about this.
I've got the Bilsteins with the 6 grooves in the body and the moveable snap ring, so height adjustment is a piece of cake. E28's use a different diameter spring, so I just transferred the stock lower spring perch and rubber to the E28 shock.
I had to clearance the floor around the outer trailing arm attaching point as it sits a little close. I found some old Chevy rod caps that fit into the gap, so I jammed them in then jacked the car up with all the weight on that point. Worked like a trained pig.
The diff cover that I used is the centered one that comes off the earlier E28's and bolts right into the stock Bav mount. My other option was an E34 cover.
 

BuzzBomb

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You're just adding more rolling resistance. Unless you really like the look of a wide tire, a 225 is more than you'll ever need. Actually a 205 is good for both economy and traction. It sounds like you're going more for looks though.
 

Mike Goble

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You're just adding more rolling resistance. Unless you really like the look of a wide tire, a 225 is more than you'll ever need. Actually a 205 is good for both economy and traction. It sounds like you're going more for looks though.
Well then, I don't think I'm gonna be the first guy here to modify my car just for looks. Also, the word 'need' seems a little out of place. Do we really 'need' leather seats, nice paint, 16" rims, lowering springs, euro bumpers, etc?
I got my inspiration from Bill Arnold, and he used 245's around. I only have 235's on the front so to average out like Bill I'll put 255's on the back. I already own the tires, Michelin PS2's, helluva deal off Craigslist in LA, so it's not any sort of a major investment.
Road racing in Mexico was a pretty good school for me as to tire selection, and I can't think of any instance where a smaller tire resulted in better times.
 

BuzzBomb

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Well then, I don't think I'm gonna be the first guy here to modify my car just for looks. Also, the word 'need' seems a little out of place. Do we really 'need' leather seats, nice paint, 16" rims, lowering springs, euro bumpers, etc?
I got my inspiration from Bill Arnold, and he used 245's around. I only have 235's on the front so to average out like Bill I'll put 255's on the back. I already own the tires, Michelin PS2's, helluva deal off Craigslist in LA, so it's not any sort of a major investment.
Road racing in Mexico was a pretty good school for me as to tire selection, and I can't think of any instance where a smaller tire resulted in better times.
Sorry, I didn't know you were building a race car. Carry on.
 

Mike Goble

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In addition to my Bavaria, I have a 1967 Nova wagon, one of 2700 V-8 wagons made in 67, very rare, and it has a Golde folding cloth sunroof installed by the dealer in 1967, making it basically a one of a kind car. I belong to a couple of Nova forums similar to this site, and it is very interesting to me how the BMW guys act to certain things as compared to the Nova guys, and vice versa.
 

BuzzBomb

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In addition to my Bavaria, I have a 1967 Nova wagon, one of 2700 V-8 wagons made in 67, very rare, and it has a Golde folding cloth sunroof installed by the dealer in 1967, making it basically a one of a kind car.
Seriously, WTF does this have to do with anything?
I've had grease under my fingernails since I was 14, building bracket racing engines for the '69 Camaro that my father bought new off the lot. I'm almost 50 now, and I've owned cars from almost every continent throughout my life and I know a little about how to make them go fast. I also own an E3.
Who cares?
Put whatever you want on your car. Disregard anything I mentioned earlier, since I know nothing anyway.:roll:
 

Mike Goble

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First off, I'm not questioning your automotive cred, folks are here because they like cars and have various levels of experience and expertise in this field. I started in 1962 with a 57 Chevy.
If you don't care, why all the questions? My inclusion of the Nova reference was just to point out the differences I find between the two automotive camps. If I was to post a similar " I'm going to install somewhat bigger tires " thread in an American car site, I would never get these questions. When I go to the Nova site and talk about putting an M30B35 with a Q-jet in my wagon, the reaction is not always positive.
 

Gary Waggoner

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Ok....back on track.. Mike, I assume you are changing just the diff right, not the complete subframe with diff attached? I was confused when shock talk was in the conversion changes. So it sounds as if the E28 diff will essentially bolt in to our coupes with minor changes to brake lines etc..Is that correct?
 

Markos

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Ok....back on track.. Mike, I assume you are changing just the diff right, not the complete subframe with diff attached? I was confused when shock talk was in the conversion changes. So it sounds as if the E28 diff will essentially bolt in to our coupes with minor changes to brake lines etc..Is that correct?
Hey Gary,

That was a necropost on your part. :D This thread is 5 years old but @GolfBavaria has probably had several thousand miles out on the e28 rear axle.
This is a cool thread and I’m glad you dug it up. I love hearing about all of the cheap gearing options. I have 235’s on my e9 and you don’t hear to many folks discussing anything larger than 225’s. I know several members with wider fires, but the topic isn’t discussed with much supporting technical information.

The e3 seems to accommodate larger tires better. The rear axle/shock/spring/trailing arm setup is different from and e9. An e28 swap into an e9 is more involved, but has been done before. Check in on posts from @bdigel here:

https://e9coupe.com/forum/threads/72-restomod-clubracer-build.15162/
 

Mike Goble

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Ok....back on track.. Mike, I assume you are changing just the diff right, not the complete subframe with diff attached? I was confused when shock talk was in the conversion changes. So it sounds as if the E28 diff will essentially bolt in to our coupes with minor changes to brake lines etc..Is that correct?
Mine is an E3 so the entire rear axle bolts right in. To put one is a coupe would require quite a bit more work.
 
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Glad this came back around. I have read it earlier and have a question. What are the trailing arm options for the conversion? I am assuming The E3 trailing arms were retained in this case. Thanks!
 
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