Will manual E30 sport seats fit in an E28?

[ChefShawn]

easily? or not....

thanks

Shawn

[JamusMcFamus]

SEARCH!

Yes, they will, with fabricated adapters.

[ChefShawn]

oh yes, thank you, i think i saw them on e-bay once.....hmmmm, i guess i should search to see if the adapter plate dimensions are posted etc.......

[blur95]

I'm working on adapters to do this right now. It measures out that the threaded holes in the e28 body are 455mm apart, center-to-center, and the holes in the e30 seats are 420mm.

I'm still not entirely sure about the e30 dimensions, though. I haven't got it in and working yet. When I measured the e30 seat rails the first time, I didn't account for slop, and came up with 415mm. at that dimension, I was able to get the seat bolted to my brackets, but it flexed the rails too far for them to move easily.

I'm 99% sure that 420mm is the right dimension, and that's what I'm going with when I continue this project sometime this week.

Now I have to figure out how to move a 10mm threaded hole 5mm over. I think I'm going to have to go with studs, and weld them in.

Hope this helps,

Ian in Portland

'84 533i

P.S. I plan on making some sets available to board members for a reasonable cost once I get them installed, and verify that they are working correctly. they are made out of 3/8" aluminum flat bar, going all the way across the existing seat mount holes in the body.

I should have that done slater this week.

[Mark 88/M5 Houston]

Considering that the seat belt integrity is dependent on properly mounted front seats; I think I'd switch from aluminum bar stock to steel for those adapters.

[Ricky535]

Considering that the seat belt integrity is dependent on properly mounted front seats; I think I'd switch from aluminum bar stock to steel for those adapters.

That's what I did. Steel bar tabs on the outboard side. The original holes on the inboard side. I have obliterated two sets of seat bases to make the e30 sport seat fit on a e28.

[blur95]

<img src="http://e28-535i.com/upload/e30-e28seatbrackets-6061.JPG">

That's plenty strong for me. That converts to about 12 million pounds of force. It will be even stronger than that because I will use countersunk flat head screws for all the holes, effectively giving me studs to mount the e30 seats on. I'm reasonably sure that the seats or the body will fail well before that point. I will do more calculations tomorrow for the tab style.

Would someone tell me what material and dimensions are used for the other style of adapters?

I need to get to sleep, so more will have to wait until tomorrow.

Ian in Portland

'84 533i

[wkohler]

Considering that the seat belt integrity is dependent on properly mounted front seats; I think I'd switch from aluminum bar stock to steel for those adapters.

That's what I did. Steel bar tabs on the outboard side. The original holes on the inboard side. I have obliterated two sets of seat bases to make the e30 sport seat fit on a e28.

First, I used those eBay adapters. The instructions said to put them on the inboard side - I currently am not a fan of that. It makes it fee like I am right up against the door - because I am. I attempted to place them on the outboard side, but due to the curvature in the floor, the bolt head would prevent the plate from securing flushish with the floor.

As for Ian's project, I got to thinking about it. You can't use the stock bolts on an e30 seat because of how thick the mounting points are. If you are trying to center the seat, you wouldn't be able to bolt the adapters in, because then the bolt heads would interfere with the seat rails. You could probably do it with some sort of pan head hex key bolt, but I don't know if you can find hardened bolts like that in this size. (10mm/1.5 - that refers to the shaft).

I am interested in hearing your thoughts on this. I was going to suggest tapping the bar, so the seats would bolt into that, but if it is aluminum (I could have swore you said stainless the other night), that would not be the best idea.

[blur95]

I'm doing one in stainless, but I have realized that it's way overkill. I now plan on using allen flathead bolts, probably stainless, threaded in and countersunk in from the bottom, giving you a stud to set the e30 seat on, then put a nut on top of. The outer bolts will need to be countersunk as well, to clear the e30 seat pads.

I'm going research the strength of the bolts a little later tonight.

Ian in Portland

'84 533i

[Ricky535]

First, I used those eBay adapters. The instructions said to put them on the inboard side - I currently am not a fan of that. It makes it fee like I am right up against the door - because I am. I attempted to place them on the outboard side, but due to the curvature in the floor, the bolt head would prevent the plate from securing flushish with the floor.

As for Ian's project, I got to thinking about it. You can't use the stock bolts on an e30 seat because of how thick the mounting points are. If you are trying to center the seat, you wouldn't be able to bolt the adapters in, because then the bolt heads would interfere with the seat rails. You could probably do it with some sort of pan head hex key bolt, but I don't know if you can find hardened bolts like that in this size. (10mm/1.5 - that refers to the shaft).

I am interested in hearing your thoughts on this. I was going to suggest tapping the bar, so the seats would bolt into that, but if it is aluminum (I could have swore you said stainless the other night), that would not be the best idea.

That's how obliterated the second set of seat bases. Grinding the original tabs then welding new tabs to get the seat centered. The first one was a flat bar welded along the lenght of the side rails. After that I took the easy route, tabs on the outboard holes.

[wkohler]

Any pictures? I might see if I can do that.

[Ricky535]

Here's the bar tabs on the e30 seats that are mounted on my 728


Manual sport seats from a euro m6 that is on my 88 535is
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Recaro trophy's on my 87 535is
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[some guy]

So I've been pouring through the archives and came across this. Any 533i guys end up with the E30 sport seats? Were you able to center the seat or did you end up shifted over to the outboard side? Any source for quality brackets?

I had read a post that talked about the 533 floor being different from the 535 so I am trying to find out specifically about this being done to a 533 (unless it's actually the same floor layout and I am remembering this wrong).

Any help is much appreciated!

Thanks!

[wkohler]

My seats are in a 533i. I used the tabs that move them outboard. I'm going to try mounting them the other way (tabs on outboard side) because you'd never think that moving the seat over an inch would make that big of a difference. I'm right up against the b-pillar/door.

[some guy]

Thanks Christopher. That is what I was afraid of. I'm pretty broad through the shoulders, and I don't think I can give up the inch. Does it seem possible to move them inboard? From what I've been reading it doesn't sound good, but it's hard to picture how everything looks.

[wkohler]

I'll see what I can do.

[some guy]

Cool, man! You rock! 8)