Sorry guys, I feel like this build has really be crappy because the photos dont show up well and they are small so, I took the time to repost them all. They should be nice and big and easy to see. I hope it helps anyway..
Gorgeous parts craftsmanship and welds!
Ditto. I like that it's not cobbled together and the time was spent to troubleshoot the little details. I personally would have made way uglier and probably less functional versions of everything you have done so far, but I'm a hack.
91 318is
83 320is
Thanks guys! I appreciate it. Sometimes its really rough out there so its nice to hear good feedback too to keep me going.
I think the trans and motor are in for good now.
I did some undercoating before I put everything back in. I am planning to undercoat the whole underneath of the car but on the passenger side its coated with oil from an excessive oil leak so I will have to wait to clean that up later on and paint it then also.
Some additional pictures for those interested on how the motor fits in the bay. It really fits nice unless youre set on running the stock brake booster, then you would have to compromise somehow. Everything else fits pretty good though.
Motor is pushed all the way back, touching the firewall.
These posts need a like button I can smash with my mouse clicker! Looks good and snug in there.
91 318is
83 320is
I started working on the rear end mods.
I thought I had everything pretty sorted out on the diff. I got a open diff 2.93 ratio from the e28 subframe I pulled. I thought that would be a good ratio to run but wanted an limited slip diff.
I found an E30 limited slip in great shape. It had 3.91 gears in it. I thought it would be no problem, I would just swap the gears on to that carrier and be all set. No deal. There is a carrier break at 3.07 and on top of that, I guess BMW really didnt make a LSD for the 2.93-3.07 diffs. I guess they did make a couple but not many and I am not up for looking for this rare bird.
So, I scratched all that and bought a 3.25 LSD off Ebay. That should be here next week or so.
If you check the pic below, it will show the difference in the carriers. You will see that the ring gears are at a different height.
The E28 subframe into E21 mod....
I am not the first to do this mod. I have seen at least 4 others document it. I will try to do my best at my version.
What the E28 subframe offers over the E21:
5 lug conversion
Much bigger/stronger gears
Better choice of gear ratios
Slightly stronger axle shafts
Disc brakes
The only downside I can see to the E28 subframe would be the extra weight. How much? I thought it was a good question so I weighed everything.
E21 subframe-complete approx 190lbs
E28 subframe-complete approx 255lbs
Trailing arm-some brakes 39lb (x 2) 78lbs
Bare subframe 29lb
Axle shafts 31lb
Diff 86lb
Rotors/calilpers/pads 31
So, looks like its approx 65lbs for the upgrade. Not too bad.
Since I took a lot out of my oil pan and I want to run an accumulator, I had to figure out a way to tap into the motor for external oil lines.
Stock Camaro LFX has the weird paper type filter and the housing is built into the casting. I found out that a Traverse oil filter housing is more like old school housings where you spin on and off a metal filter. So now I can get a oil filter relocation kit and plump my accumulator and some larger oil filters in.
This might be good to know for Camaro guys as I know a lot are searching for ways to plumb a turbo in and this would work great for that also.
Oh, another note is that the oil pressure sender is different on the Camaro and Traverse. I didnt have a large 16mm (I think) tap and didnt want to buy one so I just bought a 16mm bolt, drilled out the center and then tapped it for the sender. Looks like it will work great.
I think I got the e28 subframe sorted well enough that it will fit into the e21. I ran into some issues that I didnt see others running into. I am not sure if its me, my car or what?
I spent way, way more time thinking and measuring than I needed to. I quadruple checked everything and in hindsight, I dont think I needed to.
Here is a quick, dirty and easy way to install the subframe:
1- cut the ends off the E21 subframe, clean up the excess welds\
2- Cut off the ends of the E28 subframe. Cut them at the same angle as the mounts and as close as possible to the mounts.
3- Measure from the front side of the E21 ears and draw a vertical line at 1.625". Measure from the bottom side .9". (Picture shows 1.25" which is what I did. See below. This route, 1.625" would be correct.)
4- Place the front and bottom of the e28 subframe along these lines you just put on the ears and weld it in. Make sure the nut on the trailing arm clears the E21 ears. (see picture).
5- Cut a section out where the fuel filler line will hit the E28 subframe
6- Build a mount for the chassis to diff cover
The way above is easy and "dirty" because it will move the wheel back approx .375" from stock, or at least it did in my situation. I dont think it would be a huge deal to install it that way but I went thru the extra work to make it work in the stock location. The big problem is that the gas tanks get in the way and hit the subframe so you have to section out the subframe to fit in where stock would be.
The harder, yet stock fitting way:
1- cut the ends off the E21 subframe, clean up the excess welds
2- Cut off the ends of the E28 subframe. Cut them at the same angle as the mounts and as close as possible to the mounts.
3- Measure from the front side of the E21 ears and draw a vertical line at 1.25". Measure from the bottom side .9".
4- Place the front and bottom of the e28 subframe along these lines you just put on the ears and weld it in. Make sure the nut on the trailing arm clears the E21 ears. (see picture).
5- Cut a section out where the fuel filler line will hit the E28 subframe and also where the gas tanks will hit the subframe.
6- Build a mount for the chassis to diff cover
The time lost was spent thinking about how to get the subframe to sit correctly and not be crooked or off center etc. After thinking about it, really, you only need to make sure youre not crooked from side to side and up and down. Everything else pretty much takes care of itself. If you draw the lines on the E21 ears and cut the E28 subframe square, everything else pretty much takes care of itself. Oh, and a huge time sink was that I didnt want to make the E28 subframe too short. Dont worry about that because if you cut it flush with the mounts, its still tough to fit in. I cut mine flush and then took off even a touch more. If you dont, it will be hard to push all the way back where it needs to go and the wheel base will be longer, rather than stock.
Last edited by Erik Dlux; 01-21-2019 at 10:34 AM.
very interesting swap. looking forward to see it done.
you haven't mentioned this anywhere yet but are you planning on fabbing a skid plate ? I see that you are on coilovers and that the oil pan sticks out lower than the subframe
Yeah, a skidplate is in the plans for sure.
Wait, you did that whole thing without a jig and it fit? We're not worthy!
-John
Yeah, I thought long and hard about doing a jig but I dont think it would have accomplished anything that I was able to do with just a simple mark up on the plate. Plus, your jig is only as good as the template you use and my E21 subrame was a good bit off side to side.
More work on the rear subframe.
I will need to adjust my toe and camber in the rear since the plan is to have this car lowered. I am not a fan of welding on the adjustment plates so I decided to cut off all the mounts and make my own.
As I sat under the car when putting the subframe in, I kept looking at the stock fuel pump/accumulator/filter setup. I couldn't handle it anymore. It just looks like another BMW band aid and its a mess, especially when previous owners have spliced parts in and things have worn over time.
I took out the gas tanks, fuel and brake lines and will be replacing all of them with new. I was going to be lazy and try to run the brake/fuel lines but after pulling the tanks, I am glad I am redoing all of it. The fuel lines nor the brake lines were in great shap.
I will be bracing the subframe mounts in the middle like the factory did after I get the tanks and lines back in so I can double check clearance issues.
My battery was located in the trunk. I pulled it and am going to toss it back in the front.
I have always wondered how much extra weight youre adding by running all that cable back there. Now I know. 6lbs. Just food for thought but youre almost adding 25% of the weight of the battery in cable.
On a side note... if anybody wants a pre cut battery cable, let me know. LOL
Noooo why? Outside of balance, wouldn't you rather the space and cleaner look of having it in the boot? I guess perhaps safety concerns routing the wire through the cabin but I really like having mine in the trunk.
I'm all for weight reduction but I stop at functionality and creature comforts (minus ac). Never ubderunder why folks rip out sound deadening, for instance, for like 20 lbs.
The battery to the trunk isn't about weight savings really. It was mostly about space for me
Last edited by jaredmac11; 01-24-2019 at 03:43 PM.
I would much, much rather have the trunk space. I have soooo much space in front of my motor right now that its crazy not to put it there IMO.
Yeah, the PO had the cable running all the way back there with zero fuses in the trunk. Whole car could easily light up!
The biggest reason is to gain trunk space and clear the clutter from the cable running front to back. I really just dont think there will be any noticeable performance loss though either. I would love if somebody proved me otherwise with some science.
I considered moving my battery to the trunk, but honestly it seems like a ton of work when I can fit a ~11lb battery in the stock location far easier. If I need to put weight over the back wheels it will be in ballast where the spare tire sits.
91 318is
83 320is
Yep, that would be ideal to me too.
Heck if youre up for running one of those crazy batteries that weigh 2lbs, its really silly to even consider moving it to the back. Obviously youre gaining almost as much weight as youre moving.
That's a fair point. Newer batteries make sense to just keep in the front. I like my $50 batteries too tho
I got this one for $34.99 and it's supposed to be a PC680 equivalent. Cranking over a 1.8 shouldn't be an issue for it from what I gather.
https://www.ebay.com/itm/Mighty-Max-...0xb:rk:11:pf:0
91 318is
83 320is
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