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 Post subject: Using E36 M3 as a donor?
PostPosted: November 13, 2012, 12:23 am 
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Has anyone used an E36 M3 as a donor? I've got an M3 whose body has seen much better days, and I can only imagine that an engine that makes a 3000 pound car feel quick and agile will really be something in a 1500 pound car. Any advice?


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PostPosted: November 13, 2012, 2:32 am 
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If you're looking for easy step by step instructions from others who have braved the path forward already, you'll probably want to look elsewhere...But if you are up to the challenge, that could make for a particularly spectacular build! :cheers:

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PostPosted: November 13, 2012, 11:04 am 
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I've been doing some research on using either an E30 or E36 as a donor. There are some good points and bad points to the idea. Having an engine, tranny, and complete engine management system is a HUGE plus.

The big downside is fitting the rear suspension. The more I read, the further away I get from using a 3 series as a donor.

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PostPosted: November 13, 2012, 5:09 pm 
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There are many engines that make the power an E36 M3 engine will make (that an S50? S52?) To me though, there are many engines that make a better sound. The M3's are just a bit too raspy for my taste. Stock anyway... I'm sure you could tune the exhaust to be very pleasant without being too loud or obnoxious.

Starting from a running donor is a huge plus, but as has been said, getting the rear suspension to fit/work in a book frame or a 442 is very difficult and doesn't look the best.

If you have a running E36 M3 and want to build a really fun and beautiful car... transplant it into an E30.

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PostPosted: November 13, 2012, 5:45 pm 
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About a year ago I was toying with using an S52 powertrain. I got far enough along that I feel confident in saying that it could be reasonable done. They make good power and are surprisingly smooth, even with poly engine mounts. The pictures below are of a 442E with a few adjustments. Frame height was standard 442E.

Regarding the rear suspension: I think you’d be better off with a solid axle or double-A arm. The E36 rear uprights could probably be modified for double-A use with a little creativity. Heck, the fronts probably could as well. The strut assembly unbolts from the upright readily, and again, a little creativity could convert them to double-A arm duty.


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PostPosted: November 14, 2012, 10:01 pm 
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Thanks everyone; RTz, those pictures are just what I wanted to see. I'm already planning to go dual A arms front and rear. I also am not going to be using a standard frame. I have been doing some cad in the evennings for a few months, designing a new frame to better meet my weight, rigidity, and safety goals. Some screenshots:
ImageImageImageImage Tires are roughed in at the dimensions of a 335-30-18


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PostPosted: November 15, 2012, 12:01 am 
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I've been reading the GRM message board too much - every time I read your title I keep thinking you are using poo as your donor. :mrgreen:

Are you looking to keep the body traditional or are you going to do something different?

I like the cage concept. Will you be placing the windshield inside of the cage?

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PostPosted: November 15, 2012, 1:09 am 
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I think I will just mold aluminum to the frame structure, so it likely won't look much like a traditional locost. I haven't decided on the nose cone yet. I will be mounting the windshield inside the cage, and probably use the cage itself for mounting. I plan to put a roof on it and then a wing mounted off the back to create some weight on the rear tires at speed. I want to have a full width splitter/dive plane setup in the front of the car to counteract the effects of the wing, and then I'm playing with the idea of trying to make some venturi tunnel side-pods (this may be optimistic, but I think could be fun) to help suck the car down further. The frame needs some redesign as using my M3 is a recent idea; I designed this frame for an LSx motor and T56 originally.

Right now, solidworks says my frame is 167 pounds in 1020 DOM, a majority 1.25" 16g tube, which I am satisfied with. It's not light, but considerably stronger than any book variant and has significantly increased driver protection. I'm hoping I can build a completed car in the 1200 pound range, but I'm not sure that is realistic with the S52 and my current frame design.

I'm not too concerned with converting over suspension. I think the front spindles will be easy to make work. I don't think the rear trailing arms are even worth messing with. I will likely try to source some thing else. I'm just thinking the M3 has a very nice smooth powerband that will likely make this car feel like a rocket-ship. The nice 5 spd manual and a limited slip diff is a huge plus too.

My track width is bigger than the M3, but most of that is the tires. I think I can use the diff and axles, unmodified. I may even be able to use the rack in the front! The driveshaft will of course need modification.


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PostPosted: November 15, 2012, 6:01 pm 
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Complete car under 1200lbs? Not with that engine or frame... Not by a long shot.

Your frame design looks a bit messy. Did you read up (books) on tube frame design, or are you just "wingin" it?

Just don't tear apart the M3 only to abandon the project later. My advice would be to keep it simple if this is your first build.

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PostPosted: November 15, 2012, 10:28 pm 
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OptimusGlen wrote:
Complete car under 1200lbs? Not with that engine or frame... Not by a long shot.

Your frame design looks a bit messy. Did you read up (books) on tube frame design, or are you just "wingin" it?

Just don't tear apart the M3 only to abandon the project later. My advice would be to keep it simple if this is your first build.


I'm not sure how not to take that offensively; I've got a piece of paper claiming that I've done a bit more than "read up" on this. "Simple" views in solidworks that show clearly what is there are not my forte. I may draw up some actual prints when I've got something I think is good and post up in the frame section to see if anyone can find something I've overlooked. I assume the "messy" bit you are talking about is the reduced use of square shapes that will make this frame more challenging to fabricate but far more rigid for it. Initial FEA results are suggesting I have 11245 ft.lbs./deg. with 1020 DOM.

The frame, minus brackets is 167, I think the S52 and tranny with all the dressings is on the order of 450 +125. I think the diff is 45. Since this isn't a long range cruiser, I won't fit bigger than 5 gallon fuel cell, so we can be generous and say that will be 75 pounds. I will admit, wheels and tires will be considerable in weight. Underpanel will be 0.040" Aluminum and continuous. Solidworks thinks it will be 35 pounds. So right there we are sitting at 900 pounds before all the "extras" that will need to add to less than 300 to meet my goal. I agree, I won't hit 1200 with this drivetrain choice.


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PostPosted: November 22, 2012, 2:35 pm 
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Hi esp42089,

I am a student working toward my engineering degree.

I also happen to have an old E36 rotting in the driveway with a perfectly good M50 engine and running gear.

So, I am very interested to see where the project is going!

Keep us updated!

Cheers!


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PostPosted: November 24, 2012, 2:54 pm 
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JamesKim2 wrote:
Hi esp42089,

I am a student working toward my engineering degree.

I also happen to have an old E36 rotting in the driveway with a perfectly good M50 engine and running gear.

So, I am very interested to see where the project is going!

Keep us updated!

Cheers!


Good luck on the degree. I finished mine a few years ago. I'll start a build log once I get going on the project: I'm half tempted to just sell my M3 and grab up a C5 Z06 and have fun with that instead. Many options to ponder...


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