BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)

BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) (
-   E30 M3 (1986-1991) (
-   -   Building an E30 M3 gravel rally car :-) (

peter*g Sun, Apr-05-2015 05:30:37 AM

Building an E30 M3 gravel rally car :-)
Some of you likely saw a '90 M3 rolling chassis show up on Bring-a-Trailer auctions late last year. The bidding climbed surprisingly fast with people trying to score a cheap starting point for a restoration project.

Well, much to the chagrin of a number of other bidders, I was the lucky buyer. :)

Some folks were upset that I won the car; not just because I scored the chassis, but also because of what I plan to do with it: the ratty M3 Roller Project is being turned into a no-holds-barred Group 5 rally car.

“Sacrilege!” some of you may say. I can not tell you how many people tried to convince me to accumulate original parts and make this thing garage queen. I was barraged with negativity from the E30 M3 purists, upset that yet another car is being “lost” to racing.

To that, I say, “THBPBPTHPT!”

The M3 is a homologation special. That’s a fancy way of saying, “built to be a race car”. I have the opposite view of the purists; every E30 M3 that doesn’t get it’s neck rung on a regular basis is a travesty to me. This is my idea of the correct use of all M cars:

Before the auction came up I was already planning to build an E30-based rear wheel drive rally car – going so far as to even pick up an ‘84 325 to act as a basis for the build. The chance to build a rally monster around an M3 (saving a ratty old chassis in the process) was too good to pass up. In fact, the missing M3 subframes, brakes, and engine didn’t phase me, as using stock E30 parts never even came into the equation for me.

As many others have done before, I plan to combine the light weight and short wheelbase of the E30 chassis with the superior driveline, suspension, and brakes from more modern BMWs. In my case, I’ll be adding the subframes, suspension parts, steering rack, and brakes from the Z3 and the 3.0l motor, transmission, and differential gearing from the ‘95 US M3. This will give me durability and reliability in a car with a power to weight ratio better than 9:1. I helped build a similar car for Targa Newfoundland 10 years ago and always wanted to recreate that car for gravel.

Starting the Build

The M3 project made it’s way to me before the holidays, and we have begun the long process of converting it into a competitive racer. The first step was to get it on a frame rack and see just how bad the obviously-repaired right front corner is.

The car had clearly been hit very hard on the right front at some point (hard enough to bend the passenger side floor!), and was repaired by cutting away the old frame rail and grafting in a new section.

Unfortunately the repair was pretty poorly done, and not only is the chassis still clearly twisted but the weld was sloppy and the metal at the seam is rusted and thin.

Rally cars need to have stout bodies to deal with the stresses of competition, so the repaired sections will need to be re-done before we do anything else. Thankfully, much of the sheet metal is still available through the dealer or specialty parts suppliers. We’re basically going to graft in a new right front corner from new old stock parts.

It’s at this point most people would have run screaming from this project, but in my case this isn’t a big deal. Why? Well, unlike most restorations a rally car needs to be fully seam-welded in order to not literally tear itself apart from vibration and shock. Adding a $1000 worth of additional sheet metal is no big deal when we were going to have to hand weld each section already anyway. Thankfully I have a great build partner in Nate Walton of Bay Street European, who is not only a master technician but an artist with a welder.

The project may seem daunting to some, but the plan is fairly straightforward:
  1. Repair the body, strip it down, seam weld, and then adjust/reinforce the suspension mounting points to accommodate our newer suspension parts and Reiger rally coilovers. Once fabrication is done, we’ll send the body for blasting and then on to the cage builder.
  2. While the body is away, rebuild the suspension, steering, and brake parts we’ll reuse from the Z3 while collecting all of the new parts we’ll need (control arms, bushings, bearings, etc.). We’ll also reinforce the subframes and trailing arms to deal with the abuse of gravel stages.
  3. Rebuild the donor engine, refurbish the transmission, and source an appropriately geared and built differential.
  4. When the cage builder is complete and the car is repainted, we’ll begin the assembly process; first suspension and brakes, then driveline, and the last step will be plumbing and wiring. As a proper rally build we’ll be doing some fancy things here; including a race dash and limited wiring harness, all stainless braided brake lines throughout the car, custom pedal box and hydraulic handbrake, and even a kevlar-reinforced stock fuel tank.
  5. The last order of business will be rally prep; installation of safety gear and fire system, mounting of spare wheel, triangles, jack, and tools, and installation and sorting of all of the odds-and-ends that go into a competitive build.

The goal is to race the M3 in a national rally event before the year is out. That’s a tall order given the state of the car today (and with this being a weekend project), but it’s not unreasonable. I’m grateful to have the help of Bay Street European in San Rafael, CA to speed efforts along. The car will be a “shop project” of sorts; giving the guys something interesting to work on outside of the maintenance and repair work they do on late-model customer cars all day.

Stay tuned to this thread for updates on the build. I’ll be posting all of our progress along the way, including an in-depth look at the mechanical and fabrication work we do to get the car rebuilt and competitive. I hope it’s entertaining and an inspiration to all of you to build something you love.

peter*g Sun, Apr-05-2015 05:43:37 AM

Re: Building an E30 M3 gravel rally car :-)
Stripping the car for sandblasting

As mentioned in the previous post, the chassis is really, really rusty. :( So, we stripped the chassis down for sandblasting before we repair the sheet metal.

There were some very poor repairs from what was clearly a big accident earlier in this car's life:

With the chassis fully stripped down, we dropped it off with American Stripping in Sacramento. They'll be blasting off the paint, the bondo over the bad repairs, the sound deadening, and the rust and nastiness caked on the shell.

From there we'll repair the rusted and damaged panels, seam weld, and start fabrication.

More to come!

peter*g Sun, Apr-05-2015 05:54:37 AM

Re: Building an E30 M3 gravel rally car :-)
With the car out for blasting, I thought you might want to see some of the parts that will be going on to the car as part of the build.

The best part of this build has to be the suspension. Reiger makes coilovers for WRC, and just so happens to make a complete gravel rally coilover kit for BMW E36. With just minor modifications they'll work on our E30 shell.

We'll also be using parts from anothr WRC supplier; BRAID wheels. These are 15"x7" 5x120 gravel wheels. They'll work perfectly with the Z3 subframes and brakes that we plan to use on our build.

I also picked up an S50 and 5-speed transmission from a wrecked '95 M3. I bought it from someone who was planning to do an E30 swap, but gave up on the project. That meant I not only got the driveline, but a ton of conversion parts as well.

The last piece of the drivetrain we need is the differential. We'll be starting off with a 3.46 LSD with 50% lock-up using stock-type clutches.

peter*g Sun, Apr-05-2015 06:13:16 AM

Re: Building an E30 M3 gravel rally car :-)
The first mechanical work I took on was preparing the brake system we plan to use on the car. I purchased the front and rear subframes from a 2.8l Z3 at junkyard. They will bolt right up to our E30 shell, give us slightly beefier control arms and trailing arms than what came standard on the M3, and also came with 5-lug hubs and upgraded brakes -- brakes that thankfully will still fit under 15" wheels.

First up was to clean all of the parts and prep them for the rebuild:

With that done, I ran the parts through my Eastwood tumbler to knock off the caked on brake dust and years of grime:

Everything cleaned up well, but could use some paint to be more presentable:

And here is the finished product with fresh paint, and re-assembled with new boots and seals:

The rebuilt calipers were then packed away with brand new rotors and pads, with everything ready to be reinstalled when we get to that point in the project:

As a bonus, while working on the brakes we also did the same thing to the sway bars. A 23mm front bar is being paired with a 15mm rear bar.

bimmer777 Sun, Apr-05-2015 01:17:48 PM

Re: Building an E30 M3 gravel rally car :-)
Great project and awesome to see another rally car build on the forum! There are definitely not many e30 M3 rally cars in America, mostly e30 non-Ms running. Kudos to you for going through on the build!

It looks like the shell is in a bit rough shape but its perfect donor for a rally build. Who will be doing the cage weld?

Which Rally are you trying to build this for? There is not much towards the end of the year, and I am guessing you will likely run west coast events?

peter*g Sun, Apr-05-2015 06:02:40 PM

Re: Building an E30 M3 gravel rally car :-)
I don't have a specific event I'm trying to make. I'll shoot for doing a shakedown at some point this year so that I can address any mechanical or set-up issues. I then plan to do as many west coast events as I can next year.

My original plan was to build the car this winter and ship it back east for Empire State, but when they switched from tarmac to gravel I decided to just take my time on the build instead.

bimmer777 Sun, Apr-05-2015 06:28:10 PM

Re: Building an E30 M3 gravel rally car :-)
ESPR is my "home" event. My car wasnt ready last year to run it and this year I am just too busy. Happy that it went back to gravel but it may not even happen this year. After the crazy winter that we had, the roads are in pretty bad shape so the organizers will make a call in a week i guess.

Look forward to your build and updates! I am secretly dreaming up an e46 M3 rally car myself, but that wont happen for a year or two. For now will have to play around in this

peter*g Sun, Apr-05-2015 06:59:40 PM

Re: Building an E30 M3 gravel rally car :-)
Nice Evo. I raced an '06 Evo IX in CARS for a couple of years, and for a few years at Targa Newfoundland before that. My old car is still being campaigned up there.

I was really disappointed when they switched from tarmac. I ran my E46 M3 there last year, and finished 2nd in 2WD. I think I could have finished on the overall podium with the E30.

bimmer777 Sun, Apr-05-2015 07:44:51 PM

Re: Building an E30 M3 gravel rally car :-)
So that was you in the red e46? You car sparked the idea of e46 rally car for me :) It looked great!

Brakim was planning to run his Gallardo at the rally this year too. I was looking forward to that. But now since its gravel that will not happen. At least in the near future. He is planning to put gravel Reigers in it.

I was surprised you didnt overall podium last year. But e30 can podium for sure.

bimmer777 Sun, Apr-05-2015 07:49:36 PM

Re: Building an E30 M3 gravel rally car :-)
BTW - just got word that ESPR got postponed to October. Roads are in too poor shape.

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