BMW Compact Build

Figured I'd start a thread for it now that its finally going back together.

What I started with:



She's a porker (two light people in the front seats):



Chassis stripped:



Chassis stripping - Mitch & Grant:



Chassis stripping - Mark & Grant:



Seam welding - Grant:



Main hoop taking shape:





Dave

Why a compakt and not a coupe/sedan body style?

Isn't the rear suspension weird in the compakt?

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Michael LeCompte

Someone was telling me that the ti suspension was near-as-dammit close to E30 M3 as far as dimensions/geometry is concerned.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Rear suspension in the Compact is the same semi-trailing arm design from the E30s instead of the multi-link stuff in E36. Less adjustable, but allows use of the turrets and easier to increase shock length/travel.
Also easier to get a diff that has more readily available components. Like the Supra diff I loaned Dave and he took up to the shop that is doing the cage for him.
Lastly, rear suspension is stronger than the multi-link stuff. Compacts are more popular to build for rally in places like the UK.
Here's the basic design:


As far as diff swaps, looks like it'll be easy and it uses a 6X100 PCD like the Merkur but with M10 instead of M8 bolts. So the JVAB adapters will work by retapping to M10.

The other E36 stuff looks like this:





Oh yeah, you can also find running Compacts for $1000-1500.

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Grant Hughes

One thing I don't like it the location of the trailing arm mounts to the rear beam. Seems like that might limit the amount of droop the car is able to achieve.
We pulled one of the rear shocks off the Merkur on Saturday also for fitment of the Tim Taylor turrets in the rear as well though, so more will be known about that soon enough.

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Grant Hughes

Another interesting note:
At the Denver U-pull u-pay, there are currently two E36 BMWs, two GC8 Imprezas, two Volvo 240s, one RWD Corolla, and no Merkurs.

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Grant Hughes

Hoping to go back up to the shop this weekend to plasma out the OEM towers and get an idea on fitment of the turrets.

Waiting on a few bits of wisdom from JVL regarding what to measure & snap pics of so that I can get him all the relevant data to start working up a set of suspenders.

Toyota diff fitment and other items will probably have to wait until after the first CHCA hillclimb in a few weeks. Have to get the new cooling system ironed out on the Evo...something I hope to never have to worry about on the BMW project.

Dave

NoCoast Wrote:
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> Another interesting note:
> At the Denver U-pull u-pay, there are currently
> two E36 BMWs, two GC8 Imprezas, two Volvo 240s,
> one RWD Corolla, and no Merkurs.


They crushed yours already?

Hahaha. No, I'd take it to the scrap metal yard before a junkyard. $180 nt at the one right down the street.

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Grant Hughes

That rear suspension is basically what Datsun copied to use under the 510 and 610. It will likely have the wierd toe-change issues Datsun did. They were great when lowered and stiff for road racing but if raised and compliant they are more difficult to get right.

NoCoast Wrote:
-------------------------------------------------------
> Rear suspension in the Compact is the same
> semi-trailing arm design from the E30s instead of
> the multi-link stuff in E36. Less adjustable, but
> allows use of the turrets and easier to increase
> shock length/travel.
> Also easier to get a diff that has more readily
> available components. Like the Supra diff I
> loaned Dave and he took up to the shop that is
> doing the cage for him.
> Lastly, rear suspension is stronger than the
> multi-link stuff. Compacts are more popular to
> build for rally in places like the UK.

Compacts are quite popular in the Netherlands, and here in Denmark as well.

We have something like 3 or 4 with S14-engines (the 2.3 E30 M3 lump) running over here at quite high level.
They're really great for the short narrow tarmac stages that we see mostly.

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Brgrds
Brian

heymagic Wrote:
-------------------------------------------------------
> That rear suspension is basically what Datsun
> copied to use under the 510 and 610. It will
> likely have the wierd toe-change issues Datsun
> did. They were great when lowered and stiff for
> road racing but if raised and compliant they are
> more difficult to get right.


Put a volvo axle and 4 link back there. Sorry, sorry, I just had to say it.

what defines it as a compact? im not bmw savy.

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Gravity Fed Wrote:
-------------------------------------------------------
> what defines it as a compact? im not bmw savy.
>
> -------------
> "If at first you don't succeed, call it version
> 1.0"


Trunk has a foot or so cut off and it has a hatch. Sold in the US as the 'ti' model

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-Jason

I've heard the rear suspension in the Z3 is the same as the Compact as well. Is there truth in that statement?

Also... What suspension/steering differences are there specifically between a IS model and a M series?

Cool car. I really look forward to seeing more.

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Michael LeCompte