Vorshlag $2010 GRM Challenge car - BMW E30 V8

[Eric]

in for more!

[SamE30e]

Looks wicked!

[decay]

great thread.

i'm using a similar 5lug setup (e36 non-m shocks/springs/spindles/brakes and your camber plates with 96+ M3 control arms and THR CABs) and as you say it's not perfect but it works. given that this car is likely going to wind up about 500lbs lighter than my vert, i think you'll be happy enough with the performance... i'm just using porterfield pads and it's plenty of brake for what i do with the car.

the other thing i wanted to mention is that you might be able to find a torsen from a manual Z3 six-cylinder in that ratio, or one close to it... i recently switched from clutch-type to gear-type and it's an unreal change. have beat on the car a little bit with 225 KDW's in the wet and the diff somehow knows where the traction is and sends the power there. got mine from Jordan @ Lone Star for about the same price as i paid for the old clutch diff.

subscribed. best of luck at the challenge, do us all proud :)

[Fair!]

the other thing i wanted to mention is that you might be able to find a torsen from a manual Z3 six-cylinder in that ratio, or one close to it... i recently switched from clutch-type to gear-type and it's an unreal change. have beat on the car a little bit with 225 KDW's in the wet and the diff somehow knows where the traction is and sends the power there. got mine from Jordan @ Lone Star for about the same price as i paid for the old clutch diff.

Torsen diffs are a world of difference from a straight clutch type. They wear much longer, and have distinct handling advantages on a road course, but there can be drawbacks as well. The major limitation of a gear type (Torsen) diff is when a rear tire lifts off the ground it no longer functions - it becomes an open diff. Unfortunately this can and does happen to BMWs in autocross situations, which is the major points portion of the GRM Challenge that we're building this car for.



There are hybrid differentials that that combine the best aspects of two styles of differentials. I'm using one of these (1.5 way OS Giken) in my E46 DSP build.

More on diffs: http://grassrootsmotorsports.com/articles/whats-diff/

The clutch type uses friction discs and springs to preload the differential gears so they don’t spin as freely as they would in an open unit. As the axles try to move at differing speeds, the discs or clutches slide against each other, resisting this action. The result is a partially locked-together axle that still allows differential wheelspin, especially as the clutches wear.

A locker differential is activated and deactivated by the gas pedal: Under power, it locks the wheels together; when the driver lifts off the accelerator, the wheels are unlocked. These actions are accomplished by a series of gears and plates within the unit, and the result is much like an on/off switch. The unit is either locked or unlocked, which can create some instability as power is added in mid-corner. On the plus side, there is nothing to wear out and the units can lead long lives.

Gear differentials, like those marketed by Quaife or Torsen, use a series of parallel worm gears to distribute power to the wheel that has the most traction. The gear differential is typically more expensive than the other types, but it also has nothing to wear out or adjust. There is a downside, however: If one wheel is completely unloaded, the differential can act in the same manner as an open differential, thus making these units less than ideal for bumpier tracks and off-road use.

Finally, as with any attempt at categorizing the world, there are many variations of the three types—all different ways to skin the same cat. Some of the more popular aftermarket units are hybrids of the clutch and locker types. These units provide the benefit of solid lockup on hard acceleration, but the transition from locked to unlocked is generally smoothed out by a series of internal friction plates.

For our $2010 build we can only afford a used stock style clutched limited slip.

[decay]

There are hybrid differentials that that combine the best aspects of two styles of differentials. I'm using one of these (1.5 way OS Giken) in my E46 DSP build.

so that's how they make a 1.5. interesting. thanks for the link, i still need to sit down and read this month's GRM...

i'm not on a $2k budget but i wasn't down to spend four figures on a diff either... you know us e30 guys ;) luckily i found my torsen for just under $400. but seeing as i don't really tend to lift the inside rear driving on the street it's a great solution for me, and i can see how it wouldn't be for you.

carry on and godspeed, sir.

[So Live]

Any updates on the front suspension?

Killer build guys!!!!!!

[Bmil951]

Subscribed. Kick some a$$....

[GotCone?]

another downside to torsen is they don't start sending power around until one wheel is slipping. Which may not be such a bad thing on an AWD subaru for the most part but even less than ideal for a RWD BMW IMHO, especially one making decent torque to the wheels.

[Fair!]

Any updates on the front suspension?

Killer build guys!!!!!!

Some scattered ideas on the E30...

Still looking at options for fixing the wheelbase issues. The '95 M3 offset LCA bushings we have in the E30 right helped move the wheel forward some, and so did the '96-99 M3 LCAs, but it still needs to push forward more. The proper solution seems to be to swap in 96-99 E36 M3 spindles as well, but I just tested our 15x10" wheels ($200/set on closeout - so cheap!) on my '97 M3's stock front brakes - no joy.



The 15x10" wheels won't clear the E36 M3 front brakes (12.5" diameter). The inner barrel of the wheel hits the caliper badly, even with lots of spacer. So this is not gonna happen with the wheels we can afford to use on this $2010 project. Just for fun I slapped a 16x8" Camaro wheel on there. That's all the E36 M3 needs to clear these larger rotors/calipers, a 16" diameter wheel:



So long story short - we aren't going to burn $70 in the budget to get a pair of used '96-99 E36 M3 spindles, and we'll stick with the 11.5" diameter E36 non-M brakes we have instead. As much as I'd like to have the M3's larger 12.5" diameter brakes (for UTCC) and a better fix to the wheelbase solution, the calipers will never clear our 15x10" steel wheels - and that's the only way we can pull off this much wheel for this little budget.

There's no 16x10" or 17x10" wheel in this insane $200/set price range, of course, and 16" and 17" tire selection is even worse (all too narrow and/or too tall). The only tire that's gonna fit our little car well is going to be the 275/35/15 or 285/30/18, and we cannot afford the 18x10" wheels, either. So we'll make do with our 15x10" steelies for the GRM autocross and just have to modify the front Lower Control Arm, as we had planned. No big deal.

Now for the last wheel test fit of the day: Some used 18x11" CCWs I just bought for the hell of it:



They fit the E30 well - too bad we cannot afford the hit to the $2010 Challenge budget! But outside of the GRM Challenge itself, these wheels could be used on this car. There's a good 10mm of room to the strut, and the wheel only sticks about 2" outside the fenders (these E30 M3 fenders won't be used, but they have don't even have any extra flare width over the stock E30 non-M fenders), which is the same as our 15x10" wheels. We can make the flares clear these wheels, too.



I've been playing with all sorts of wheel/tire combos this week:


18x10" D-Force with 285/30/18 on BMW E46 330Ci, with M3 front fenders slapped on

Cheers,

[Bimmerman325i]

Terry,

I don't know if it's possible, but can you run the 96-99 M3 spindle with the non-M E36 brakes? or fab a spacer/bracket to do so?

Bimmerworld is selling brand spanking new E36 M3 spindles for $35/each right now. If you can get the calipers and rotors to work with the spindles, your geometry problems are all but solved.

[Fair!]

Terry,

I don't know if it's possible, but can you run the 96-99 M3 spindle with the non-M E36 brakes? or fab a spacer/bracket to do so?

Bimmerworld is selling brand spanking new E36 M3 spindles for $35/each right now. If you can get the calipers and rotors to work with the spindles, your geometry problems are all but solved.

Yea, I know about the Bimmerworld spindles - you are about the 12th person to point this out. :D And we thought seriously about using those, but cannot fit the M3 brakes inside our 15x10" wheels. We also cannot afford to take the hit to the $2010 budget for the various other bits needed to make these work.

And these spindles DON'T fix all of the wheel centering problems....



The E30 M3 above has E36 M3 spindles, '96-99 M3 LCAs, 95 M3 offset bushings, and E36 struts... and the wheel still is not centered within the wheel opening. Its better to use the M3 spindles, it helps, but it doesn't make this swap perfect. That car also has a staggering +10° of caster.

Thanks,

[iflytii]

Those CCW's are sexy!

[Mr. Horsepower]

Now, what about the Sport Evo seats??? For sale?

[Fair!]

Now, what about the Sport Evo seats??? For sale?

Yea, as soon as we get these reclining seats out of the car I'll post them for sale. I don't know what brand they are - looks like eBay. :D

[Fair!]

Update for March 25, 2010: Better late than never? I'm a little tardy in updating the E30 project from work we did 2 weeks ago. We've had some thrashing on the E46 since then, including the first autocross in it (at the Texas National Tour, where it took 1-2). And we've had the busiest week of business ever here at Vorshlag, followed by the new busiest week on record.



Anyway, the GRM Gang of 8 met on Thursday March 25th and we had 3 crews going at once (3 of us met again last Thursday, but sat around and watched an F1 race instead of working - doh!). One crew was busy cleaning - the T5 transmission was thoroughly cleaned (externally), and the rear calipers were cleaned as well. Amazing what you can do with a brass wire wheel brush and a parts cleaner. They calipers will be rebuilt with new seals, pads and rubber lines (and under the safety umbrella none of it will ding the budget - yay!) but the T5 will remain as-is. Don't wanna crack open that case, or risk screwing something up (bad karma). And yes, its a $100 T5. And we have another identical $100 T5 as a spare. That's not some crazy deal, just simple CraigsList searches, done locally. Its not a popular T5 version - its one everyone ignores. More about this not-so-special T5 transmission soon.



We had another group that bolted the trans to the bellhousing and played with some other parts I can't discuss, but if I show any of that I'll spill all the beans - so it'll have to wait. :devil look:



We had another crew of team members removing the stock halfshafts, diff, and 4-lug hubs. That was a bit of a chore, but we had the tools and the know-how to get 'em off - and we did it clean. The rear wheel bearings went unscathed, thankfully. We'll be sliding in the 5-lug hubs (junkyard sourced from a Z3) soon enough, along with the Z3 rotors and rear calipers.



We have a LSD equipped E30 diff in a very desirable (for our build) 2.79 rear ratio in hand, delivered all the way from Nebraska free of charge by a kind soul that was coming down to the Texas Tour two weekends ago. Saved us a bundle in shipping this 90 pound lump! Thanks again Christy. :) Not much to see with that yet - its still in a garbage bag, and its oily.

The car is temporarily sitting on the wrong trailing arms and 5-lug hubs - these rear arms and hubs are straight out of a Z3, and widen the track by a whopping 3.5". With the hubs swapped into the proper E30 trailing arms we only gain about an inch of track width over stock, or so my crude measurements make me think (see rotor pics at the bottom of this post). We raised the rear ride height all the way up, thinking the little 15x7 bottlecaps wouldn't clear the fenders. It looks... hilarious. We just wanted to get it off the dang lift so we could prep the E36 M3 and E46 330 for upcoming track and autocross events they are being run at this Saturday and Sunday (we just don't have enough on our schedule).



The E30's old M20B27 motor and Getrag 5-spd trans are being sold this Friday for $300, and that will take the purchase price for the E30 back to $200 in the budget. Once the front and rear seats are sold that should bring the sum down to nearly $0 - which is a common achievement among $200X GRM competitors.



We've got a bit of reinforcement work to do on the stock E30 rear trailing arms, subframe, trunk floor/diff mount, and several bushings to whittle out of some scrap Nylon that Derek found, but that's going to have to wait until next time.



Cheers,