And won consistently, even though no one else could drive his car.

Has anyone actually driven a solid diff in a car? SpecE36 is allowed a 25% diff or a welded diff. Consensus is that the welded diff would be insane. I'm wondering if there is a minority report.

Mark also had 1500hp. A solid diff helps put the power down. I imagine you can get the rear end to drift a bit with 1500hp... He is also known for an insane amount of trail braking.

Peter beat me to it. I'm not sure a normally aspirated M50B25 is going to make anywhere near enough power for a locked diff to make any kind of sense. The only locked diffs you see in motorsports these days seem to be on dragsters and off-road trucks running on loose surfaces.

I wonder if anyone runs them on the track? I know most of the old IMSA guys used to run Detroit Lockers and stuff, so there must be something to it in high-HP/massive-torque settings. Seems like it would be a recipe for terminal understeer for guys like us.

I was wondering because I am spending a lot of time waiting for my inside rear to touch the ground. Shift-light, shift light, Screech, bog bog, go. It is also irritating to have the rear inside come up mid-corner while you are trying to balance the car with throttle.

I guess insane trail braking + power oversteer made it all work. If it was good someone would be using it. I have heard informally that there are spece36 cars with 75% diffs, but it's hard to tell which ones from the outside and I'm not interested in going there.

From the point of view of competition in class I'm guessing that the really fast guys aren't cheating, so they are putting up with this too, and I'm getting well and truly smoked fairly.

From the point of view of driving a balanced race car, I'm irritated. There was actually less of an issue when we had less sticky tires last year, but the new tires are faster and we can mix it up better with the big boys on their hoosiers, so I'm not going to lobby that we switch to all season general-cooper-no-names in the name of balance. Allowing a better diff wouldn't fly either at this point given that we just switched diffs from 3.91 to 3.15 for unfathomable reasons.

Probably I won't run out and buy a welded diff to see if I'm the one guy who can figure out how to use one in a car with sticky tires and no power.

Sounds like the SpecE36 suspension is too soft for R-comp tires. Most SpecE30 racers have the same complaint. No one understands why they went with the highly unpopular H&R Race suspension when all the "fast on a budget" E30's were running Turner J-Stock springs and Bilstein Sport dampers. Why reinvent the wheel when you already have a proven (and very affordable) setup that's known to be a terrific match to RA-1 tires? One can speculate that H&R offered enough $$$ support to convince NASA to stick with them.

As for the diff: do the rules specify a "welded" diff...or just a "locked" diff? If they only say "locked," then maybe you can go with something like a Detroit Locker that only locks under acceleration. If I understand correctly, those diffs free-wheel until power is applied. So turn-in understeer should be less of an issue.

In discussions I have had with bmwcca rules people, as far as I can tell, the sponsorship opportunities offered by a spec class far outweigh handling considerations.  The spece36 spec suspension is softer than the stock (JCW) suspension on my sporty mini cooper GP street car.  It would have been nice if someone had built a car and spent a year or so racing, modifying, racing, until they had something that seemed like it would be a well balanced  awesome spec car.  Instead, we are working this stuff out now with an active class and it will be hard to change things.  

Car perfection seems to be bugging me more than other people in the class. It might make sense for me to eventually move to a class where there is a little more freedom to spend myself into a smoking crater.

I've just been looking at the bmwcca prepared rules. Strangely, prepared is not just "more" than spece36. I'd actually have to put stuff back onto the car and add 140 pounds before experiencing all that freedom.  The rules are the rules.