GCU = air shifters?

As for fluid. Redline Heavy Shock proof is the ONLY fluid I would run in a gear box subjected to forces beyond its ratings. I had a STOCK 5 speed last for over 2 seasons of AutoX / Pro Solo launches at significant power levels and very sticky tires using nothing more than that fluid.

The same set up with regular fluids would only last a couple of events, at most, before going boom.

Think long and hard about what "ECU" stands for, then substitute the word "Gearbox" into it.

Don't most people call it a TCU rather than a GCU?

I know that most car manufacturers call it a TCU but perhaps it is different for aftermarket units.

Keith

Amsoil Severe Gear 250 is supposed to be even better than Redline Shockproof. It's also thick as wet concrete, so you can expect it sucks up some more torque. Anecdotal evidence quoted here:

Amsoil Severe Gear SAE 250, Medicine for Weak Transmissions

says that it will keep a 1 weekend transmission alive for an entire season.



There are several other weights now, but I don't know of any reliability data on the lighter weights relative to 250.

AMSOIL Synthetic Gear Lube - Gear Oil

I think I broke at least 3 5 speeds running nothing but redline heavy shock proof.

Broke seven 5 speeds and four 6 speeds and counting. Stacking them up like cord wood.

I broke 7 5 speeds before going to heavy shock proof. After I went to Heavy Shock Proof I only broke 1. Results speak for themselves.

My results were that the shock proof made no difference in time between failures.

Makes sense to me. I tried Shockproof in my diff and I've never seen a fluid break down so quickly and so massively. Nothing Redline makes has decent heat tolerance, in my experience (based on uoa results). I could see it working in an autocross car that doesn't get the gearbox hot, but not doing jack shit in a road race car that essentially overheats the gearbox every session.

When I was much lower Hp ~200 doing mostly track stuff . I also ran all sorts of mixes of tranny oils. The redline mixes of different amounts of shock proof grades, straight shock proof and down to straight mt90 all seemed to produce higher temps than even just cheap volvoline synthetic. actually Royal purple 75W-90 seemed to have the lowest friction. but nothing made a noticeable difference in extending tranny life when I bumped up power levels with over 300 ft-lbs of torque and even though some ran hotter than others I never burnt tranny oil eather. With the 6 speed Amsoil MTG feels the best with the syncros so that is what I have been using.


I did just order some Amsoil severe gear SAE250 to try. Maybe it will do something.

Have you guys tried dumonde tech trans fluid? Its shitty when its cold bite efect once it heats up.

Yep broke a 5 speed with that in it too. lasted two weekends. I broke a clutch fork shift ball at Thunderhill and put it in at AR auto on my way from Thunderhill to Packwood for autocross a few years back. friction characteristics were different in it seemed to get more slippery when hot but its not particularly high viscosity when cold.

Seems like the focus of that oil was how it behaved with syncros not so much about low friction or extreme contact pressure.

Getting
- New motor mounts (70D)
- New gears (main+3rd)
- Some Castrol oil
- 12.9 bolts for the extension housing
- Slight detune low-rpm

Should be good for another season.

Can't help it, Grand Torino reference.

Stupid question: Has anyone experimented with coolers on the gearbox or differential?