lock pins - made from spring steel
pinion shafts - made from roller-bearing steel and after harden

 

So the shafts get stuck inside the gears probably from overheating, expanding fracturing or whatever. In any case, it implies heavy load on diff.
If you put superstrong pins to hold shafts from rotating with the gears, then what? Either shafts will go, or the gears will destroy.
The solution should be to prevent the shafts from getting stuck inside the gears. The pins are just a fuse there.
David, can you comment on how exactly you are dealing with this problem?

 

The pins we have seen completely fail and break.

 

Simple answer to not breaking the transmission is to change the transmission fluids.
I abused my evo on track, gravel till today which is already 10000 KM and no problem for transmission or clutch.
Good luck guys and please dont babysite your car!

 

I would suppose its best if the pins broke than anything else.

 

It would make every gear 'taller', but not mess up the ratios between them.

My goals:
1) finish the 1/4 mile in 4th gear with some room to spare.
2) better gas milage/less wear and tear @ 80mph.
3) I also drive it on small road course which is 95% second gear, and I think it might put me in a better part of the powerband for the faster stretches and save a shift or two into 3rd.
4) I could also run a smaller dia/lighter tire without worrying about spinning the motor even faster on the hwy.

 

I bought a used trans to rebuild that already had the pins broken on it. He had an upgraded turbo, running meth, somewhere around 450whp/400ft-lbs, I believe.

My current trans is still holding up at about 380whp/340ft-lbs..... for now.....

 

That's what I'm wondering. Just how much power were people putting out with their X's to break the tranny and/or differential pins? I'd like to think that it would be able to hold up to definitely stock power, and hopefully with some mods. ~350 hp/tq at wheels.

At what point should you upgrade your trans and differential? I know it's cheaper if you do it before it breaks.

 

I don't think it's the matter of how much power you have in the car, but certain conditions where diff is overheating causing the shafts to get stuck. You can break the pins with a stock car (which already happened not once).

 

What would be the best place to go for a built tranny?

What are aftermarket options for the diff in the tranny as well as the others?

 

Bump for any more info on development of a taller final drive!

 

Kevind says you don't need it. He thinks you should be able to redline the car and shift and be in boost still. I told him you were having this issue and see what he thought.

 

David, my mileage is still low ( about 4400 miles ) what can I do to prevent this? A fluid change to a particular type? Perhaps a different shifting method?

 

You could send your trans in and have it worked on to prevent the problem. It doesn't seem anything that you mentioned will prevent the poor engineering design...

 

It's possible that with a really quick shift from 4th to 5th you would only lose .2-.3 seconds and ~2 mph but if you are shooting to optimize quarter mile times that extra shift really stinks. Maybe a "No Lift to Shift" option would improve that as well. If the car was laying down oh say 800 crank HP like the AMS time attack car, then it would be no big deal shifting to 5th at ~115 mph since that would be right after the 1/8 mile and you can finish the back half of the quarter in 5th from 115-140 mph for a low 10 sec pass. The problem is laying down 800 crank HP and having to row the gears that fast has got to be inefficient to say the least, it already feels like overkill with my GT30 with gears that are too short.

Probably it would be ok with around 600 crank HP or mid/high 10's at 128 mph where 5th would feel like it's pulling you through ~15 mph of speed versus under 5 mph like it is now at 500 crank HP. So maybe the answer is just mo power: cams, intake manifold and race gas to get better use of shifting to 5th!