Drenth gearboxes

[Reaper]

450 pound bike plus a 180 pound rider and a tiny contact patch put alot less stress on a motorcycle transmission than a 2800 pound car. They also don't last much past 40K miles and have their oil changed constantly.

[Ultramaroon]

Originally Posted by Reaper

450 pound bike plus a 180 pound rider and a tiny contact patch put alot less stress on a motorcycle transmission than a 2800 pound car. They also don't last much past 40K miles and have their oil changed constantly.

I would agree except the gearboxes are designed proportionally to the application. I've split a few cases on street bikes and the bearings always took a shit before the dogs.

Maybe it's just a matter of application. People buy an aftermarket tranny pretty much exclusively for track use so they're 100% getting spanked all day? Dunno. It just doesn't make sense.

[Dipstik-sportech]

Originally Posted by edeekeos

Wow. This is unsettling. What's crawford doing with theirs? Don't they have a 450+ setup?

They have 450 crank HP. I'm at near as makes no difference dyno proven 500whp and I've never destroyed 4th gear.......yet.

[FirestormFRS]

Do the swap to the Tremec and stop wasting money on OEM trannys.

Seek and you shall find.

[D K]

Sequential makes no sense whatsoever unless its a dog box.

Race transmissions are often conservatively rated for use over a long event, such as 24hrs.
That being said, a roadracing application is much less strenuous than a drag type application.
Our boxes shear 4th just like the wrx boxes shear 3rd. Most likely the rrason is that its farthest from a carrier bearing which allows shaft flex.
Straight cut gears are much more immune to this than helical gears.

Spur gear with a dog engagement is what works for me, but that comes with a heavy price more ways than one.
Complete teardown around 75 hrs being one.

However, a proper race box can be torn down in minutes as I remember swapping out gears in a Hewland in less than 30min.

[D K]

On a side note....
If someone was to design a spray bar for our cluster with a cooler, I bet we would increase our trans strength considerably.

[Reaper]

Originally Posted by FirestormFRS

Do the swap to the Tremec and stop wasting money on OEM trannys.

Seek and you shall find.

Already found it. He wants 5 times what I just paid for a stock transmission for just the tremec conversion bellhousing.

[D K]

Originally Posted by Reaper

Already found it. He wants 5 times what I just paid for a stock transmission for just the tremec conversion bellhousing.

Which Tremec? Magnum or TKO?

[Dipstik-sportech]

And as I've stated numerous times, no matter what he tells you without major internal mods the tremec will not shift over 7000rpm.

[Reaper]

Tko. Magnum won't fit in the tunnel. Liberty gear says they can fix that. But I have no personal experience with a dog faced tremec at 7k rpm.

[mike the snake]

The Drenth and Elite boxes are "drop gear" designs I think, so servicing is pretty easy if you know what you're doing.

http://www.eliteracingtransmissions....l300-6s-evo-2/

[xwd]

They are as is the Hollinger. The proper race transmissions are definitely going to be easier to work on and deal with than an OEM one which isn't really meant to ever come apart.

The Hollinger box was used in the GT86 rally america car Nameless was a part of. Not the same exact box since it was a custom job to fit it, but same basic gearbox/gearset. That car was turbo using a EFR of some sort, but wasn't pushing a ton of horsepower.

Does anyone know of anyone making a replacement dog/straight cut gearset for the stock transmission case?

[mike the snake]

Don't you think the cost of straight cut gearsets with dog engagement would probably cost near what one of these other boxes would cost? Plus the cost to convert to sequential?

Plus, our boxes have shown to be weak, modifying them might help a little, but compared to a racing gearbox, I don't know.

Originally Posted by dwx

They are as is the Hollinger. The proper race transmissions are definitely going to be easier to work on and deal with than an OEM one which isn't really meant to ever come apart.

The Hollinger box was used in the GT86 rally america car Nameless was a part of. Not the same exact box since it was a custom job to fit it, but same basic gearbox/gearset. That car was turbo using a EFR of some sort, but wasn't pushing a ton of horsepower.

Does anyone know of anyone making a replacement dog/straight cut gearset for the stock transmission case?

[xwd]

I don't think a sequential dog gearbox is really necessary for just about everyone. It would be a pain in the ass to drive on the street as much as the Hollinger guy shows how civilized it is. You would really want the setup they have where the ECU automatically rev matches on downshifts. They are using a Motec which is another $4K, not sure if you could rig an input via Ecutek to do something similar.

People had some success in the Impreza world with replacement gearsets, PAR engineering makes a synchro set for the 5MT which guys have taken to fairly high HP levels. It's nowhere near the cost of one of these sequential boxes and besides the whine of straight cut gears it's still synchro'd and drives like a stock gearbox.