Hi speeders,
Today I raced an Alpha12 GTR with a Dodson x0000$ gearbox claimed 1153whp and killed him pretty easily.
We did 60-160mph rolling races and I believe the car does not produce more than 850bhp...
It confirms me better speaking about times vs dynosheets (****s!).
This is the nice point but my gearbox became a bit "chewy" and my 3rd gear synchro went, of course a stock gearbox couldn't lasts 850ftlbs for long...

So I need your experience to fix and upgrade my gearbox (already stupidly rebuilt it stock 5000km ago).
I know 97GT2 gears can't be bolt in a 97TT, that's all...
Good advices needed!
Thanks,
P.

 

why not buy a 996tt gearbox and build it? then all the 997gt2 gears bolt in as well as the billet trap door side plate and shift forks from cms

 

That is perhap's/probably THE solution, sure.
I have heard about 997TT gearbox upgrades but no news for monthes...
I have heard again the 997 gearbox cast case is stronger vs 996's.

 

unless your sticking a mainshaft out the side i doubt the strength of either would be an issue. if the 997gt2 gears wont fit your box maybe check with guard transmissions? do they have any custom setups that would fit? can you build a dogbox out of the 997tt trans? prodigy would be the person to ask he has a 997tt and works closely with tim941nyc who has built just about everything porsche turbo

 

I think guard was working on it but I don't know if it is out yet.

 

I know there are a few of us ready for some 997 gears. My personal gear box is fine now, but once I get my new motor installed I dont think it will last long.

 

2 options are here:
- first one, solid, available: a built 996TT gearbox.
- second one: to rebuild the 997TT one, I would like, but what's the point with the available parts?
In the first case (996) already known, will it truly hold and last true 1000hp/850lbsft?

For sure Swole Powell and Prodigy will be in the same boat very soon imho...

 

I am curious on the clutches that are being used in these gearboxes that are failing in the 997's. I know with the last 10 revisions of a certain clutch on which I will not speak the name (like Harry Potter), it had issues with the discs dragging between shifts which obviously would cause issues.

Are we seeing sprockets being sheared clean? or synchro / random damage?

I know that in some of my older cars that had "bullet proof" transmissions, heat was one of the main issues. Using certain types of fluid helped, but a dragging clutch was a huge issue in most of the failures that were seen other than heat related or just weak gears period.

How are a lot of these 997's making 800+whp managing without issues? I know that there most likely are a lot of them that don't post about it, but I figure we would hear more if this were the case.

Thoughts?

 

Hi Rob,

-my clutch is a twin disc from Protomotive, not the lightest but smooth and efficient. I don't believe it drags between shifts.

-The gearbox is still in the car for now, I expect the clearance washers and pignons faces being machined by the axial force dued to the helical cut under heavy loads, so excessive clearances and uncertain gear locking.
Notice the gears (all) do NOT pop up once locked.

-I use the same trans oil as GT3 cup, my car is serviced by an official French Porsche racing team.

-my experience tells me until 950-1000Nm this gearbox is ok, above 1000Nm the issues are coming, my car seems producing 1150Nm (840Lbsft) according to the Vbox tool, I believe the 4.5' 60-130 with no shift (in 4rth only) is my gearbox killer.

Thxs for input,
P.

 

Numbers are just numbers...peak power vs. useable power - all vary.

My GT-R makes only 840awhp but she seems to move pretty good. I do pretty well with cars up to 1,000whp. I didn't know Dodson made transmissions for the GT-R though - the only ones I have heard about are Sheps and Jacks...and mine tore up 5th gear badly with about 870 lbs.tq. The 4.2L makes boggles of torque.

But my 911 with only 635awhp (thanks Protomotive!) also seems to run pretty good with cars making 200 more whp - the torque was turned down all the way to 635 also to try to keep everything intact and two years later, she i still running strong.

If you are making 800lbs of tq, it is only going to be a matter of time until things break.

 

In my personal experience the 997 tt trans can hold around 1000 wtq with no problem, it only depends in what gear you achieve this tq.
As some know the 3rd gear is prone to fail in lower tq levels (around 800wtq) but if you manage your tq delivery and increase/release it by speed (possible with the better stand alone ecu like PRO EFI) then you will possibly loss some acceleration on 3rd but regain most of it back in the higher gears as you will be able to get higher tq.
So until better /stronger gears are available the only way to prevent breakdown is tq control.

 

I have no knowledge about this topic but i do know someone was trying to sell a sequential transmission recently.

 

Has anyone tried cyrotreating the gears for more strength?

 

My car is a tiptronic making 760whp & 689wtr . I ended up blowing up the torque converter and pump just last week. Me and my Indy shop decided to rebuild upgrade the transmission gears and go with a nice strong stall converter. This tells you weather you have manual or auto , once you're at that 700whp+ range it is a must to upgrade transmission . Better to play it safe than be sorry.

 

News,
I have to say I adjusted myself my twin clutch as it was not bolted by Protomotive but here in France.
As my goal was to have a no slipping clutch I voluntary let it drag a very little bit thinking it will break in, instead of letting a clearance.
At the beginning ok it was dragging a little and effectively broke in and I didn't feel it anymore.
But before this GTR came I never ran very fast because winter and not a lot of fast cars to play here.
I remember during the run the faster I run the harder was the shifting.
I shared with Todd and techs and finally believe yes my clutch was still dragging.
In a few days the gearbox will be out, Todd send me a new clutch preset by him and I hope only the synchros went, I will share.

Ps: and clever advice Rob, out of clutch brand.