neverstop

So I want to hit the standing mile (and 1.5 mile event) and Shift Sector events, I have a 2005 corvette with ~680whp and 630tq that has a nearly new RPM built t56 with ~3k miles on it. The transmission shifts like butter and I love it but I just heard that the t56 can't take >700whp in 5th or 6th gear, wish I had known this before as I would have upgraded to the tr6060 when I had the transmission out....

I would really like to turn the power up to 750-800whp and go rip it through 5/6 gear but I don't want to drive all the way to the event and then break my car on the 2nd run....

How many of you out here are running t56 tranny with 700whp+ that have done standing mile events and given the car full throttle through 5th and/or 6th gear multiple time?

any insight you guys can share is much appreciated.

oscs

iTrader: (19)

A large portion of failed gears in the T56 are Becuase of inadequate lubrication. Install a trans pump and go for it.

https://ls1tech.com/forums/manual-tr...rip-trans.html

JoeyGC5

iTrader: (24)

I've made 15+ standing mile passes on my RPM built stage 4 6speed from 175-195.12mph with no issues and clean fluid at every change. I normally drive it like I stole it, have clean clutch fluid and smooth operation, with frequent gearbox ATF fluid changes.


Rick Hoback has taken his stock 99 C5 M6 STS twin to 203mph and beats his like no other on the road and standing mile courses as well.

Harleyreb1

Good to know, I'm in this same boat, I'm building a 200+mph standing mile fbody with a t56

stevieturbo

I've done many many 1.25 mile, 1mile, 1km runs over the last 8-9 years or so with my T56.
It's an old box with the crappy 5/6, not the one piece cluster gear/shaft.

Many many 190+ runs, even more 180+ runs, and also one 200+ run.

Traction is the only problem Ive had ! lol

Ive a 3.27 rear, 255/40x17 tyres for most runs, although using 235/45x17 now and the 0.74 5th gear which seems me hit 200mph around 67-6800rpm.

Most recent runs a month or so ago...box was screwed as far as shift mech goes so really couldnt do anything until I got into 4th and 5th, 3rd was near impossible to get, but managed to go from 123mph at the 1/4 to 183.7 at 1km. 5th gear worked fine

If the run wasnt screwed up because of gearchanges it would have been 180+ at the 1/2 mile and 190+ at 1km

Yes there are stronger options out there, yes you can uprate on many levels. But I wouldnt be too concerned about the T56. They are strong.

oscs

iTrader: (19)

I installed a used pump/fittings and hoses for less than $150. It's worth the insurance

stevieturbo

Oil isnt the issue with the 5th/6th gear.

It's how the rear part of the box achieves it's drive connection to the front, where the 5/6 mate with the main cluster.

That is the weak area.

The oil pump mod aimed at the input gear is mainly to tackle oil moving away from the front of the box under hard launches.

oscs

iTrader: (19)

Most guys that installed a pump did so becuase of high speed issues (long periods of time with no fluid) and not short periods associated with launches. Nearly all the gear failures I've heard of/seen have been on FI cars in 3rd gear or higher not launches. Read the thread there is a lot of good info from trans builders and everyday people in there. You are correct that the 5/6 gear section of the trans is inherently weak but I still believe a pump can help tremendously. The heat that is created from an inadequately lubricated input shaft/meshing of the gears can translate to the entire trans very quickly.

stevieturbo

A pump will make zero difference whatsoever to the 5/6 gear interface with the main cluster which would always be submerged in oil...even more so under acceleration.

Fitting a pump would actually have the opposite effect of potentially reducing oil levels at that point though due to further oil movement in the system.

The pump is purely to lubricate the front gears which may lose oil under acceleration.

oscs

iTrader: (19)

I agree that a pump won't directly help the 5/6 cluster as stated previously but installing a pump never hurt or starved a t56 under acceleration like you maybe suggesting and a quick row through the gears (strip) is not where gear failures frequent. Keeping any piece of equipment properly lubricated instead of just half of it has obvious and not so obvious benefits. I would also like to point out that the amount of fluid it took to fill my pump and lines was very very minimal

At the end of the day his question was about the 5/6 gear mesh so I suppose you are correct as a pump does not directly prolong the life. I guess what I'm saying is I feel it is a good and cheap upgrade that can have many benefits.

neverstop

thanks guys, it sounds like my t56 "could" survive this application at this power level but the more I think about this the more I want the confidence at 200+ mph and the ability to do 40+ passes of 160+ mph in a day that I'll likely see at some of the local roll racing events. It seems like my transmission is fine at my current power level but the rest of the setup has potential to do much higher power numbers also and I'd like to be able to crank it up without worrying too much.

appreciate the input everyone.

anyone want to buy a nearly brand new RPM stage 5 t56 that works perfectly and barely a few thousand break in miles of street driving? I have receipts and guarantee it works perfectly.....

pretty damn dissappointing, I wish my tuner or RPM would have mentioned this when I was upgrading my whole drivetrain

stevieturbo

Why not speak with RPM to see exactly what you have inside ?

at a stage 5, it may already have the uprated 1 piece cluster for 5/6 etc

When I had mine done 7 years ago elsewhere, **** like that just wasnt avaialable. It'd be commonplace now

neverstop

thanks Stevie, my t56 has all the goodies but they seem to think the risk is of the t56 potentially shearing the gears off the shaft on 5/6th gear and the solution is that the tr6060 just have bigger gears.

RPM has a bit of an inherent conflict of interest if I call the barber and ask him if I need a haircut so good to hear the consensus here to help me with my decision and decide maybe how close to the edge of the t56 I might be.

stevieturbo

So that's a potential problem then relating to the one piece cluster that would differ from the older 2 piece ?

How many such failures have they actually seen ? If any ?

neverstop

they said they thought it was an issue in any t56 as the size of the gears are just not huge and so if you're putting 1000hp through them it can be an issue. He said they've seen "more than a few" t56s with 1000hp (at the engine) rip the gears apart and he said that for the 700+ whp cars the tr6060 is the way to go and they have quite a few guys running around with 1000whp on built tr6060 trans without issues.

I'm not an expert here though and just repeating what I was told.