Tahoe 6-Speed T56 Conversion

[digitalfiend]

Thanks for the feedback y'all...

talk about something out of the ordinary lol good for those whose truck are supercharged or has other mods a friend of mines went through 3 trannies within months apart due to his supercharger

Yep...now I can look into a turbo or supercharger upgrade without worrying about the transmission grenading.

How does the short throw feel in a truck as opposed to a small car? Reason I ask is I've only driven cars with a short throw and trucks and jeeps with the long shifter

The short throw feels AWESOME. I've driven a couple mustangs that had aggressive short throw shifters and it feels exactly the same way. I held off posting this until after I got the short throw mod done because the stock T56 shifter is not designed to be used in a Tahoe and desperately needs to be upgraded. Unfortunately, I went a little overboard with it though and the throws are a little too short. I think I'm going to do a new one that's only a 1.5" extension instead of the current 2" extension on the inside of the shifter...this should help strike a happy medium of the throws being just right. The current 2" setup is totally functional, but it's just not as tame as I'd like it to be.

750 lbs of torque. I wanna see a burn out video. Nice work!!!

+1, we need a video

You two are crackin' me up. Just to be clear, the tranny is *rated* at 750 foot pounds...I'm still at the stock levels of output on the 5.3 engine that came with my Tahoe. However, despite the engine being stock, this mod really brings the truck to life and I can abuse it like a sports car when I feel up to it. When I upgrade the rear gear to a 4.10 I'll post a burnout video or two.

Very cool...

I must be getting old though, I'm pretty content with an automatic on my commute. I drove stick shift on my 100 mile commute for 3 years and I've had enough of that. LOL.

I still have my 6spd Corvette for my fun car when I feel like rowing through the gears, so I haven't totally walked away from manual gear selection.

Four speed automatics were a great improvement over the previous 3 speeds but were pretty fragile and they're antiquated now when you see what's out there.

My STS-V and my Audi A6 have 6 speed automatics in them and those two extra gears really make a difference. I had a Mercedes with a 7 speed auto for a month as a loaner car and even with a four cylinder the car was always in the right gear for what I needed from it. I believe Mercedes is working or has an 8 speed automatic now.

Your conversion is definitely a clean job from appearances, glad it work out for you.

Thanks Wake! I'm still young and stubborn enough that I don't mind driving the manual. And yes, the extra two gears make a huge difference.

 

[BirchyBoy]

I'm not familiar enough with models, but the T-56 seems to be built for sports cars based on Wikipedia. I wonder how it would be for towing a trailer. Have you put any thought into that?

 

[Rivieraracing]

Talk about a cool idea, would love to have a stick shift in the denali!

 

[digitalfiend]

I'm not familiar enough with models, but the T-56 seems to be built for sports cars based on Wikipedia. I wonder how it would be for towing a trailer. Have you put any thought into that?

Good comment about the sports cars...great question about towing too...I overthink most things so of course I thought of towing!

Normally, yes, the T-56 is built with a rating of 300-400 ft pounds of torque and intended to be used in a 3000-4000 lb car. With that stock rating I wouldn't try towing much at all.

However, the T-56 with some internal upgrades similar to the one I'm running should give a lot of capability to tow. Personally, I don't regularly tow anything, but I'm comfortable that my Tahoe will tow anything I will be throwing at it. There has been *some* discussion of this in the original performancetrucksDOTnet thread. In this post from the conversion thread, TurboGibbs writes:

"FYI - I just towed 8500 lbs for 3 hrs at 75-85 mph on hilly terrain with an LS7 clutch and a LS1 T56.
I guess it is a good towing trans too!"

The biggest thing to watch for once you have an upgraded T-56 when it comes to towing is the clutch...don't put a basic stock camaro clutch in one if you're going to tow a lot of weight. If you're going to tow a lot of weight then you should invest in an upgraded clutch, like an LS7 or aftermarket clutch. In fact, you should plan on running a beefier clutch anyways because of the difference in weight of a Tahoe compared to a camaro. I went with a basic used clutch just to get my project off the ground and I'll be upgrading the clutch to something stronger if/when it dies.

These transmissions have been used in everything from camaros to vipers to corvettes. It's definitely possible to snap the input or output shaft of a *stock* T-56 by launching ******* slicks with nitrous...but that is also why companies like Tick Performance have different levels of upgrade/rebuild packages that are rated to handle from 450 to 900 ft lbs of torque.

If you really want to go balls out and run an extreme turbo/supercharged/nitrous setup through a T-56 then you could always go with a rebuild package or upgrade to the T-56's big brother the T-56 Magnum. I almost went with a Magnum but I decided against spending the extra money for a Magnum after I realized the great availability of used T-56 trannys, repair parts, and strengthened upgrade parts.

 

[M Hankel]

Awesome job man!! Funny I found ya on PT today in searching for parts for my own T56 swap lol.... I was going to mention, depending on your tire height you could definitely go with a deeper rear gear than a 4.10. I ran 4.10 gears in my camaro as a daily driver and also freeway commuting 120 miles a day without a problem and that was with a short 26.5" tall tire. I'd go with a 4.88 at least if your tire is around 30".

Play around with this calculator and you'll see what I mean. You will thank me later.
http://www.ringpinion.com/Calculators/Calc_RPM.aspx

Mike

 

[Chevy305]

I love to see these conversions! I despise my auto too and hope to do this swap soon. I read that thread over on Performance Trucks a little while back and its great for a 2wd but I'm 4wd so that complicates it a bit for me. I want to run a NV4500 and ditch my autotrac tcase for maybe a 241 or similar.

How's the shifter placement? Is it awkward with the armrest down or is it more comfortable?

Sent from my Galaxy "LS3"

 

[hoe]

Op you did a nice project kudos for that. But honestly the 4l80e is a better stronger transmission Than that. You did nothing wrong at all at stock power levels. Some hd silverados are stuck shift. But the 1tons etc were 80e auto trans. A used 80e with a shift kit can rollout 800# easy and hold 600hp fairly easy too. That's sorta hwy I went 80e. Plus turbos spool faster with auto.

I'm looking for a corvette. And I'm looking to put a 80e auto into it.

 

[M Hankel]

Op you did a nice project kudos for that. But honestly the 4l80e is a better stronger transmission Than that. You did nothing wrong at all at stock power levels. Some hd silverados are stuck shift. But the 1tons etc were 80e auto trans. A used 80e with a shift kit can rollout 800# easy and hold 600hp fairly easy too. That's sorta hwy I went 80e. Plus turbos spool faster with auto.

I'm looking for a corvette. And I'm looking to put a 80e auto into it.

The word "better" is one hell of an exaggeration when comparing the two transmissions. Built T56's have lived behind 8 sec capable cars so I'm not sure why you chose that description. Every trans can break at some point. If you read his first post he didn't do the swap solely for strength but because he enjoys "driving" a vehicle with a clutch. For a select group of people an automatic is very boring and disconnected from the vehicle, myself being one of them. I personally hate having an auto constantly hunt for the correct gear, giving it gas and wondering if its ever going to downshift etc. With a manual trans you always know what to expect in any condition. I will also be looking forward to a 5-6 mpg increase on the highway.

Mike

 

[Chevy305]

^^^^ Well put. Auto transmissions just feel lazy to me. I want be engaged in the driving experience and have full control over my vehicle. No auto transmission can anticipate the road ahead like I can.

Sent from my Galaxy "LS3"

 

[01ssreda4]

Nice work.