T56 6spd Manual Transmission install into a Gbody

Built6spdMCSS

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Someone asked me if there was info about this so I figure this would help some people out.

Putting a T56 6spd into a Gbody is pretty simple and straighforward, not much to it, just like installing any other Transmission pretty much.

It's good to start with getting all the parts:

T56 6spd Transmission (LT1/LS1 Fbody or GTO Type)
Clutch, Flywheel, Pressure Plate, Pilot Bushing/Bearing
Clutch Pedal & Hydraulics
Shifter & Crossmember (several companies make one now for Gbodies)
Depending on what you have in the car you may need a driveshaft or work done to the current one you have if you do not want to buy a new one. It uses the standard GM 27 Spline Slipyoke

I bought and built up a low mileage (like 20k miles on it) Tremec T56 6spd Transmission. Along with it, I bought the GM LS7 Clutch Kit with ARP Flywheel Bolts., I have a 6.0l LS Engine in my car, you guys with the Gen 1 & 2 SBC just get the appropriate parts & LT1 Fbody style T56 Transmission.

Since most of these cars were factory automatic there is no factory Clutch Pedal that will work with this. You can buy one from the few people that build them, or you can build your own.

I installed the Master Cylinder on the fire wall like it would have come in a LS Fbody. Once I did this I built a Clutch Pedal using parts from an early 90's S10 Pedal. This seemed to work perfectly for the geometry and full movement of the Master Cylinder. The geometry and movement are critical in this case, it has to have full movement as straight as possible so the rod will not bind and bend.

$7 at the junkyard and a few hours of time I had a Clutch Pedal built

Sueh4JO.jpg


I hammered on the fire wall until I got it flat to get the proper angle for the Master Cylinder

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The Fluid Reservoir was mounted on a bracket I made then bolted to the Brake Booster

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I used a longer grade 8 bolt and mounted it next to the factory Brake Pedal. I cut the Brake Pedal down so it would clear the Clutch Pedal and use the proper size Pedal Pad

2l55eGX.jpg


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I bought the T56 and got to the shop with it, then tore it down for inspection. Everything looked pretty much new but I always upgrade them

dgz4YP0.jpg


Parts showed up a couple days after to build it with the LS7 Clutch Kit. If going LS buy a Speed Bleeder, they are worth it

EC340Ug.jpg


I re-built the T56 with the upgrades and it was ready for install

sr2a0ji.jpg


Pilot Bushing installed and LS7 Flywheel was bolted to the back of the 6.0l

2L1bC7i.jpg


LS7 Clutch Disc and Pressure Plate installed

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Recently I over-hauled my setup and installed a Monster Stage 3 Clutch, it's holding much better. Putting the pic here for reference.

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Slave Cylinder with Speed Bleeder mounted on the Transmission ready for install into the car

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Once I figured out where the Transmission ended up I cut the hole for the Shifter

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After the shifter hole was cut then the Crossmember was installed into the car and driveshaft bolted up

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The Shifter was then installed and the Center Console put back together. I made the custom Shifter Plate for my SS

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I painted an extra gear indicator plate that I had to put on the speedo to cover up the original automatic gear indication

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Then bleed the Clutch out and take it for a drive. Nothing much to it really and it's pretty fun to row gears with..

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ssn696

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[I annotated my questions after finding some posts from earlier this summer.]

1. Is that a Jeg's 700-R 4 crossmember? It looks like the driver's side had to be bolted on under the frame rail extension. Any issues with the trans mount being 'tilted'?
- The answer is Jeg's - from the LS1tech posting.

2. What mods to the trans tunnel were required? Looks like 'none'.
- The answer is massage via hammer only - from the Speedo PIC HEAVY posting.

One new question: who fabricated your chromoly driveshaft? I need one of those.

Thanks for taking the time to take photos and write this up. Thumbs up on making this a sticky.
 
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pontiacgp

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I'd put a double on the firewall. I cracked the firewall this year and broke the shaft on the master......

CLUTCH%20PEDAL4_zpsoaetqy8q.jpg
 
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ssn696

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Built6spdMCSS

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Jun 15, 2012
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Thanks for taking the time to repost the photos and description on this forum from your LS1Tech thread.

In summary, you have documented the recipe to make a stout Gbody with all the best hardware that arrived after the end of the G-body era.

http://ls1tech.com/forums/conversions-hybrids/1788493-merv-s-1984-monte-carlo-super-sport.html

Thanks man, I put a ton of info in it.

ssn696 that thread there is the old one, this one here is the new one and has alot of updated info in it for people.


[I annotated my questions after finding some posts from earlier this summer.]

1. Is that a Jeg's 700-R 4 crossmember? It looks like the driver's side had to be bolted on under the frame rail extension. Any issues with the trans mount being 'tilted'?
- The answer is Jeg's - from the LS1tech posting.

2. What mods to the trans tunnel were required? Looks like 'none'.
- The answer is massage via hammer only - from the Speedo PIC HEAVY posting.

One new question: who fabricated your chromoly driveshaft? I need one of those.

Thanks for taking the time to take photos and write this up. Thumbs up on making this a sticky.

Yea, that is a Jegs 700R4 Crossmember installed the way it is to accommodate for the T56 Transmission height into the tunnel. I raised the tunnel about an inch and that was as far as I wanted to go. Crossmember has been modified to work correctly, pic updated.

Driveshaft was made at a local driveshaft shop here that unfortunately went out of business. It's 3" seamless Chromeoly steel rated for 800hp with 1350 Spicer Joints.. It might be heavy but it's balanced and you can't really tell it's there. I've never had issues with it.

I'd put a double on the firewall. I cracked the firewall this year and broke the shaft on the master......

CLUTCH%20PEDAL4_zpsoaetqy8q.jpg

You can barely see them but there are some large washers there, that and the Master Cyl is actually metal instead of plastic, so sandwitching everything together nice and tight. I hammered on that area of the firewall too so it's been work hardened, and if you notice a slight bevel in for strength. I'm willing to bet it's a little stronger than just plan sheet metal.
 
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pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
You can barely see them but there are some large washers there, that and the Master Cyl is actually metal instead of plastic, so sandwitching everything together nice and tight. I hammered on that area of the firewall too so it's been work hardened, and if you notice a slight bevel in for strength. I'm willing to bet it's a little stronger than just plan sheet metal.

I had one of the rods on the right side that the F body used to strengthen the firewall but could not fit the rod on the left side so I used a large washer. It took about 4 summers but it cracked the firewall on the left side. I just wanted to mention it cause I got stuck with it about 60 miles from home.
 
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81cutlass

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Feb 16, 2009
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You don't happen to have the measurements on where the hole in the floor gets cut?

Good info on the clutch pedal using s10 stuff. Did you determine the angle on the pedal by guessing or mocking it up? Im assuming you just put the master in the firewall and cut the pedal off the upper part and position it in place before welding?
 

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