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#540667 - 03/03/08 05:21 PM All that have installed a T56 into a G-Body...Help
79MeanGbody Offline
Member

Registered: 08/15/05
Posts: 315
Loc: Columbus Grove, Ohio
I installed my LT1 T56 yesterday. Went in smoothly but I'm having a clearance problem between the top of the T56 and the tunnel. I have an Iceman T56 x-member and for it to be installed correctly the trans. would need to go up another 1"-1.5". The problem is that it is hitting the tunnel right now. Iceman said I could send him the x-member to check it in his jig to make sure its the correct one but I'd like to avoid that because I have a feeling its the right one. There is a rubber piece on top of the T56 that I may take off to see how much clearance I can gain but I'm doubtful it will be enough. Does anybody know if the 78-81 Cutlass tunnel might be just a little smaller? Please offer some suggestions. Thanks
_________________________
'79 Cutlass
-10:1 Crate 350 - Worked Vortecs - XE274 - Edelbrock 750
-Hedman Long Tubes - 2.5" True Duals - X-pipe - Dynomax Bullets
-T56 6 Speed - LT4 PP - RAM Powergrip - Pro 5.0
-8.5 Grand National Rear - Posi - 4.10s
-Hotchkis Springs & Sway Bars - Boxed Rear Control Arms & 1LE Bushings
-F41 Frame Braces - PST Front End Kit - XH Steering Box

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#540670 - 03/03/08 05:28 PM Re: All that have installed a T56 into a G-Body...Help [Re: 79MeanGbody]
SS402 Offline
Member

Registered: 02/06/08
Posts: 4656
Loc: Beaverton, Oregon
just modify the tunnel, no big deal...
_________________________
George
Monte, Gone but not forgotten

The More I Learn About Dogs
The Less I Like About People

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#541011 - 03/04/08 03:21 PM Re: All that have installed a T56 into a G-Body...Help [Re: SS402]
nycitis Offline
Member

Registered: 08/18/05
Posts: 973
Loc: New Windsor, NY
what SS said, you have to use a really big hammer especially for the reverse lockout.
_________________________
build it like you love it, drive it like you stole it..

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#541087 - 03/04/08 06:54 PM Re: All that have installed a T56 into a G-Body...Help [Re: nycitis]
mmc427ss Offline
10+ Year
Member

Registered: 01/14/00
Posts: 2607
Loc: Pottstown, Pa
I'm not sure if there is a difference between a 79 Cutlass and the later G body in the tunnel area. You want to keep the rear output shaft of the trans close to the original output shaft location to maintain your drive line angles, which is about 3 1/4 degrees down on the engine/trans.
The LT1 T56 is the shortest of the three T56 you can use which helps your install. Remove the reverse lockout for initial install and cutting of the hole for the shifter mounting area on the trans to go up throught the tunnel. The two upper bolts on the tailhousing and the two rearward bolts on the detent cover plate will probably hit the tunnel also and need relief. When the motor torques over these bolts will hit the tunnel so make sure they have enough clearance. After you have the trans sitting on the crossmember mark the area that needs to be massaged for reverse lockout clearance. Use a ballpeen, dolly and a block of wood to stretch the tunnel. I had my trans in and out 10 times until I was satified.
There is an ear on the left front side of the trans, cut it off, you don't need it, makes putting the trans up into the tunnel much easier without it.
Don't cut the hole for the shifter any bigger than necesssary, measure five times trim five times until the hole is right. You'll want to install a shifter boot to the tunnel to seal out noise, dust, heat and water. A good boot is #10267518, has steel in it's flange and makes a very good seal with a little RTV.
If you would like a few PICs of the shifter hole, reverse lockout relief or anything else email me at bobglf@aol.com, be happy to help you with anything.
Bob

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#541093 - 03/04/08 07:07 PM Re: All that have installed a T56 into a G-Body...Help [Re: mmc427ss]
79MeanGbody Offline
Member

Registered: 08/15/05
Posts: 315
Loc: Columbus Grove, Ohio
mmc, Thanks for the advice. I hammered the tunnel to where I am about .5" from the mount slipping in. So I need to clearance at least another inch to allow for the engine to torque. Yes that boot you mentioned is a nice piece, I have it. i used it as a template for cutting my shift hole. Clearance around the reverse lock-out solenoid is good. I have to remove the rubber-bump stop from the top of the T56 yet and I'm also getting new body bushings to help with clearance. With an 8.5" rearend I figured I would need a driveshaft length of 47.9" does that sound right? Thanks!
_________________________
'79 Cutlass
-10:1 Crate 350 - Worked Vortecs - XE274 - Edelbrock 750
-Hedman Long Tubes - 2.5" True Duals - X-pipe - Dynomax Bullets
-T56 6 Speed - LT4 PP - RAM Powergrip - Pro 5.0
-8.5 Grand National Rear - Posi - 4.10s
-Hotchkis Springs & Sway Bars - Boxed Rear Control Arms & 1LE Bushings
-F41 Frame Braces - PST Front End Kit - XH Steering Box

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#541195 - 03/04/08 10:29 PM Re: All that have installed a T56 into a G-Body...Help [Re: 79MeanGbody]
mmc427ss Offline
10+ Year
Member

Registered: 01/14/00
Posts: 2607
Loc: Pottstown, Pa
Good to see you got some clearance for the lockout. I think getting the trans clearanced was the hardest part of the swap.
I installed an After-market T56 and an 8 1/2" rear at the same time when I did my install. Had Denny's make me a 3 1/2" HD alum shaft with 1350 joints, put a 1350 yoke on the rear. My shaft length was 49 7/16" using Denny method of measurement. That would be from the center of the rear u-joint to the end of the trans tailhousing. Length would be considerably less if you're measuring from the joints, center to center. My A/F T56 is about 1 3/4" longer than an LT1 T56. Check out Denny site, http://www.dennysdriveshaft.com/ good info about shafts and measuring length. he likes to see about 3/4 sticking our of the seal. When the rear suspension is in full droop is when the driveshaft gets the shortest. With the rear springs removed, measured 49 5/16" full compression, 49 7/16" at ride height, 49 1/8" at full droop hanging off the shocks. That's why you can't make the shaft to long, you need some play at the trans end.

Bob

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#541200 - 03/04/08 10:43 PM Re: All that have installed a T56 into a G-Body...Help [Re: mmc427ss]
mmc427ss Offline
10+ Year
Member

Registered: 01/14/00
Posts: 2607
Loc: Pottstown, Pa
A little lockout info. Pigtail connector for reverse lockout #12101857. Backup light pigtail is #12085485. You can get the rest of the backup light harness out of an early 80's pickup truck and just plug it into you car.
Some people will not put power to the lockout and just use brute force to move the shifter into the reverse gate against the spring pressure of the lockout. I put a lighted rocker switch on my console to activate the lockout. That wasn't idiot proof enough for me so I put a warning buzzer on it also. You flip the rocker and the switch lights up, the buzzer annoys you enough that you put the trans in reverse and turn the switch off right away. The trans will slide right out of reverse easily with no power to the lockout. Don't ask me how I know it's VERY easy to go from 4th to reverse in a T56 if the gate is open.
Bob

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#541297 - 03/05/08 09:47 AM Re: All that have installed a T56 into a G-Body...Help [Re: mmc427ss]
Tunedss86 Offline
10+ Year
Member

Registered: 11/13/00
Posts: 2140
Loc: Eastern Virginia
Seems like I remember reading somewhere that cars that didn't have an OD tranny (200R4), the tunnel was smaller & would need some persuading with a BFH to get it to fit.
_________________________
Scot
86 Monte SS
Soon to get a 400+ hp LS2/T56
http://www.pro-touring.com/showthread.php?78375-86-Monte-SS-getting-an-LS2

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#541313 - 03/05/08 11:27 AM Re: All that have installed a T56 into a G-Body...Help [Re: Tunedss86]
79MeanGbody Offline
Member

Registered: 08/15/05
Posts: 315
Loc: Columbus Grove, Ohio
Thanks for the info mmc427ss and tunedss86. I have the reverse lockout, backup light, and vss pigtails already. I am going to order some body bushings later on here after I decide if I want solid or poly. Probably will end up with poly. This should give me more clearance as my bushings are original 1979 pieces plus it was on the to do list anyway!
_________________________
'79 Cutlass
-10:1 Crate 350 - Worked Vortecs - XE274 - Edelbrock 750
-Hedman Long Tubes - 2.5" True Duals - X-pipe - Dynomax Bullets
-T56 6 Speed - LT4 PP - RAM Powergrip - Pro 5.0
-8.5 Grand National Rear - Posi - 4.10s
-Hotchkis Springs & Sway Bars - Boxed Rear Control Arms & 1LE Bushings
-F41 Frame Braces - PST Front End Kit - XH Steering Box

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