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6 speed manual swap

CaseyS

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731
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Louisiana
Quite a few detail flags here.

First the overall length of 29" will be a problem. Thats 2.5" longer and will likely prevent being able to stab the transfer case due to the frame member in the way. The 6060 box is 1.5" longer than a standard t56 case and that may be what this is based on. Also a 6060 box appears to have a 31 spline output not a 27 so your driveshaft won't work.

Maybe cbetts can get some measurements on the 5 speed but I would assume the length is the same as the 4l60e.

The first link is just a 2wd tail housing so you can't fit a transfer case adapter to it. The second link would work i think but $700 is pricey, damn.

Google a corvette c5 t56. This would be my starting point for a roll your own. Fan a transfer case adapter and cut and spline that output to the correct length for the factory drive train locations. The thing on this would be the 0.5 6th ratio but you should be able to swap a different 5/6 ratio with any 1-4 combination.

Keep researching and keep posting. Lots of detail traps but good discussion.

transmission2.png
 
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GreatDaneHummer

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994
Location
Chicago
The T56 that RD Gear makes can be made with the correct 27 spline and they can either leave it un drilled so you can match up the transfer case or they can pre drill it for our 4:1 Hummer specific TC. I had the H3 up on a lift last night with 2 techs, to measure things out and I will have to redue both frame mounts / crossmembers. If I am to keep the torsion bar setup for now I will have to custom make longer ones as it will be moved rearward 2 inches. There is some fabrication that needs to be done but now that I have ironed out some of the issues I do not think this will be that bad of a custom install. I have a local shop down the road with a 4x4 dyno and they are able to do any tuning or custom software that is needed. Total budget cost is around $15,000 for the entire drive train replacement etc.
 

GreatDaneHummer

Well-Known Member
Messages
994
Location
Chicago
2.97 2.07 1.43 1.00 .74 .50 OR .80 .63

This is the gear ratio's for the T56 RD Gear. With the 27 spline you can use either .74 .50 or .80 .63 over drive gears. I would choose the .80 .63 combination so at least with 4.56 ring / pinion I could drive in gears 1-5 without issue.
 

amrg

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15000 is alot of money for this! How much would the 6l80 be?

Offcourse once you go manual a RWD transfercase would be nice!

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GreatDaneHummer

Well-Known Member
Messages
994
Location
Chicago
The RD Gear offers a modified 4:1 transfer case for the H3 that is already set for 2wd High / 4wd High / 4wd Low. I do not know the cost of it. For the 6l80e you can find a cheap used one possibly or if you go with new performance ones mad dog is $5295, monster is $4995 and PATC is $5,000 plus. Keep in mind the $15k is an estimate for the entire drive train. New 6.2l crate motor, 6 speed trans, accessories, tuning, custom crossmembers and driveshafts. My tech buddies, dad and I can knock this out without an issue but it all comes down to money like always haha.

*6l80e will still need additional work to adapt to the H3. If I remember correct there was some kind of custom harness that is available etc? It is not plug and play. Someone has done it on here already.
 

amrg

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15k entire drivetrain explains it all.

As for 6l80 the harness is plug and play (if you get it from tbms) and you need an adapter to mount the tramsfer case.
The most complicated part is getting the appropriate valve body that works on the truck VIN and getting it programmed.
The most labour intensive part would be dissassembling a perfectly working trans to swap in a different output shaft.

As for the transfer case you mentioned, didnt not know there was one. If it works fine with the electronics it would be great! Offroad it would be fun esp on the sand!!!

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GreatDaneHummer

Well-Known Member
Messages
994
Location
Chicago
Get a hold of George with their RSG 4x4 Division and he can explain more than I can about what transfer case options he has available. Their main number is 800-227-1523. For me I am just done with auto trans issues. The manual trans solves so many issues for me and dislikes about the H3. I like the idea of setting the gear to what I want and then running cruise control so the days of hunting for what gear to be in will be over. GM had such potential to make the H3 truly great right from the start and they failed IMO. They should have done the H2 front axle with the alpha 5.3 from the start mated to a 6 speed auto. This would have made it ... wait for it ... legendary haha.
 
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