Rock crusher 4 speed
04-21-2010, 10:14 PM
#2
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at the minimum......I'd think
1. a different flywheel to accomodate the normal style clutch for the older transmissions. A one-piece seal flywheel for a T5 third gen or from a 87 and up truck should work I would think.
2. Probably would need an aftermarket hydraulic set-up since adapting manual clutch linkage would be a nightmare I bet.
3. Cutting a new hole for the shifter farther forward than the T56 hole.
4. A longer driveshaft
Probably alot more stuff..I haven't done this swap, but am a little familiar with the differences between the two.
If it's a REAL M22 rockcrusher with the nearly straight cut gears.....I would sell it to a collector and buy something stronger. The "rockcrusher" is fairly stout, but I've always heard BW Super T-10's and the new Richmond T-10's are better. Not sure I'd go through all that for one of those either. Real rockcrushers bring big bucks from restorers. Even the regular M20 and M21's are bringing good money. Would go a long way on a much better transmission for a 4th gen.
Still.....if you want to try it. I'm sure it could be done, and would be different.
1. a different flywheel to accomodate the normal style clutch for the older transmissions. A one-piece seal flywheel for a T5 third gen or from a 87 and up truck should work I would think.
2. Probably would need an aftermarket hydraulic set-up since adapting manual clutch linkage would be a nightmare I bet.
3. Cutting a new hole for the shifter farther forward than the T56 hole.
4. A longer driveshaft
Probably alot more stuff..I haven't done this swap, but am a little familiar with the differences between the two.
If it's a REAL M22 rockcrusher with the nearly straight cut gears.....I would sell it to a collector and buy something stronger. The "rockcrusher" is fairly stout, but I've always heard BW Super T-10's and the new Richmond T-10's are better. Not sure I'd go through all that for one of those either. Real rockcrushers bring big bucks from restorers. Even the regular M20 and M21's are bringing good money. Would go a long way on a much better transmission for a 4th gen.
Still.....if you want to try it. I'm sure it could be done, and would be different.
04-22-2010, 01:39 PM
#3
You are taking a huge step backwards from the T-56. I have 2 Camaro's, one 4 speed & one 6 speed. I would never convert to a 4 speed, but often considered putting a 6 speed in my 68.... I would bet the 6 speed is stronger overall, plus it shifts better.
Sell the M-22 (if you really have one)... most just think they have a Rock Crusher & it is an M-20 or M-21 & buy a good built 6 speed that fits.
Sell the M-22 (if you really have one)... most just think they have a Rock Crusher & it is an M-20 or M-21 & buy a good built 6 speed that fits.
04-22-2010, 02:00 PM
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You are taking a huge step backwards from the T-56. I have 2 Camaro's, one 4 speed & one 6 speed. I would never convert to a 4 speed, but often considered putting a 6 speed in my 68.... I would bet the 6 speed is stronger overall, plus it shifts better.
Sell the M-22 (if you really have one)... most just think they have a Rock Crusher & it is an M-20 or M-21 & buy a good built 6 speed that fits.
Sell the M-22 (if you really have one)... most just think they have a Rock Crusher & it is an M-20 or M-21 & buy a good built 6 speed that fits.
04-22-2010, 07:52 PM
#7
If he has a bunch of them & they are not over $1000ea. then I doubt they are the Rockcrusher M-22.
That is a common misused name in the performance world.
They are way outdated to have a demand in the performance world, & more desired by the collectors of muclecars. Many better transmissions are out there for your performance car.
That is a common misused name in the performance world.
They are way outdated to have a demand in the performance world, & more desired by the collectors of muclecars. Many better transmissions are out there for your performance car.
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04-23-2010, 04:58 AM
#9
I seriously doubt it would be a step backwards..... If you are in it to win it this set up works very well and i am sure there is a way to adapt this to an Lt1 clutch as well... Very well known company did this swap and the car picked up ALOT over the T56
https://ls1tech.com/forums/manual-tr...ello-4spd.html
https://ls1tech.com/forums/manual-tr...ello-4spd.html
04-23-2010, 10:15 AM
#11
ive had an m-22 in a 75 chevy shortbed build and it was the strongest tranny ive ever had. EVER.put it through more abuse then anything i dont know how u can say a t56 is stronger. maybe im wrong just personal experience
04-23-2010, 01:00 PM
#12
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Nobody has asked this question yet, so, why do you want to swap a t-56 for a rockcrusher? What application will it be for, street or strip?
04-23-2010, 09:57 PM
#13
The Muncie transmissions were not the strongest of transmissions, nor did they have a favorable first gear for drag racing. The term RockCrusher has gained urban legend status over the years. Fact is I know them rather well. In the 60's & 70's racers were swapping Chrysler transmissions & Ford Toploaders in Camaro's because of the Muncie strength/gearing issues.
The subsequent BW Super T-10 was also a better trans.
As for the T-56, they are very strong, but their syncros are not nearly as beefy as the Muncie. The T-56 will not withstand as much powershifting as a Muncie, but for fast, easy shifts, the T-56 wins hands down.
Personally I've broken many input gears & clusters in Muncies on 4-500hp street cars, but my only failure of a T-56 has been twisted splines (at 650rwhp on slicks), & never a gear failure.
The subsequent BW Super T-10 was also a better trans.
As for the T-56, they are very strong, but their syncros are not nearly as beefy as the Muncie. The T-56 will not withstand as much powershifting as a Muncie, but for fast, easy shifts, the T-56 wins hands down.
Personally I've broken many input gears & clusters in Muncies on 4-500hp street cars, but my only failure of a T-56 has been twisted splines (at 650rwhp on slicks), & never a gear failure.
Last edited by Lonnies Performance; 04-23-2010 at 10:05 PM.
04-24-2010, 08:02 AM
#14
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The real claim to fame of the M-22 is that there was never a doubt when there was one around. Those spur cut gears are noisy, and the spur gear is it's weak link. With a spur gear, you never have more than one gear tooth at a time engaged. With a helical gear you still have only one tooth at a time engaged, but you can make that one tooth longer and therefore able to withstand more load within the same space that the spur gear uses. It's also a bunch quieter.
Last edited by fleetmgr; 04-24-2010 at 08:07 AM.
04-24-2010, 08:50 AM
#15
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There is not a answer for that Question yet. I am in the middle of doing research for my build. Looking for opinions. I am watching my next door neighbor sell them as fast as he can find and rebuild them. I think I am leaning tords street and strip.
