4 spd trans help

2390 Views 14 Replies 9 Participants Last post by MAVEN, Jun 6, 2007

kwplot34

Discussion Starter · Jun 3, 2007

help with this trans identification please. is it possible to determine what clutch DIA and spline size and how many teeth on spline without pulling the trans? from doing some research i have come up with this, it is either a 10.5" 1 1/8 spline with either 10 teeth or 26. or it is an 11" 1 1/8 spline with either 10 teeth or 26.

if it is a 10.5" can you use an 11" instead?

and is a borg warner and a super t-10 the same thing?

i have also heard this tranny called an m-21, but i thought that ment muncie,but that was not true, that means close ratio. so im kinda lost here any help would be great, just trying to get all my parts rounded up before i do my engine swap.:thud:

thanks for your help Kevin.

OH BTW: pilot bushing or bearing seems like you can use either one, is one better than the other?

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Duke94

· #2 · Jun 3, 2007

L-48 used 10.34" Dia clutch, L-82 used 11.0" clutch.
Input shaft on L-82 is 1 1/8" and has a 26 tooth spline.

M21 is close ratio 4 speed made by Borg Warner which is a Super T-10.

M20 is wide ratio also BW. Note that GM used the same trans code weather it was a Muncie or BW.

On the pilot bushing, either would work fine. GM used millions of bushings.

big2bird

· #3 · Jun 3, 2007

kwplot34 said:
OH BTW: pilot bushing or bearing seems like you can use either one, is one better than the other?

I would use the bushing. They are more foregiving when it comes to alignment.

gtr1999

· #4 · Jun 3, 2007

The ST-10 is a good tranny. I believe the base 4 spds in the late C3 switched over to Saginaws and they are junk. I think it was in 78-79 but you'll have to do some research as I could be wrong. The L-82 got the ST-10.

Use the bushings. If you use the bearing then you have to dial in the bellhousing. Not a bad idea to do regardless but for sure with the bearing and if a scattersheild is used. Off set dowels are made for this. I know Norval has posted the procedure in the past.

If using a bushing DO NOT buy one from a catalog. A lot of them now have a % of metal in them and could cause a friction weld problem. Sounds crazy but why take a chance? Go to your local NAPA and have them pull out the vette bushing( all the same anyway) put a magnet on it, if it sticks pass on it and ask for the camaro bushing. Check it until you find one that is not magnetic. I sent 3 lakewood bushings back to Summit for this problem. NAPA had a camaro one that was what I wanted and 1/2 the price of the summit part.

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tracdogg2

· #5 · Jun 3, 2007

Kevin,
Count the bolts on the side cover. Muncies have seven. ST-10 has nine. All muncie cases are the same 66-73. Regardlees of the code on the right side by the midplate all m20, m21, and m22 gears, fine or coarse spline can be installed in any of the cases. The orignal input shaft was identified by the grooves but all replacement shafts don't have any grooves. A physical inspection is the only way to be sure.
To put an 11" clutch in place of the 10.5" will require a 621 or a lakewood bellhousing. Also the flywheel is larger using a 168 tooth ring gear versus the 153 10.5 flywheel.
Clutch discs are available with 10 or 26 spline, 10.5 or 11 inch. The only part that is corvette specific is the clutch fork.
The tailhousings are interchangeable. In 1971 GM changed from the 10 spline input to the 26 spline. At the same time they changed the output shaft from 27 to 32 spline and a larger yoke.
Mike

kwplot34

Discussion Starter · #6 · Jun 3, 2007

Thanks everybody for the info, that helps alot in ordering my parts. also thanks for heads up on the pilot bushing would never have known that one. along with your help and this site http://fiedlerh.home.att.net/BW.htm i learned alot. if you have not seen this site you should check it out.:thumbsup: But of course some you old timers probably knew all of this anyway, or helped write it :laughing:

thanks Kevin

bteague

· #7 · Jun 5, 2007

L-48 used 10.34" Dia clutch, L-82 used 11.0" clutch.
Input shaft on L-82 is 1 1/8" and has a 26 tooth spline.

M21 is close ratio 4 speed made by Borg Warner which is a Super T-10.

M20 is wide ratio also BW. Note that GM used the same trans code weather it was a Muncie or BW.

On the pilot bushing, either would work fine. GM used millions of bushings.

the m21 and m20 are muncie not borgwarner.allare good trannys and will interchange with no mods to your car

kwplot34

Discussion Starter · #8 · Jun 5, 2007

bteague said:
L-48 used 10.34" Dia clutch, L-82 used 11.0" clutch.
Input shaft on L-82 is 1 1/8" and has a 26 tooth spline.

M21 is close ratio 4 speed made by Borg Warner which is a Super T-10.

M20 is wide ratio also BW. Note that GM used the same trans code weather it was a Muncie or BW.

On the pilot bushing, either would work fine. GM used millions of bushings.

the m21 and m20 are muncie not borgwarner.allare good trannys and will interchange with no mods to your car

I think i would have to disagree with you on m21 & m20 are muncie only, from research and help from this forum m21 & m20 also relate to the BW trans, m21 for close ratio, m20 for wide. also if you go and check out the site that is linked in my post right above yours that is all about the BW trans, you will see that they refer to the BW trans this way too.
thanks for your input.

MAVEN

· #9 · Jun 5, 2007

Yes, Borg Warner is "the same as" Super T-10, Borg Warner is the maker of the Super T-10.

M20 4spd Manual.
M21 4spd manual, close ratio.
M22 4spd manual, close ratio, heavy duty.

These are simply RPO codes, they DO NOT specify the actual transmission make/model.

M20 was used from 63-79(all RPO's were numeric before 63 and only one trans choice after 79, no more close ratio, resulting in change to MM4 RPO.)

M21 was used from 66-79

and M22 from 66-71 and was always a Muncie.

Late Shark era Borg Warner boxes could carry M20, M21, or even M18, M24 RPO's

The Muncies as posted had 7 bolt side covers while the BW's had 9, to further confuse(illuminate?) the junk Saginaws had 7 bolt side covers like the Muncie but had their reverse lever in the side cover where the Muncies is in the extension housing

BW wide ratio T-10s have no grooves on the input shaft, Super T-10 wide ratios have 3 grooves and Super T-10 close ratios have 2 grooves

Muncie grooves vary by year but its generally accepted that later production(after 65) M20's have 2 grooves, M21's have 1 groove and the Rockcrussher M22 has none(the groove count and from what Ive seen consistency in implementation varies greatly in 63-65 boxes)

As a little bit of supporting evidence the ZF 6speed box used from 89-96 shares the same MN6 RPO as the rear mounted Tremec T56 in the '97 and up C5 and C6 platforms.

Clear as mud, right?

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kwplot34

Discussion Starter · #10 · Jun 5, 2007

MAVEN said:
Yes, Borg Warner is "the same as" Super T-10, Borg Warner is the maker of the Super T-10.

M20 4spd Manual.
M21 4spd manual, close ratio.
M22 4spd manual, close ratio, heavy duty.

These are simply RPO codes, they DO NOT specify the actual transmission make/model.

M20 was used from 63-79(all RPO's were numeric before 63 and only one trans choice after 79, no more close ratio, resulting in change to MM4 RPO.)

M21 was used from 66-79

and M22 from 66-71 and was always a Muncie.

Late Shark era Borg Warner boxes could carry M20, M21, or even M18, M24 RPO's

The Muncies as posted had 7 bolt side covers while the BW's had 9, to further confuse(illuminate?) the junk Saginaws had 7 bolt side covers like the Muncie but had their reverse lever in the side cover where the Muncies is in the extension housing

BW wide ratio T-10s have no grooves on the input shaft, Super T-10 wide ratios have 3 grooves and Super T-10 close ratios have 2 grooves

Muncie grooves vary by year but its generally accepted that later production(after 65) M20's have 2 grooves, M21's have 1 groove and the Rockcrussher M22 has none(the groove count and from what Ive seen consistency in implementation varies greatly in 63-65 boxes)

As a little bit of supporting evidence the ZF 6speed box used from 89-96 shares the same MN6 RPO as the rear mounted Tremec T56 in the '97 and up C5 and C6 platforms.

Clear as mud, right?

clear as mississippi mud :rolling: . what a nightmare, wonder why they changed trans and manufatures so much? just to confuse us later in life :thud:

thanks for you input. i think :crazy:
kevin

TimAT

· #11 · Jun 5, 2007

Try this
http://i160.photobucket.com/albums/t188/TimAT_vette/31A22RB07VL__AA280_.jpg

:rolling:

kwplot34

Discussion Starter · #12 · Jun 6, 2007

TimAT said:
Try this
http://i160.photobucket.com/albums/t188/TimAT_vette/31A22RB07VL__AA280_.jpg

:rolling:

Thanks Tim that clears everything up now :laughing: It's like the clouds parted and the sun popped out :rolling:

smatazz

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84rzv500r

· #13 · Jun 6, 2007

So that tranny laying in my junk pile is a ST-10 Close ratio? :surprised

It is a Borg Warner and has 2 groves on the input shaft (26 spline) and 32 spline output... Casting case date is 1975...

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kwplot34

Discussion Starter · #14 · Jun 6, 2007

84rzv500r said:
So that tranny laying in my junk pile is a ST-10 Close ratio? :surprised

It is a Borg Warner and has 2 groves on the input shaft (26 spline) and 32 spline output... Casting case date is 1975...

sounds like it and looks like the one in my 78. you might want to pull it back out of the junk pile. or just send it to me and i will find some use for it :laughing:

MAVEN

· #15 · Jun 6, 2007

Yeah, I'll take one of those ST-10 yall've got laying 'round. Drop it right in my '78 Malibu. Saves me the expense of buying a T101(yeah Ive got high hopes.....)

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