Hot Rod Forum banner

Manual conversion. Best 4 speed?

8K views 58 replies 7 participants last post by  bigdog7373 
#1 ·
I've been wanting to put a 4 speed in my 78 firebird for a while and while i'm restoring it i figured i might as well do it. It has a sbc in it.

Couple of questions.
1. What parts do i need? And i mean EVERYTHING to get the job done.
2. Whats the best 4speed that will work in my car? I'm in love with the sound of the m22 rock crusher, but i'm not sure if there are better options. I want a nice smooth feeling trans.
3. Where is the best place to buy?
 
#36 ·
You can see the M20/21 gear on the left vs. the M22

Only the M22 has the straighter cut
The M22 was available only with a 2.20 1st gear (should have a 3.73 or numerically higher ratio)
26 spline inputs and 32 spline outputs only mean the transmission was approximately 1970-1974 This is not M22 specific
All kinds of muncies have cases with drain plugs now
 

Attachments

#37 ·
Picking up the transmission monday. I'd like to make a list of all the parts i should grab. Remeber his car is pontiac powered, mine's got a sbc. Here's whats on the list so far:
Tranny,
Shifter
All linkage
Bellhousing
Clutch
Clutch fork
Drive shaft
Cross member
Pedals

Now i know there's a few other things i'm missing so if someone could tell me what they are and where they are located that would be awesome.

Does anyone know if the clutch is cable or hydraulic?
 
#38 ·
77 TA should be a hard linkage, not cable nor hydraulic, it will have a pushrod/ bell crank linkage. I make sure to check the gear cut to make sure its a true "rockcrusher". but 750 bucks is still a good deal on a m21 or m20. I would be sure to grab the transmission crossmember. Also i think pontiac bellhousing bolt pattern to block; is different than chevy, so that may not work for you. But Im not a pontiac guy so I don't know for sure.'
 
#39 ·
Well time for an update.
Feast your eyes!


M22 rock crusher! Complete with hurst shifter, cross member, and drive shaft. All for....... 900 bucks:thumbup::thumbup: Everything else was worn out looking so i left it alone. Will buy all new stuff to swap it in.
 
#41 ·
Yea hensaid he was pretty sure it was an m22. I wont be upset if it's not though. I'll have to pull the side cover and check it out. I only paid $900 for it with the shifter and cross member so even if it is an m20 i'll still be happy with it. :thumbup:
 
#42 ·
They always tell you it's a M22 when they own it or use to own it. :D It's like every old Mustang with a 302 in it is a Boss. If you see enough of them you can tell what it is by looking at it. They only used the fine spline Muncie for a few years and then it was replaced by a BW Super T10. There are websites that can tell you the ring count on the input shaft. The input shafts can be from a different transmission if someone worked on it but chances are it's what came on the transmission.
 
#45 ·
Muncie I.D.

here's a link for Muncie Identification, one of the best in my opinion. Muncie 4 Speed Transmissions... so far seems to me you have a 26 spline d M-20. made in 1970 to 74. But you still need to pull the side cover to check the (cut) of the gears to know for sure. Also to V8-4spd... not all Muncie trans case ear were broken from torque abuse. A really common failure is using the bellhousing to transmission bolts to line up with the pilot bushing. Also improper grade of bolts. I used Grade 8 bolts, flats, and lock washers. But I always torgue them properly, I replace my lock washers at any teardown too. Also a transmission jack is worth it price ( in broken case ears :smash:) in proper placing of your transmission.... as opposed to the wood block on a floor jack as we all have done
 
#46 ·
Looks like it might be an m20 cause of the 2 rings... Can't know for sure til i pull the side cover and check out the gears. It looks to be in very nice shape. No broken ears or stripped bolts or anything like that. All gears go in smoothly. I'm happy with it.:thumbup:
 
#49 ·
http://www.dandltransmission.com/muncie66_70.jpg
dont take it apart.note: the main shaft rides on uncaged bearings,lose 1 and you are in trouble.A transmission guy can see enough by taking off the cover.second gear synchros wear quickly and 3rd gear hold back wears and the transmission might jump out of third when down shifting into 3rd,especially coasting down hill.

also with this transmission,dont get into the habit of leaving your hand on the shifter when cruising around town. This applys to most standards,,,
 
#52 ·
A lot of good info in here. If its a GM gearset; its an M20. However, a lot of companies back in the day made replacement gearsets, and we have no clue if they knew what the ID grooves meant.

You can put it in 1st gear and turn the input ten times; if the output turns 22 times (2.20 1st gear) its an M21 or M22. If it turns 25 times (2.5 1st gear) its an M20. You got a reasonable deal, if it doesn't leak like a stuck pig. Make sure you adjust the linkage properly, and the shift stops as well (if there are any).
Don't lean on the shifter as said before, it makes the shift forks and synchro teeth wear faster/ unevenly.
You only really need a quart of trans fluid. I know they say fill it up; but that fill hole migrated a lot. The gearset needs a quart to live happy. I'd go to Napa and have them order a qt of Sta-Lube p/n SL24229. Its a non Synthetic GL4 rated 80w-90 (I think, might be 75w90). Its a bit thicker than the synthetics and its not as prone to leaking out of every crevice.

Enjoy it.
 
#56 ·
That kit is everything from the pedals to the clutch fork. If you don't have a bell housing for a manual tranny you will have to get one, along with the clutch fork, release bearing. The bearing you can get at any automotive store. You can also get the bell housing and fork new if you want, from that site also. Like someone mentioned earlier, you also need the bushing/bearing in the end of the crank.
 
#57 ·
Ok so i guess it would be a good idea to make a list.
The linkage kit
pedals
bellhousing
flywheel
clutch and pressure plate
clutch fork
release bearing
and the bearing at the end of the crank (does it have a name?)

is that everything?
One more question, the tranny i have is a muncie but the car only came with a t10. The linkage kit is the same?
 
#58 ·
The crank one is a pilot bearing or bushing.
THe linkage kit will be the same.
Might need a tranny mount too.
Crossmember to bolt tranny and mount to also.
Possible starter change too depending on whether you use a 153 or 168 tooth flywheel.
Buy a matched clutch kit too. You need to match the pressure plate to the throw out bearing. Raised finger plate uses a short throw out bearing and a flat finger uses a long bearing.
Depending on spline on output shaft you might need a different yoke for your driveshaft.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top