CS455

Hey Folks,
My 1970 442 has a 455/turbo400 auto setup and I am toying with the idea of a manual trans conversion. I hear the M22 is the way to go. Besides the pedals, linkage, bellhousing and clutch assembly what else will be needed? Longer driveshaft? Different frame crossmember? Thanks.

CS455

is this any good?

http://www.ebay.com/itm/1970-72-CUTL...item3f0411ef09

chrisneu68olds

Funny, I asked the same question just a few days ago.

Quote:
Originally Posted by chrisneu68olds

1. What is the path for moving from the TH-400 to a 3 or 4-speed?
2. What is the path for moving a from a 3-speed to a 4-speed?
3. Should I plan to build out as a manual transmission to start with or is the move from auto to manual simple enough that it is a swap?
4. If this has been done by anyone on CO (Duh, I am sure at least one of you have), what is involved and is there a link on here that explains how you did it?

Thanks!

The difference between AT and MT cranks is that AT cranks usually do not have the hole bored for the pilot bearing needed for an MT. This hole can be cut by a machine shop. The Search function will lead you to a dimensioned drawing on this site.

The TH400 is longer than the manual transmissions, requiring the crossmember to move rearward. Since this trans was an option for 1967, the frame will have the holes already drilled. You'll need a shorter driveshaft and TH400-unique front yoke (or conversely, a longer driveshaft and MT front yoke when you switch). Also, the different crossmember location requires different front and intermediate e-brake cables. __________________
Joe Padavano

2blu442

The crossmember is the same, you'll just need to move it forward and use the bolt holes for the TH350. You'll need a shorter driveline but depending on the transmission, some of them used the larger yoke like the TH400, others the smaller like the TH350.

As far as transmission its what you'd prefer. My 1970 442 came with an M21 and unless your going to race it you probably don't need the extra strength of the M22. You may have some pretty tall gears since it was an automatic car from the factory. If you end up changing the rear end gears than you may want to consider an overdrive transmission and putting something really fun like 3.91's in the rear.

This is your car to do with as you choose. But all that said, if it has a numbers matching transmission I'd encourage you to hang onto it and cut the floorboard as little as possible in the swap. OR... keep the 442 original and pick up a Cutlass to modify. The reason I say this is many of these cars lost their original drivetrain when they were young. I've got six 442's and only one has the original engine, transmission and rear end. So whenever someone wants to modify a car that's all original I encourage them to keep the parts so they have the option to restore it to original again if they ever want to. Or consider picking up a Cutlass that is much more common and doesn't have the collector value and personalize that into the car they want. But again, its your car and I don't want to step on your toes telling you what you should do with it. John

costpenn

Hello,

I'm in the process of doing the same on a 72 vert. Depending on how correct you want to do the changeover, there's LOTS of little things I've found I've needed over and above the Shifter, trans, clutch/pressure plate/throw out bearing kit, pedal set-up, bellhousing, and driveshaft mods that can get expensive:

Z Bar
Z Bar mounting studs (frame and engine block)
Flywheel
Crankshaft modification (if not drilled for M/T pilot bushing)
Pilot Bushing
Correct reverse lamp switch
Correct Neutral Safety switch
Correct Neutral Safety Switch Harness extender (?)
Bushings for shifter
Wavy washers for shifter trunnions
Bushings/Hardware for Z bar
Lock out linkage rod
Bushings/Hardware for lock out linkage
Rod - Clutch Pedal to Z Bar
Rod - Z Bar to Clutch Fork
Bushings/Hardware for clutch rod
Clutch Fork
Clutch Fork Dust Boot
Firewall Plate
Firewall Plate Dust Boot
Correct Accelerator Cable (if speedo on trans is on Drivers Side)
Shifter trunnions (if not included with the shifter)
Correct "thin" nuts for the shifter trunnions
Shifter Plate that bolts to the tranny
Bolts that hold plate to the tranny
Bolts that hold shifter to the plate
Flywheel bolts
Trans to Bellhousing Bolts
Bellhousing to block bolts (maybe the same as the A/T mounting bolts)
Pedal Pads (if yours are worn)

Believe me - I'm not trying to discourage you, it's worth it, but I found all these little parts add up pretty quickly unless you can find all of it in a complete set up - and still, some items will still have to be replaced.

Good Luck!!

CS455

Thanks. I agree its not smart to change up a numbers matching car.
Mine is not numbers matching. If I have to mess with the crankshaft then this will have to wait. Thanks for the replies!

Rickman48

Put a looser converter and a shift kit in it and have fun!
I had a BB Chevelle and blew 5 4-speeds - went to a T-400 and B+M Holeshot - no more problems!

507OLDS

The TH400 shares the same length as the large-output 4-spds,like most M22's,and any 71-up M20/M21 with the large output tail.Same yoke too.I just did another auto to 4-spd swap for another customer over the summer,with a 71 442,455/TH400,and swapped it to a correct 71 M20,with the large output,and the driveshaft stayed the same.
If you want to keep your car correct for 1970,then I would look for a correct 70 M21,which has the small output,like the TH350.A driveshaft from any 2-door 70 Cutlass,with a TH350 & 12-bolt O-axle,will be correct.
I think the list above is pretty accurate.You will also need a longer speedo cable,as the 4-spds have the speedo output on the driver's side.

My442

Speedo cable needs to be 69" long.

I did my 70, and used all GM parts.

Refirbished GM stuff is 10X better than repop stuff.

Also, I recommend a Centerforce clutch. It has light pedal pressure and great gripping power.

507OLDS

I sourced the speedo cable from NAPA.They did not have it listed correctly in their database,but they had some other references that you can view each end of the cable,and the cable length,which is what I did,and got the correct one.i kept the box for the part number.It was about 1/2 the price of what the vendors sell them for.
Another thing you will need to change is the front e-brake cable,and the equalizer cable,regardless of what Muncie you install.Why? The crossmember gets moved forward for the 4-spd cars,and is in the same location as the TH350,so you need the shorter front cable for the pedal,the longer equalizer cable,and the slightly shorter hook that attaches the equlizer to the crossmember.I have found these cables at the parts stores,but again,their info in their database is not accurate,and will throw you off.The cables needed,are the same ones for a TH350,but the databases don't breakdown between the 2 types(TH350 & TH400).It just says with or without turbohydramatic.We all know the front brakes have nothing to do with those cable,BUT for whatever reason,I tried "with front drum brakes",and walla!,it spit out the correct cables that I needed.
Am I getting too picky?

joesw31

Brian, I have spent hours looking at the NAPA catalogs as things are not listed as they should. The problem is finding a store that has the books and loaning them so that you can do your home work.

For the 4 speed change over parts. Some of the aftermarket stuff/ repro is just not right. It's best to get an assembly manual and study it. A correct change over is not a clutch asm, trans, etc. There are a lot of things. Example: A good muncie will cost $800 to $1200, and that is for something that works.

507OLDS

Yes,the NAPA closest to my house has been there for quite awhile.the guys that work there aren't too helpful,but there is a lady that works there that's always willing to give it a try,and that is who got me the books to look at.I had the original cable out of one of my cars as a reference.The one I got was an exact match.I even found a few that were longer than the 68".They just can't be shorter than that.I think that some of the mid-70's A-bodies used a long cable like that,but I haven't had one in-hand to try.
Yes,if you "just want a 4-spd",then I'm sure there are a few things that you can do without,but the conversions that I do are exact to every piece & detail.

My442

The parking brake cables worked fine on my car after the swap.

Expect to pay $3,000 to $3,500 for parts to do a 100% GM change over.

Your labor is free.....

One thing that I did was have the M21 rebuilt with a Masiero M22 gear set. You get the famous rockcrusher whine.

My Muncie was rebuilt by Ed Hartnett of EH 4 Speeds. He is on eof the top Muncie rebuilders in the USA.

PS - I have the floor tunnel from the donor car if you need a template.