• 10.1 What are common transmission swaps?
• 10.2 What do I need when converting from an automatic to a manual?
• 10.3 What do I need when converting from a manual to an automatic?
• 10.4 How do I install XXXX automatic transmission?
• 10.5 How do I install XXXX manual transmission?

For a V8 or 4.3 V6:

• TH350 and TH400 3-speed automatics
• TH700R4 overdrive automatic
• TH200R4 -- weaker than TH700R4 but lighter, can be beefed up; was used in Turbo Trans Am, so torque arm mounts can be found, but it's not easy
• 4L60E (electronic version of TH700R4, for LT1 and LS1 engine swaps)
• T5 and T56 manuals from '82-up Camaros and Firebirds (the shifter is in the right place and they have mounts for the torque arm) NOTE: Pre-1991 T5 transmissions have a problem with munching 5th gear at high RPMs (in any gear) due to problems with the counter gear. Gear Zone sells a better counter gear stabilizer and claims this fixes the problem.
• Muncie or Richmond 4-speed manual

For a Buick V6 or other engine with B-O-P bolt pattern:

• TH350
• TH200R4 overdrive automatic
• T5 manual
• use B-O-P to Chevy bolt pattern adaptor (TCI part #230000) and use any SBC transmission

Bad ideas:

• Truck manual transmissions: shifter is too far forward and gearing probably not optimal (trucks like to tow)
• Any automatic transmission from a 4 or 6 cyl car used behind a V8

Just in case you're curious, power loss for various auto transmissions:

    Powerglide    18 hp
    TH350         36 hp
    TH400         44 hp
    Ford C6    55-60 hp
    Ford C4       28 hp
    Chrysler A904 25 hp
    Chrysler 727  45 hp
  

First get a manual pedal assembly. These interchange for all H-bodies. Older H-bodies use a pulley for the clutch cable. Trade the flexplate for a flywheel. Might need a new driveshaft and torque arm if the transmission isn't the same length.

The transmission crossmember behind a V6 or V8 is the same for automatic and 4-speed, but different for 5-speed.

The torque arm mounting is also different for the 5-speed.

Make sure your engine crank is machined to accept a pilot bearing. For a small block, the 6.2 diesel bearing is recommended; it's a tougher unit and fits.

Denis (denisst78) says:
"Last year I also converted a v-8 monza to auto trans. Drive shaft was the same. Torque arm was the same. Crossmember was the same. What extra you need: tranny, tranny cooler, tubing for the cooler, auto trans oil, flex plate, converter, shifter + neutral switch, shifter cover plate, couples of wire (to rewire neutral and reverse switch), converter cover, torque converter bolts, shifter cable and bracket (monza specific)."

• TH350: Vegas require some minor firewall "massaging" where the transmission tunnel meets the firewall. The bellhousing bolts will be tough to get to--one person cut holes in the firewall to access the bolts from inside the car (use rubber plugs). Monzas require only factory pieces since some came with the TH350.

  Larry (vega_man_larry) writes:
  "The 1975 Vegas have a unique floorpan. They are sort of a hybrid between the old 70-74 and new 76-77. The floor pan really doesn't have a place to mount the transdapt transmount as it is too narrow and too short. You can jack the trans all the way against the trans tunnel and it will still be too short. The 76-77 cars already are outfitted for a V8 as the pan is the same stamping as used on the Monza and they are universal. For the '75 you need to get a Monza V8 mount or go with aftermarket parts. I have a Don Hardy tubular mount that connects at the stock '75 trans locations and mounts a turbo 350. My car is a '75 and I had this mount installed."

  Brew (mongoose_brew) writes:
  "Through most of the years, GM has made three basic types of TH350 transmissions:

  • Ones that will bolt up to a Chevrolet.
  • Ones that will bolt up to Buick, Olds and Pontiac (Cadillac too); these are nicknamed BOP(Buick-Olds-Pontiac) transmissions.
  • And finally transmissions that have both Chevrolet and BOP patterns. These are called Dual Pattern Bellhousings.

  Look at your tranmission and count the amount of holes around the perimeter. If it is a dual pattern, it will have ten 1/2" bolt holes. Do not count the alignment pins.

  If it has six bolt holes it is a BOP tranny. The extra holes will be at the 9, 11, 1 and 3 o'clock positions.

  Just an extra note: GM also made dual pattern flexplates. It takes three fine thread bolts to mate the torque converter to the flexplate. On almost all of the flexplate, there are six bolt holes. One set of three is set to a smaller diameter pattern while the other set is a larger diameter pattern."

  Denis (denisst78) notes that a dip stick tube from a 1981-older Camaro should fit the Monza but might need to be bent a bit.

  Cliff (dracer327) says to:
  "Cut the end of the tube (trans end) allow about 1-1/2" above the o-ring. Clamp heater hose to the tube. Correct length of hose to make the right length. This will allow the flexibility you need."

  To mount a torque arm, ideally, you can just find factory V8 Monza parts, which include a special TH350 tailshaft housing with mounting holes for the torque arm, the torque arm itself, and the bushings and bolts used to mount the torque arm to the tailshaft.

  Note: The V8 Monza torque arm uses a round bushing that "tacks" the torque arm to the transmission, allowing no front-to-back movement. However, such movement is helpful when the rear end moves a lot. The 3rd-gen Camaro and some non-V8 H-bodies use a clamshell-type bushing and torque arm that can slide back and forth as the rear moves. If you want to use the Camaro-style system, you can get a kit from B&M (made for 3rd and 4th-gen Camaros) that mounts on a regular short TH350 tailshaft housing. You'll also need play around with different torque arms and bushings. One combo is a shortened 4-cyl/auto Monza torque arm plus GM bushing as follows: GM 10024028 insulator + supp and GM 00527689 insulator.

• TH700R4: Cut clearance in the transmission crossmember mount area (not the crossmember itself). Mount the crossmember so that the front two holes are matched with the rearmost two holes on the crossmember mounting area--this leaves one pair of holes unused on the crossmember and two pairs of holes unused on the body. Build a bracket that attaches the body to the unused set of holes on the crossmember, for extra strength. Finally, if you have a torque arm suspension, use the tail housing from an F-Body (Camaro/Firebird) TH700 so the torque arm can mount up. If you already have a TH350 tailhousing with the torque arm mount, you can put it in the TH700. When you do this you need to cut the output shaft about 1 1/4" inch (there should be a groove there in the shaft). The driveshaft and torque arm will also need to be shortened.

  Brew (mongoose_brew) adds:
  "The 700R4 is either 7" or 4" longer than a 350, depending upon if your 350 is a short tailshaft or long tailshaft. [actually 3 1/8" according to someone who sells conversion kits]

  If your engine is relatively mild, consider the 700 R4s or the 200-4Rs from an F-Body; they utilize a similar torque arm as the Monzas.

  One last note. If you are trying to figure out how to run the lockup without a computer, contact TCI or B&M transmissions. They sell vacuum switches that will operate the lockup, just like on pre 87 GMs. You must have a way to utilize the lockup feature or you will burn up drive and overdrive. Unless, of course, you pay a trans shop to do some drilling insdie the trans for you to enlarge the correct passages."

• TH200R4:

  Larry (vega_man_larry) writes:
  "I'm using a 2004R that was originally installed behind a Buick G/N Turbo car. I had the transmission built by DelTrans (they build all of Posies transmissions). It has a Hardened input shaft and sprag, extra clutches, modified valve body and the torque converter is a special one off deal with many custom hardened and heavy duty parts.

  I used the TCI lockup kit to wire mine in to the car. There is a special brake switch that you can get that you can use to unlock (switch off) the current to the lockup converter. One of the last issues of CHEVY High Performance shows how to wire up the trans using this switch for the lockup only in 4th.

  The 2004R has a .6 overdrive. My car is set up for touring with 3.0 gears and does 80MPH at a little over 2000 RPM so the engine doesn't even make a sweat, and with all the HP I have on tap she leaps to 100MPH with ease. However if you're building a Drag Car a powerglide is a much better choice."

  John (Lord_Varon) adds:
  "The 200-4R is a much better choice of a tranny for you thn the 700-R4. Why? You ask, here are some reasons. 1. The 700 will take some pounding on the tunnel to make it fit, the 200 fits perfectly. 2. The 700 weighs considerably more than the 200, although that may not be a consideration. 3. Take a look at the gear ratios for the two trannies in question. The step from 1st to 2nd on the 200 is much tighter than the 1-2 shift in the 700 so you lose less RPM. 4. Durability isn't a question as the 200 was in the Grand National, and High Perf Pontiac is running one behind a mildly built 455 in a GTO. Granted it is best if you have a 200 gone through and some performance parts put in in place of the stock parts, but the 200 in mine is working beautifully after several years of abuse. As to the mounting of mine, I not only had the torque plate shortened, but the cross member was moved back about two inches to line up with the transmission mount and I had a special bracket made from 1/4" plate to actually mount the torque plate to. As I stated earlier, I have been running this combo behind a mildly worked 6 for several years and never had it break a sweat. The 200 is also cheaper to find and build over big brother 700 and many came with universal bolt patterns to allow bolt up of any GM engine."

  Ian (ian_mccrimmon) writes:
  "Both the 200 and the 350 are (from what I read) 27 3/4" in length and use the same 27 spline output shaft. The sticking points will be trans mount point; the 200R4 is in the same spot as the TH400, 26 13/16" from the bellhousing; also the torque arm mounting, as the 200R4 does not have a tailshaft."

• TH400: Different length, different output spline, different yoke. May require a bit of tunnel "massaging" due to extra bulk. Consider using a swap kit (TH700 or TH200 to a TH400) made for a Camaro.

• Misc notes:
  • Lots of fun with torque arm mounting
  • Upgrade to hydraulic system for HD clutch?
  • If keeping cable, use diaphragm pressure plate.
  • Check firewall for movement at clutch pedal--add reinforcement.
  • Check pulley for cable fraying.
  • Hayes 10 1/2" 30lb 153-tooth flywheel for SBC: part #490-10-330

• Muncie and Richmond Super T-10:

  Idea from Robert (twelve_second_vega):
  "Assuming you have a manual trans and V8 already, find a TH350 with a torque arm mount on the tail housing. Cut this mounting "lug" off and weld it onto the bottom of the Muncie or Richmond tail housing (heli arc). Now the transmission should just replace the old manual unit, however, you will need to shorten the reverse shift rod."

  Kevin (SoloII_74) writes:
  "I have a '74, and it does share the floor pan of the '71-'72 Vegas. I am continuing to use a Saginaw in my car (as required by the SCCA rules) but I see one small problem with using the standard Vega Shifter with an Super T-10, the Saginaw has all of the shifter lugs on the side cover, while the both the Muncie and Super T-10 have reverse on the extension housing. The original floor mounted shifter shift arms are designed to fit a Saginaw. My recommendation is to use a the Hurst shifter (I am, because it has a better feel & more positive action). Of course you will have to get one for the transmission you will be using, and you will have to cut the floor pan some to fit. A bulge should not be necessary if you select the right mounting kit. You will also have to figure out which shifter handle you will want to use to position the handle where you want it to be. Hurst has lots to choose from. The original '72 automatic shifter hole will have to be filled in. As you said, it is way too far forward to work. Purchase some reproduction carpet for a '73 or '74, and the shifter cut-out location should be better for you, but it will fit that earlier chassis. I do suppose if you really, really want the super sleeper look, you will want to use the stock floor mounted shifter, but you will have to do a fair amount of custom fitting on your floor (since you do not have the original '73-'74 4 speed drive shaft tunnel). If you were really, really intent on using the old stock shifter, I would recommend finding an old junk '73 or '74 and cutting the shifter mounting area out of the car. You will still have to modify the shifter arms to fit any transmission other than a Saginaw. Now about that torque arm question. I have an idea for you. It is what I am doing about an improved torque arm for my car. I bought the shorter torque arm "kit" (better overall suspension geometry) from Jegs. It is intended to be used on the 3rd & 4th gen F-bodies, but once modified, it is an excellent starting point for a Vega or Monza. You will have to narrow the driveshaft tunnel bracket and modify the torque arm to match up with the H-Body rear end, but I think you will like the result. As a plus, you don't have to worry about unbolting the torque arm should you have a problem with your transmission. The stock torque arm will fit, (even the '72 body) with some minor mods, but the Jegs torque arm is an attractive option."

  Tony (Tonyhallo) writes about mounts:
  "The only stock type mount that will work on the 71-74 Vega is the 75 Monza unit. The 76 models changed mounting type in that the crossmember bolts screw vertically into blind nuts verses the early early version where the crossmember is held on with long bolts that pass through both the crossmember and a mounting bracket. I believe the Hooker version will work with any combination since it's universal in nature. I would look for the 75 v-8 Monza unit."

• T56 six-speed transmission from a 1993-1999 Camaro or Firebird: Tony Hallo writes:

  The following is my experience installing a Borg-Warner T56 six speed transmission in my 1971 Vega. I was lucky to find and purchase a totaled 1996 Trans Am with an LT1 and six speed transmission. My original plan was to install a tuned port engine and 5 speed transmission but just couldn't past on the LT1 and six speed. I removed the engine, wiring harness, PCM (The new name for the ECM), transmission, pedal assembly and clutch master cylinder from the donor car. Considering the equipment that I salvaged, the $2200 purchase price was quite reasonable.

  The six speed is quite a large piece of equipment with two overdrives. It is rated at 450 ft-lb. of torque and supposedly more reliable than the B-W T5. I was a little worried after I removed the transmission and it was sitting on the floor. Will this thing ever fit in the Vega? I figured that I could always sell it and buy a 5 speed if it wouldn't fit in the car. T56 are going for $1500 in my part of the country.

  I installed the engine and transmission as an assembly. I'm using Monza factory V8 mounts and was fortunate to find a 1975 Monza rear transmission mount (According to Crazy Dave their worth their weight in gold). The 1975 Monza rear transmission mount will work in the early model Vegas. The engine/transmission assembly was difficult to get into the engine compartment due to it's length. I had to change to rigging several times before I could get the assembly in. After the engine was in the compartment it was apparent that some significant modifications would be necessary to get the transmission up into place.

  The transmission mount on the T56 is 7" behind the stock mount. The transmission hump in the bell housing required some major beating to provide the necessary clearance. I didn't think that hammering would provide acceptable results so I cut the hump out in the bell housing area. Back to the donor car for a section of floor. I cut the rear section of the hump out from the front of the transmission mount reinforcement to the front of the parking brake lever hole. Since I am installing sub-frame connectors in the car, I cut the hump and floor out over to the location of the sub-frame connectors. Only about 3" of the hump was left in place which made reinstallation easier.

  The Trans Am bell housing floor section was fit in and tacked. The section of the original hump was moved back 7" to allow use of the stock Monza cross member. A piece of 18 gage sheet metal filled the hole that was left. The floor reinforcement near the transmission mount will be welded directly to the sub-frame connectors when the project is completed. The parking brake lever will be relocated to provide adequate clearance. The T56 shifter is in a comfortable position in the Vega.

  Onward to the clutch. The B-W T56 uses a hydraulic clutch. I had previously removed the master cylinder from the donor car. The late model F body clutch master cylinder is a curious looking device. The cylinder is positioned at approximately 45 degrees from the vertical plane and bolts to the floor board/firewall area. The master cylinder uses a remote reservoir. I removed the mounting bracket from the Trans Am pedal assembly and installed it on the Vega pedal assembly on the outside of the clutch pedal. I had to tack weld a 7/16" flat washer on the bracket since the Trans Am pivot hole is larger than the Vega. The bracket was used to determine the position of the master cylinder on the Vega floor board/firewall. The only problem I encountered was the Vega firewall is dished out towards the engine compartment right where the master cylinder would be located. This dished area provides for additional travel of the brake pedal Time to get out the cutoff wheel and remove a section of the firewall. I bent and installed a piece of 18 gage sheetmetal that provided a flat surface for mounting the master cylinder. The holes where located with the bracket and drilled. The master cylinder fit just above the frame rail out of the way. The reservoir was mounted to firewall just above the brake master cylinder. A 1/4"X1"X2" piece of steel was welded to the stock Vega clutch petal arm at the top and drilled in the same location as the Trans Am pedal assembly to provide the correct geometry. It was necessary to grind a small section of the pedal frame to provide clearance for the pin and arm when installed. I believe this installation would benefit all those installing manual transmissions. The wiring harness block is located right where a conventional master cylinder would be located. The F body master cylinder is mounted under the wiring harness. Some modifications would be necessary to hook up the hydraulic lines since the F body lines are held in with roll pins and sealed with o-rings as compared to the typical flared tubing. I still have to move my wiring block because the roll bar is going through the firewall right where the block is located. I think that a conventional clutch master cylinder would have been difficult for me to install due to the location of the roll bar.

  Since the new F body cars use an electric speedometer, I will be installing a conversion kit from Stealth Conversions that provides for a mechanical speedometer drive. Information can be see at their web site at www.jagsthatrun.com.

  NOTE: This writeup, with pictures, appears in the Tech Tips section of HBOA Online: http://www.inwave.com/~bacchus/HBOA/.

  michman11 adds this regarding hydraulic clutches:
  "GM has manufactured vehicles with hydraulic clutches for many years. The y car (corvette) and the f cars (camaro/firebird) both had/have small block engines. Early versions had an external slave cylinder which was mounted to the bell housing. I'm not sure if the cylinder could be mounted on an h body due to tunnel clearance. Your best bet would be to obtain a late model hydraulic clutch set up which moves the slave cylinder into the bellhousing. The slave cylinder is mounted to the front of the transmission on the bearing retainer and replaces the throw out bearing. This design is known as a hydraulic throw out bearing. Mc Loed offers a hydraulic throwout bearing which is compatible with all "old style" small block bellhousings. The hydraulic lines (supply and bleed) exit the bellhousing through the throw out arm hole. I run the McLoed bearing on my h body. Performance is excellent."

• Manual transmission from a 4.3L V6:

  Denis (denisst78) writes:
  "The bellhousing from the 4.3 WON'T fit the 3.8 (231 buick) but will fit the 3.8 (229 chevy). If you want to use the hydraulic clutch bellhousing from the 4.3 you'll have to use a adaptor plate between the engine and the block. Those are sold by Trans Dapt, TCI, API, and others."

• General thoughts about adaptor plates from Denis (denisst78):
  "I think they don't recommend using those adaptors with a manual trans because you'll need to place a spacer between the crank and the flywheel or use a taller throw out bearing (so the clutch won't over travel amd retain a good geometry). The second problem is the pilot bearing the input shaft of the trans must be centered in the crank. Maybe you could make a spacer that will move your flywheel a 1/4 inch out and machine the inside bore so it will accept the pilot bearing or bushing (use a bearing for GM 6.2 Diesel; it's much better than a bronze bushing)."

• T-50:

  Robert (twelve_second_vega) writes:
  "Keep in mind the T-50 is almost 4" longer overall than a Saginaw and the Mount Pad is 3" farther rearward too. The Driveshaft and Torque Arm are unique also. There are basically (3) driveshaft lengths in the "H" Body cars (measurements are tube length only from weld to weld):

  1. 4 Cylinder with Automatic or Saginaw: 46 1/2"
  2. V6/V8 with Automatic or Saginaw: 42 1/4"
  3. V6/V8 with T-50 Transmission: 39 3/4"

  The V6/V8 Torque Arm bears the numbers "5343" and the V6/V8 with T-50 bears the numbers "5353".

  The distance from the Bell Housing mounting Surface to the Centerline of the Transmission Mount Bolt Holes are as follows: Saginaw: 14 1/4", T-50: 17 1/8"

  Your 1977 chassis has (2) sets of holes for the Transmission Crossmember and you would use the rearmost holes for the T-50."