Upgrading Your M body to Manual Transmissions
Below is edited and compiled information from member Thunderstruck
(Steve Knickerbocker) on swapping a 4-speed manual or 5-speed manual transmission into an M-body. Note that this swap requires considerable planning, knowledge of parts interchangeability, junkyard scrounging, mechanical and fabrication skills. It is NOT for novices, nor is it for the faint of heart. However, it is a very worthwhile and rewarding swap if you like going through the gears.4-Speed (A833) Swap
Several issues with this. First, there were some 4 speed V8 M-bodies built by the factory but they are rare enough that I have never seen one. I have seen a ton of 4-speed F-bodies (Aspens/Volares) though, with 4-speed wagons being a common sight. There were many factory produced Slant 6 combos, so while you can use the pedal assembly out of any manual transmission Slant 6 M-body or F body, you cannot use the Slant 6 clutch linkage. Nor can you use the Slant 6 bellhousing, flywheel or clutch.
If you wish to use factory parts, What you need is a V8 4-speed F-body body donor, which IMO is the best donor candidate for this swap. So, what you need to swap an A833 4 speed into an M body is the following.
- An A833 4-speed manual transmission from ANY A, F, or M body. It doesn't matter whether is is a V8 or slant 6, or OD/non-OD. Some trucks with OD appear to use the A/F/M body version so look there too. Grab the shifter if it's there and especially if it's an OD version. A truck A833 is about 4" longer than an F/J/M/A body A833. Which is about the same length as the 727. So if your M-body has a 727, the driveshaft will work with the truck (also B/E body) A833. If your M-body has a 904 transmission, then the shorter F/J/M/A body A833 uses the same driveshaft. However, there is an issue using the longer A833 in the M body. The shifter will not bolt up in the right place. You will need to make an adapter. Go to Bigblockdart.com for details. The OD trans in the trucks and later A bodies is an A833. It just had a gear swap by the factory to change the ratios - something the factory did a number of times during the A833's production life. The gear spread between 1st and 2nd is not that big, unless you have a torqueless sewing machine for a motor, heck the drop between first and second in my 05 Neon is bigger.
- A shifter. Hurst still sells a shiny new Indy shifter for the A body A833, which is the same for F or M bodies. It is for NON-OD transmissions though, so the shift rods are different. You might be able to fab the one rod that is different. This is up to you and your fabrication skills. If you have the factory shifter rods, they will work with the Indy shifter mechanism. Dig into the back of the Hurst book and you will find this shifter.
- A V8 bellhousing. Slant 6, LA and B/RB engines all use different and non-interchangeable bellhousings. The only exception is that some trucks use a bellhousing that will accommodate both the Slant 6 ans LA patterns. However, they have rear motor mounts as part of the bell. This shouldn't interfere, but they are big, heavy and awkward.
- A V8 flywheel. 318 engines are internally balanced, so the flywheel should have no metal removed from the crank side surface. 360 engines are externally balanced, so the flywheel should have places on the crank side where it has been drilled (slightly countersunk) to remove metal. If it's internally balanced or externally balanced, you better get the right one for your engine. While you're at it, you better get the right one to fit the bellhousing too. A 130-tooth flywheel is typical, while a A 143- tooth unit is not.
- Clutch pedal assembly out of any manual transmission Slant 6 M-body or F-body. Truck pedals will NOT bolt in. I have a set of them and they are not the same as the F body ones which fit the M-body just fine. Can you make the truck pedals work? Probably, but I didn't bother to try as I found a good donor.
- A V8 clutch that fits the flywheel. Usually the 10.5" or 11" SCALLOPED (10.95" actual). They fit the 130 tooth flywheel. The 11" clutch fits the 143 tooth flywheel. Confusing the 11" for the 11" scalloped clutch will aggravate you.
- Some sort of clutch linkage setup. McLeod makes an hydraulic throwout bearing (part number 1400-10), for the 23-spline A833. $266.67 is an old quote from McLeod. The manual F-body Z-bar mounting hardware can also be modified to work.
- A pilot bushing for the crank. And YES you need one. All production cranks are drilled on the end for the pilot bushing, BUT on automatic transmission equipped cars, the cranks are not final reamed to fit the pilot bushing. Fortunately, NAPA sells a special bushing (part number 615-1033), which is designed to fit into the crank's unreamed hole. Another option is to spend a few more ducats and get the MoPar Magnum engine setup. It is a sealed, needle bearinged unit designed to press into the torque converter centering ring. Send $50 and I'll send you the part number, . The part number is 53009180. This part doesn't use the older pilot bushing hole. You choose your flavor here.
- Floor Hump. I used a manual transmission only floor hump, which I cut out of an 80 Volare with my shiny new cordless sawzall, thanks redheaded one. If you don't want to use a hump, how you deal with the hole in the floor to accommodate the shifter is your business. I do know you can't just cut a hole for the shifter to poke thru and be done. Anyone with any experience with a side shifted trans knows this but I find plenty of people have no problem showing their ignorance. Then argue they aren't. Seal it well so you don't breathe fumes or road spray.
- Driveshaft. If you are replacing an A904/998/999 automatic, then you can reuse your driveshaft, but you might need to change the slip yoke to the A727 style. It will depend on the A833's output shaft.
Do you have to do exactly what I did to swap in an A833? No, but using the factory stuff made it easy with minimal fabbing. You could probably use A body stuff, but I have no idea how close to working that stuff is. 5-Speed Swap
As for a 5 speed, there are many ways to do that. You can swap in a kit from several manufacturers based on the Tremec if you want:
(Note: the above kits are not specifically made for F/J/M cars, so you should check with the manufacturer.)
The 5-speeds used in Dakotas and Rams are real bulky. But in either case it's not nearly the issue in an M body, or any other transverse torsion bar car, as it is in older MoPars that use the transmission crossmember as the rear anchor for the torsion bars. The V6 5 speeds are fairly weak. They are Ok behind a stock 318, but I'd be leery behind a stock 360 or a warm 318. The V8 5-speeds from the trucks can be used, but they are truck transmissions, big and not geared towards (geared, lol) car use.
My preferred 5-speed setup, based on cost vs. performance is the R154 swap.
A real brief synopsis:
- Bellhousing from an AX-15 equipped Dakota
- R154 5-speed transmission from a Toyots Supra Turbo
There is some custom fabbing needed to accomplish this. However, on a scale of 1 to 10 (1 being easiest) with the aforementioned A833 swap being a 1, I rate the R154 swap at a 3, the Tremec swap is a 6 (If you DIY and don't use a kit).
I might do this swap on my 65 Cuda and document it. Ought to be almost the same for an M body,
with a few minor exceptions, like the specific donor for pedals and any driveshaft length changes.
That about sums it up.
Steve Links to Steve's site:Additional 4-speed Swap Notes Compiled from Old Threads:
- Spikekid999: "My dad put a 4 speed in his 5th Avenue. He got the center hump and pedals out of a Volare. He left the original (5th Avenue) column in it because he wanted to keep the tilt. The only thing he had to do was move the highbeam switch to the floor like the older mopars because something with the original would otherwise get sheared off by the clutch pedal."
- CudaZappa: "The 5 speed from the Dakota has a granny first gear, really short, like a 3.27:1. Tthat's steeper than the OD 833s 3.09 (which is also DAMN tall). They did put 5 speeds behind the
5.2L Magnum but it won't be worth it in a car application, and it is also weaker than the A833."
- S-type: "The truck tranny is a lousy choice. The gears are a poor selection for a car, and the shifter is a joke. Go with an A833 or Tremec."
- Remy-Z (Current owner of Steve's 4-speed Diplomat) "ONLY advice I'll give here: Listen to Thunderstruck. I own the rolling testbed he built now. It works. I've had no problems with any of the work he's done to the car in the pushing three years I've owned it."
- Diagram showing dimensions of the A833 (Courtesy Mopar Chassis Manual)
- Toyota R154 5-speed transmission (Courtesy Gary Evans)