Tremec Info

(Last Revised: 8 November 2001)

Tremec TR3550 5 spd Installation

I bought a GM converted TR3550 (425 lbft rating) version from Dark Horse Performance. The other place that I've seen that offers a Tremec 5 spd for GM is Fortes. I bought from Dark Horse to save money (approximately $250 on the TR3550). Anyway, Fred Sanderson at Dark Horse treated me very well trying to figure out just what parts I would need. He converts the Tremec from Ford to GM by:

Ordering it from Tremec (or swapping himself) with the "old-style" shorter Ford input shaft. It's 1-1/16"x10 spline. It's a little longer than the GM version, but works out fine. See below for details on that. You need to use a GM to Ford pilot bushing or bearing. Lakewood makes a roller type for this. (Note that you will need to get a clutch disk for a Ford application that will interface with this input shaft. Since I was using a 10.5 inch GM flywheel, I went with a McLeod 10.5 inch dual friction disk for 1-1/16"x10 spline, like used in a 5.0L Mustang.)
Machining the pilot diameter (that registers it in the bellhousing) and throw-out bearing sliding surface on the input bearing/shaft retainer down to GM specs. He may also shorten it. I don't know if it is longer on the Ford.
Re-drills the top two tranny-to-bellhousing mounting holes, and drills new bottom holes in the mounting flanges for the tranny.
Provides a GM to Ford speedo cable gear/cable converter. Be aware that the inner cable needs to be a few inches longer to reach into the converter and driven gear. I bought a new cable inner for my JTR speedo cable. You may also want to consider a 90 degree adapter to be nice to the speedo cable. I also had to get a black (20 tooth) speedo driven gear for the tranny to make the Datsun speedometer read correctly with the 3.7:1 ratio rear and 26" diameter rear tires.

I think that's it. I paid $1550US for it. It came with a new slip yoke and a pilot bushing, plus nice 12-point grade 8 bolts for attaching it to the bellhousing (needed for clearance).

The Tremec shifter is 1.5 inches forward of the T-5 shifter. It still comes out in the stock hole with the JTR mounting, and the HEI distributor cap 1/2" forward of the firewall. With a SouthSide Machine 6 position shift handle (more 5.0 mustang goodies here), the shift handle is right in the middle of the tunnel hole.

Flywheel, Clutch Hydraulics and Throw-out bearing, Bellhousing:

For a flywheel, I used the 16 lb. nodular iron Chevy piece used in the 1983-1992 Camaro Z-28 H.O. and TPI engines. That saved 9 lbs over the standard unit.

Pilot Bearing:
I ordered a GM to Ford Lakewood Pilot Bearing from Dark Horse Performance. It was a very close fit (from it hitting the splined portion of the input shaft) before the tranny spacer plate, but now it rides in the middle of the pilot length of the input shaft.

Clutch Hydaulics:
I used a Mcleod hydraulic throw-out bearing for a GM T-5. It's a pretty nice piece, and costs (ouch!) $259. I calculated that for the clutch pedal height to be the same as the brake, and the resulting short clutch master cylinder movement, I'd need a 7/8" diam. master cylinder. Another $200 for an AP Racing short version from TrueChoice Motorsports. Ouch! I tried this part (and sold it) part number CP2623-194. The clutch pedal was quite stiff and the total throw of the pedal is 4 inches. Since then, I've installed a Girling remote 3/4" diameter master cylinder and remote reservoir mounted to it with AN fittings. This give more throw than I'd like (from brake pedal height to the floor to get the full 0.030" clearance Mcleod recommends for a diaphram clutch) but the pedal is just a bit stiffer than any manual trans car from the factory.

I made (4) 18 gage steel bracket/covers to handle the exit of the hydraulic hoses of the TO bearing from the bellhousing that have grommets where the two hydraulic hoses exit the bellhousing. These are screwed into the bellhousing with a bunch of small stainless screws. I've fashioned a bracket to hold the ends of those hoses to the bellhousing using a bulkhead AN fitting and a cushioned cable clamp. A braided hose with various steel brake hose fittings connects the master cylinder to the slave.

Transmission Spacing for using the Hydraulic TO Bearing:
To have the correct spacing between the throw out bearing and the clutch diaphram (using the hydraulic TO bearing and the stock 1LE 5 liter Camaro TPI clutch pressure plate), I had to space the tranny back off the bellhousing. I made a 1/8" spacer out of aluminum plate. The clutch disc is a dual friction piece for a 10-1/2" Ford from McLeod.

Bellhousing:
This is all bolted to a Lakewood blowproof bellhousing. I had this sitting around from years ago, and decided I'd seen one too many cars mangled from blown flywheels (a beautiful 57 Chevy - the owner got to keep his feet, luckily), so I decided to use it. To gain ground clearance, I trimmed about 6 inches off the perimeter flange at the lowest point, parallel to the ground, as installed in the car. Yeah, it's not acceptable by the NHRA now, but it's way safer than an aluminum one.

The blowproof bellhousing is for the larger diameter Chevy flywheels, so it interferes just slightly with the tunnel about 4 to 5 inches back from the firewall, and about 6 to 8 inches below the tunnel opening. I used a rubber hammer to move the tunnel a bit, to gain about 1/4" of clearance.

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