Some people have asked me how I was able to get a transmission to fit onto and work with the American LaFrance bellhousing and flywheel. (ALF for short) Hopefully these photos will help you out. First, I decided to not use an original Auburn transmission as they are expensive (actually I sold mine to help finance the build) and they are not as robust as I like my stuff to have. I bought a GM designed SM-4654 speed truck transmission. These units have legendary strength and reliability, also, they are common and cheap. Second- I made a Pilot bushing out of oillite bronze,drilled and tapped the original flywheel so that my Chevy pressure plate would bolt up. Third- I came up with what I call a bellhousing, but is probably more of an adapter. (I do not recall the offset dimensions as it was a 'one-off') The main body is a piece of 1/2" plate. Next was just a lot of measuring,welding,and machining! Fourth-along the way I decided to use a Hydraulic throwout bearing, as the ALF and Auburn bellhousings are different in how the brake and clutch pedals mount and work.
Jumping ahead- do NOT be a 'cheap ass' when you buy a Hydraulic Throwout bearing! Ok, you CAN, but be prepared to do the job twice. I had to remove the engine and trans 3 times to get a setup that would work. My nicely painted frame, now oily,dirty, and scratched. Three days of labor down the drain,yes, it pretty much sucked. I will showcase my mistakes: 1) A "Stock" clutch means a DIAPHRAGM type setup!! A "Stock" Chevy "Borg and Beck" is completely off of the charts as far as the parts catalog companies are concerned. (with my truck trans I bought a "Truck" clutch originally) Do not try to use one with a hydraulic throwout bearing. Been there, done that. Failed!
ALF flywheel designed for a "Pot" style clutch. Inside you can see where I drilled and tapped the six holes for my "modern/common" clutch.
11 1/2" clutch and pressure plate for a Chevy truck sits down inside perfectly! (not pictured is the Borg and Beck I tried at first)
Hydraulic Throwout bearings. Cheap one(99$) on the right that failed, "GOOD" one ($215) on the left that works great.
The entire thing torn apart to replace the Hydraulic throwout bearing that failed. Here you can see my 'bellhousing' adapter on the transmission.
Everything "Blown apart" on the Garage floor, not a great photo, but this was not a lot of fun either! Pull engine, push frame outside. Three times!
Remember that the Auburn's have the rigid frame "X" member? Yeah, that means that the transmission comes out with the engine, as there is not any room the slide the transmission back for access.
Pay close attention to the throwout bearing hose connections. The "cheap" one uses the fittings screwed into the side of the body as the anti rotation stop with a tiny O ring to seal the fluid.The constant vibration against those fittings stresses the threads, and it starts to leak. When you try to tighten it back up, you will discover that the threads are barely 2 threads deep into the body, strip easily, and are some bastard metric uncommon thread! There is not enough material depth to re-tap even to 1/8" pipe. The second one I got from Summit racing. The "good" throwout bearing has the hose connections in the base of the body, and the side of the base has a machined slot that works as the anti rotation. I used a 3/4" bore master cylinder as recommended by the mfg, bleed and shim/space accordingly.
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