I am designing an adapter plate to go from the 4cyl in the HJ to a Chevy trany. I am thinking 1/2" aluminum should be thick enough, or? Constructive suggestions please. Thanks.
It depends if you need a counter bore one one side and a alignment ring on the other . 1/2 probley would work but a if needed a loose 2nd piece ring could be used. I made one from Chevy trans to early Ford falcon and started with 1" ,when done was about 1/2 but the pilot ring on engine side was about 1/4" high so material was about 3/4 at that point.Needed to use the Ford release assy. on the Chevy trans nose so made a sleeve for the Ford assy to fit the smaller Chevy nose.
threads, if any, need sufficient engagement. alignment ring or dowels need proper attachment. the changes it makes to the clutch spline fitting the input should be considered. the changes it makes to the pilot end of the input mating to the pilot in the crank should be considered.
When I made my aluminum adapter for my T5 to flathead I used 1" thick flat stock. The reason is like John Evans said about an alignment flange for both the bell housing and the chevy T5. The first photo is the part that mates to the bell housing, the second pic is the T5 nose.
Is this an adapter going between the HJ bellhousing and the GM standard transmission? Or are you mating up a GM bellhousing to the HJ block? I would start making up a full-scale mock up out of plywood, just to get everything to fit roughly. Most home improvement stores have birch cabinet-grade plywood, which you can get in a 24" x 24" piece and it's pretty dense material. Bob
Thanks all. I am going to use an automatic in this car. I retired as a 30+ year machinist in a papermill so have lots of experience fabing adapters etc. I have traced the two patterns on a cardboard to see what overlaps what. My plan is to drill the plate using the HJ bellhousing as a template, which has two 3/8" reamed holes to align it to the HJ block. I will then clamp a standard bellhousing to the plate and dial indicate the trany hole to we ensure the bellhousing is true to the engine, and then drill/ ream the plate for a dowelpin. I will also fab an adapter to bolt onto the crank to center the convertor. 1/2" will give me proper thread depth and I will be using 3/8-24 fine bolts into the adapter. I still want to hear other opinions as well as what thickness the aftermarket plates are.
Consider that the trans shaft has to fit into the crankshaft pilot bearing a certain distance, this dictates the thickness of the bellhousing+adapter. Check this distance and make the thickness of the adapter accordingly.
1 . I wouldn't use fine threads in aluminum for anything 1a. Especially for a transmission 2. If 1/2 is what's needed based on the spacing needed then that's what you need . But if no bolts go directly thru trans bell housing into the block I'd go with steel. 1/2" will flex if the bolts are far enough away from each other. I'd imagine a socket head cap screw to hold plate to block ? the recesses of those wont leave much meat under them in 1/2" either. FHCS are know to shear the heads right off. You could always make it out of 3/4" and then fashion a crank spacer to properly locate the converter. You may need one anyway? 3. will you be using a custom flex plate or adapting something from the Henry J? I have no idea how the starter mounts or flywheel/ring gear arraignment on those? I'm sure you'll need something there.
That's a good point 31Vicky has about the bolts. I used only course SHCS's on mine. I suppose you could aways run a steel 3/8-24 heli-coil insert into the aluminum, I have had success with those when I made some shifter knobs and on a more larger scale we used those thread inserts on a gas-tank blow mold at work a few years back. Brent
Just my $0.02. I bought one for my T5 to Ford 170 conversion. It fit between the bell housing and the T5. Also the width was just enough to compensate for the longer T5 input shaft, and seeing the T5's length was different from my original 3spd, I didn't have to alter the driveshaft length. It had 4 bolts countersunk from the adapter to the bell housing and then the trans was bolted to the adapter. Not sure if any of that was helpful or not. Good luck.
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