12 volt test

I started off by removing the bolt that holds the coupler and putting a drop of loctite to make sure it doesn't come out. Even if it did the coupler had to be pressed on and I can't imagine it will ever move again, at least not without using a puller.

Then I attached the spacers and adapter plate to the motor. Again using some loctite and torqued these bolts to 40 ft lbs. With these bolts, and despite them being recessed were still very close the flywheel so I shortened the heads by .07" each using a bench grinder. I didn't want to risk them rubbing after perhaps the motor and transmission warmed up.

Next the flywheel was bolted on. The original specs called for 90 ft lbs of torque but I dropped this down to 70 with a small drop of loctite. The original crankshaft this was on was a hardened steel. The steel we are using is considered soft and I didn't want to risk pushing the material too hard and strip out a hole on something that took so long to make.

We can now attach the clutch and clutch housing. This part can be tricky if you've never changed out a clutch. You'd think they'd design these different to avoid the problem but they don't. The problem is the clutch itself needs to be centered with the housing, and therefore the transmission input shaft. If you simply tighten all the bolts the clutch will probably be too low (gravity) and you'll never be able to push the transmission and motor together. Usually you can just buy an alignment tool that you slide in while you torque the bolts. I didn't have one so made one out of a 17mm socket and some electric tape. It wasn't perfect but allowed me to slightly move the socket on an extension until I could see it was aligned before tightening the bolts. These bolts called for 19 ft lbs and again I used just a small drop of loctite.

Next came the hard part. The two guide pin holes we drilled are very slightly off and it requires some elbow grease to get them started each time. After I finally got it together I realized the clutch arm had fallen out and I had to start over. This is a reverse clutch and it actually pulls on the clutch instead of pushing into it to release. It makes hooking the clutch arm into place tricky and has to be done at just the right time while you're mating the motor and transmission.

Now the grand finale! I was so nervous to apply the 12v to the motor afraid I'd hear some rubbing, clanking, or just see the whole unit vibrating badly. All of this of course unfounded since I witnessed all the machining work. So I wired everything up and then touch the final wire to the battery. Luckily the transmission cross brace was still attached because that's what kept the whole unit from falling over as the initial torque kicked in. The motor always instantly reached its top speed for 12v and output shaft of the transmission was spinning happily along. Very quiet, very smooth...woohoo it works!

Of course the initial test wasn't enough as I was just too excited. I had to go get my wife, bang on my neighbors doors (he helped me strip the car down originally), call my uncle, try out a few of the gears just to see the output shaft spin at different speeds.

Here is a quick shot of the completed assembly after the 12v test.


Another shot so you can see another angle.


Next comes hoisting the motor/transmission into place in the car and taking measurements for the motor mount that needs to be built next.

Adapter plate and coupler complete

I finally got some time from my uncle to machine the parts and it took longer than we anticipated. Engineering as you go and a lot of measuring twice before you cut really added to the time but I think we'll end up with a reliable setup.

I loaded up the truck with everything I could think I needed and headed to my Uncle's house.


First was to create the coupler. The coupler needed to be 3.125" OD with a 1.125" ID with a .25" key. Here is a picture of the raw metal before we began to work with it.



A shot of the metal slowly getting turned down to the diameter we need.


It's starting to take shape. You can see the end is a little less than 2" wide and about .200" deep if I recall. We did this so the coupler could sit flush against the motor bearing and wouldn't be able to work its way in.


Here we are cutting the coupler slightly longer than we want it. This was the only step of the lathing process that had enough friction to require a lubricant.


Now we are slowly shaving off the end to bring it down to the exact length we need.

After the basic coupler was shaped out we broached out the key way using a 40 ton press. This was so cool to watch I forgot to take pictures.

Next we needed to drill and tap the holes. We used the flywheel as the template and a drill bit that was the same size as the hole to make an initial mark before moving down to the correct bit. To use the existing bolts you'll need an 11mm drill bit and a 12mm - 1mm pitch tap. This is not at all easy to find. My Uncle had to order it from a supplier he uses. You won't find this at Napa or Ace as it's a very uncommon pitch for that diameter.


Here is a picture of the final coupler installed on the motor. A couple things I didn't capture on film was the recessed washer and bolt which screws in from the front. We had to recess these to give clearance for the transmission input shaft. We also are using a beveled hex bolt and we beveled the washer on the lathe to match and recess the bolt further. A quick coat of paint to help with rust and we are done. Notice the black garbage bag duct tapped around the motor. This is quick and cheap to do and will prevent anything getting in the motor during the build.


Here is the simple yet invaluable alignment tool. Basically the adapter plate has an existing 4" ID and the coupler is 3.125" OD. So we machine this tool to slide over the coupler and then the adapter plate slides over that allowing us to perfectly align the plate with the center of the transmission.


Here is the shot making sure the alignment tool works. It's a tight fit, just like we want. The outer darker metal ring is the steel alignment tool.


There were quite a few steps again here that I couldn't take pictures of. We needed more hands than we had.

The first thing you'll do is use any alignment pins on the transmission and mark those across first. Simply slide your plate onto the alignment tool and find a good position that will make sure no part of the transmission is sticking out past the edges. Then using a rubber mallet give the plate a whack over the pins to mark out their location.

In order to start marking your holes you'll need a couple of things. First is a good set of transfer punches. This can be placed in different sized holes and mark the center where we'll need to drill. There were four holes on the tranny that were threaded and we couldn't use a transfer punch. We bought extra bolts and cut the heads off and turned a perfectly centered point in the lathe. We could then use our mallet again to mark these locations and drill them all out.

After we had all of our holes drilled out we butted the transmision to the adapter plate and secured it with a few bolts and marked the outline which you can barely see as a scratch in the metal.

Now comes the cutting. In our case the most precision cutting tool we had was a plasma cutter.

It's not a perfect cut but only took about two minutes. I later took a grinder to the sides to clean it up a little bit but it doesn't need to be perfect as this edge is only cosmetic.

So next we realized the flywheel didn't have enough clearance and was rubbing on the plate. We then had to bevel the inside ring of the plate and recess the four motor bolts. I believe we put those in about .150".

Here we finally have the transmission mounted to the motor! The clutch and flywheel at this point were not actually attached to the coupler. My uncle and cousin held the assembly in place while I snapped a quick picture.

The next step will be to tear this back down and reassemble it with proper torques specs, locking compound, etc and then finally give it the 12v test!

I also had about 80k miles on this setup so I'm going to spend the money and replace the pilot and throw out bearings while I'm here. I'm thinking of just replacing the clutch too as it does show some decent wear.