Union Jack

Restoration of My 1967 AH Sprite MK4

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Note: Each photo below can be clicked for a larger view

Chapter V -- Install the Engine and 5-Speed

I actually purchased and received the 5-speed adapter kit from Rivergate several months ago and I have had the gearbox for several years. Although the car has been ready for a while, other projects have kept me from preparing and installing it. In addition to the basic adapter, I also purchased the two options they supply. The first is a custom slave cylinder that includes a braided hose directly to the master cylinder. The Sprite slave could have been used but this one is supposed to give better feel and it greatly simplifies the plumbing. The second option is a speedometer cable that mates to both ends without modification and includes a gear set matched to my rolling tire diameter so the speed reading is correct.

Gearbox mods Adapter The Model A chassis is pretty well done and waiting for wheels to return from the powder coater and new tires to arrive from Lucas so Dan ran out of work temporarily and started on the Sprite 5-speed setup. This is where we are after a couple of days. The modifications to the gearbox are done and the adapter is installed, replacing the original steel back plate on the motor. I had to grind clearance for the oil pump cover in the rim of the bell housing. See the crescent shape cutout in the upper right of the left photo. Also had to cut out clearance for the slave cylinder. Lower right in the same photo. Finally it needed a large hole cut through for the Lucas starter bendix. Lower left in the photo. That is the new clutch release bearing installed. The adapter plate, itself, did not require any modifications although I did polish the edges just for looks. There is a liberal amount of silicone in various places between the motor and the plate, some of which was a little tricky to apply.

Nearside done Offside done A couple of days later we finished fitting the adapter and gearbox to the motor and here it is ready for test fitting into the car. So, naturally, we tried it. Actually, it was probably closer than I expected, based on all the stories I have heard. It went over the radiator horns without too much effort then we tilted the rear down severely to begin entry into the tunnel. Again, no real problems surfaced but it stopped about an inch short of lining up with the motor mounts. At that point, the rear mount was hard against the rear cross member while the bell housing was against the heater plenum and the oil pan was a good quarter inch short of clearing the front cross member with zero clearance.

Rear done More grinding The only viable option was to pull it back out to grind about an eighth of an inch extra clearance from the back of the bell housing and to grind the upper bolt of the slave cylinder that would eventually interfere with the frame rail as the instructions suggested. These photos show the back of the bell housing before and after that additional grinding. That was Friday. First thing Monday, we tried again. this time it got a little closer but still the crankshaft pulley would not quite clear the front cross member. Again we pulled it out and did more grinding in that same spot for the same reason. This time, I produced a tiny through hole that I patched with a thin coat of JB Weld applied like bondo. On the third attempt, it went in although I did have to give it a good shove from the front to finally get past the cross member.

The last step on installation was to install the lower section of the two-piece rear mount. The upper section is bolted to the tail of the gearbox before installation since that would be inside the tunnel and unreachable later. The lower section is added after installation and bolted to the cross member from below then to vertical extensions through the tunnel from inside the car. Finally, the two sections are mated by extensions outside the tunnel. There was an unexpected problem with this method as described in the supplier's instructions. It seems that the supplier of the mount changed the design a little without notice. This made the upper plate wider at the front that at the back. In fact, it was wider than the space between the vertical extensions of the lower plate, making it impossible to slide it in from the front. We had to pull the whole installation back out a few inches to allow the lower section to be inserted from behind then slid back to the front. Since the displacement put the pulley back above the front cross member, it was too tight to fit back in. Again, some extra force was required to put it back in place. The camera angle exaggerates it a little but the first photo below gives a pretty good idea of the design flaw. Dan finished the rear mount installation and we ended another busy day. We did scratch a little paint at the front and rear cross members and the heater shelf which I touched up with a brush. These photos show the final installation.

Rear mount Left side Right side

Heater box U-Joint In the left photo, you can barely see the final clearance between the bell housing and the heater box if you look really closely. The right photo shows the last remaining issue with the installation. The rear mount raises the tail shaft just enough to make the U-joint tap the top of the tunnel at one point in its rotation. This is not an unexpected problem. In fact, there are several known solutions. One popular one is, With the car on jack stands and engine running in gear, toss a broomstick into the tunnel so the U-joint catches and beats it against the tunnel from inside, making clearance. I admit, I am not brave enough to do that. Instead, I worked on it with a crowbar, using leverage off the U-joint until I got about 1/4 inch clearance. I hope that is enough. Time will tell.

Actually, the last remaining issue is the modification of the Datsun gearstick to work. I will save that one for later. Meanwhile, I wanted to ensure that everything else fit properly so I began temporarily installing all the stuff that attaches to the motor. I don't have a manifold gasket yet and the sources are all shut down due to the corona virus so this will all have to come back off.

Manifolds Heat shield Carburetors
Air cleaners Front

Well, Harold found a manifold gasket and gave it to me. During some slack time on other stuff, I got it all removed and reinstalled properly. On advice from Mike Glass, I also eliminated the PCV valve and routed the crankcase vent directly to the nipple on the air cleaner can. I also installed the generator and fan belt. Only things left are connect the fuel lines, add fluids and crank it up. Then, of course, the gearstick modifications.

Long Pause for Work on A Lot of Other Stuff

As it is almost time for the first test drive, I thought it time to do the essential gearstick modifications. I cut the Datsun stick as specified in the kit instructions, 1-1/2 inch above the pivot hole center and 7 inches from the top. That leaves a piece about 2-1/2 inches with a small bend in the center. I checked the fit in the car and it looked like the stick would be a half inch or so to the left of center so would not fit the rubber gaiter. I checked with Rivergate and was told there is no spacer in the kit and one is not usually required. I tried moving the rear of the gearbox a little toward center but if it moved it was very little. So, I decided to use a short piece of the cutoff for the spacer as it was just about the right width. Trying to hold two half inch round pieces together while making initial tack welds can be a challenge but we persevered. I decided to use the stick welder at 75 amps, DCEN for the best penetration. Here is the finished result, both in and out of the car. First photo just shows the modified stick. Second shows how it fits to the gearbox. Third shows with the finish cup and gaiter installed except I had not found the screws for the cup yet.

Gearstick Gearstick Gearstick

This chapter is now complete