Transmission Crisis

 For a long time I’ve been planning to attend  the 18th annual Gold MicrocarClassic and drive my Heinkel 120 miles to the top of Mt. Wachusett. Unfortunately, on Tuesday morning (3 days before the event) I shifted my car into reverse and ended up going forwards. Clearly I did something that needed fixing if I wanted to get there on Friday.

I’d had a problem like this before and I thought I’d settled it.  Last year I had a spring clip slip off one of the transmission shafts, exposing a key which proceeded to fall out and make it impossible to shift into reverse or past second gear. I was hoping lightning hadn’t stuck twice, because fixing it was a major project.

As it turns out, it was EXACTLY the same problem. 

The Key That Fell Out of The Heinkel Gearbox

If I wanted to go I had to the Microcar Classic I needed to complete the following steps:

1. Remove the engine from the car
2. Tear down the entire engine in order to split the cases and remove the transmission
3. Swap out the transmission from another source
4. Rebuild the engine
5. Reinstall the engine

6. Adjust and road test

Let’s hope this doesn’t happen to you! It is fixable, but it’s an 18 hour job.

If you ever have to do any of the steps above, here are some tips to speed up the process and assure a good result:

Removing the engine: I’ve done this several times; it takes about 90 minutes. Some things I’ve learned here:

1.       Slide the entire carb off of the manifold so you don’t have to adjust it later;
2.       Unscrew the shift cable (so you don’t have to adjust later);

3.       Scribe a line on the end of the gear selector so you can remember how to line it up when you reassemble;

4.       Make a note of the clutch setting. The easiest way to remove the clutch cable is to slacken the cable at the adjuster on the housing and then remove the actuator arm.

Tearing down the engine:  Most people might actually take their time and enjoy this step, but I was in a hurry.  I’ve done a total teardown four times and it takes about 3.5 hours. I have a Heinkel engine stand and a really clean workspace, I cover all horizontal surfaces with plastic, and use resealable plastic bags to store and label all the parts.

·         Some tips here:  When you pull off the clutch, zip tie all of the nuts, bolts, washers, shims and plates together in the exact same order  so you don’t have to remember. You should also do the same with the drive chain and clutch basket. They need to be pulled off as a unit, and often have spacers and shims up against the bearings that you won’t notice until it is too late.

Finding new parts; I decided to break into an extra 200cc engine case I had to scavenge parts. This engine was partially disassembled for a reason; I just hoped it wasn’t for a drivetrain issue!  I’ve been told that you cannot selectively replace transmission parts, and you are better doing a complete swap. I pulled this engine apart as well to get to the gearbox.  I did find a humorous surprise: check out the homemade clutch cover gasket!

Homemade Clutch Cover Gasket Made from Cereal Box

This piece had slipped out of the shaft after the covering spring must have been pried off by shifting into reverse.

Rebuild the engine: I’ve covered this in some earlier postings, but I learn new things each time. I thought it would be a great opportunity to fix some small leaking I had, so I tried a little extr a silicone gasket maker behind the part of the head where the pushrods pass through.  The most important thing here is to adjust the valves and points before reinstalling the engine, because it is a lot harder to do once the engine is in the car. 

Reinstall the engine:  Here’s the best way I’ve determined to handle this:

1.       Put the rear of the car on blocks to raise it about 4 inches (100mm) higher than it normally sits. Put blocks on the front wheels so the car does not roll.
2.       Put the engine on a mover’s dolly (like this) and use a series of sliding wood wedges under each side of the engine mount to adjust it up and down as needed.
3.       Get a low profile racing jack and position it under the movers dolly or engine so you can jack it into alignment with the lower mounting bolt holes on the car frame
4.       Jack it into place and partially tighten the lower bolts.
5.       Remove the dolly, and reposition the jack so you can pump/pivot the engine to line up with the top mounting hole on the frame of the car.
6.       Insert the large engine mounting bolt so the cotter pin hole on the  bolt end is aligned vertically (so you can see through it when you look down on it).
7.       Tighten the nut only while holding the bolt into position (this makes the cotter pin easier to insert).
8.       Insert cotter pin from the bottom and bend as required.
9.       Tighten lower bolts.

Adjust and road test:

Put back all of the cables as you removed them;  you should be on the road with minimal adjustment. If you did any replacement work while inside the engine (like clutch plates), you will have to make some adjustments.

 I finished my road testing late on Friday afternoon. Rather than drive 35 miles in weekend city traffic on a freshly and hastily reassembled engine, I chose to leave early Saturday morning and arrived in time for the day’s festivities.  I bowed out of the 120 mile ride- I didn’t want to push my luck. Instead I got a ride in a Citroen Mahari (an ABS plastic truck) and made some new friends. By next year I’ll be ready to try again!

Microcar friend John in a Mahari