736 repairs

You can make a very satisfactory fix without the trouble of pulling and re-quartering the back two sets of wheels.

The right rear axle bushing is always the one that wears out first(from forward operation), pushing the axle left, the right rear wheel into the frame, and the worm wheel off center.

Use one(or two or as needed) 671M-22 clips/retaining rings and snap them on to the drive axle to the left of the worm wheel.  You want to have between half to the full width of a 671M-22 clip of end play in the axle for best performance. Keep the entire gearbox & axle lubed well with a synthetic HP grease(Lucas Red 'N' Tacky #2, eg.).

If you can source some clips with the same inner diameter as the 671M-22, but larger outer diameter, that would be beneficial.  The last good tip I heard was to use an appropriate number of plastic bread closure clips(cut to be round) instead of the 671M-22.  Very little friction with that method and they too slip right over the axle and stay on.

Rob, The bushings are worn so bad that the drivers not only move side to side but they also move up and down an excessive amount. The flanges are also rubbing on the back of the drivers in front of them. Seems like replacing the bushings is the best way to repair it. Before I tear it down I will try the e-clip trick to see if that helps with the lurching. I noticed that if I run it slow it will bind with the drivers in the same spot every time. I will also run it with the linkage all removed. John,The nubs that you refer to were not engaged in the slots when I got it. I had the motor out and it has no up and down play but does have about .015 end play is that to much? Someone has tried to lube it to get it to run better because everything is full of white grease. Thanks guys.

VERY worn.  Probably run a long time w/o maintenance.

With all the linkage removed, only the rear drivers are powered.

Also replace the connecting side rods with new ones. They get worn out and the engine will never run smooth no matter what else you do.

If you are going to pull the wheels of, first scribe a line carcass the center of the axle and onto the wheel hub.  This will help you get the wheels exactly lined up where they came off and quartering will not be a problem.

Well today I finally got a chance to replace the bushings and side rods on my 736. I marked the axles and drivers and used a modified battery terminal puller to remove the drivers. The replacement bushings had to be reamed after installation as they were a heavy press fit in the chassis. I made a stepped driver to install them to prevent damage. After lube and assembly the engine now runs smooth, no more jumping or lurching even at low speeds.Also now the drivers do not rub against each other. I am glad I took the time to repair it.

Hi - Old 736 is a beautiful engine and I'm glad you got yours fixed.  I followed the thread with interest, as I have one myself.  No running problems so far, though.  Have fun.