Just picked up an 801-019 Transaxle. Rebuilding it to go fast with horizontal input.

I just picked up the aforementioned 801 transaxle. It seems in good shape on the outside, although the wheels are very firmly rusted onto the axles. The input pulley was also rusted onto the shaft, and I had to cut that off. But now I have a good transaxle to start my three wheel microcar project.

So I'm about to open this up. I have a couple goals. First, replacing the grease with gear oil and checking on all the seals and bearings and such. I noticed in the manual that it has real ball bearings for the axles, which is nice.

The other thing I want to do with it is convert it from a vertical input to a horizontal input. The engine I want to power it with is an 8hp briggs flat head that is horizontal shaft and sounds beautiful. This means I have to extend the input axle. Since it sticks out on one side for the brake, I could either stick a pulley on that side, or extend the other side, depending on the direction I need to drive it. I have access to machining equipment at work, and I was thinking of drilling and tapping a hole in the end of the shaft, and threading on another piece of shaft to lengthen it.

Also, I'd really like to keep reverse. Since removing the reverse chain is a common modification, I wanted to ask about that. I was thinking of replacing the chain with new from TSC. I heard somewhere that the main reason the chain fails is because it's cheap garbage chain. Can anyone confirm that for me? Any other advice for me?

Keep in mind that since my goal is a microcar for on road use, the transaxle will be seeing gentle use besides the increased speed.

Oh, one more thing. If and when my shift keys break from shifting, I want to modify the shifting system. Motorcycle transmissions are the same size, and they shift just fine. The main difference is their shift keys are rigid, and ours are flimsy and designed to spring into the gear slots because there's no space for the teeth in between gears. So I was thinking of machining out some solid ones that don't spring in. Then, I would remove 2nd and 4th gear, and make spacers to replace them. This would allow me to have a space to move the teeth into and out of gear, very similar to a motorcycle dog box, without the strength loss of having the spring action. What do you think of that idea? It would be super easy to make the keys and spacers on the CNC at work.

Yes, the wise answer would just be to buy a motorcycle engine. However those are far more expensive, even on the used market. Also, I would then have to procure a separate differential and figure out reverse. It would all be far more expensive than this transaxle. Plus, that's boring.

Converting it to horizontal input?

Yes, of course I’m watching.

IMO, if you extend the input shaft, support it with TWO pillow blocks and drive it from between those blocks. End of any issue I think. Take the strain off the input shaft except for torque.

Interesting idea on the shift keys. I have no idea but I will enjoy watching.

I too have some ideas for a horizontal shaft engine. There is a Peerless 700 out there begging...

i have two dixon hydro transmissions and they are FNR boxes pretty much if you ran stock gearing and put a sprocket on the wheel hub and ran it to the axle i can build a side by side with a hydro transmission so it could potentially pull a ton of weight up a hill slowly and have no issues the side by side would be made from the dixon chassis. which is a similar idea to yours and i also have a 8hp flatty

If I wanted a hydro I would've just bought a torque converter.

Well, I got the case apart, and have begun the degreasing process. There were about two cups of water inside. Since the wheels wouldn't come off the axles, I decided to just split the case in the car and leave wheels, axles, and diff all together for now.






While it's apart, at the bare minimum, I want to do some preventative maintenance. I want to replace all bearings and bushings. I want to replace the reverse chain. Once I get the gears and shafts de-greased, I'm going to take some dimensions and make a few cad models. At the bare minimum I want to make cad models of the shafts, gears, and shift keys and collar. I'm not going to reverse engineer the cases without a good reason. Hopefully this isn't too expensive, as my hobby budget isn't very big. I'm working on selling my motorized bicycle to fund this project, but so far all the buyers on marketplace have flaked out.

I think for the first iteration of my vehicle, I'm going to leave it vertical shaft driven, and power it with a cheap push mower engine off marketplace. I'm hopefully picking up a 6.5hp push mower on thursday with a briggs quantum engine. That will just make things a bit easier the first time around. Once I get more experience with my first build, I'll improve/rebuild it with a more powerful engine. Weather that's with a horizontal shaft engine or I find a cheap vertical shaft riding mower engine remains the be seen. I'll probably start a build thread in the coming days.

I got it all cleaned out, except for the differential. It's in fairly good condition. There's some minor wear on the shift keys and the gear dogs. The input small bevel gear has some wear, but the large one is mint. The chain looks in good condition. All the needle bearings seem fine.

However, there are some issues. The ball bearing on the input shaft is seized, so I have to get one of those. Also I'm missing the shaft seals on the countershaft. I also want to get two new axle bearings.

I'm having trouble finding the shaft seals for a good price. They're 5/8 x 1/16 square o-rings, and I need 3 of them. Alas, I can only buy them in big packs from industrial suppliers. I might have to use round o-rings for the time being.

The main shaft bearing is a 6302 unshielded. I can buy a 2 pack of sealed ones on amazon for $7 and remove the seals.

The axle bearings are 6203 I believe. Those are cheap on amazon too but the reviews say I need to open them up and put my own grease in them. Also I haven't confirmed this. I'll measure them before I place the order.

I also ran some numbers. In order to go 45mph at 3600rpm I'll need to spin the input shaft at around 8000rpm. I'll need a 2.5in pulley on the input shaft and a 6in pulley on the engine. Using an AX belt I should be close to the limits of the belt, but not way outside. As long as I stick to lower horsepowers for now. With an AX belt the sideways forces on the input shaft shouldn't be too high, but it's still a concern. I'll just have to build it and see what happens.

Round o-rings should be OK for a while at least. Since this is a slow speed application, I wonder if you could find square o-ring stock and glue up your own? One of the first real uses for superglue was for making o-rings from stock. Might work...


IMO... a negative prediction I’m afraid...

8000 RPM input will kill the transmission.

@Nevadablue

Luckily I found this video yesterday.

This person has basically the same transmission. They took the gear that slides on the midshaft gear piece, and put it on the countershaft gear instead. This swapped that mid gear ratio from 0.43 to 2.32 This will allow me to easily reach high speeds without having to drive the input shaft very fast at all. The modification is pretty easy too.

I also came up with a couple different designs for alternative gear changes, and printed out some prototypes. First, I made the dogs and spacers like I was originally planning. But also I had the idea to do a poor man's synchro. This is a round spacer in place of the 2nd and 4th gears that has a v cut into the inner diameter that the existing shift keys will pop into. This will allow them to pop into the spacer, and then apply force between the spacer and the face of the next gear as you continue pushing the shift lever towards the next gear. The friction between the face of the spacer and the face of the next gear would hopefully allow some synchronization action, before the gear shifting force build up and pops the shift keys back out of the spacer and into the gear. I think I might try to make these out of steel to try first.

Here's a picture of the prototypes I printed out to test fit. The dog box style keys and spacers are on the left. The spacers are set screwed onto the shaft with the gaps in line with the key slots, so the new non springing shift keys move freely through them. My only concern with this method is the impact on the gear inner cogs. These gears are steel buy some of them do have some wear on the inner teeth.

This is why I want to try the synchro method first. You can see the v slot on the inside of them in the picture. Hopefully next week I'll be done using the CNC for work projects for a while and I'll be able to machine some synchros. Also, on a positive note, while I can't really make splines, these gears have big enough teeth that I can machine them out of plate steel on the CNC with our smallest end mills. So I should be able to cut replacement shift keys and replacement shifting side gears pretty easily.

It looks like the shift keys are machined flat, and then bent before heat treating. I made the cad model with this in mind. I'll have to upload the cad models to my github or somewhere.

Alas, I won't have this transmission back together until after labor day weekend, since I have to order the bearings and stuff.

You should be able to post links? Also there is a youtube button you can can use to embed youtube videos.

Good news, I wish you luck. Please do show us the CNC work as you go also. This is FUN!

Progress. I got the big gear pressed into the little gear. This flips that ratio from 0.43 to 2.33, and makes my speed spreadsheet look FAR more favorable. I also had to remove a part of the transmission case, you can see the spot in the picture. I might have to put a bigger pulley on the transmission than the engine. Also, I picked up a 6.5HP push mower for $10. This should be plenty enough horsepower to start with. Alas, my bearings won't be here until sunday. Also, I still haven't touched the differential yet. All I need to do with it is clean the grease off and pull the axles out so I can replace the axle bearings without having to try to remove the wheels from the axles. I'd like to have this back together next week.

Oh, and I might try to get those synchronizers machined before I put the case back together. I'm thinking about making them out of aluminum or maybe nylon. I think steel wouldn't have enough friction against the gear faces to be effective.






I do have a question though. What type of gasket maker do I use for the transmission case? There are many types available, and I want to be able to easily disassemble the case.

I use the permatex black that repels grease and oil. May be overkill but I've had luck.

For the synchronizers... do you have any delrin in the shop? It is pretty stout stuff.

Delrin isn't a good choice. It's very low friction. Which is the opposite of what we need. Id rather use a high friction material like high glass content nylon or something similar. Otherwise I'd just use steel on steel.

So I finally managed to sell my motorized bicycle for $180, so it's time to start my project thread.

@Nevadablue

I put the transmission back together. There's a couple bolts that broke instead of coming out that I didn't put back in. I want to fix that eventually. Also both the brake caliper bolts broke trying to get the caliper off. But it's back together for now.

I started the project thread. I probably won't post any more to this thread.
https://www.atltf.com/t6686-the-mowercycle-a-microcar-road-legal-trike#116388

The case bolts are notorious for failures. Be very careful with them. They are apparently self tapping things and need to be started by hand when reinstalling them. Turn them backward until they drop into the existing threads in the case, then turn them in by hand before tightening. Grrrr... on the broken ones. Again, be VERY careful when removing the broken ones. Heat from a propane torch, a sharp drill and good easy out, lube, heat and patience are your friends. 
Good luck!