Technical Torque monster - options?

[mcf12sf]

Hey forum!

1. Very grateful for all the wisdom here!
2. My 69 L now has a 67 hp, 106 ft-lb Zero Motorcycle motor and 13kwh battery aboard (~90 miles range). All supporting cast came along for the swap: controller, twist throttle, charger, dash, even the 12v cig lighter circuit is charging the stock 12v battery.
3. It’s a hoot. Running without clutch. Pick one and go, third still spins the wheels and works best. Heat from staying m in one gear seems to be ok so far.
4. BUT… Diff sees to be struggling.
   • I’m getting loud clunk sounds in every gear on engagement.
   • It skips out of traction under heavy load.

I knew I’d have to deal with all this torque someday, so here we are.
I really want to keep the stock box if I can. Gears are solid.
I don’t need mesh - not shifting.
I just need strength for one gear of torquey madness.
Good news - 25mm drive shafts already in there.
I don’t really want to go in and shim this diff to have it get loose again. Is that likely?
I trimmed off the top bolt of my bell housing so would love to avoid the 126 housing swap.
Can I stick with this box as is and just beef up the diff?
Is that an option?
Is this not the diff at all?
What would you do?

If you’re curious, here’s a deck on the build.
Play by play is on my insta here.

Thanks!!!!

 

[smart51]

If the diff is struggling with the torque through 3rd gear, try it in 4th. You'll have less acceleration of course, but more top speed. If you're spinning the wheels in 3rd on a dry road, you've got more torque in 3rd for the tyres as well as the diff.

 

[JumpJet]

Have you checked the rubber driveshaft couplers? The rubber in the coupling is a notorious weak point. There are some CV joints made though - eg: https://www.ricambio.co.uk/products/steel-uprated-coupling-cv-joint-kit-classic-fiat-500-126

 

[mcf12sf]

This has some promise! Thanks JumpJet. Will check. Any specifics on looking for on wear / slippage here?

 

[mcf12sf]

I’ve already upgraded these to beefier toothed couplers, so didn’t think to check here, but will add this back to the list of potential culprits

 

[ride106]

I have nearly the same motor in my EV swapped giardinera - the watercooled ME1616 version, but I'm only running 100 volts and that works out to about 35 HP. I actually tuned the torque curve down to avoid turning the gearbox into mush. When I started out, I didn't have a strong enough motor mount and the transmission would twist and slap the underside of the car on anything but the mildest starting torque. I thought it was something wrong internally at first and then realized what was going on only later.

Looking at your photos, the frame you have fabricated for the battery and motor probably eliminates that chance of gearbox movement, but I would at least look at the two rubber-backed mounting bolts on the front side of the transmission. Mine were shot and it was a cheap/easy fix.

Also check how low or high the gearbox sits now that you have the new motor mount. Ideally it's right around where it used to be height-wise so the axle shafts aren't forced at too steep an angle.

 

[the hobbler]

I have nearly the same motor in my EV swapped giardinera - the watercooled ME1616 version, but I'm only running 100 volts and that works out to about 35 HP. I actually tuned the torque curve down to avoid turning the gearbox into mush. When I started out, I didn't have a strong enough motor mount and the transmission would twist and slap the underside of the car on anything but the mildest starting torque. I thought it was something wrong internally at first and then realized what was going on only later.

Looking at your photos, the frame you have fabricated for the battery and motor probably eliminates that chance of gearbox movement, but I would at least look at the two rubber-backed mounting bolts on the front side of the transmission. Mine were shot and it was a cheap/easy fix.

Also check how low or high the gearbox sits now that you have the new motor mount. Ideally it's right around where it used to be height-wise so the axle shafts aren't forced at too steep an angle.

Quite bluntly, I amazed that the gearbox is still in one piece, being that it was designed to fit onto an engine that produced just 26 ft lb of torque! Have you checked the actual 'sliding-couplings'---the parts that are splined on the axle shafts? The splines on these 'sliding-couplings' are the weak point on the cheaper (none heat-treated) couplings.The good "heat-treated" coupling has a bluish hue around the splines area--this is the result of the heat-treatment. I have the Polish (Motomax) C/V couplings on my '695' replica and they do away completely with all the Fiat parts of the coupling---sadly they are getting very difficult to find now

 

[mcf12sf]

I have nearly the same motor in my EV swapped giardinera - the watercooled ME1616 version, but I'm only running 100 volts and that works out to about 35 HP. I actually tuned the torque curve down to avoid turning the gearbox into mush. When I on only later.

Looking at your photos, the frame you have fabricated for the battery and motor probably eliminates that chance of gearbox movement, but I would at least look at the two rubber-backed mounting bolts on the front side of the transmission. Mine were shot and it was a cheap/easy fix.

Also check how low or high the gearbox sits now that you have the new motor mount. Ideally it's right around where it used to be height-wise so the axle shafts aren't forced at too steep an angle.

Ok ride106, this is awesome. A lot lands. I’ve been working on new mount plate holes to adjust transmission height. I’m running a few cm lower than stock. And will check the front rubber mounts. That rotation could be what’s going on. It feels like a skipping under load, not of main gears, something else.

I think it might be time to mount some camera a and see it live

How’s the me1616 holding up? That water cooling is handy.

 

[mcf12sf]

Quite bluntly, I amazed that the gearbox is still in one piece, being that it was designed to fit onto an engine that produced just 26 ft lb of torque! Have you checked the actual 'sliding-couplings'---the parts that are splined on the axle shafts? The splines on these 'sliding-couplings' are the weak point on the cheaper (none heat-treated) couplings.The good "heat-treated" coupling has a bluish hue around the splines area--this is the result of the heat-treatment. I have the Polish (Motomax) C/V couplings on my '695' replica and they do away completely with all the Fiat parts of the coupling---sadly they are getting very difficult to find now

Yes hobbler! The left side slide coupler came worn away, so I upgraded with these.

 

[the hobbler]

Yes hobbler! The left side slide coupler came worn away, so I upgraded with these.

One of the perennial problem with both the 500 and the 126 gearbox's is that unless you have VERY high-quality (and it can be difficult finding them sometimes) drive-shaft boots on the side of the gearbox, AND their angle coming out of the gearbox is"spot-on", is that they will leak. There are a couple of ways to cure this problem, both of them from a pair of very clever Polish engineers. They both have u-tube films to show how to carry out the modifications---if you (or anybody for that matter) would like to contact me direct, ( [email protected]) I will happily pass on the details of these films.

 

[fiat500]

One of the perennial problem with both the 500 and the 126 gearbox's is that unless you have VERY high-quality (and it can be difficult finding them sometimes) drive-shaft boots on the side of the gearbox, AND their angle coming out of the gearbox is"spot-on", is that they will leak. There are a couple of ways to cure this problem, both of them from a pair of very clever Polish engineers. They both have u-tube films to show how to carry out the modifications---if you (or anybody for that matter) would like to contact me direct, ( [email protected]) I will happily pass on the details of these films.

Tom...can you post that publicly please?

 

[mcf12sf]

Tom...can you post that publicly please?

Plus one on that!

Also, here’s my config. Less than a degree off horiz.

 

[the hobbler]

Plus one on that!

Also, here’s my config. Less than a degree off horiz.

The 2 engineers, both Polish, are Miraslaw Siwiec and Michal Wos. Miraslaw's idea is to slightly modify the seal carrier (it has to be the aluminium version) in the rubber boot to prevent oil building up behind the seal, and eventually leaking out---look on:--"axle seals conversion fiat 126p" Although the spoken word in the u-tube is Polish, it has English sub-titles which make the whole job simple to understand. I have carried out this mod on a 126 gearbox that I was fitting into a 500---it works!
Michal Wos on the other hand has come up with complete re-vamp of the seal. The complete kit is not very expensive (about £70 +carriage). It can be watched on:-- "fiat 126p/500 modyfkacja uszczelninczy". and he can be contacted on:---"[email protected]". I have purchased 1 of his kits (does both sides)---he is easy to deal with, and the kit looks to be well engineered. It will only fit the '25mm' drive-shafts. Both modifications can be used on the 500 and the 126

 

[fiat500]

Thank you Tom...very helpful.