We've got a 2011 mule trans 4x4 for a bit of a fixer upper project.
2 issues persist, she jumps outta high gear and it doesn't go as fast as it should.

Here's what I know:
- machine seems to function well aside from these issues, starts, runs and drives great.

- doesn't jump outta high very often and only under heavy load like a steep hill

- belt and clutches seem to move properly and smoothly, drove it around without cargo bed and belt cover today. New belt

- it's only capable of getting up to about 20 mph driving then acts like it's hitting its governed speed ( surging to slow down), but spins up to 25 like it should when on jackstands.

Anyone have any insight as to what can cause this speed issue? And what's the most likely cause of it falling out of high?

Thanks in advance and happy new year!

 

Noticed today that the primary clutch is easy to push in by hand. Is this a sign that its time for a rebuild and could it be our issue?

 

The outer drive pulley sheave "floats." Belt tries to shove it out, when running centrifugal weights try to shove it in, so a balance between speed of drive pulley and belt tension is achieved. Worth trying a new belt, they get narrower as they age, so altering the speed at which gears are changed. There was a machining fault on the 4010 Diesel which should have had a recall, the driven pulley outer sheave wore fast in it's bore and wobbled about (spring pressure stops this from being obvious) this caused a sudden deceleration when going downhill, rather like selecting 1st instead of 3rd by accident, on a manual gearbox car, but I doubt if this is your problem.

Check the gear linkage to ensure it is fully going into high and low. If it is, the selector mechanism or gear dogs must be worn.

 

Already a tried a new belt when we first picked it up in the spring and it changed nothing. I know the clutches on my old snowmobiles are far harder to push in, and this mule lived a rough life on a hobby farm. I figure the clutch is weak just thought I'd ask here first due to the price of a rebuild kit... fathers a mechanic we've just never done a belt clutch or had troubles with them before.

The gearbox shifts beautifully I'm almost certain the shift forks or main dogs are messed up, just want to fix the slow issue first and doing the full 25mph is fine for us

 

We replaced the primary spring and the spring and shoes in the secondary and still no speed increase at all. New belt. Secondary spring is in factory position.

Anyone know Why the speedo still works when i unplug the speed sensor on the transmission? The machine seems to go into a limp mode and is even more gutless as well when this is unplugged

Machine still spins up to 25 on jackstands but only about 20 driving. No codes, brakes not dragging, runs very well.

 

Whatever you unplugged on the transmission can't be the speedo sensor or the speedo wouldn't work. Your terms primary and secondary have me confused, but neither drive or driven pulley have shoes. Not exactly sure how fast a Mule should go. I have driven a 4010 diesel a few years back and think about 20mph was tops, unless going down hill.

 

Thats what I figured but the wiring diagram in the service manual says it's the speed sensor by wire colour and theres only one. Makes no sense to me eiether. It's also the only thing electrical on the transmission aside from neutral safety.

Primary- drive pulley
secondary- driven pulley
shoes- I've heard them called buttons, the wearable plastic pieces inside a driven pulley.

It's supposed to be governed to 25mph or 40 km/h.
Only other thing I can think of is belt deflection which checks out okay but thinking of removing a shim anyways and trying it.

 

Removed a shim in the driven pulley and still no luck. Probably gonna have to swallow my pride and take her in to the dealer if nobody here has any ideas

 

Did you manage to fix it after I've got same top end speed problems? looking in the direction of speed sensors etc as engine is running OK and it will spin the rear wheels on wet tarmac with the front brakes on.
Its been used daily for ages but now does about 12 mph intermittently then works OK it seems to me to be an electrical fault governor wise.

 

I was having similar issues with not being able to reach 25mph in high gear but had no issues running wide open in low gear which pushed me to believe it was an electrical/sensor issue, not fuel supply. I would take off in high gear with full power but once I reach around 20-22 mph it would feel like it started losing power or throttling down until around 17-19 mph and then speed back up to the 20-22 and lose power again. I ended up just ordering a replacement speed sensor from Amazon for around $20 (local dealer quoted me $115). Easy to replace one little 3-wire harness and a bolt to remove the old one and replace it with the new one(I did end up robbing the O-ring from the original speed sensor for the new one because the one it came with was slightly thicker and hard to get back in and I didn't want to brake it). After that, I have had no problem reaching and maintaining 25mph in high gear any more.
Hope this helps my local dealer was suggesting fuel pump/ filters, but that didn't make sense to me because I had no issues with fuel in low.