Hydrostatic Transaxle is "Jerky", stop and go

[Rivets]

Just looked at your pics and those two idler pulleys look toasted. Can’t tell by looking, but if you spin them in your hand and feel any roughness, replace.

 

[Kimberly5]

Firstly that belt is toast judging by the crack in one of the photos.
Secondly it is either the wrong belt or is severely worn.
The proper belt , which is expensive is a wrapped kevlar fibre belt.
That belt appears to be a plain unwrapped el cheapo ( cause I know better than all those thieving rat bags who force me to buy those overpriced funny colour belts when a regular one at 1/4 the price will work fine ) belt.
If it is a plain unwrapped belt then you problem , or a large part of it, lies there.
Unwrapped belts are designed NOT TO SLIP .
They quickly get hot & sticky just like your car tyres.
Wrapped belts are designed to slip for the purpose of clutching.
Your belt should be # 21546076 which is an A 90.375" belt.
Plain belts are made in whole inch sizes only so pretty sure you will find it is a plain A90 belt.
If Mr Half Witt had bought a wrapped Kevlar A 90 he may have gotten away with it
But using a plain belt that is also 3/8" too short is asking for trouble.

The new belt arrived. It seems to be of much better quality than the old belt.

As I noted in the previous post, as I was fighting to remove the pulley B with plate 190, the brake became stuck/locked down in the fully depressed position. I do not believe I can even install the new drive belt until this problem is resolved. How can I unlock the brake?

 

[Kimberly5]

Mr. Rivets,

Here is a 25-second video showing what happens when we spin pulley B. It feels fine to me, but I do not really know what I am looking for. Any thoughts? Thank you.

 

[Kimberly5]

I apologize, gentlemen. I did not realize how to release the parking brake properly. I just released it, amazing!

We will try to find the time to install the new drive belt. Thank you for your help.

 

[Kimberly5]

Update:

We have replaced the drive belt with the kevlar belt that Mr. Bertsmobile1 suggested. For posterity, here are some tips for replacing the belt on this model.

1. Start by looping the belt on the front end pulley (engine shaft pulley). Do not start by looping on the transaxle (rear) pulley.
2. On this model, there is no need to loosen the nut for the steering shaft. The belt squeezes through the right side of the shaft as in the diagram below.
3. Make sure the parking brake is ENGAGED during the process. This loosens things up.
4. The hardest part is looping it onto the rear (transaxle) pulley. the fan is soft and flexible, so you can slide it over piece by piece starting from either side. Again, this is the hardest part so be patient.

So to be clear, there is no need to remove any of the pulleys or the steering shaft in the process of removing/replacing the belt.


After replacing the belt, there was little to no improvement in the "jerk" problem. We did not replace the pulleys. I am now even more interested in Mr. Bertsmobile1's suggestion regarding the brake/clutch adjustment. Mr Bertsmobile1, I hope you can find the time to clarify which part of the assembly below we need to adjust. Thank you!

 

[bertsmobile1]

SO remove the brake caliper by undoing the 2 small bolts either side.
Clean out the brake and the brake pins also make sure the disc is free on the spline.
reassemble the brake,
Check the operation of the brake.
If you still have jerky release of the clutch, back off the centre nut on the brake lever a very small amount.
Test, readjust, test readjust.
Because the single pedal both clutches & brakes you have to find a balance between the belts going tight & driving the mower and the brake releasing the mower.