L48 Transmission slower going forward

[orangedeerekiller]

Hi folks, new to forum and new to me L48 HST
Hoping to find reason it goes faster in reverse than forward.
Manual says all ranges should be same for/rev speed.
The pivot for the for/rev pedal has a lot of play, not sure if that will cause this problem, maybe some bushings or a adjustment on linkage under the deck?
All hydro operation seems strong, hopefully this is something simple.
Thanks for any help . Jim

 

[lugbolt]

The pivot for the for/rev pedal has a lot of play, not sure if that will cause this problem

It will.
Welcome to OTT, Jim.

 

[orangedeerekiller]

I thought it might but i did try to manually hold the pivot point in one place and push pedal down forward but did not seem to make much difference, may need to take it apart and see what i can manufacture for shims and bushings.
Is there anything else that could cause this? I have searched for this as best i can, and could not find much . Thanks

 

[G.rid]

Mine was opposite when I got it. Dead slow in reverse.

I did machine a bronze bushing for the peddle which helped some. Most of the help was to adjust the linkages. Have a look at the WSM. It has about 3 different lengths that need to be set. It's all underneath so if you don't have a garage, it's a crappy time of year to mess with it. It's all turnbuckles so not too bad of a job. Loosen the jamb nut and adjust the turnbuckles, then remeasure, repeat.

 

[rbargeron]

.....new to me L48 HST. Hoping to find reason it goes faster in reverse than forward.....

Hi Jim, From working on an L48's HST linkage its clear that wear or looseness in the pivots, springs, damper, neutral holder, can have a big affect on performance. Most HST symptoms start in the linkage.

With that said, there is some related reading here about an L48 with very slow reverse. The machine barely moved backward and at least one dealer had determined the HST needed to be replaced.

I bought the machine as a project and eventually found by readjusting the regulator and servo piston reverse function became acceptable. As time has gone on, reverse has again shown weakness. The tractor is usable but reverse and forward aren't the same. I think some tiny metal shavings are caught between the pump/motor and valve body, allowing a pressure drop in reverse, less severe with cold oil, more when hot.

The difficulty around HST's is they rarely have a mechanical failure inside. Factory advice in the WSM is to just replace it whole in many cases. This results in few shops knowing how to repair them.

Mine was opposite when I got it. Dead slow in reverse.....

G.rid, how did yours get resolved? Is it ok now?
Take care, Dick B.

 

[orangedeerekiller]

Just completed reading that entire thread, and it was one interesting read, bad start to story and then the build up to the happy ending.
Makes me feel a little better that this maybe a minor problem.
I did notice the difference in the speed when i bought it, but had it in my head that if reverse was good, then it had to be an adjustment, took a chance and bought it.
When i got it home i found a dead tree and put the FEL against and eased into the pedal, felt no slippage and very strong, just the actual speed seems to be the problem.
Wish i had your knowledge of the HST system, its amazing to read how you came to that find.
I think sometimes i have pretty good problem solving abilities, then i read about someone like you , and realize , i am not even close.
I will look at linkage 1st, pivot pt slop, then go from there.
nice to know someone can always help fix my mess. Great site.

 

[orangedeerekiller]

Are the shop manuals online anywhere, like to look at adjustment procedure.

 

[G.rid]

G.rid, how did yours get resolved? Is it ok now?
Take care, Dick B.

Adjusting the linkages is all it needed. That was two years ago, it's been fine since.

When I first got it, I was trying to spread and smooth soil. Reverse was about half the speed of forward. Now after adjustments, reverse may be slightly faster than forward. I may not have been as diligent with the measurements. I've just been too busy to bother readjusting it.

 

[200mph]

Are the shop manuals online anywhere, like to look at adjustment procedure.

WSM are available from your dealer or can be found for purchase on line. If you plan on continuing to do repairs, the manual is invaluable.

Or maybe someone else will know where a pirated copy is available.

 

[G.rid]

I worked that in as part of the deal when I bought my L48 from a dealer. He tried to talk me in to a flash drive with all the manuals. I convinced him that if something breaks down in the back 40, I want a hands on paper copy! He ended up seeing it my way by having his secretary print it all out and put it in a 3" binder.
Looking back on it now, I should have asked for both.

I've never posted photos here yet. I'll see if I can at least take a picture of the page you need for adjusting the hst.

 

[G.rid]

I'm not sure if its just me but when I went to adjust everything, I needed to re read this about 5 times to get it straight. At the end I made a quick sketch of the rods and just wrote the lengths that they're supposed to be. They could have made it a lot simpler to follow.
...check rod 1 which is (5) but also length 'd' ... Wtf?

The neutral setting page is important too. There's another thread about HST tractors creeping.

 

[orangedeerekiller]

Thanks, that would be better than guessing at it, i looked at it today and seen that linkage is a little more complex than i thought.
I think i can get it better with a bushing thru the pivot, and some adjustment, but can't beat doin it by the book.

 

[rbargeron]

......I think i can get it better with a bushing thru the pivot, and some adjustment, but can't beat doin it by the book......

Thanks for the kind words in post 6. I've been scratching my head on hydrostats a while now. I hope your machine responds to linkage improvements. Its a good sign that it didn't seem to slip pushing on that tree. Before I adjusted the regulator on mine, it made an extra hissing sound in reverse.

Diagnosing it would go better if the WSM included more detail. It treats the HST as only semi serviceable - no reconditioning or inspection criteria. Component sub-assemblies (regulator, pump, motor, valve plate etc) are listed as available.

Good luck - Dick B

 

[orangedeerekiller]

Had some time to monkey with it today, i lifted up on the pivot and on the forward pedal at the same time and it picked up speed and i could tell it loaded the engine more , so i think i am on the right track.
I like the pedal setup on my B21 better than the L48, but the brute power of the L48 is great at on 72 acre lot, so my B21 is going to a good home, my brother in law has been salivating over it for 2 years, waiting for me to find a bigger machine.
He will be on here soon, i am sure.
The B21 has a hydro leak that has been alluding me for a long time, so hopefully he can use this site to find that issue.