654/early Unidrive grabbing two gears at once

[Greentored 3,217]

Having some issues with my newly built 654 trail bomber. All was fine for a bit, the suddenly am having issues when shifting from 1 to 2, it is picking up two gears at once. I pulled the shifter out a half dozen times and every time, the detants are not where they should be for neutral. I cant for the life of me figure out how this shifter can 'jump' out of position and allow me to' pick up' the other fork without returning the opposing fork to neutral.

Online research shows there was a pin and detent update in 1965 for this issue, and another fella was explaining a theory about the shafts being in blind holes, creating a vacuum, and pulling the fork back into gear when the shifter is moved out of position.

What say you, Unidrive gurus?

Edit to add: shifter 'ball' shows normal wear, set screw shifter retainer adjusted properly, no broken internal parts.

Edited April 10, 2020 by Greentored

[Racinbob 11,207]

Even with the older style shift rails and stop pin it really shouldn't be as serious as it sounds. An earlier service bulletin called for 40w oil to minimize the issue but it wasn't long after that they changed the rails and pin. The ideal thing would be to find the newer rails with the deeper neutral detent and with the flat milled the length of them and a 3/4" stop pin to update things. Or maybe just try the 40w oil. 

Edited April 10, 2020 by Racinbob

[gwest_ca-(File Mod) 11,095]

Shifting too fast allows that to happen. Try this.

When you leave 1st gear and get to N don't remove the shifter from that 1-R shift rail for a second. A pause will allow the vacuum to bleed off.

Then pick up the 2-3 rail and carry on.

Do the same when downshifting.

 

Garry

[Pullstart 63,096]

Yep!  You should be at a complete stop to shift, so count an extra second or two before moving from neutral.  Grinding a flat spot in the shift rails will help break the vacuum if you ever pull it apart, or use thinner oil in the meantime.  

[pfrederi 17,866]

I would think if you are trying to build a "trail bomber" a hydro would be a much better choice allowing you to adjust quickly to changing traction conditions with out having to come to a complete stop as you do with a gear drive.  i would want a 10 pinion Charger /Electro

Edited April 10, 2020 by pfrederi

[ebinmaine 68,330]

Are you shifting while moving?

[stevasaurus 22,863]

You could open the trans, pull out the shift rails, take out the roll pin and slide off the forks.  Then grind a flat along one side of the rail.  This will release the vacuum.  You still need to come to a complete stop before shifting, and you should start out in the gear you want.  @Racinbob

Bob, I'm going to look for pictures, but I think the pictures were yours.   

These are what you have...

 

This is what you want...

 

[Racinbob 11,207]

Here's a later rail (left) compared to the older (right). Note the deeper neutral detent::

 

 

Here's another set of rails. I think they just changed the manufacturing process which is why the detents go all the way around. No difference in the function:

 

 

Here's the service bulletin"

 

 

 

[Greentored 3,217]

Thanks fellas! The fluid that came out of this thing looked like a combination of mud, molasses, and water, so I drained and filled with 2 quarts of ATF/WD40 and ran it on a jack for a while, then refilled with 10w30. I THINK it should be ok, hell, newer stick shift cars are running ATF, hydros run engine oil, so I figured the lighter the better for the shift fork vacuum issue.

@ebinmaine, I know you guys arent going to like this, but yes I am shifting on the fly. I gave up on doing the 1-2 and have had zero lockup issues since using R or 1, then stopping, shifting to 2nd and going from there. It actually does quite well shifting from 2-3 on the fly, if im careful, it will drop right in quite impressively and quietly. Winding her up in 2nd, banging 3rd and yanking the front tires off the ground is quite the ride, but I will not make a habit of this- I dont think theyre THAT bomb proof LOL.

@pfrederi Well see how she does, but if (when?) this Unidrive lets go, Id entertain a hydro swap

PS- I dont know if these early Unidrives are the same as the later ones, but if this is some kind of sought after piece that is making you guys cringe by beating on it, I will gladly give it up to someone in trade for a more common trans that wont hurt any feelings if it grenades.

seriously....

[Pullstart 63,096]

Yeah, unidrive is just the Wheelhorse term for manual transmission and differential in one I believe...  before your blow it up, we need video of that!

[Greentored 3,217]

On 4/11/2020 at 10:18 AM, pullstart said:

  before your blow it up, we need video of that!

If the cameras had been rolling yesterday evening, you wouldve gotten a good show. Standing start, second gear wheelie, right on into third, and she suddenly got REAL wonky at speed. At the exact moment I got to a stop, the right rear tire fell off. Snapped the cast iron hub

Currently looking for what donor machines would have a steel, 5 lug hub for a 1" axle, if any.

[stevasaurus 22,863]

#5086 transmission had 1" axles and 5 lug hubs...1972 Raider 8 & Raider 10...1973 8 & 10 hsp 8 speeds.

[Greentored 3,217]

@stevasaurus  thanks bud!  Found a pair for 25 bucks from a guy on the facebook Horse page and they showed up today.

As for the shifting issues, I switched to 10w30 instead of gear oil and have been cruising it around a bit, fluid looks great, trans is not even getting warm, and I have stopped attempting 1-2 shifts without coming to a complete stop and waiting a few seconds in neutral after using R or 1. So far zero issues.

Appreciate all the help fellas! Im gonna consider this a done deal til I pop the cases apart and do the shift rail mods, at which time will probably cut full keyways in the axles

[Redrider01 5]

Sorry to jump on your post but I couldn't find one to help with my problem.  I have a 654 that won't go I to neutral.  I pulled out the shifter and lined up the forks.  Still no neutral.  It will roll about a foot or 2 and then grab a gear.  I watched the forks when moving the tractor and they stayed in the neutral position.  Any ideas?

[gwest_ca-(File Mod) 11,095]

Sounds like you may have a broken bolt in the differential carrier. The bolt will slide out of the carrier and hit something in the transmission preventing the axles from turning. The bit of travel you are getting is the distance the broken bolt has between obstructions. Don't force it.

Pulling the transmission and splitting the cases is not a big job. Then you just lift out the axles and differential assembly.

The small pinion gears spin on a pin. Later design had a one-piece gear and pin so much stronger.

The hardest part of the job is getting the wheel hubs off the axles.

This is the transmission you should have

Section 2 is the service manual needed.

Observe which way the bolts go into the differential carrier.

If a bolt is not broken it is possible a tooth has come off a pinion gear inside the carrier preventing it from turning.

Let us know what you find and keep asking questions.

 

Garry

 

[Redrider01 5]

Gary,

Thanks for the detail!  I will let you know what I find.  

[Redrider01 5]

On 6/26/2020 at 7:20 AM, gwest_ca said:

Sounds like you may have a broken bolt in the differential carrier. The bolt will slide out of the carrier and hit something in the transmission preventing the axles from turning. The bit of travel you are getting is the distance the broken bolt has between obstructions. Don't force it.

Pulling the transmission and splitting the cases is not a big job. Then you just lift out the axles and differential assembly.

The small pinion gears spin on a pin. Later design had a one-piece gear and pin so much stronger.

The hardest part of the job is getting the wheel hubs off the axles.

This is the transmission you should have

Section 2 is the service manual needed.

Observe which way the bolts go into the differential carrier.

If a bolt is not broken it is possible a tooth has come off a pinion gear inside the carrier preventing it from turning.

Let us know what you find and keep asking questions.

 

Garry

 

Garry,

I finally got into the transmission.   Many bearings are rusted.  Especially the 1533's.  Looks like I'll need to find a working trans and use this one for parts.

[ebinmaine 68,330]

38 minutes ago, Redrider01 said:

Garry,

I finally got into the transmission.   Many bearings are rusted.  Especially the 1533's.  Looks like I'll need to find a working trans and use this one for parts.

Get a hold of Lowell or Joette at Wheel Horse Parts And More which is one of our vendors.

 

They will take right good care of you and save the transmission you have. 

[Redrider01 5]

1 hour ago, ebinmaine said:

Get a hold of Lowell or Joette at Wheel Horse Parts And More which is one of our vendors.

 

They will take right good care of you and save the transmission you have. 

There are a lot of bearings in there.  I'm afraid I'll have $500 or more in parts.

[ebinmaine 68,330]

2 minutes ago, Redrider01 said:

There are a lot of bearings in there.  I'm afraid I'll have $500 or more in parts.

Maybe try Lincoln at A to Z tractor..

[ebinmaine 68,330]

I definitely understand the logic of not wanting to spend a ton of money like that. 

Lincoln might be able to save you some because he sells good used parts. 

 

 

[stevasaurus 22,863]

I'm thinking that if you replaced every bearing and seal you would be just under $200...maybe $150. ???    If your gears are in good shape, they can be cleaned up and sand blasted with plastic bead, or electrolysis, or diesel fuel and wire brush and be OK.   Give us pictures of gears and bearings and we can see if they are useable.

 

[Redrider01 5]

2 hours ago, stevasaurus said:

I'm thinking that if you replaced every bearing and seal you would be just under $200...maybe $150. ???    If your gears are in good shape, they can be cleaned up and sand blasted with plastic bead, or electrolysis, or diesel fuel and wire brush and be OK.   Give us pictures of gears and bearings and we can see if they are useable.

 

Hard parts are useable but the needle bearings are falling apart and the ball bearings were froze up.  If I could get ALL bearings for a fair price I would replace them and have a good transmission.   I did see someone selling the 1533 bearings for $65 each.  Not sure on the others but I'm thinking that's gonna put me at $300 or better.  

[Redrider01 5]

3 hours ago, stevasaurus said:

I'm thinking that if you replaced every bearing and seal you would be just under $200...maybe $150. ???    If your gears are in good shape, they can be cleaned up and sand blasted with plastic bead, or electrolysis, or diesel fuel and wire brush and be OK.   Give us pictures of gears and bearings and we can see if they are useable.

 

 

[sqrlgtr 552]

On 11/11/2020 at 7:19 PM, Redrider01 said:

 

Ive seen alot worse than that rebuilt wouldn’t hesitate on rebuild.Already been mentioned but get on “wheelhorsepartsandmore” under transmissoins and you will find the kit you need.Best I remember the bestest mostest complete kit was under $250,and that included the use to be hard to find 1533 brgs.