8 Speed Transmission Case to 6 Speed??

[oliver2-44 10,894]

Is the 8 speed transmission case the same as the 6 speed case?

I have 2 spare 8 Speeds and wondering if I can build a 6 speed without too many replacement parts.

No 6 speeds around here so far.  A six speed would be nice since its directly interchangeable with some of the  3-4 speed brake linkages and the 953/1054 brake linkage.

So I been studying the transmission manual, parts list, pictures and @stevasaurus videos trying to determine if a 8 speed case could become a 6 speed.  I know the brakes are on different shafts, but looking at part list drawings and pictures it sure seems the angled brake band mount is the same. I'm thinking they just made the brake band a little different.  I would need a couple of different gears, but a lot of them are the same.  The bearing holes in the cases look the same best I can tell from pictures.  @Racinbob I know you recently had a 6 speed on the bench.  If you or anyone have a way to compare the 2 cases, especially the brake band mount and bearing hole sizes I would appreciate any comments you can share. 

 

The next question is can an 8 pinion differential be used in place of the Limited Slip Differential.  I seem to recall reading it can, but haven't found that info again.  I wouldn't mind a LSD, but I already have a good usable 8 speed diff with 1-1/8" axles. Are the 8 speed differential gear to 6 speed brake shaft gear teeth count compatable? 

 

I appreciate any info and thoughts ya'll can share.

[oliver2-44 10,894]

Doing a little more looking, I see the 5060 parts list show a right case #7066, left case 6941 and the 103916 8 speed shows a right case as 8163  and left case as 6941

So the right case halves have different part numbers and the left case haves have the same part number.

They sure look the same in pictures, so what's the difference?

[Racinbob 12,142]

I've wondered about that a few times but short of actually doing the change it would be nearly impossible to know for sure. Having one of each open at the same time would help. I think the cases will interchange. The obvious would be bearing changes and different shafts. The 8 speeds use a brake rod that goes over the top of the drum and has a dogleg in it. The 6 speed rod is straight and shorter. The brake bands are reversed but it might be possible to interchange. As far as the case part #'s often times Wheel Horse changed something insignificant that really doesn't affect interchangeability. I'm thinking it's possible to change an entire 8 speed for a 6 speed with nothing more than some simple linkage changes. But again.........I haven't actually done it.

[ri702bill 9,827]

Having done an 8 speed swap on my 854 years ago, this much comes to mind.

The 6 speed is a simpler swap, the input shaft & pulley are the same, externally, as the 4 speed. The brake & parking brake are in the same location. Ask @Handy Don.

The 8 speed is the opposite on these two items - the input shaft is 5/8", not 3/4". This nesessitates a special new pulley. The brake band mounting is reversed - the action of the rod goes from push to pull. I used a Raider style ros for this. I did not bother to try to come up with a solution to the parking brake, as 1st in low range is about as good.

[ebinmaine 74,040]

1 hour ago, Racinbob said:

it's possible to change an entire 8 speed for a 6 speed with nothing more than some simple linkage changes.

 

I believe that's true. 

 

I've had a 12?7 here in the past that was changed to a 8 by a PO. 

 

I gave up on that because of the linkage and EATING belts. 

But I digress.....

 

 

 

6 hours ago, oliver2-44 said:

anyone have a way to compare the 2 cases,

 

I could do that Saturday. 

I have a 6 speed disassembled on the shelf. 

Maybe an 8 too but that could happen anyway. 

 

 

[Racinbob 12,142]

2 hours ago, ri702bill said:

The 8 speed is the opposite on these two items - the input shaft is 5/8", not 3/4". This nesessitates a special new pulley. The brake band mounting is reversed - the action of the rod goes from push to pull. I used a Raider style ros for this. I did not bother to try to come up with a solution to the parking brake, as 1st in low range is about as good.

 

Actually both pull the brake band tight to the drum. The 8 from over the top, the 6 from below. The 4 to a 6 swap is pretty simple. Of course provisions will have to be made for the hi/low shifter which will vary by tractor model. A 3 or 8 to a 6 requires the linkage changes but I don't see that as an issue. I thought about putting the 6 in the Reborn B-80 just for the limited slip but I decided not to. I'm thinking a young fella is going to do the 854 swap thing with it. Don't know for sure.

[ebinmaine 74,040]

3 minutes ago, Racinbob said:

. The 4 to a 6 swap is pretty simple. Of course provisions will have to be made for the hi/low shifter which will vary by tractor model. A 3 or 8 to a 6 requires

 

 

You're headed down the right road but the numbers are reversed a little.

 

Three and six are compatible. Direct bolt in. Four and eight are compatible. Direct bolt in.

[953 nut 61,411]

I did the six speed in a 953 swap about twenty years ago. Two of the mounting holes did not line up so one hole in the plate had to be elongated slightly and the other hole I drilled and tapped into the transaxle case.

I used the 953 differential and axles in the six speed. To use the ten pinion you would need a pair of  GT-14 axles or have a machinist cut a snap ring grove into the axles because of the tight clearance in the area of the limited slip spring. I have not looked into the eight pinion but there may be enough clearance inside to use the roll pins to retain the 953 axles.

Edited 7 hours ago by 953 nut

[702854boy 144]

2 hours ago, Racinbob said:

I'm thinking a young fella is going to do the 854 swap thing with it. Don't know for sure

I'm planning on it

[Racinbob 12,142]

2 hours ago, ebinmaine said:

 

 

You're headed down the right road but the numbers are reversed a little.

 

Three and six are compatible. Direct bolt in. Four and eight are compatible. Direct bolt in.

 

You are 100% correct. I had it backwards. I always do that in my head but now I done put it in writing. 

[Handy Don 14,441]

3 hours ago, 953 nut said:

I used the 953 differential and axles in the six speed. To use the ten pinion you would need a pair of  GT-14 axles or have a machinist cut a snap ring grove into the axles because of the tight clearance in the area of the limited slip spring. I have not looked into the eight pinion but there may be enough clearance inside to use the roll pins to retain the 953 axles.

Exactly. The Limited Slip function is entirely contained within the differential/axle assembly.

 

I have no idea if an LSD with axles would directly replace the 8-pinion differential and axles of an 8-speed.

Will the bull gear mesh properly with the different final gear which is NOT carrying the brake drum in the 8-speed. 

Do the outer diff plates mate properly with the inner axle bearings?

Are the axles the correct lengths?

 

I believe I saw a document that instructed dealers on how to convert in the other direction, i.e. swapping an 8-pinion diff in to replace a 10-pinion LSD. Can anyone dig that up?

 

[953 nut 61,411]

2 hours ago, Handy Don said:

Do the outer diff plates mate properly with the inner axle bearings?

The interchangeability of transaxle components seems limitless. Paul @pfrederi put a limited slip from a Sundstrand in an eight speed and I put the differential from a 953 into a six speed. Some 1970 transaxles had Torrington B-348 bearings because of a temporary unavailability of 1533 bearings but if you remove the race from the end plate of the differential a 1533 will fit right on there or the Torrington could be pressed into the transaxle housing.

  

[stevasaurus 23,397]

A few things guys...the #5073 is a 10 pinion, Limited Slip that is considered an 8 speed transmission...soooo the brake drum and linkage will be the same and a direct bolt in as an 8 pinion differential.  With that in mind, you should only have to change out the differential & the mushroom gear...or vice versa.

   There is a Service Billitin that explains what needs to be done to change out a 6 speed 10 pinion differential to an 8 pinion differential.  This change over SB (I think) says you only need to change out both the 10 pinion differential & mushroom gear for an 8 pinion differential & mushroom gear.  Again, if you go this route, you do not have to mess with any linkage or brake drum.

   Both of the above transformations are designed to use the same transmission case that you already have.

   It seems you guys want to change a 6 speed case to an 8 speed case or change out an 8 speed case to a 6 speed case.  Both will bolt in directly, but now you need to deal with all the linkage and brake drum.  This is not all you would need to change out though.  You also need to swap the cluster gear shafts, the mushroom gears, the cap and threw bearings on the left side of case.  The bull gears and the small gear of the 11/44 tooth gear will mesh, but the length of the gears cut into the mushroom gear may be an issue.

   The 8 speed cases have the clutch on the left and the brake on the right.  The 6 speeds and 3 speeds have the brake and clutch on the left side.  I am not sure what a 4 speed does with their linkage.

   @953 nut had to drill new holes (2) to mount a different transmission on his 953 because he has a "Heavy Duty" original transmission and those holes do not match up with the other Uni-Drives.  His 3 speed trans came with 1 1/8" axles and the "Bevel Gear Differential.

    I hope that hejps a little.    

[Racinbob 12,142]

What I'm dealing with is a young man wanting to put a 5060 on his 854. Looking at my 854 next to the 5060 I think the hardest part will be the hi/low shifter. Definitely not trying to swap internals. 

[Racinbob 12,142]

That being said I don't think it would be a biggie to swap cases. Essentially removing all the components including bearings. Somewhere in this thread that's what was sorta asked. I think doing a bunch of marrying components from both a 6 and an 8 might be fun but a potential can of worms. Also a one pedal to a two pedal tractor has many more issues which is one of the reasons I decided to leave my Reborn B-80 as is. I'll be meeting the young man and his Dad tomorrow.