Wheel Horse Unidrive transmission rebuild - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
 
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post #1 of 11 Old 01-26-2006, 06:45 PM Thread Starter
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Wheel Horse Unidrive transmission rebuild

I am in the process of restoring a 1958 Wheel Horse model RJ-58 and will be giving the Unidrive model 5003 a update differential kit along with any other N.O.S. parts I might have for the old side plate transmission. This early Unidrive had wide gear teeth on the differential gear , it had 31 teeth on the bull gear and the updated differential bull gears has 43 teeth. The finer tooth pattern gives more metal to metal contact which means more strenth. The hardness of the updated bull gear is signifcantly higher also as the old style was a cast piece and the new gear is machined steel.
Getting the bearings out of side plates proved to be harder then it looked , each bearing is seated in a ring which is welded to the sheet steel side plates. On the left side plate I had to break apart one of the bearings then use a die grinder to cut into the race enough to use a puller to remove the broken bearing. Heat was out of the question to remove the bearings because the side plates are too thin and might warp.
The differential got treated to new pins for the pinion gears , the pins are held in place by a 3/16 roll pin. Now when you change the differential bull gear the spur pinion gear (which is called the brake shaft gear in a Undrive because the brake drum is also on this shaft) must also be change so the teeth will mesh properly. Originaly 90 weight gear oil was used for the early Unidrive side plate transmission but new oils have come out since 1958 and 85-140 weight oil will be used after the rebuild.
Bill in Richmond , Va.
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post #2 of 11 Old 01-26-2006, 08:31 PM
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Re: Wheel Horse Unidrive transmission rebuild

Does the final drive gear ratio change with the mod?

Looking forward to more updates on your restore.

Volfandt
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post #3 of 11 Old 01-26-2006, 08:59 PM Thread Starter
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Re: Wheel Horse Unidrive transmission rebuild

In short NO, the final drive ratio is the same , these are straight cut gears and have the original diameter as the original type gears. All three speeds have the same gear ratios.
1st gear is 66.8 to 1
2nd gear is 42.4 to 1
3rd gear is 24,6 to 1
reverse is 51.5 to 1
NOW add the Lo to the Hi/Lo and you get these Lo range ratios
L1st is 267.2 to 1 ...... this is why your Wheel Horse can pull a house down
L2nd is 169.6 to 1
L3rd is98.4 to 1
reverse is 206.0 to 1
Bill in Richmond , Va.
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post #4 of 11 Old 02-05-2006, 08:47 PM Thread Starter
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Re: Wheel Horse Unidrive transmission rebuild

I finaly got around to finishing the rebuild on the Unidrive model 5003 for my 1958 RJ-58 Wheel Horse ...... well it's been sittin' on the bench for two years so it's about time. After installing the new bearings on the side plates the side plates were bolted to the main case and held loosly with a few bolts to bench check the operation of all the gears. Now since these bolts are original to this transmission from 1958 they are not grade 8 bolts , so each bolts was carefully torqued to 210 inch pounds (almost 18 foot pounds) and again the operation of the transmission was checked by turning the input pulley and shifting the gears and watching the axles to make sure they turn correctly.
The new seals were installed and now all that left is to paint the transmission. Once installed I will use 85-140 weight gear oil.
Bill in Richmond , Va.
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post #5 of 11 Old 02-06-2006, 12:20 PM
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Re: Wheel Horse Unidrive transmission rebuild

Does that tranny have the differential pinions thingies? I heard that you have to add more if you want to do ground engaging work, just wondering how hard to would be to do, to see if its worth bothering.
Thanks
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post #6 of 11 Old 02-06-2006, 06:18 PM Thread Starter
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Re: Wheel Horse Unidrive transmission rebuild

On some of the eight speed Unidrive transmissions the differential carrier used only 4 pinion gears but the carrier would hold 8 pinion gears , so all's one wouldhave to do is and 4 more pinion gears. This will make the differential stronger by doubling the gears. A Unidrive with the 1-1/8 inch axles and 8 pinion gears were the strongest , here is a list of the Unidrive model numbers for this transmission.
5091
103907
103916
103918
You can find this transmission in some of the B and all of the C series Wheel Horses.
The early six speed had 10 pinon gears that also had a cylindrical spring to put pressure on the pinon gears to make the differential a positraction type.
Bill in Richmond , Va.
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post #7 of 11 Old 02-09-2006, 07:45 PM
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Re: Wheel Horse Unidrive transmission rebuild

bill from richmond?? dude!! how the heck are ya?? would you believe i just sold my commando 800 last weekend? i owned it since 1986 or 7. same one i bought in norfolk.
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post #8 of 11 Old 02-10-2006, 06:16 PM Thread Starter
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Re: Wheel Horse Unidrive transmission rebuild

I'm still busy doin' the Wheel Horse buisness some times aorund the clock!
The 633 diesel BEAST is my lastest creation (although I have another Wheel Horse idea in the works right now) , the diesel engine is a west German Hatz model E 75 which is a 7 hp model ........ it'll pull the stumps outa' the ground!
Bill in Richmond , Va.
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post #9 of 11 Old 03-07-2006, 06:36 AM
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Re: Wheel Horse Unidrive transmission rebuild

BPJunk--Working on a B-80 series and I have a problem with the tranny--is there a tag on it, per say, to give me the model number??
tkxs in advance...


Sometimes you just have to laugh..To keep from going insane!!
Jimmy Buffett
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post #10 of 11 Old 03-10-2006, 11:44 PM Thread Starter
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Re: Wheel Horse Unidrive transmission rebuild

Glen ,
Is the transmission a 3 speed or 6 speed ? What is the problem with the Unidrive ?
Bill in Richmond , Va.
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post #11 of 11 Old 06-18-2019, 02:31 AM
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Just a note to say I once read the 10 pinion setup is said to be weaker than the 8 pinion is?
Not sure if its actually true but' its something I read so I felt I'd toss it in the ring here.
So' (if true),adding more pinion gears is only stronger up to the 8 pinion setup?

If memory serves me correctly I believe it said adding those 2 extra pinion's weakened the metal cage they set in due to the lack of metal it has then? Sound feasable to any pullers & mechanical minds?

This info may have been meant for high power pulling tractors "only" I don't remember well, sorry its been a long while since reading that but I wouldn't sweat it if I had a tractor with the 10 pinion Uni-Drive myself since I'm not extremely hard on my equipment really.
I don't have any idea what tractors had the 10 pinion setup either. Yrs ago I read that info.
I have always wondered what tractors do have the 10 pinion setup though? A D-series maybe?

Anyone know if this info is even true or not please chime in for our thoughts? Thank you all!
Sorry long post..
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