What is the difference between the 5091 8 Speed & 103907 8 Speed Transmissions?

[fireman 1,021]

Does anyone know what the difference is between the 5091 8 Speed & 103907 8 Speed Transmissions? Both have 1 1/8" axles and both use the 8 pinion differential. I have the Wheel Horse 6&8 Speed Service Manual but it doesn't mention any difference.

 

I am combining two tractors into one and have to decide which transmission to put in the keeper. The 1976 B-60 has the 5091. The 1977 has the 103907.

 

Any help is appreciated!

[Eric857 54]

they're both B series machines? I want to say that the 5091 is a heavier duty trans but I may be wrong. 

[fireman 1,021]

The 1977 is a C-160. It looks like the 5091 came out in 1974 and the 103907 came out in 1976. The 5091 was last used in 1976 so maybe there were some changes or improvements made. It looks like the 103907 was only used in 1976 and 77' then in 1978 they came out with the 103916. 

 

Somebody here i'm sure knows what the differences are and what changes were made!

Edited May 23, 2014 by fireman

[Eric857 54]

go with the 5091 it was used in the early 70s c series models so I think you are better off because the 103907 was only used in the Bseries machines and which werent made for as much work therefore the 5091 would be the heavier duty transmission

 

 

Hope that helps

[rmaynard 14,909]

To the best of my knowledge, the 5091 did not have a dipstick. The 103907 (1976 & 77) had a short dipstick tube, and the 103916 had a long dipstick tube. Other than that, they are the same.

[Eric857 54]

that could be true. I am basing my answer upon the information about the different series of tractors, the B series being the one for a homeowner who mows their lawn and does light duty garden and towing work and the C series being the mid duty for a large garden and more heavy duty hauling, they were built better as I'm sure you know, they had heavier duty transmission and the more horse power (no pun intended) Thats why I would say go for the 5091 but if I am in no position to tell you that you are wrong about them being identical because I have never own or run a machine with either of them in it so for all I know theyre identical and the only difference is the dipstick, in which case it is really a matter of preference for you. 

 

 

Hope that helps explain my reasoning

[fireman 1,021]

Eric,

My 1977 C-160 has 103907. The 5091 is in the B-60.

Thanks for the info Bob. I was kind of thinking the changes were going to be sutle. I do remember something bolts in the pinion breaking or backing out but not sure which tranny that was.

[rmaynard 14,909]

In 1974 and 75, the B series included only the B-80 which was a 4-speed, and the B-100 which was automatic. In 1976 the B series included the B-60, B-80 and B-100. Those three used the 5091 or 103907 and were every bit as much of a garden tractor as the C-120 or C-160 other than horsepower. The B-145 Electrac had a Peerless transmission. The 1977 B-60, B-80, B-100, C-120 and C-160 8-speeds all utilized the 103907. In 1978, with the change in design and the fuel tank being placed on the seat, the dipstick tube had to be lengthened, so the 103916 became the part number.

 

So, depending on whether you need a long tube or short tube dipstick, should be your only consideration when deciding which one to use. They are all basically the same otherwise.

[Racinbob 10,295]

I'm betting that the only difference is the dipstick. Both transmissions were used in B and C series in 1976. In 1977 it looks like the 103907 was the only one used. in 1978-1982 they went to the 103916 in everything except a few models with the 5086.

[stevasaurus 22,232]

Yep, both are 8 pinion, 8speed with 1 1/8" axles.  It only takes a difference like the dip stick to give it another number (or upgrade).  One other thing to check is the length of the axles...that is how much axle sticks out of the axle tubes...there are some different lengths out there because of the fenders, and the tires they came with.  Other then that...all the guts are the same and the brake shaft comes out the same spot in the trans housing. 

[fireman 1,021]

Thanks for all the input guys. 

[fireman 1,021]

Just checked and the transmission in the 1976 B-60 has a dipstick. Okay here are the facts. The model number off the tag on the B-60 is

61-07K801 which confirms it's a 76' B-60. According to the chart in the picture below which is a screen shot from the transmission service manual it should have the 5091 which shouldn't have the dipstick. Only thing I can think of is the transmission was repaired or replaced at some time in the tractors life. The first picture is of the B-60. The second pictures is the C-160. They look identical to me!

 

 

 

 

 

[rmaynard 14,909]

Jeff,

The 5091 did have a dipstick.

That was a mistake in my first response.

[fireman 1,021]

Ok that answers that

[stevasaurus 22,232]

Jeff, they are basically the same transmission.  It could be the difference in the size of the fill plug/or the thread size of the drain plug...this is what it is in the 5007 and 5025 3 speed uni-drives back in the early 60's.  I doubt the difference is internal for what you have.  If they did one little change, they gave it a different number...much like Kohler with their spec numbers for their engines.  The only real way to find the difference...tear them both apart and check it out...been doing that for a few years now.  Just know that it is cosmetic, and they are both Section v in the manual...which means they are the same...basically.  I can assure you that the guts are the same and the bearings and seals are the same.  Same number of pinions...check length of the axles...same number of splines on the splined shaft...same number of teeth on the 11/44 gear...might be a small difference in the bull gear and how it fits with the differential housing...just guessing...could be the difference between a "C" clip and an "E" clip holding the axles in place

[slammer302 2,154]

I believe it was just a difference in the dip sticks

[fireman 1,021]

Thanks Steve. I think that's what i'm going to do. Tear them both down and check them out.

[stevasaurus 22,232]

Let us know what you find Jeff.  Racinfool40 (Mike) and I have been trying to figure some of this out for a few years.  You really need to have those transmissions to tear down to find out.  I just got my first 6 speed to tear down last week.  Can't wait to get into it...doing 2 suburban #5010s trans first.

 

Check this out...one of the 5010s has the S8K ball bearing on the brake shaft...the other one has the torrington B-1212 needle bearing on the brake shaft.  You would think that would mandate a trans number change...like one is a #5010 and the other a #5011...but NO.  This is 1960...this just takes a service bulletin   Things were easier back then. .

[leeave96 487]

that could be true. I am basing my answer upon the information about the different series of tractors, the B series being the one for a homeowner who mows their lawn and does light duty garden and towing work and the C series being the mid duty for a large garden and more heavy duty hauling, they were built better as I'm sure you know, they had heavier duty transmission and the more horse power (no pun intended) Thats why I would say go for the 5091 but if I am in no position to tell you that you are wrong about them being identical because I have never own or run a machine with either of them in it so for all I know theyre identical and the only difference is the dipstick, in which case it is really a matter of preference for you. 

 

 

Hope that helps explain my reasoning

I see your logic, but for whatever reason, Wheelhorse at times and with different models put the strongest trannys in the lightest offering and sometimes vice versa. I had a C-111, Briggs engine. Fine tractor, but IMHO, was on the lower end of the scale. 8 pinion / 1- 1/8 axles. I believe some 8 hp Wheelhorse's had the same while the mighty 518H had an Eaton 700 tranny.

I now look closely at the model and year.

However, after reading and searching, I am of the opinion that the 4 pinion / 1 inch axle trannys are very stout too. Wouldn't hesitate to throw a moldboard plow behind one.

[Racinbob 10,295]

First hand example. I purchased a 1976 B-80 brand new and on the dealers floor (Chandlers). The price was right. Yes, Wheel Horse advertised them being for a smaller yard, etc. Wheel Horse used both the transmissions in the B-80's that year. They also used both transmissions in the C-120 and C-160 that year. The main differences between the B-80 and the C series (in 1976) was the seat, low vs high and arm rests on the top models, the rear tire size, 22-750 12 vs 23-850 12, headlights standard on the C series and maybe a gauge or something. The rest of the tractor was identical. I installed a headlight kit right at the start, put 23-850's on it, a nicer seat, and ultimately a K-341 when I wanted the 8hp for an 854. It became a C-160. For 24 years I tilled, plowed, mowed a massive yard, pushed dirt and snow, blew snow and pulled things that I'd probably be afraid to now (at my old age). It was still in top shape when it was sold for our venture in full time RV'ing and finally moving down here. I believe what Steve and others are saying is that the only difference is the dip stick, drain, clip, or something else insignificant to the strength of the transmission. Offering a version with less bells and whistles was probably was a marketing ploy to help folks justify buying a new Wheel Horse.