Damaged Imput Shaft

[G60michael]

Hi all, Rebuilding my Transmission and Transfer, and began stripping it down for overhaul, and found there is damage in the end of the Input shaft where the 24x Needle Rollers run on. The Main shaft Side is fine, however the Imput Shaft Side has pitting in the hard facing surface the needle rollers roll on, has anyone seen this before ?

The Photo Below, is one I pulled from a "Parts" Box, as you can see the damage to the surface inside the main shaft where the rollers run on, the gearbox I'm rebuilding has the same damage but on a lesser scale. I'm abit lost as to what to do next, im thinking get the shaft machined out and a new custome machined harden sleeve to be installed ? any Suggestions or tips greatly appreciated.

[Esteban]

im thinking get the shaft machined out and a new custome machined harden sleeve to be installed ? any Suggestions or tips greatly appreciated.

Michael, the solution you propose could be the best one, but it might end up being too costly. Maybe you have friends in that trade.

Once the transmission is in 3rd gear, the two shafts are rotating as one. In regular driving that will be more than 80% of the time. I would try to polish the nicks a little bit, call it good, and install new roller bearings. Chances are (my guess only) that the transmission will be good to go for years.

For additional piece of mind, after one year of use you can dismantle and check again the condition of the input shaft race.

By the way, member Coyote Patrol found that you can replace the loose needle bearings (24 of them) with a KT202627 Needle Bearing Cage 20x26x27mm. Installation will be simplified as well.

[G60michael]

Thankyou Esteban, my biggest concern I wonder is, if the pitted surface will cause the new needles to chip and loose there hard facing aiding in Premature failure aswell?

[MadTripper]

Playing armchair quarterback here so bear with me....


Would it be possible to hone it out to a point you could upsize your roller bearings? Kind of picture honing an engine cylinder and then using slightly larger pistons and rings.

Tripper

[G60michael]

G'day MadTripper, that's my original plan mate, bore it out to take a hardend sleeve that would be replaceable if ever wears, you would be able to run 4mm needle rollers then which would be more durable.

[Esteban]

I think Tripper suggestion is the best. You’ll have to find a caged roller bearing with an oversize to what you have at the moment:

Inside dia. 20 mm
Outside dia. 26 mm

The rollers have 2.99 mm ea, and a total of 24 make for a tight fit. You’ll need to go necessarily to a caged bearing, since trying to find a bigger roller that will tightly fit will be a nightmare. I’ll send you a drawing tomorrow.

With a caged bearing you don’t have that problem. Maybe one with an outside dia. of 27 mm as an example.

[Esteban]

One option I found as an example. The length is only 20mm, but you don't have to worry about the condition of your input shaft.

Caged Bearing 20x26x20L.JPG

https://www.grainger.com/category/power ... r-bearings

Type:.....Drawn Cup
Bore Dia.: (mm).....20
Outside Dia. (mm).....26
Width (mm).....20
Max. RPM.....12,200
Dynamic Load Capacity (N).....15,700
Static Load Capacity (N).....26,000
Temp. Range (F).....-5 - +212
Cage Material.....Steel
Technical Specifications
Brand.....INA
Item #.....4ZZX3
Mfr. Model #.....HK2020
Country of Origin.....USA

"drawn cup needle roller bearings have a deep drawn, thin-walled outer ring. Drawn cup needle roller bearings are typically used in applications where the housing bore cannot be used as a raceway for a needle roller and cage assembly, but where a very compact and economical bearing arrangement is required. These bearings are mounted with a tight interference fit in the housing. That enables a simple and economic design of the housing bore, as shoulders or snap rings are not required to locate the bearing axially"

The only thing is that it will block the oil passage that shows in your picture. Not sure if that's a big concern since oil will get there no matter what, but it's something that needs to be checked.

[G60michael]

Thankyou Esteban, I couldn't find any bearings here when i sourced them, and had trouble finding the 3x27.8 needle rollers, so a fitter mate actually turned me up a hardened spacer ring to run in conjunction with slightly shorter needle rollers that are regularly available.

When i ordered my bearings, the bearing supplier suggested and supplied 2 of them Drawn Cup needle roller bearing, he couldn't get a 20mm wide one, so he supplied one 20x26x16 and one 20x26x12 I think they we're the sizes, which would give a total width of 28mm, and said I could run them side buy side.

My biggest concern at the moment is Now Oil Starvation if i was to run the drawn cup rollers. The only other option maybe to run 2 Skinner drawn cup rollers either side of the oil feed hole in the gear teeth ?

One more thing that comes to mind is running the 2 bearings side buy side, if one happenes to seize up and the other doesnt, that would then damage the imput shaft

[Esteban]

....My biggest concern at the moment is Now Oil Starvation if i was to run the drawn cup rollers. The only other option maybe to run 2 Skinner drawn cup rollers either side of the oil feed hole in the gear teeth ?

One more thing that comes to mind is running the 2 bearings side buy side, if one happenes to seize up and the other doesnt, that would then damage the imput shaft

It looks that you are on the right track, and between what you've find there and some ideas thrown here, a solution for this cases can be implemented.

Your idea of leaving the oil hole uncovered by the drawn cup rollers can work. The question will be how to prevent them from sliding together and covering the hole?

Initially I thought that the oil level will be partially covering the shafts, but it looks that it's lower. The following is a picture of my transmission showing a filler plug that I installed years ago. In red you have the oil level and in yellow the position of the input and output shafts (the perspective might be deceiving, but definitely the center line of the shafts is higher than the oil level). The oil gets in the needle bearing due to the splashing inside the case, and then, since the shafts are rotating, actually the oil will flow out of the recess in the output shaft, towards the 3rd gear synchro ring due to the centrifugal force. Just theory at this point . If that's the case, the splashing of the oil inside will also get to the other parts, making the hole redundant.

I will not be concerned with one of the drawn cup rollers failing. It might happen but after a long time. If this vehicle is going to be your daily driver, maybe of some concern, easily taken care with a dismantle of the transmission after 2 years. Otherwise, it will be good to go for the rest of its life.

Michael, you'll have to inspect all this and tell us what you think. Also, please take some pictures of the solution that you finally implement.

Transmission oil level.jpg