Truck Transmission Rebuild-Bearing Fit

[Peabo]

Greetings, I have a Spicer 5 speed from an IH single axle truck with aluminum case that lost the input shaft gear and countershaft gear (all started with bad tooth). Tearing everything down I noticed that the main shaft and countershaft bearings and races just fit snug in the case, not a press fit. No evidence that the bearings spun in the case. It seems that the pre-load from the shaft end caps keeps everything snug but I could still pull them all out by hand. Is this normal? I'm not that experienced when it comes to transmissions. If it is normal should I use locktite bearing retainer when I go back together with it? Thanks!!

 

[Russ from MN]

In general with machines the race that rotates is the one that needs to have a little interference fit. Think of a trailer wheel bearing, the outer race rotates, so it's a tight fit, the inner race does not, it just slides onto the spindle. In your case if I understand correctly the outer race does not rotate, so it doesn't need to be an interference fit. If it was me and the race seemed too loose, I would put a little loctite on it, you should never have to take it apart again anyhow. Good luck!

 

[wore out]

(quoted from post at 06:51:17 09/27/21) Greetings, I have a Spicer 5 speed from an IH single axle truck with aluminum case that lost the input shaft gear and countershaft gear (all started with bad tooth). Tearing everything down I noticed that the main shaft and countershaft bearings and races just fit snug in the case, not a press fit. No evidence that the bearings spun in the case. It seems that the pre-load from the shaft end caps keeps everything snug but I could still pull them all out by hand. Is this normal? I'm not that experienced when it comes to transmissions. If it is normal should I use locktite bearing retainer when I go back together with it? Thanks!!

"It seems that the pre-load from the shaft end caps keeps everything snug"

NO pre-load on the bearings there, typical "spec" is in the range of 0.002" to 0.005" ENDPLAY, NOT pre-load.

 

[chvet73]

Although Im far from an expert on this, Im in the process of rebuilding a Mustang T5 transmission right now. Its sitting on a bench disassembled waiting on parts to come in.
All of the races in this trans are loose and have shims to set the preload. So Im guessing your spicer is the same setup.

 

[the tractor vet]

Nope they just slid in and out . Nothing fancy , no need for and modern Guppy goooo , they had a couple seals , paper gskt. , on some old transmissions they did use gskts as shims that came with the gskt and seal pkg. and on those that did you measured the thickness of the gskt you took out and if you were use the same bearings that is what you put back in . When installing new bearings you could try the same thickness and do a hand feel on how it turned or you could put the caps on and snug them down and do a feel test then ya used a feeler gauge as to what ya may need then subtract about .005 or so for gskt crush .

 

[4wdtom]

What Russ said.

 

[wore out]

(quoted from post at 14:48:51 09/27/21) What Russ said.

1. If the fit is so loose it concerned me It wouldn't use the casting. That being said it's probably just fine, if much of an "interference fit" the aluminum would potentially be galled when the bearing is pressed in.

2. I would not Loctite a tapered bearing race in a transmission, the race will be pushed up against the retainer when the transmission is loaded and align itself slightly to the bearing cone in use.

3. WHY do so many of you INSIST on using the term "pre-load"?

Differential "side bearings" and pinion bearings ARE pre-loaded, the bearings in his old truck transmission are NOT.

 

[Cuznguido]

To keep it simple, only tapered roller bearings are preloaded.

 

[Janicholson]

Angular contact ball bearings are lightly preloaded in every case. Jim

 

[Tramway Guy]

Russ from MN is correct.
The moving element of a bearing is tight and the stationary one is not.

 

[Charles in Aus.]

I replaced bearings and seals in a 1957 Ferguson post hole digger that has an alloy case .
One infuriating aspect is that with use and the heat developed the casing expanded dramatically , much more than the steel bearings and gears within .
This had to be compensated for when replacing the gaskets and adjusting the contact area of the crown wheel and pinion .
I would imagine a truck gearbox would get very hot over time .

 

[caterpillar guy]

Aluminum case with steel bearings and shafts sounds like a disaster waiting to happen. Never had a gear transmission with an aluminum case yet.

 

[Welding man]

There are thousands of International Medium Duty trucks on the road with Dt466s and Aluminum Case 6 +1 Spicers in them. Also 5 speeds with 2 speed rears. They give very few problems. I have seen them go a half a million miles with no issues.

 

[the tractor vet]

Biggest problems is the scyro 's are taken out on 2nd. , third and forth from someone thinking they can shift them like a drag car , yea sometimes a bearing will let go , a seal will start leaking . But you are correct they will run many many miles and when they do fail it does not cost ya and arm leg and first born to rebuild.

 

[jimg.allentown]

Really? I had a 1966 Corvair that had a modified Borg-Warner T-10 in it with an aluminum case and steel gears. Where have you been?

 

[3LFarms]

Large aircraft use slip fit bearings in aluminum gearbox housings all the time. Most of the time, they will fall into place at room temperature.

 

[Peabo]

Hey guys just wanted to follow up and say thanks for all of the help. What was said about the rotating shaft having the interference fit made alot of sense. Thanks Again!

 

[Peabo]

Yessir, Indeed I did use the improper term for what I was trying to describe. Thanks!