something getting loose in the drivetrain

[tree98]

It's like it isn't "catching" As soon as you roll on the accelerator after a shift. You can feel a slight clunk when it "catches" not as noticeable when the truck is loaded. All the U-joints look good. Is it common for a ring and pinion in the rear end to get worn out? or maybe something in the tranny? kenworth t-800 straight truck 265" wheelbase cm870 18 speed 46K rears

[Squish099]

(02-24-2018 )tree98 Wrote:  It's like it isn't "catching" As soon as you roll on the accelerator after a shift. You can feel a slight clunk when it "catches" not as noticeable when the truck is loaded. All the U-joints look good. Is it common for a ring and pinion in the rear end to get worn out? or maybe something in the tranny? kenworth t-800 straight truck 265" wheelbase cm870 18 speed 46K rears

Yes the ring and pinion wear and the tolerances get bigger between them.with the truck parked and in gear either grab the u-joint yolk on the rears or try to get a long screwdriver behind the u-joint and work it back and forth, there should be some very slight play but very minimal, The way the gears mesh doesn't allow for a lot.

[tree98]

(02-24-2018 )Squish099 Wrote:  

(02-24-2018 )tree98 Wrote:  It's like it isn't "catching" As soon as you roll on the accelerator after a shift. You can feel a slight clunk when it "catches" not as noticeable when the truck is loaded. All the U-joints look good. Is it common for a ring and pinion in the rear end to get worn out? or maybe something in the tranny? kenworth t-800 straight truck 265" wheelbase cm870 18 speed 46K rears

Yes the ring and pinion wear and the tolerances get bigger between them.with the truck parked and in gear either grab the u-joint yolk on the rears or try to get a long screwdriver behind the u-joint and work it back and forth, there should be some very slight play but very minimal, The way the gears mesh doesn't allow for a lot.

Roughly how much should it move in each direction? half an inch each way?

[Squish099]

I would think an inch of play would be considerably loose, running the risk of stripping teeth of either or both the ring and pinion. Ive never messed with a semi rear end, but the gear mesh, which determines how tight the rear end feels is determined on the bench by painting the ring gear and spinning the pinion, looking at the mesh pattern and adjusting to get it right. The helical cut gears in a rearend shouldn't have much play at all.

[tree98]

(02-24-2018 )Squish099 Wrote:  I would think an inch of play would be considerably loose, running the risk of stripping teeth of either or both the ring and pinion. Ive never messed with a semi rear end, but the gear mesh, which determines how tight the rear end feels is determined on the bench by painting the ring gear and spinning the pinion, looking at the mesh pattern and adjusting to get it right. The helical cut gears in a rearend shouldn't have much play at all.

Would the whole diff need to be replaced or can they replace just the ring and pinion?

[Squish099]

(02-24-2018 )tree98 Wrote:  

(02-24-2018 )Squish099 Wrote:  I would think an inch of play would be considerably loose, running the risk of stripping teeth of either or both the ring and pinion. Ive never messed with a semi rear end, but the gear mesh, which determines how tight the rear end feels is determined on the bench by painting the ring gear and spinning the pinion, looking at the mesh pattern and adjusting to get it right. The helical cut gears in a rearend shouldn't have much play at all.

Would the whole diff need to be replaced or can they replace just the ring and pinion?

They can rebuild it, while its apart us a good time to inspect the axels and replace all the bearings

[Chamberpains]

If it's 1 of the rears, check the oil for metal shavings or little sparkly particles all thru it. Jack up the axle and spin the wheels, you'll hear it clunking and grinding. If it's to the point of "catching" and clunking then it's already way past the point of saving. You will have metal all thru the oil and out to the wheel bearings. You will need to replace the rear end and wheel bearings and races.
Most rear ends or differentials in big trucks are remanufactered and prebuilt. You just pull the axles out and unbolt the rear section from the axle housing, then pry it out. The front rears or power divider have to be slid off the thru shaft on it's way out and slid back on thru shaft on it's way back in, but is simple enough to do. Just time consuming and messy to clean all the shavings out of the axle housing. If you've done a wheel seal before and look at the rear and say "ya, I can wrestle something that big" than don't be afraid and do it yourself. But have a friend handy to help with the wrestling and lining things up.

This is a how most power dividers or front rears look.


And this is what most rear rears look like.

[Nilao]

If it is the front diff and you have a power divider you have an extra set of gears to account for. Mine has the same catch as yours and has for 200k miles. It’s on my list of things to pull and have rebuilt though. Just taking care of bigger issues right now.

As a matter of fact my front yoke has some slip in it. Meaning I can move it up and down a bit. Never measured it but I know the bearings are loose in the yoke. Has not ruined the yoke seal but I will be pulling it this spring and hauling it to my local rebuilder to have them gone through. Just need it to warm up enough so I can work without my finger going numb.

[tree98]

I just did a wheel seal on that axle, I didn't notice any metal flakes and the bearings and races looked fine. I think I'll drain the oil and have a good look at it.Maybe that will give me some idea of how worn it is ??