Where can I find the axle ratio on the differential for our 2003 U320? I might be getting the ring and pinion gears changed next week because of the noise our coach is making.
I thought I remember seeing it somewhere but cannot find it.
Thank you
Ed
I found a couple old posts saying the U320 has a 3.91 rear axle ratio. I DO NOT know if this correct, so do your own due diligence.
Replaced P-3 Carrier and Bearings (http://www.foreforums.com/index.php?topic=28863.msg242249#msg242249)
Replaced P-3 Carrier and Bearings (http://www.foreforums.com/index.php?topic=28863.msg242404#msg242404)
The odds of the gears being bad are very low. Wheel bearing? Drive shaft? Trans output bearing? Motor mount?
no matter what you believe the ratio to be, if you do remove old differential, count the teeth to be sure the replacements are the same if you want the same performance.
Any chance the sound is from the bearings on the differential or transmission? It is hard to diagnose gear noise. Also I assume there is an adjustment in how pinion meshes with ring gear.
Once the ring and pinion have been run in any adjustments to them will only create more problems. Carrier bearings or pinion bearing can make noise. If the bearings are bad and the coach gets too much mileage afterwards the ring and pinion will go bad..
3.91
If you think the differential gears/bearings are bad,change the oil to a good synthetic and see if that helps with the noise,you'll
know you have the correct weight and new oil,would be the least expensive thing to do and if later you get new gears just save the
new oil.
There should be a tag on the rearc end and it will have ratio stamped into it
Thank you for the responses. I will look for the tag on the axle. The differential fluid was changed 20K miles ago. Looked at it again yesterday, still light in color and no particles floating around.
Once the ring and pinion are run for a while and establish their mesh pattern any noise from then (other than normal noise) usually happens at a specific speed. If the noise is all the time at any speed then maybe look at bearings.
These things are big heavy duty contraptions. They make a lot of noise in anycase. I had Keith Risch at MOT go for a ride with me to listen for abnormal sounds and see how it handled. He drove. He said it drove well and sounded like it should. Ours is the only one I have driven for any time so my sense for what is right by noise or feel is very limited.
Allisons had a problem with the output shaft bearing and a nut that came loose. Can't remember it now but it might have been on the retarder equipped transmissions. I would check before replacing the ring and pinion. Quite a bit of labor setting up a new ring and pinion. It's not just R&R. Bit of an art to it so it's not noisy after installation. There is also a crush sleeve, bearings, preload and correct torque to consider.
If a rear end whines, the ring gear as well as the pinion can be adjusted until the contact patch is perfect. This will get rid of any whine if the gears and bearings are good. No particles or on magnetic plug are a good sign.
Pierce
I swapped in a whole new (used) differential to change the gear ration in my u270. The used one was from a truck and did not have polished gears. It made a slightly higher gear whine going down the highway, but it's not noticeable over the wind noise of me going faster, lol.
I believe the Allisons that had that problem were the MD3060 on the 8.3 engines, not on the m11 with hd4060
Foretravel decades ago, was rumored they bought some farm/truck rear axles that were quite loud, some were replaced after delivery. Looks like RV axles are put together differently so they are quieter.
Oshkosh built Foretravels chassis long ago and to save $43 wholesale cost they used non "whisper quiet" rear axle housing gears. In Oshkosh's defense they had not built rv chassis before and the tiny howl was not noticeable in any other use
I changed the rear axle lube to B & M drag racing rear axle 85/140 oil and added a few pints of gm positraction rear axle additive to the housing on every 300 cat ORED I sold and the tiny howl under a load went away.
In 50k miles or so the gears polished themselves from use and the ring and pinion could be reset on a bench and were noise free afterwards.
This is the pattern I set up on my 9" in the Camaro Have over a hundred runs on it now.
Needs caulk (yes, a boat thing)!
And I SUSPECT that rear end noise is NOT the dominant noise (or concern)!
Nice job with the gears. White gear setup grease?
A guy with a Rambler I knew told me he got a real deal on a rear end for the one that went out in his car. He just installed the used R&P himself. A couple of days later, he was not so happy. My wolf can howl but not as much as his car did.
Good to see someone that can do more than change a lightbulb. ^.^d ^.^d ^.^d
Miller time means wire feed to me not beer.
P
Yes white gear set up grease. Still have the white lead from years past. Dana 60's and Olds
I like the white, I use Prussian blue on the valve seat faces when I do cylinder heads on the bikes. The white might be way easier to see..... ^.^d
Crane man did you ever use a "spool" rear end? Henry's machine shop part?
That is a spool Mark Williams I believe.
My buddies and I had Henry's build a spool for us with ten spline axles to fit the olds. 1.5" axles.
He asked if we minded that he built a few more. No problem.
Found out he built 10,000 of them.
Same as the tow hubs we made up.
Chuck and Bob, are you talking about Henry's Machine Shop in L.A.
I'm sure Bob is. I didn't use him, Had Cooks machine make up some axles in the early 70's
Cook? "Mumbles?". Old buddy from Qualifiers ll drag race car club. 50 years ago. Scary. Mert Littlefield and don cook did the motormounts and dropped in my 427 engine into my 58 corvette in cooks driveway. In Trade for a small block intake manifold and $40.
We drew the spool setup in the orbit coffee shop in Long Beach then took it to Henry's to machine it.
Same as the tow hubs. Had to be careful as with the tow hubs on the rear the car rolled if unhooked from the tow bar.
Sorry for the hijack. Went to a 3.08 ratio rear with the big block.
30moh per 1,000 rpm in fourth. Over 200 wound out.
I put a 327 with a Chevy truck 3 speed in a 3.4 Jaguar sedan back in the mid 1960's. The engine destroyed the rear end so Henry's narrowed an Olds rear end for me. Nice job. Then it started tearing out all the body spot welds.
The hood had louvers in it and when racing at night, the AFB would go lean, backfire and blow huge flames through the louver and onto the windshield.
Henry's did take their time getting things done.
I used a LB lawyer to get the single entry bonds to import the cars into LA/LB and spent quite a few times in the Orbit. Norm's too.
Pierce