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Inside axle of rear differential
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craigaramsey
Posted 2017-08-16 5:26 PM (#4879)
Subject: Inside axle of rear differential


Contributor


Location: Cleveland, Ohio
As some of you may know, I'm broken down in Montana with a broken rear differential. They've located the part numbers for the pinion and ring but are stumped on where to find the inside axle. The part number for it is 3202T690B77. Anyone have any idea where I might find another?

I'm flying back to Ohio with my family on Thursday so it's not super time sensitive but if there are ways to save money such as used parts I'm definitely open to that.

Thanks,
Craig

Here's a link to the album with pics: http://www.fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid...

Edited by craigaramsey 2017-08-16 5:31 PM
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hemi354az
Posted 2017-08-16 6:46 PM (#4881 - in reply to #4879)
Subject: Re: Inside axle of rear differential


Extreme Veteran

50025
Location: Scottsdale, Aridzona
Google has a very good search engine and it says . . . "Your search - 3202T690B77 - did not match any documents."
Wrong number . . . transposed number . . . who came up with that number ? It is unlikely that a custom made part has such a number. If it was a DANA part that was modified then that number would show up "someplace" the Google would have found.
Picture of that number on busted part ? Is there an axle on the "other" side ? Does it have a part number on it ? Different # ? Same # ?
Lou #120
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craigaramsey
Posted 2017-08-17 1:30 PM (#4884 - in reply to #4881)
Subject: Re: Inside axle of rear differential


Contributor


Location: Cleveland, Ohio
OK, I have a correction, the part number I need is for two Shafts (differential output) and it is RSD-3202-T-6390. It's almost impossible to find. I might be better off trying to get an entire rear end out of a parts FMC. I do have the Dana 70 rear end right now.

Anyone have any info on Motorcoach Restoration in Illinois? They don't return calls or emails but I'm wondering if it's worth it to try to drive there and see if they have parts.

Thanks,
Craig
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BigRabbitMan
Posted 2017-08-17 1:53 PM (#4885 - in reply to #4879)
Subject: Re: Inside axle of rear differential



Expert

100010010025
Location: Cottage Grove, OR
You will need to decide if you want to stay with the Dana differential or convert to the Rockwell. I don't know what all is involved in converting back to the Rockwell but it may be significant. Do you know what the ratio of your existing differential is? A change in differentials will most likely change that ratio. The original Rockwells were 4.625 to 1 ratios. I believe there are other ratios available. A taller ratio is desirable with the conversion to the DD 8.2 with the 4 speed tranny that you have and would be the reason it was switched out for the Dana differential in the first place.
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LCAC_Man
Posted 2017-08-17 9:50 PM (#4886 - in reply to #4885)
Subject: Re: Inside axle of rear differential


Elite Veteran

5001001001002525
Location: Oceanside, CA
I'd find a parts rig and get the stock Rockwell back in there and not worry about the gear ratio. Putting money in a flipped Dana 70 that's running the gears in reverse is a poor investment.
You can deal with gear ratio changes later when it's home and you have better control of the situation/cost.
I'd actually consider having it shipped home now so that you can control the situation.
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hemi354az
Posted 2017-08-17 11:58 PM (#4887 - in reply to #4886)
Subject: Re: Inside axle of rear differential


Extreme Veteran

50025
Location: Scottsdale, Aridzona
The numerically LOWEST ratio for the Rockwell F140 Differential as used in a "stock" FMC R2900 Motorhome is 4.63:1. Please see - http://www.canadawideparts.com/downloads/catalogs/meritor_outOfProd... - Page 4-3.
That has been an issue for the FMC 2900R since it was first made in 1973.
The 8.1 or 8.2 Diesel and Allison trans may have been installed in #983 in such a position that returning to a "stock" Rockwell F140 differential may not be possible with respect to fore/aft space and a "short" driveshaft, and pinon height being aligned with trans out put. The "corrected" axle Part Numbers above are right out of the FMC Parts Book (Fig 18-2, Item 40) which are very UNLIKELY to fit/interchange with the as yet unidentified #983 differential, although it is WAGed to be a DANA 70 type. I do not think DANA diffs use Rockwell axles. It is not known what "issue" has been discovered with the Differential Axles in the DANA (?) installed in #983 The pictures of the failed pinion shaft (see pictures in Albums) show a clean brake all the way across the shaft typical of a surface flaw/crack that progresses a small distance every revolution. A high magnification could show the typical striations of that type of failure. Often the striations can be counted and "cycles to the failure" are indicated. That failure has been slowly happening for a long time. It most likely was due to some nick or scratch or machining flaw at the surface.
Perhaps the Differential currently used in #983 must be repaired for continued operation. What ever some think of upside down and reverse rotating differentials . . . THAT very "custom" differential made the TO/FROM Al-Can HiWay trip without issue , and other miles of service before that.
Len makes a good point that that repair might be better accomplished after it is TRUCKED to it's "home Base".
Zoom ON ! Lou #120

Edited by hemi354az 2017-08-18 12:05 AM
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borrmann
Posted 2017-08-18 7:34 AM (#4888 - in reply to #4887)
Subject: Re: Inside axle of rear differential


Contributor

25
Location: Bluevale, Ontario
Flipping the axle changes the whether the coach goes forward or backward it does not mean that that the gear rotation has been reversed. The engine is rotating clockwise (as viewed from the front of the engine), the transmission output shaft in a forward gear is rotating clockwise and the differential is still being spun clockwise in the correct gear engagement. Frank
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LCAC_Man
Posted 2017-08-18 8:05 AM (#4889 - in reply to #4879)
Subject: Re: Inside axle of rear differential


Elite Veteran

5001001001002525
Location: Oceanside, CA
Frank is correct on that, I had it in my mind that it was running on the coast side of the gears but that isn't right, with it being flipped and pushing it is loading on the correct side of the gear. The only issue would be increasing the lube level to ensure the pinion was still flooded in that higher position.
Still, a Dana 70 is just not strong enough to be in that application, you have no safety factor at all.
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B. Sitton
Posted 2017-08-18 8:23 AM (#4890 - in reply to #4889)
Subject: Re: Inside axle of rear differential


Extreme Veteran

100100100100
Location: Ignacio Colorado
The first Duramax conversion l had seen back in 2007 was running a Spicer 70. They were pulling a car through the mountains of Colorado. There is a coach in Delta Co. waiting for restoration that had a Cummins and still has a Spicer 70 sitting in it. The owner still plans to get it back on the road.
Bill
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LCAC_Man
Posted 2017-08-18 8:32 AM (#4891 - in reply to #4890)
Subject: Re: Inside axle of rear differential


Elite Veteran

5001001001002525
Location: Oceanside, CA
Maybe with a low horsepower/torque package and low towing weights you can get away with it. I suppose I look at it from how I use my rig, I'm at 22,500-24,000 GCWR frequently and I make 700+ftlbs of torque so the 140 rockwell really is "just" strong enough for me..
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PLUM72
Posted 2017-08-26 5:52 PM (#4911 - in reply to #4879)
Subject: RE: Inside axle of rear differential


Contributor


Check these guys...
https://www.ringpinion.com/

If nothing else might be worth a conversation for a possible lead.
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coolkat
Posted 2017-09-19 4:06 AM (#4986 - in reply to #4879)
Subject: RE: Inside axle of rear differential


Contributor


try truck pros
http://www.truckpro.com
they are pretty good
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