Questions and Answers
Dodge Rear End
Q. Hi, I have a question about the rear differential on my 1992 Dodge Ram 250 Van. This is a Roadtrek Class B conversion motorhome manufactured by Home and Park in Ontario, Canada. It has a 318 V-8, automatic transmission.
Recently the left rear wheel bearing seized just as I was returning from a weekend trip. I took it to my mechanic who quoted me $400.00 to replace the wheel bearing and brakes, or $1500.00 to install a used rear end. Apparently the seized bearing had spun in the tube, damaging the housing, and he felt that replacing the bearing was only a temporary fix. I opted for the more expensive repair.
When I got the van back, there was SERIOUS vibration from 25 to 40 mph, I immediately noticed a significant drop in gas mileage, and the speedometer was reading low. I had previously calibrated the speedometer using a GPS, and had found that 57 mph indicated was 55 mph actual. A new check with the GPS showed 50 mph indicated was 57 mph actual. This is a change of almost 20%.
I reported these problems and returned the van to the mechanic. He replaced the yoke and speed sensor (and charged me $300.00) with essentially no change in symptoms. I returned the van again, and he reportedly rotated the yoke by 180 degrees. This mitigated the low speed vibration problem, but had no effect on the indicated speed error. In addition I am now noticing a high speed vibration which occurs at 50 mph and above. This sound is a constant "rumble" similar to the sound made going over a steel deck bridge. Upon releasing the accelerator the sound briefly peaks then goes away.
I suspect that they put in a rear end with the wrong gear ratio, although the mechanic claims that he was told (by the junk yard) that there is only one rear end gear ratio available for this van.
My questions are:
Is this true? Could they have used the wrong rear end?
What would cause the vibration? I suspect drive train because it is correlated to power delivery, and not tire speed.
What should I do? I have already spent nearly $2000.00 and have no confidence in the repair.Any insight you can provide would be appreciated.
Regards,
DaveA. Well Dave, there are actually three rears for that van. Externally they look the same, but inside there is a difference. There is an 8¾, 9¼ and a 9¾ ring gear and that will make a difference.
There is also a Dana/Spicer drive axle and a Chrysler 60, 70, 80 drive axle with and without Trac-Loc. There is a metal tag on the differential that has the model drive axle stamped on it. It is there to give the required information for repair or replacement.
As for your questions:
Yes, it is very possible they put in the wrong rear end.
The wrong rear could cause the vibration. The drive train is calibrated to work smoothly and when you change something there is a good chance of a problem arising.
What to do? If they still have the old rear, they can take the numbers off the tag and get the correct rear and install it. And there should be absolutely no charge for the work.Whether through inexperience or incompetence, it was their mistake and it should not cost you anything for them to rectify it.
Additional Information provided courtesy of ALLDATA
