pappy127 Posted October 9, 2009 Share Posted October 9, 2009 I recently replaced the front carrier on a 86 R model with a rebuilt unit. The old one had busted the ring and pinion gear under a heavy load. Ran the truck a couple of short trips and the rear end seems to be making a chunking sort of sound under load again. At times the sound seems to be emanating from the tranny/clutch area and other times from the new rearend. I was wondering if the peanuts might have been put in backwards to cause this. The reason I wonder is the guy that picked up the rear for me mentioned something about the guys doing the rebuild didn't seem too sure while they were doing the job. He was watching at the time. Thank you for any help on this. Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/ Share on other sites More sharing options...
Superdog Posted October 9, 2009 Share Posted October 9, 2009 Does your truck have an overdrive transmission?If so,are all 8 rear tires matched? Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41610 Share on other sites More sharing options...
fjh Posted October 9, 2009 Share Posted October 9, 2009 To check that out simply flip the power divider lock out swithc if the noise goes away the problem is there! Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41621 Share on other sites More sharing options...
pappy127 Posted October 10, 2009 Author Share Posted October 10, 2009 The truck has a duplex tranny. It's got 5 on the main and hi/lo/reverse on the 2nd stick. As far as I have noticed the tires are matched. I haven't really paid them a lot of mind but I will check them tomorrow. Some of them may have a little more wear than the others but I've never had a problem with that before. I never thought about that switch but I will also check that. Thanks to all. Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41651 Share on other sites More sharing options...
HK Trucking Posted October 10, 2009 Share Posted October 10, 2009 Double check to make sure that "rebuilt" differential that they sold you is the same ratio as the original. If it's a slightly different ratio compared to the other diff in your tandems, the power divider will "clunk" while trying to compensate for the different ratios, and yes, that clunking can sound like it's coming from the transmission because the sound is transmitted thru the driveline.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41652 Share on other sites More sharing options...
pappy127 Posted October 13, 2009 Author Share Posted October 13, 2009 Got a chance to check this thing again today. The tires are well matched. The thing doesn't have a power divider switch in the cab or lines to the rearend for a power divider. I could've sworn I saw the forks for the divider in there while I was working on the thing. May be old age kicking in again I don't know.The differential is supposed to be a 4.17. Are there some numbers somewhere that I can verify this? Driving down the road today the rear would make a sound like when you drive over the rumble strips along the side of the road. Won't do it all the time nor can I make it do it. Just does when it takes a notion to. When I got back after about a 6 mile round trip I checked and the pinion housing on the front was noticeably warmer than the rear or either housing. I am wondering if the pinion was not properly shimmed. And one more thing. The drive shaft slip joint can be pushed up and down about an inch or so. Didn't see any wear on the shaft yet but it definitely needs seeing about. Thanks guys. Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41893 Share on other sites More sharing options...
tech_j Posted October 15, 2009 Share Posted October 15, 2009 Look on the flat sloped area on the front of the carrier. The ratio will be stamped there, and most likely have a layer of paint covering it. If the noise is terribly noticeable, I would start by pulling the plugs out of the diff. and power divider to inspect for metal. You never know about shade tree mechanics. There can be much work involved in setting preload on the bearings and little room is left for error. As for the slip, a little play is tolerated but around an inch seems a bit excessive... Replace it! Quote Torque wrench? Can I put an air hose on it?? Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-41948 Share on other sites More sharing options...
cuznguido Posted December 5, 2009 Share Posted December 5, 2009 Since it was just worked on, I would check the pinion nuts. Those things need to be TIGHT and the keeper between the nuts needs to be bent over to prevent it from backing off. You can do this without taking it out of the truck. I would also make sure that there is no debris down in the carrier from the previous issue. The mechanics should have washed it out good, but you can't count on that. Quote Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-44581 Share on other sites More sharing options...
hatcity Posted December 5, 2009 Share Posted December 5, 2009 Snapped axle?You stated you busted the carrier with a heavy load Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-44583 Share on other sites More sharing options...
HK Trucking Posted December 5, 2009 Share Posted December 5, 2009 Since it was just worked on, I would check the pinion nuts. Those things need to be TIGHT and the keeper between the nuts needs to be bent over to prevent it from backing off. A 1986 would have the retaining bolt to secure the yokes to the input shaft and thru shaft splines.Yes , I agree, they do need to be tight.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-44588 Share on other sites More sharing options...
HK Trucking Posted December 5, 2009 Share Posted December 5, 2009 The drive shaft slip joint can be pushed up and down about an inch or so. Fix that. You need to take that driveshaft out and bring it to a shop that specializes in building driveshafts.That is undoubtedly causing torque sensitive vibration in the drive line.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-44589 Share on other sites More sharing options...
MACKTRUCKS4 Posted December 6, 2009 Share Posted December 6, 2009 If you check the ratio's and they do match, double check by pulling the side cover off of the rear you put in and check the gears themselves for the right ratio. I have heard stories of shops putting in the wrong ratio inside and not changing the outside numbers. I too at one time had the same problem and it turned out to be miss-matched ratio's. The front rear would get hot because the power divider was jumping due to the ratio's not matching. Quote Live every day like it's your last, because one of these days, it will be. Link to comment https://www.bigmacktrucks.com/topic/10982-r-model-rearend-problem/#findComment-44702 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.