Jump to content

hurtin rear end


Recommended Posts

Hauled the camper up to the hills last weekend to go huckleberry camping. On tight to not so tight corners i'm getting a huge pulsating grind coming from the rearend of the truck. I have always felt a grind when I'm loaded and turning tightly on asphault or concrete but not near this bad and not with pulsation. This weekend I was on loose gravel and dirt and still got the bad grinding.I just assumed I had posi. because of the grind on dry pavement and in the winter the diff stays locked no matter what. In fact I've come close to wadding the truck up a few times as a result. I also go through rear tires like mad, which I thought was a diesel torque thing. Now the questions. Has anybody experienced this and what did you find? How do ID what type of diff and gear ratio? I've only seen 3.55's and 4.10's on the web, I can measure approx with tire/driveline spin calc. What is the general feedback from eaton detroit trutrac diffs. If I have to replace mine I was thinking of going that direction.I'm headed to my shop to start tearing into this problem. Thanks for any input. Bret

Link to comment
Share on other sites

Hauled the camper up to the hills last weekend to go huckleberry camping. On tight to not so tight corners i'm getting a huge pulsating grind coming from the rearend of the truck. I have always felt a grind when I'm loaded and turning tightly on asphault or concrete but not near this bad and not with pulsation. This weekend I was on loose gravel and dirt and still got the bad grinding.I just assumed I had posi. because of the grind on dry pavement and in the winter the diff stays locked no matter what. In fact I've come close to wadding the truck up a few times as a result. I also go through rear tires like mad, which I thought was a diesel torque thing. Now the questions. Has anybody experienced this and what did you find? How do ID what type of diff and gear ratio? I've only seen 3.55's and 4.10's on the web, I can measure approx with tire/driveline spin calc. What is the general feedback from eaton detroit trutrac diffs. If I have to replace mine I was thinking of going that direction.I'm headed to my shop to start tearing into this problem. Thanks for any input. Bret

Link to comment
Share on other sites

  • Administrator

Usually the tag is on the differential showing the ratio or looking the glove box for the tag showing the gear ratio and on some trucks the tag could be under the hood to. I would pop the differential cover off and look and see what's happening. You might want to have a camera ready to pop a picture or two.

Link to comment
Share on other sites

Gear ratio should be posted under the hood if the sticker is still there. 3.55s should be running around 1800 rpm at 70 mph with an auto, and pretty close to that with a standard. If your up over 2100 rpm at 70, you likely have 4.10s. This is with stock tires. Need to clarify where the noise is coming from, are you positive it's coming from the ring and pinion or is it possibly coming from the outer bearings in the axle? If it is only making the noise while turning I would suspect the differential also, but I like to be sure before I tear into something. How does your diff oil look? Do you know for sure its got the additive (and the proper amount) in it? The condition of the oil will tell you alot. My former truck developed a chatter when turning corners. At the advice of a driveline guy I pulled the axles and removed the entire diff assembly and liberally dueched the clutches out with brake cleaner. I used about 2 cans of the stuff, then blew them out with compressed air and put it back together. Worked like a charm. Reason for the chatter was the clutches got gummed up (truck had 350k miles) and they werent effectively doing their job when making corners. I caught it in time and over 50k miles later the truck is still on the road.

  • Like 2
Link to comment
Share on other sites

Mine has been this way since I got it and I really wish it was open. I don't go through rear tires but its not easy to drive fully locked. Like Jason said, an auto with stock tires and 3.54 will be around 1900 at 70 locked in od but a 5 speed will be about 2100 an a 6 speed will be closer to 2000.

Link to comment
Share on other sites

Alright, they are 3.55's. I checked oil level, good. Removed diff cover and drained oil. No shavings or particulates in the gear oil, remarkably clean actually. I can rotate either one of the wheels about 3/4 of an inch before the opposite wheel starts turning. There is a pretty good knocking sound from the drivers side of the diff as that wheel finally engages. I have video on my new iphone but am somewhat iphone ignorant and cannot upload it at this point. I will try to get some video soon. thanks for your input. Bret.

- - - Updated - - -

http-~~-//youtu.be/FVmPndHfVMc

ok here's the link to my video
Link to comment
Share on other sites

Alright, they are 3.55's. I checked oil level, good. Removed diff cover and drained oil. No shavings or particulates in the gear oil, remarkably clean actually. I can rotate either one of the wheels about 3/4 of an inch before the opposite wheel starts turning. There is a pretty good knocking sound from the drivers side of the diff as that wheel finally engages. I have video on my new iphone but am somewhat iphone ignorant and cannot upload it at this point. I will try to get some video soon. thanks for your input. Bret.

- - - Updated - - -

http-~~-//youtu.be/FVmPndHfVMc

ok here's the link to my video
The movement you have between the wheels is about the same as my truck. Just rebuilt the rear diff in mine. The sound/pulsation is most likely the clutches in the rear axle. Either the friction modifier that is supposed to be added to the oil was forgotten or has broken down. You said something about the tire wear, if you have a lot of tight turns and the diff is locked constantly for the most part you will have it. One seemingly popular thing to do to the rear diffs in these trucks is to restack the clutches in the rear so the axles will be more solidly locked together. They were not very effective in keeping the wheels turning the same speed from the factory due to how the clutches were stacked. I restacked mine for more aggressive locking when I rebuilt the rear and have very similar sounding clicks and a pulsation going around tight turns. Haven't really had any excessive tire wear though.
Link to comment
Share on other sites

gotta say movement looks normal to me. but the cross pin looks worn maybe. The symptoms you described sound to me like a lack of friction additive. it's not hard to pull the axles out and inspect the splines. un;ess you feel liek taking the diff apart, i'dd put it back together add GL5 then the additive. it's a friction modifier.

Link to comment
Share on other sites

Well I got the diff on the workbench and tore it apart. Just as diesel4life said my clutches were not only gummed up but one of them was worn quite bad on the outer rim. I'll see about getting a replacement clutch pack tomorrow. I put the tear down on video and will add the reassembly and post it for those who may be interested. Thanks for the feedback people. That's what makes this such a great site.

  • Like 2
Link to comment
Share on other sites

Really sounds like to me the spider gears are toast (those are what allow your wheels to spin at different speeds while turning)...Pinion and Ring gear are still functional other wise the whole thing wouldn't turn. Either way sounds like time to rebuild the rear end. Or might be quicker to find a wrecked truck and buy it from a junker. Just my :2cents:

- - - Updated - - -

Easiest way to test this as well is put it up on jack stands and put the transfer case in neutral and see if your tires will spin opposite of each other or they spin the same direction.

Link to comment
Share on other sites

Really sounds like to me the spider gears are toast (those are what allow your wheels to spin at different speeds while turning)...Pinion and Ring gear are still functional other wise the whole thing wouldn't turn. Either way sounds like time to rebuild the rear end. Or might be quicker to find a wrecked truck and buy it from a junker. Just my :2cents:

- - - Updated - - -

Easiest way to test this as well is put it up on jack stands and put the transfer case in neutral and see if your tires will spin opposite of each other or they spin the same direction.

When truck is in neutral and I spin one tire the other spins in the same direction. spider gears don't move. So you're saying that means time for a rebuild? :stuned:
Link to comment
Share on other sites

When truck is in neutral and I spin one tire the other spins in the same direction. spider gears don't move. So you're saying that means time for a rebuild? :stuned:

For some reason on this post i didnt get to see your video that you had posted earlier. Dont mind me just didnt have all the info!:doh: Seems like you have it under control!
Link to comment
Share on other sites

As long as the oil changes are kept up in the diffs there isn't many problems with them. I've seen trucks with 500k on an original rear end, my former 00 has recently topped 400k and still running around with zero problems other than when I had to clean up the clutches and while I was in there I also replaced all the seals. With the notoriously light ___ ends limited slip has its advantages on snow/ice covered roads in the winter time as well.

Link to comment
Share on other sites

People are surprised how well limited slip trucks get around when it snows. The only 'problem' I have is with a Dave G. tranny is it goes into gear so solidly that it will begin to spin without even moving the truck when it is real icy.

Link to comment
Share on other sites

×
×
  • Create New...