Grinding Sound In Reverse only (1 Viewer)

[Pascoscout]

Was out in some snow today and had a high pitch grinding sound (sort of like missing a shift in a manual trans) when I put it into reverse and hit the gas. The sound only occurred when I was in high range with the CDL switch on. I put it in low range and no noise. My front locker also won't engage again (high or low range) but it's been acting up so not sure that's related.

I couldn't tell exactly where the noise was coming from but I could feel a vibration through the gear selector so I was leaning towards transmission. Was coming front the front/middle area of the car for sure, didn't sound like it was the rear axel. Since it only did it in high range maybe something to do with the VC? Maybe not engaging correctly with the CDL switch?

 

[lumbee1]

For what it's worth.

My Cruiser started making a gawd awful noise like a feral cat hissing but only when reversing. Oddly enough I had no other symptoms and it only seemed to happen in my driveway. I searched on mud and found several posts pointing to a U-joint. I dismissed them since I just greased the u-joints and it made no difference in sound. Since I didn't know the age on the u-joints, I decided to replace the ones on the rear shaft first. I dropped the shaft and popped the rear u-joint off first. Full of grease and still in great shape. I popped the front u-joint caps off and found rusty dust where the needle bearings used to be. Two caps contained dust and two caps full of grease.

Needless to say, u-joints fixed it up. I didn't notice any other changes from the new u-joints other than being silent when reversing in my driveway.

 

[baldilocks]

Is your 80 still full time fwd? Do you have a CDL switch installed in the dash? Had you just changed transfer case configuration or had you already been driving around in the configuration it was in when the noise occurred?

 

[jonheld]

Search results for query: squeal in reverse

forum.ih8mud.com

 

[Pascoscout]

Is your 80 still full time fwd? Do you have a CDL switch installed in the dash? Had you just changed transfer case configuration or had you already been driving around in the configuration it was in when the noise occurred?

Yes still full time fwd. I added the CDL switch a few years ago. I've been driving in the same configuration since then and have no drive train modifications other than the tires (33's). I rarely use the CDL switch but it does come in handy on snow/ice road conditions to have high range with both axels getting power. In this case I was not on the road, out on some sand dunes and got bogged down going up a hill. Was in high range with CDL switch on. When I put it in reverse it made that grinding sound for about a second when I first hit the gas then it went away. I should note I was backing down the hill not up it. Did it several times as I worked my way up the hills. I stopped and shifted to low range and it didn't do it anymore.

No issues driving around and doesn't make it in any forward gears. I spent about an hour pulling other stuck rigs out driving around in low range, backing up and down hills and it never made the noise again.

 

[baldilocks]

Don’t know if this is related but, I’ve gotten into the habit of going from whatever gear is selected to neutral and then to park because, at times, when going directly from in gear to park I get a grinding noise like what you described.

I wouldn’t be too concerned at this point. It may be worth the time it takes to inspect you front drive flanges.

 

[Pascoscout]

Search results for query: squeal in reverse

forum.ih8mud.com

Thanks. I had searched for grinding in reverse and didn't come up with some of these.

Sounds like my issue. I wasn't paying attention to timing but since I was working my way out of snow I suspect I was shifting in and out of reverse rather quickly and not pausing. Will have to look into the "click" settings for line pressure too. Best thing I ever did to my tow rig was up the line pressure and get rid of the soft shift factory settings.

 

[Pascoscout]

Don’t know if this is related but, I’ve gotten into the habit of going from whatever gear is selected to neutral and then to park because, at times, when going directly from in gear to park I get a grinding noise like what you described.

I wouldn’t be too concerned at this point. It may be worth the time it takes to inspect you front drive flanges.

Thanks! Yeah from the results @jonheld posted it sounds like I may have been shifting back and forth too quickly. Terrible noise though! May have to add a tranny over hall to the long term list of things for this truck (couldn't hurt). Engine is due in another 20K or so, maybe both at the same time.

I have to replace the inner axel seal on the front again anyways so will take the time to inspect everything when I have the axel torn down.

 

[baldilocks]

Yes, the noise does get ones attention. You can predict the need for an engine rebuild? How many miles does your 80 have on it? Mine has 305k, which is not close to the highest that’s been posted to Mud, and she operates very well burning a negligible amount of oil. From what I’ve gathered, the transmission can outlast the engine.

 

[Pascoscout]

Yes, the noise does get ones attention. You can predict the need for an engine rebuild? How many miles does your 80 have on it? Mine has 305k, which is not close to the highest that’s been posted to Mud, and she operates very well burning a negligible amount of oil. From what I’ve gathered, the transmission can outlast the engine.

Predict no, but I've just planned to get it done at 300k. Not going for any longest mileage on original engine records here . I am at 286k and put about 6k a year on the truck. It is burning a small amount of oil.

Plus I kind of want to get it done before parts start going NLA.