Scraping sound coming from trans or further back?

[cdoggwsu]

So I've noticed while driving at higher than about 35 mph if I let off the gas the front end sounds like it's grinding for a second and then it stops. If I give it a little gas is grinds quickly then goes away. By feathering the gas pedal between accelerating and decelerating it will continue to grind.

I took a look under it a while back and noticed the passenger side tie rod end was scraping on the balancing weights so i figured that was the problem but after having them switched to the stick on type it's still grinding. I checked the top of the caliper and the bracket all around the rotor and there is no sign of scraping so I'm kind of at a loss.

Could this be coming from the front diff? The hubs (manual) are unlocked but is it possible they aren't fully disengaging? Any input is appreciated. Oh, this is the 88 K5 in the sig, open 10b 3.73 front end. The wheels aren't stock and the clearance is pretty tight.

 

[BlazerBud]

Get under it and spin the front drive shaft. make sure the hubs aren't half engaged or something, jam a screw driver into the knuckle u-joints one at a time to make the opposite one turn while you spin the front driveshaft by hand. One real cause of funny noise is having one hub engaged and the other not.

 

[GNERGY]

Jack up each front wheel, one at a time and see if you have any top and bottom play ( wiggle it ) then turn it and see if it turns smooth. Might just be a wheel bearing going bad.
Tarey

 

[gt1009]

I feel like the sound might be coming from your transfer case. I have a 208 also and I have heard that if the chains are a little stretched out they will do that.

 

[resurrected_jimmy]

my 91 burb had that exact same sound symptom caused by the slip yoke on the front driveshaft being worn out/stripped/galled. The front slip yoke wouldn't slide so it was causing major stress on the T-case. Didn't find the problem until it broke my transfer case in half.

 

[cdoggwsu]

Thanks for all of the replies, guys. I'll check all of it out.

Get under it and spin the front drive shaft. make sure the hubs aren't half engaged or something, jam a screw driver into the knuckle u-joints one at a time to make the opposite one turn while you spin the front driveshaft by hand. One real cause of funny noise is having one hub engaged and the other not.

This was what I originally suspected, the hubs are for sure turned to the fully unlocked position, although I'm still thinking that may be part of the issue.

I feel like the sound might be coming from your transfer case. I have a 208 also and I have heard that if the chains are a little stretched out they will do that.

I thought it might be the transfer case as well, but the sound really seems to come from pretty far forward. When I changed the t-case fluid the chain felt tight, although to the touch it probably doesn't prove anything.

my 91 burb had that exact same sound symptom caused by the slip yoke on the front driveshaft being worn out/stripped/galled. The front slip yoke wouldn't slide so it was causing major stress on the T-case. Didn't find the problem until it broke my transfer case in half.

I haven't notice anything strange around the front driveshaft but then again I wasn't really looking before. Is there a relatively easy way to check this?

Jack up each front wheel, one at a time and see if you have any top and bottom play ( wiggle it ) then turn it and see if it turns smooth. Might just be a wheel bearing going bad.
Tarey

I had also considered the wheel bearings, although wouldn't they be screeching the whole time, not just at the accel/decel threshold? That is really the only solid lead I have as it doesn't happen any other time and doesn't appear to be affected by 2 or 4 wheel drive nor when the hubs are locked or unlocked.

Could bad u-joints at the knuckle cause something like this? I'll know more tomorrow when I can jack it up and wiggle them.

 

[resurrected_jimmy]

very badly destroyed wheel bearings will crunch, I've had it happen a few times when they got full of mud and totally skipped the screaming stage. Getting the front tire off the ground and spinngin it by hand and checking for play will tell you if its wheel bearings or tie rod clearance pretty quickly

 

[cdoggwsu]

Ok so here's a quick update. I jacked up the front end, nothing feels loose or has any play knuckle u-joints look good and front d-shaft slip yoke is sliding free. Everything has been freshly greased and looks fine.

On the other hand, I took a quick peek in the hubs (manual) and they are packed (literally stuffed to the brim) with grease. I was under the impression that grease packed hubs were a bad thing, at least with aftermarket warns and such. Please take a look at the pics below and let me know what the deal is.

Also, is it normal for the hubs to have some play in them? I can pull both sides out slightly (enough to fit a fingernail in) even when they are tightened down all the way. The first two pics are the passenger side the rest are driver side.

 

[cdoggwsu]

Anyone?

 

[Chaddy]

Isnt there supposed to be a big o-ring that goes there? And for the crunching, I would inspect all the ujoints and pull the cover.

 

[cdoggwsu]

Besides there being way too much grease in the hub, out of focus pix don't count .

Can't tell from the pic, but I seem to remember a rubber o-ring seal on the outer part?

Yeah all I had was the cell for a camera and it doesn't like up close pics. According to the service manual there is an o-ring under the clutch cup. I haven't taken them apart yet so I can't verify. I'm gonna scrape all the grease out and see what's in there.

 

[85chevy1]

i love my lube just as much as the next guy but damn you put my lube fetish to shame. XD haha

 

[6.2Blazer]

Correct, the locking hubs are NOT supposed to be packed with grease like that. They should only have a light layer on them, I always just cleaned mine and put a layer of white lithium spray grease on them.

Being packed full of grease can make them not function correctly, so I think there is a chance the noise could be coming from them as they are definitely not fully disengaging and possibly the varying torque loads could cause the gears to rub together.

Pull the locking hubs out, clean out all of the grease except for a real light layer, and resintall.

 

[cdoggwsu]

Alright. So I started pulling the hubs apart tonight and I can't get the inner snap ring (#85) out to save my life. Is there a trick to this? It's too small to get a pair of pliers in there but not enough grip to get the tip of a screwdriver onto.

I'm also not seeing a few parts that are listed in the service manual. Are #99 and #97 under the clutch cup, cause I don't see either of them above it. The o-ring (#98) is there and intact. Thanks as usual, fellas.

*EDIT* - Nevermind, I'm retarded. Found #99 (duh!) and got everything cleaned up. We'll see if this fixes any of the grinding. FWIW I didn't see any evidence of grinding in the hubs so while they needed a cleaning it may not have been the issue.

 

[cdoggwsu]

Well it's still grinding...

I could still swear it was coming from the front end but as many of you have mentioned, the t-case is a likely suspect as well. The rear pinion angle is pretty nasty due to the 4" blocks, so I'm going to shackle flip it (via DIY4X) and see if that helps.

 

[NV_K5]

Take your rear driveline out (assuming you can without loosing oil) and test drive it.

 

[onetonbb74]

x2 on the driveshaft. My angles were off, everything was tight and it sounded like rocks were in my transfercase and it made grinding noises. I fixed the rear shaft angle and now no noise.

if you have a slip yoke rear shaft, and you want to pull it and drive just to check if the rear is the problem, get a 20oz coke bottle and cut the top off and duct tape it over the rear output housing and it will hold the fluid in the tc for the time being.

 

[protechk5]

yeah im going to say its the rear drive shaft. my old k5 with 6" lift and 241 made the same noise your describing right when getting off and on the gas.

 

[TC4x4]

shifter cable

I had to re align my shifter cable for 4x4 when i lifted my truck, i realgied it and it when away.

 

[MTBLAZER89]

I had a similar problem once, and it turned out to be the inner wheel bearing had spun on the hub. Every time I let off the gas I got a slight grind feeling. I guess with the weight distro going front heavy on decel would cause it to spin, but normal driving it would operate normally. Just something else to check if you go back in there.

Also agree with the driveshaft being a culprit. Out of whack u-joint angles will do the same thing, but its usually more of a whole vehicle shake in my experience.