Drives fine in 2wd - 4wd feels horrible

Anything related to the stock drivetrain, engine, transmission, axles, wheels...

Moderator: F9K9

User avatar
adrenalnjunky
Crew Elite
Crew Elite
Posts: 895
Joined: Sun Jul 27, 2003 11:32 am
Location: West Monroe, Louisiana
Contact:

Drives fine in 2wd - 4wd feels horrible

Post by adrenalnjunky »

Ok, if some of you have seen my other threads recently, I has a shock replacement job that turned into shocks + upper a-arm bushings +2 new CV joints.

I got everything buttoned up and it runs much better in 2wd - need an alignment, cause I can see that my camber isn't the same on both sides.

I went out to a parking lot and turned slow circles of varying diameter, both directions to listen for any weird popping and feel if anything seemed like it wasn't right. Everything is beautiful in 2wd.

confession: I hardly use 4wd anymore. I used to go find mild trails/dirt roads etc back when the truck was newer, but I've had so many front end issues with this truck that I have really gotten away from using 4x4 other than briefly just to circulate some lube around the diff.

I engaged 4Hi @ about 25-30 mph in a straight line and felt the front end lock in - feels like some drag is put on the system - more than I remember it having years ago when I used it more. As soon as I started a turn the front end felt like it was coming apart - binding and whirring, the front end felt like it was grabbing, and being forced to turn the wheels. It seemed like what you would feel if a MT tire were grabbing the fender and ripping it to shreds. It's actually hard to put into words how bad this felt. After that started I straightened back up and tried a turn the other direction. (this is all at low speed) Same result. I straightened up and the problem endured. I put the truck back in 2wd, and had to back up to get the axle to disengage.

2wd still seems like normal operation, other than I have a diff fluid leak from the driver side CV interface. My prybar job to get the CV out must have damaged the oil seal there. Yet another chance to pull the front end apart.

here's one random though I have - about 2 years ago, my rear diff carrier exploded in the pumpkin requiring my repair shop to source me a whole new (used) axle assembly. I have 3.42's in the truck. They told me it was a 3.42 gear axle - but what if it wasn't? What if they were told it was a 3.42, but it's really a 3.73 and they didn't check? I've barely touched 4x4 since that work, and I've felt some binding/whirring when I did (not as bad as last night though). I thought I was experiencing a CV issue at that time, and was putting off fixing it.

Is there an easy way to test the 4x4 system without damaging anything? Off the ground maybe?
[size=75]Thanks, CHRIS
2000 S10 Blazer 4x4 4Dr. -- 2" PA BodyLift, Daystar Shackles, TB Crank, 1.75" Rear wheel spacers, Yakima roofrack, 30" BFG AT's.
1969 VW Bug -- airbagged and in pieces.
1962 VW Karmann ghia -- rusting over in the corner. "That's not a tool--that's a damn brick!"[/size]
User avatar
adrenalnjunky
Crew Elite
Crew Elite
Posts: 895
Joined: Sun Jul 27, 2003 11:32 am
Location: West Monroe, Louisiana
Contact:

Re: Drives fine in 2wd - 4wd feels horrible

Post by adrenalnjunky »

Oh, and I've got a spare front diff sitting in storage. I don't know what gearing is in it either, but at least I could rebuild that one without having the truck in pieces for more than a day.
[size=75]Thanks, CHRIS
2000 S10 Blazer 4x4 4Dr. -- 2" PA BodyLift, Daystar Shackles, TB Crank, 1.75" Rear wheel spacers, Yakima roofrack, 30" BFG AT's.
1969 VW Bug -- airbagged and in pieces.
1962 VW Karmann ghia -- rusting over in the corner. "That's not a tool--that's a damn brick!"[/size]
User avatar
HenryJ
Admin K Elite
Admin K Elite
Posts: 12705
Joined: Tue Oct 01, 2002 9:14 pm
Location: Ontario, Oregon
Contact:

Re: Drives fine in 2wd - 4wd feels horrible

Post by HenryJ »

Don't ever try to turn on dry pavement, or in good traction conditions with 4x4 engaged. It will bind and jerk like crazy. There is no way to differentiate the front from the rear in a turn. They turn at different speeds in a turn and the transfercase can not slip.

"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving!
- ThunderII KE7CSK
User avatar
_STUCKY
Crew Elite
Crew Elite
Posts: 866
Joined: Wed Feb 08, 2012 6:07 pm
Location: Central IL

Re: Drives fine in 2wd - 4wd feels horrible

Post by _STUCKY »

Yea I'd check the gear ratio in the rear just to make sure. I almost caused major chaos in my k5 when I swapped in a bigger rear axle (3.73 6 lug semi float 14 bolt) because I assumed I knew what gears the front ( 3.42 stock 10 bolt) had. I even had the driveshafts in and had been driving around before I realized it, but luckily I never locked the hubs or pulled the t case lever. That was a gear change that I didn't put into the budget. :twisted:

But I'd guess that's not the problem, because since you can't unlock the s10 front axle and the front driveshaft turns all the time, I would assume something would have exploded by now if the gear ratios were different.

I'd put it on jack stands or a lift and put it in 4lo at idle and take a look all around if it was mine. Sorry I'm not of much help.
User avatar
adrenalnjunky
Crew Elite
Crew Elite
Posts: 895
Joined: Sun Jul 27, 2003 11:32 am
Location: West Monroe, Louisiana
Contact:

Re: Drives fine in 2wd - 4wd feels horrible

Post by adrenalnjunky »

No- you've echoed all of my thoughts. Even the "non-budgeted" gear change. If I do have 3.73's in the rear - I dunno if I go back to the shop that put the rear end in the truck, cause I don't want to go back to 3.42 with 30" tires. I dunno of he'd even do anything for me, but this shop is old, and has played me really straight over the years.

I plan on jacking one rear wheel off the ground tonight (open diff) and turning it through 2 rotations while counting driveshaft rotations. My mark should complete 3 full rotations, and either end up about halfway through a 4th rotation for 3.42's and about 3/4 through for 3.73's. I should be able to determine it that way - i can't see there being enough play/lash in the system to throw it off by that much, especially if I'm not herky-jerky when turning the tire.

I may go find me a nice gravel/dirt lot to go and test the 4wd again if the rear end is a 3.42, as HJ stated, pavement isn't the place for that.
[size=75]Thanks, CHRIS
2000 S10 Blazer 4x4 4Dr. -- 2" PA BodyLift, Daystar Shackles, TB Crank, 1.75" Rear wheel spacers, Yakima roofrack, 30" BFG AT's.
1969 VW Bug -- airbagged and in pieces.
1962 VW Karmann ghia -- rusting over in the corner. "That's not a tool--that's a damn brick!"[/size]
User avatar
HenryJ
Admin K Elite
Admin K Elite
Posts: 12705
Joined: Tue Oct 01, 2002 9:14 pm
Location: Ontario, Oregon
Contact:

Re: Drives fine in 2wd - 4wd feels horrible

Post by HenryJ »

adrenalnjunky wrote:...
I plan on jacking one rear wheel off the ground tonight (open diff) and turning it through 2 rotations while counting driveshaft rotations...
It has been my experience that rolling the vehicle in a straight line is more reliable.

Put a chalk mark on the drive shaft and the bottom sidewall of one tire. Have a friend push the truck while you watch from the side to count driveshaft rotations. One rotation of the tire = how many revolutions of the driveshaft?

For the front axle that is going to be difficult as the axle shaft needs to be engaged. That requires the axle be engaged.
I think I would find a nice loose gravel road. Mark both shafts and a front and rear tire. Make one rotation of the tire in a straight line with 4x4 engaged. Make sure the front and rear as well as both driveshafts make the same rotation.

That should show you if there is a gear ratio difference.

"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving!
- ThunderII KE7CSK
Lil-j
Crew Elite
Crew Elite
Posts: 177
Joined: Tue Sep 11, 2007 12:22 pm
Location: Brunswick, OH

Re: Drives fine in 2wd - 4wd feels horrible

Post by Lil-j »

This front ends noise when turning on dry pavement is normal like Henry said. If you are in mud snow or something like that you won't have that problem. Unless there is some issue that I'm missing.
User avatar
killian96ss
Crew K Elite
Crew K Elite
Posts: 2669
Joined: Tue Sep 09, 2003 11:53 am
Location: Sacramento, California

Re: Drives fine in 2wd - 4wd feels horrible

Post by killian96ss »

There's no way you have diferent gear ratios front to rear because if you did your truck would not move in 4wd very far without breaking something. It would be very obvious!

Steve