Is this normal or is something wrong?

midnit

New Member
Joined
Sep 30, 2011
Location
Charlotte
I recently purchased a lifted blazer (s10) and I need some clarification from someone who actually knows (unlike myself) if the behaviors I am seeing are normal for the equipment or not.

So quick info, it has a sas, front is dana 60, back is a corporate 14. Detroit lockers front and rear. Milemarker locking hubs. NP231c with fixed front yoke, slip rear.

In 2wd with unlocked hubs it drives great.

In 2wd if I lock the hubs (on pavement) - once I get to about 10mph the truck begins to shudder. Not just the steering, but the whole truck. I have been too nervous to go any faster, once the shudder starts if I slow down it goes away. This is going in a straight line, not turning.

In 4wd hi, without hubs locked, in 4wd in general there is a ticking/clicking sound that is constant but not loud. Once I get to about 30mph it sounds like you were lightly trying to shift without a clutch. Not hard gear grinding but like they where just touching.

In 4wd hi, with hubs locked, (on pavement), I get the shudder at 10mph and I hear the light clicking as above.

In 4wd hi, with hubs locked, on gravel, I still get light clicking but no shudder and I don't believe the light gear grinding is heard - but I may have not been going faster enough.

4wd low engages and is slow - because of the mods to the truck the transmission doesn't know its in low so it wont shift out of 1st...so until I fix that I don't know how it runs in low.



So I tore the transfer case down and I saw no problem with any of the gears, chain, bearings, seals - it all looked good. I saw nothing that would "grind" once engaged into 4wd so I am at a loss as to the sounds I am hearing. I did not pull apart the 4wd syncro's though (thats going to haunt me). While apart shifting by hand seemed to indicate when its in 4wd its in 4wd - it would either work or not. I reassembled and tried it again with same behaviors.

So, if anyone can shed some light I would be most appreciative. I am not new to wrenching, just new to 4wd vehicles.
 
Clicking/ticking is most likely your detroits unlocking. Have you ever had a locked 4x4? The shudder might be bad rims or poor ballance of tires. I did not see you mention weather they are beadlocks or not and what size tires it has. Really need more info imho.
 
Wheels are not beadlocks. The tires are BFG A/T 35x12.5x16.5.

I have not had a locked 4x4 before so I have no idea what is normal and what I should be trying to fix :)

The shudder only happens when the hubs are locked, and seemingly only on pavement. I did not notice it on gravel.
 
midnit said:
Wheels are not beadlocks. The tires are BFG A/T 35x12.5x16.5.
I have not had a locked 4x4 before so I have no idea what is normal and what I should be trying to fix :)
The shudder only happens when the hubs are locked, and seemingly only on pavement. I did not notice it on gravel.
Click to expand...

To me that sounds like normal behavior. :) Maybe someone else will chime in. I'm not the best at figuring out problems on the web sight unseen.
 
you don't want to run it with the hubs locked on pavement.
 
The clicking could be driveshaft u-joints, and the shuddering could also be driveshaft issues. I'd pull the front shaft and inspect it really well.
 
The shudder could be due to slight chages in gear ratio, coupled with detroits, it could cause these symptoms. Like 4:10 rear and 4:11 front. normally this doesn't cause a problem, BUT when you figure in detroits, it tends to change things.

You could put the truck on jack stands and make sure it is safe, not wobbly at all. Put the stands under both axles, even pull the tires. Then start the truck and put it in drive, hubs locked, and in 4hi. You may be able to better diagnose the noises this way. You could tell exactly where they are coming from.

Good luck!
Todd
 
jeepinmatt said:
The clicking could be driveshaft u-joints, and the shuddering could also be driveshaft issues. I'd pull the front shaft and inspect it really well.
Click to expand...
I was also leaning this direction. Bad u-joints in the front shaft or a bent front shaft will cause those symptoms. Bent shaft might not cause the clicking, but bad joints certainly would.
 
sounds like front drive shaft
drive it without it installed & hubs locked
 
Ok, I put it up on stands today and ran it a bit.

I identified the light clicking was something contacting the front driveshaft and took care of that.

The louder clicking appears to be the hubs. I know nothing of locking hubs but I took off the outer part and everything inside seemed ok...meaning not obviously broken. Do hubs normally clack when engaged? Could it be because the front wheels had no resistance?

There was no shudder while on stands.

The grinding did happen while on the stands. Its coming from the transfer case and sounds like gears skipping over each other or perhaps a chain skipping. I only hear it in 4wd hi, but again I can't go more then 10-15mph in lo right now. There is no grinding under 10mph, around 15mph it starts and if I go faster the sound can change a bit but its still there off and on.

So as I take the transfer case out and open it up what should I be looking for? The last time everything looked good but I wasn't sure how to tell if the chain had stretched. I saw no indication of it slapping the case on the inside. This is an NP231c. Even if it was the chain, I wouldn't have expected it to skip with zero load.
 
The hubs shouldnt clack when engaged, but the detroit certainly will under certain circumstances.

I didnt know your blazer still had the 231c. It shouldn't grind while in 2wd if the chain is slipping. However, if the input or output bearings are fragged it definitely will cause a lot of banging and jerking. BTDT. If those bearings are shot, 4wd driving makes a hell of a racket.
 
willness33 said:
The hubs shouldnt clack when engaged, but the detroit certainly will under certain circumstances.
I didnt know your blazer still had the 231c. It shouldn't grind while in 2wd if the chain is slipping. However, if the input or output bearings are fragged it definitely will cause a lot of banging and jerking. BTDT. If those bearings are shot, 4wd driving makes a hell of a racket.
Click to expand...

It does not grind in 2wd and all the bearings felt and appeared to be solid when I tore it down last week - not that one couldn't have decided to fail afterward.

Actually I didn't take apart the input, I just tried moving shaft and gears to see if they were appears to be tight and they did. But I could have missed something.
 
Oh, ok. I thought you had taken the shaft off already. I'm going bet a beer that you have a trashed u-joint in the front shaft. It should be pretty apparent when you drop the shaft.
 
Wondering if your planetary is not full engaging?? Might want to try and take the linkage loose and shift it in by hand. Take note of where the shifter is when it is supposed to be in 4WD , and then see where it is when put into 4WD by hand.

The hubs may appear to be making the noise, but most likely it's traveling from the detroit out to the axles and the end, the hub.
 
Just for kicks get someone to put it in 4x4 and see if the exhaust is hitting trans/tcase or anywhere ive seen this cause a ticking that sounds like trans on my jeep dunno if thats it but worth a shot.
 
I removed the front driveshaft this morning and tried it on the stands and the transfer case made no noise. The u-joints feel and look fine but I did notice the yokes appear to have been grinded at in an attempt to increase its flexibility. I now remember the previous owner said he lowered the front because it was binding.
The driveshaft is a 1350 at the front output and 1310 at the diff. The angle doesn't look like a problem but...what do I know.
I have not driven it without the driveshaft, just ran it in 4wd hi on the stands - I should have a chance to drive it later today.
 

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I just got to drive - without the front driveshaft, hubs locked. There was no shudder, no noise, it rode great. I put it into 4wd even though there was no point, I just wanted to hear it again in 4wd and again it made no noise with the driveshaft off.

So it appears all who bet on the driveshaft were correct :) But what is wrong with it? ujoints "seem" fine, I had assumed it would be pretty obvious if they were bad. The yokes have that grinding on them so maybe they are binding? If so, what shall I do? I don't want to go lower :) Double cardan? More appropriate yokes? How does the angle look?

Thanks for the input guys!
 
It could be that the u-joints are out of phase with each other. Can't really tell from your pictures. This should help illustrate:
awww.i_bmw.com_gallery_data_509_medium_Phase.jpg


Here's a decent article I found that should be helpful:
http://www.4x4wire.com/toyota/tech/driveline/
 
Good call Matt. If the pics were taken without the truck moving in between the two, that's exactly what it looks like. The pinion looks low from that pic and the upper joint angle looks a little steep, but it's hard to tell without better pics.
 
jeepinmatt said:
It could be that the u-joints are out of phase with each other. Can't really tell from your pictures. This should help illustrate:
awww.i_bmw.com_gallery_data_509_medium_Phase.jpg


Here's a decent article I found that should be helpful:
http://www.4x4wire.com/toyota/tech/driveline/
Click to expand...

Ahh, yes the pictures are from the same time - the truck has not moved. They are out of phase. Thank you for the link!

I also discovered on close inspection of the ujoints that a couple of the needle bearings were broke. So for good measure I will replace the u-joints.

I think I'll take the driveshaft to Universal Automotive just to have them check it out.

Thank you guys SO much! Hopefully I can get the driveshaft back on today and see how it rolls.
 
willness33 said:
Good call Matt. If the pics were taken without the truck moving in between the two, that's exactly what it looks like. The pinion looks low from that pic and the upper joint angle looks a little steep, but it's hard to tell without better pics.
Click to expand...
The pinion does look low in that picture but its level. The upper is steep, the transfer case angles down to the back of the vehicle so that front output is steeper than it has to be. Is it too steep?
 
I'm sure Universal Automotive will fix you right up, I've had them make me a few driveshafts, always with good results. The angles themselves don't look terrible. I'd wait till you got the driveshaft fixed before getting too involved with the angles. You might can just pull it apart at the slip yoke and put it back together in line. But a straight shaft without a double-cardan isn't too expensive.

Glad we could help.
 
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