Pilot bearing and clutch opinions and feedback '97 NV4500

[schiker]

My transmission input bearing wore out and clutch burnt up I think.

The story.....
I was going down the interstate running 70 mph and I heard a squeal develop. I couldn't feel it in the stick started to slow and tried to push the clutch pedal in and it was mushy and went to the floor. Pulled onto shoulder and the clutch started slipping and squealing louder smoke coming up from cowl and it starts to choke it down but slipping too. I stop and the engine stalls transmission in 5th as the clutch won't release. Gray smoke steams from the cowl. Engine oil pressure and temp ok. I put the transfer case in neutral and the engine cranked up fine.

I have the transmission out and the input shaft feels real wobbly and the pilot bushing is approximately 1/8 inch bigger diameter than original. The clutch disc is not down to the rivets and has some wear groove indicators still visible but think it went all wobbly and smoked the disc & pressure plate from thermal overload??? It has been shifting fine but a bit harder to get into 2nd gear at a stop light just lately. Spin down has been fine going into reverse. I'll probably take it to a local shop to rebuild and probably at minimum need input bearing, input shaft, and synchro's.

So now I have to decide what clutch and pilot bearing to reassemble with. I think I want to use a RAM clutch. They are headquartered 2 hrs away near where I grew up in Columbia, SC and hear from a close mechanic they are really good. Home town is a big plus and worth some extra money IF the product is good. Other options are ZOOM and LUK Gold maybe. I redid the clutch 100K miles ago and it was a Luk Gold. The center section looks ok not broken but the springs are worn some more than I think they should be maybe???? The original owner had a clutch job under warranty at dealer due to input bearing failure is what he said at 60K miles. I did a clutch job at 120K miles due to center hub of clutch disc failure.

What about pilot bearing / bushing???? I don't think I like the needle bearing style so its either a Oilite /bronze bushing or Kevlar. What have ya'll heard about the Kevlar life and performance. I am a bit disappointed the bronze bushing was wollered out significantly.

Opinions, stories, and feedback wanted about clutch brands and pilot bearing.

 

[ak diesel driver]

If your having that much clutch/trans issues I'd be checking trans/clutch/bell housing alignment. Also check the runout of the flywheel after its bolted onto the crank. I've seen a couple that the crankshaft side of the flywheel had to be machined to get everything to run true.

Sent from my Studio 5.0s using Tapatalk

 

[schiker]

Point taken but the transmission has 225K miles (need to update mileage in signature) so I don't think its that bad. GM clutches are to blame here I think. I don't know what happened at 60K miles but was probably GM warranty milking and a clutch failure. The original owner said he was towing an RV and went to push clutch in and pedal went to the floor and did not disengage. Dealer did all work and probably maxed out the warranty claim.

Again at 120K it was a clutch issue. I replaced the clutch, PP, flywheel, pilot bearing, and hydraulics but did not do anything to the transmission but emory clothed the input snout. The needle pilot bearing gualled the needles to the snout. I sanded them off and installed a bronze bushing.

So the tranny itself has 225K miles and if it had a good clutch and pilot bearing from the factory would have lasted a lot longer.

 

[schiker]

I called Ram, South Bend, and Perfection (Zoom) Clutches. South Bend and Perfection did not give the Kevlar bushing a glowing review and said they recommend the roller bearing and that is what they provide in their kits. They both did not really seem interested in selling the Kevlar bushing anymore. Perfection went as far as to say it was better for applications where the input shaft was a bit worn and it was more a repair bushing. Ram also puts the roller bearing in the their kits but Ram said they were still selling the Kevlar bushing and did not have much negative feedback.

Perfection said they did not offer a Zoom high performance clutch for the 6.5. Their clutch was OEM class but not the double row of springs like LuK and had a hub more like the Valeo clutch disc and said it had 5 springs. South Bend said theirs was a stock center section and the picture looks like LuK center section.

So I am having a bit of indecision. It doesn't help that all the main suppliers say there picture is representative and actual product may differ.

 

[WarWagon]

"The needle pilot bearing gualled the needles to the snout. I sanded them off and installed a bronze bushing"

Sounds like the input shaft may have issues being worn in the pilot bearing area. It may have been shot a long time before the final failure.

 

[tanman_2006]

Get a rebuild kit and synchros from Blumenthals (in oklahoma) they will get you an input too.

 

[GM Guy]

I have started hearing that the bushing will drag on the shaft, making shifting not as smooth. we are planning to put a ac delco roller pilot bearing back in dad's 92.

check ebay, there is a fancy bearing drivier especially for 6.5L NV4500 trucks. it was a kent moore dealer tool, and they are on ebay for less than 20 bucks.

 

[schiker]

Stay tuned. I want to take a picture of how short the engagement of the input shaft is to the bushing. I need to section the bushing and look at where the input chamfer actually contacts inside.

It appears there is a line contact on the needle rollers where the chamfer on the input shaft will rub. And I think it rubs and wears a line into the needles and wears them out much faster than it should. The bushing may be the way to go and install slightly proud of the crankshaft. There appear to be plenty of clearance before it meets the spline chamfer.

Here is how I had the bushing installed. Is this wrong? One tech line guy said he seated the bushing to depth and that sounds bad wrong. I did not measure it but is maybe 0.060 - 0.100 into the crank. I think it should be flush at least. But if stack up is as bad as I think I am surprised no one has mentioned this as at least an area to be concerned about.

 

[schiker]

You can see a little bit of shadow at the back of the bushing where the input shaft wore into the bushing but left some of the original bushing diameter. The input shaft does not go all the way through the bushing although it has plenty of clearance before it hits the bottom of the bore in the crankshaft.

I am thinking this is really bad or another GM marginal design at least. But I need to look at where the chamfer runs on the roller / needles. If you are about to install a needle bearing really look at this closely.

 

[schiker]

Here is how I had the bushing installed. Is this wrong? One tech line guy said he seated the bushing to depth and that sounds bad wrong. I did not measure it but is maybe 0.060 - 0.100 into the crank. I think it should be flush at least.

One tech guy said insert the bushing as deep as it would go. That sounded bad wrong. Should it be to the depth of the counter sunk area or flush with the very end of the crank.

I put it about the depth of the one I took out which was installed buy a GM dealership.

I had a friend make an install tool. It fits the bushing like the input shaft but has a full square face to drive it into the bore.

 

[jrsavoie]

I installed the few I installed to flush. You can not get a puller on them if you sink them to deep.

I've had good luck with Ac Delco or GM parts. 800,000 miles on the 89 and went through 3 clutches. The first clutch blew a spring but still looked great, other than that. The 2nd clutch had the throw out bearing go bad - I did not replace the throw out bearing when I did the first clutch. The 3rd clutch was still running when the engine seized.

 

[Will L.]

When they are in to deep and can't get a puller on them, I make a dowl that fits ID snug, fill half way with grease and smack the dowl with a 5lb sledge. The grease works behind it and pushes out the bearing.

I always thought flush was correct depth, only done 1 or 2 for that tranny but no come back. Hope I didn't do someone wrong.

 

[schiker]

I have heard of the grease/soap trick bet that works but depends on if bushing has some size to it and not bad chewed up. Last time my bearing cup was worn badly and chewed up not sure it would have sealed. I used a slide puller and eventually got it. This time I sawed the bushing with a hacksaw to thin the edge and was able to use a bolt and hook pry it out easy enough.

I should have measured the bushing depth but really thinK it was closer to 0.060 depth but it was an eye ball measurement. So with that said I was loosing almost 0.200 inches of bearing surface on the bushing (and looks like I have 0.300 ish clearance wasted). And that would have put the chamfer edge on the rollers of a GM pilot bearing. I think this is bad.

Keep in mind this input shaft is OE 1997 and has 225K miles as far as I know. When I did the clutch at ~100K miles ago I took the tranny to a transmission shop to see what they would charge for input shaft and the shop owner sanded it a bit and said it wasn't that bad he would run it with a bushing and it lasted I don't know 7 ish years 100K miles.

 

[schiker]

And that 0.060 depth is trying to be extra critical that I put it too deep. I did not think it was sunk excessively deep.

That last picture of the roller bearing is on the shaft at close to the depth the bushing was installed. And here is an approximation of where the chamfer edge might have rubbed the rollers

 

[schiker]

Think I am on to something here that may explain why some roller bearing seem to fail early due to errors? Opinions?

Right now I am leaning towards a bushing and installing it flush to 0.060 out of the countersunk crank bore. After checking the new input shaft is the same length and seeing what the rebuild shop says for what they have seen on variances etc.

 

[jrsavoie]

I have started hearing that the bushing will drag on the shaft, making shifting not as smooth. we are planning to put a ac delco roller pilot bearing back in dad's 92.

check ebay, there is a fancy bearing drivier especially for 6.5L NV4500 trucks. it was a kent moore dealer tool, and they are on ebay for less than 20 bucks.

Got a link to that tool?

 

[schiker]

Here is a picture of the seal from the front side and another picture of back side of bearing. I also thought of how there is no seal in the rear of the bearing. And if there was one it wouldn't be on the shaft if it was set a little too deep. For mine it appears flush would still leave very little shaft diameter to seal on and I think the chamfer would fall away before it sealed good. Its a blind hole so not much danger in getting debris and clutch dust into the bearing from the rear but it has no seal to retain grease. Its a much bigger void than a U joint cap and wonder if grease just doesn't stay around the rollers in the bearing as well. Its also a caged roller for even less void for grease. I guess that is for assembly ease as rollers would easily fall out bumping the transmission into place. The Transmission shop suggested filling most of the void in the crankshaft behind the pilot bearing with wheel bearing grease.

What have ya'll done on assembly to help ensure longevity. Opinions of leaving a roller bearing sticking out of the crank by 0.060 and packing almost full with wheel bearing grease vs a solid pilot bushing.

Any suggesting on getting the right amount of grease in crank bore void. Asking for my input shaft back or use alignment tool and fill cavity them squish out excess.

 

[GM Guy]

Got a link to that tool?

http://www.ebay.com/itm/KENT-MOORE-..._Automotive_Tools&hash=item3f2086cd0c&vxp=mtr

 

[GM Guy]

I wonder if the goofy tool I just posted may set the depth to what GM wants? that is what I am hoping for anyhow. got any GM service manuals handy that may shine some light on it?

 

[ak diesel driver]

"tool I just posted may set the depth to what GM wants" might also keep it square in the hole