Help me diagnose trans/clutch issue.

[cramezl]

Specs:
86 K20
350
4 speed (low, 1, 2, 3)

I don't normally use low gear when taking off from a dead stop. 1st gear is plenty low for that. But, a lot of times when taking off, there is a noticeable shudder. No other time than taking off. I really have to baby it to avoid the issue, but if I give it any amount of gas it will shudder the whole truck. Do I need a new clutch? Or an adjustment? Not really sure what's going on.

 

[89Suburban]

Sounds like the flywheel is glazed or you are running out of clutch material.

 

[austinado16]

Agreed. The flywheel and/or pressure plate will get hot spots on it from being overheated by a slipping clutch....generally that's caused by drivers who rest their foot on the clutch pedal all the time, but there are other causes. Anyway, these hot spots are uneven "blotches" which cause the friction material on the clutch disk to be grabbed unevenly.

Couple of other possibilities:
-Bad transmission and/or motor mounts
-Bad springs in the clutch disk

Sometimes you can get a little relief from "clutch judder" by starting out in 3rd or 4th and really slipping the clutch. NOTE: I'm not suggestion some 3,000rpm take off where you're smoking the clutch. Just take off normal, and use sufficient throttle and a slow enough movement of the clutch pedal, that the take off is smooth and you don't stall. This will give a little polish to the flywheel and pressure plate surfaces, and can sometimes buy you some time.

The cure is to replace the clutch disk and pressure plate, and have a machine shop take a few thou off the flywheel surface, as well as the surface that the pressure plate bolts against, so that you maintain proper clearances when it's reaassembled. SOP for a good machine shop, and not that expensive.

 

[foamypirate]

The cure is to replace the clutch disk and pressure plate, and have a machine shop take a few thou off the flywheel surface, as well as the surface that the pressure plate bolts against, so that you maintain proper clearances when it's reaassembled. SOP for a good machine shop, and not that expensive.

Good thing these trucks don't have a DMF...my 07' Accord has one and needs to be replaced soon. I can't find a machine shop that will touch the thing, look like I'll have to buy new...

 

[cramezl]

Hmm I'll have to take a peek in there and see what's going on. Would glazing be visible to the naked eye? Or by touch?

 

[MrMarty51]

Good thing these trucks don't have a DMF...my 07' Accord has one and needs to be replaced soon. I can't find a machine shop that will touch the thing, look like I'll have to buy new...

If the flywheel is`nt too bad, I have sanded them down with a D.A. sander, moving round and around, turning the flywheel every six or eight revolutions of the sander.
Works good if there is no obstructions on the flywheel.

Hmm I'll have to take a peek in there and see what's going on. Would glazing be visible to the naked eye? Or by touch?

Have to pull the transmission and clutch to peek in on it.

 

[HotRodPC]

Clutch chatter can also be caused by a wet clutch. As in oil from a rear main seal leak getting on the clutch disk, or possibly brake fluid from the slave clylinder if it's leaking at all and can reach the clutch disk. Many times you'll think this isn't possible, but it is possible with the help of gravity and wind as you're driving down the highway. Got any leaks in that area???

 

[Irishman999]

Hmm I'll have to take a peek in there and see what's going on. Would glazing be visible to the naked eye? Or by touch?

No, if you look up in that bell housing all you will see is clutch parts covered in metalic dust looking stuff.

http://www.gmsquarebody.com/forum/showthread.php?t=2339

I put a clutch in my K1500 a while ago and took plenty of pictures just for this occasion.

 

[cramezl]

HRPC I have plenty of oil leakage that could be the culprit. Just one of many things on my list

Sent from my HTC Hero S using Tapatalk 2

 

[HotRodPC]

Check up inside there and see if its got alot of oil in that area. If in the event that is the issue, you might want to fix the leaks AND get a new clutch disk. Sometimes you can clean the clutch disk with brake clean, but if it's had a long time to saturate it and absorb it, eventually the clutch with start shredding and be short lived. If it's over 50% worn, I'd just replace the clutch. $100 and be done with it, but fix any leaks first.

 

[cramezl]

Any good ways to trace the source of the leaks? It looks like both valve covers, but the whole motor is so oily it's hard to tell. I was thinking of just cleaning as good as I could then let it leak some and find the source

Sent from my HTC Hero S using Tapatalk 2

 

[HotRodPC]

For your clutch, you're going to be more concerned with pan gasket, rear main seal, or clutch slave cylinder. Valve covers could do it, but if your bell housing is tight to the block, that should be a major issue. How about a cover on the clutch and flywheel? Do you have one on it or is it open to all the elements?

 

[cramezl]

There is a cover on there

Sent from my HTC Hero S using Tapatalk 2

 

[HotRodPC]

There is a cover on there

Sent from my HTC Hero S using Tapatalk 2

That's good. So you know nothing from underneath is getting splashed up in the clutch area. This also helps in diagnosis. There should be a weep hole in the cover. If there is fluids leaking out of the weep hole, then you have a problem. There should be nothing inside the cover except dry clutch dust from wear.

 

[cramezl]

I finally got under and partially removed the cover. Too lazy to remove the starter so I didn't come all the way off. The inside of the cover and bell housing were oily. The part of the flywheel I could see didn't look too bad. The crappy picture of the cover is the inside part

Sent from my HTC Hero S using Tapatalk 2