Clunk in Clutch

[JGrefenstette]

my clutch is still origional with about 270,000 + miles on it. its started clunking when i begin to engage it in 2nd gear and its worst, if im in reverse and have it half engaged then push the clutch in, it clunks bad. i can feel my clutch getting worse, primarily when starting out in 2nd. it just slips more and grabs kinda funny.



-how much time to i have left with this old clutch?

-whats the clunking noise?

-is a clutch job on these trucks very difficult? (how long should one take?)

-is the Con-OFE a good choice for these trucks?



thanks guys

 

[pepecat]

pushing in and out and clunking sounds like the throwout bearing more than the clutch. When clutches wear out or get "old" they just slip.

 

[JGrefenstette]

hmm. yea that sounds about right. i assume its a combination of both.



once the clutch is engaged fully i can floor board it in any gear and it WONT slip, but when im easing off the pedal as it engages, thats when i notice it slip/take longer to engage.

 

[PToombs]

Just pull it out and fix the darn thing! Or better yet, I'll give you $200 to take it off your hands. The thing is almost scrap anyways, and that's more than the scrap guy will give you for it. :-laf

 

[JGrefenstette]

haha, yea yea i know... its basically unsalvagable might aswell push the old dog off the cliff.



haha, on a serious note. i do plan to put a new clutch in it before to long here, but since im starting diesel school in a little over a month, and im gonna be spending a lot of money on tools, tuition, rent, etc. ill milk this old clutch as long as she'll let me.



what do you think is the best clutch for my dime though? med. -heavy towing, 300-400 hp. somthing around that range? and id prefer a moderate engage. what clutch do you have?

 

[PToombs]

Mine is stock. Well, stock replacement. I don't have a clue what to tell you on a replacement. I'd go with a SB, but I've been hearing the Valairs are holding up well too.

Why don't you replace it now, while you're at home? So if you have problems during replacement, you don't have to depend on it to get to class or whatever the next day? I'd rather have something in good shape and reliable to go away to school with. Just my . 05 worth.

 

[JGrefenstette]

yea i agree with what your saying about doing it at home and all. but the reason im wanting to do it at school is, its a diesel school. ive never done a clutch before. and i will more than likly be able to do it in class one day. and might even get a price cut on the clutch if its ordered through the school. and im not worried about having problems there, cause ill be doing it with some of the best diesel mechanics in the area. as far as getting to class... . my boots may be pretty well worn out, but ill be darn if the aint got couple hundred miles left in em :-laf:-laf if i cant do it in one day with the help of my teachers/classmates, i reckon id deserve to be walking to class



one question about these clutches for you... on my clutch, when i press the pedal it has good tension at the top 3/4's then the last 1/4" it eases off a lot. thats how most stock clutches seem to feel... ive felt an after market clutch in a getrag, and the tension felt like a big spring, as still at the floor as it was at the top? are all aftermarket clutches like that???

thanks for the help pete.

 

[dpuckett]

My W350 has an organic Valair clutch that I picked up cheap. MUCH smoother engagement than the stock Sachs, and seems to hold the torque, though I have yet to thow more than about 30psi boost (3rd gear) at it yet. So far, so good. Full 13" disc; had the flywheel bored to take the ball bearing pilot.



DP

 

[PToombs]

Jimmy, I don't know about the aftermarket ones, but I bet that's right. The stockers get easier so people won't complain to the dealer. Kinda like how Chevys were always cushier riding that the others. Don't want the customers leg to get tired at a stoplight! :-laf

 

[GCroyle]

Clunking. Try this, drive at a speed in 2nd or 3rd that allows you to briefly accelerate, then quickly back off, repeat, repeat. If you hear your clunking sound, most likely your torsion damper is kaput. It is loose and the springs are moving allowing the hub assembly to hit instead of maintaining a constant contact with the parts, some in the industry call this a Tip In / Tip Out test. If this matches your complaint, the release system is not involved at this point and can be ruled out except for the normal high mileage wear that you have.



The time to repair it, depends on skill level, attention to detail, crud, tool collection and patience. don't try to beat the book on your first job, learn, detail it and enjoy the results.



Caution, the 1st Gen cast iron cover is a bit heavy and the flywheel certainly is. At this mileage I would examine the pilot bearing section of the input shaft very carefully for damage.



And depending on what system you install, lets assume your did replace it with the same original style (apples to apples comparison) do not be surprised if the new clutch is easier to push than the old one. It is a normal characteristic of these clutches to get harder to push as the disc gets thinner.



Good luck.

 

[WJune]

I have used both of the factory clutch disc with no problem. They must be pretty good to take hard use for 200K an more. While you have trans out, seperate it from the 205 an grease the sleeve. My first truck clunked an then ruined spline on the 205. 2nd truck the sleeve was dry an rusty already. With the age and mileage you may want to replace rear main seal while clutch housing is off.

 

[dpuckett]

"They must be pretty good to take hard use for 200K an more. "



Yup. The clutch in the Green Goober has almost 300K on it (not the original from the truck), and the disc is in great shape. Or it was 2 years ago when I rebuilt the transmission.



DP

 

[JGrefenstette]

gcroyle, the clunk is when i begin to engage the clutch. like when the plate first contacts the flywheel, thats when i start going forward. when i accelerate in gear like you said, it dosent clunk, just surges cause the loose rear end.



it clunks the worst in reverse if im engages and then disengage the clutch under acceleration.

 

[GCroyle]

The test doesn't really want acceleration, it needs a quick almost abrupt accel/decel repeat and repeat, kinda like you just punch tapped the go pedal, if you just hard accelerate, it loads the damper in one direction and it would not likely "clunk". At your mileage original system, I'm still open to a torsion damper that is just plain worn out. Need to consider other sources, slip joints, u-joints etc.



Are you going to tear it down?

 

[JGrefenstette]

yea i understand what you mean about the acel/decel. there is no clunk once the clutch is engaged with the flywheel. the clunk is only during engage/disengage.



ive been told that the surge i feel when i acel/decel once in gear is from worn out spider gears in the rear end. cause i can twist my drive shaft a fair amount aswell. all rear u-joints are new.



i know nothing about transmissions. ill be at diesel school in a month. and i plan to do the work there. rear main seal, clutch/flywheel, pilot bearing (probly roller-type), syncros in transmission, and anything else that needs doing.