Buckin' and kickin'!

[mtrdrms]

I cant seem to figure out why my truck doesnt want to start from a stop smoothly!!! (Its an 87 with 350 SM465 6"lift and 35's 8lug 4.10) The symtoms are - once the truck gets hot I cant seem to feather the clutch to keep the truck from bucking. Its like the clutch doesnt slip at all, it bangs hard between grab and let go, grab and let go. Its terrible and it makes driving the truck a pain in the ass not to mention I look like a jackass.

So here are my diagnosis:
The clutch is only about a year old and I didnt clean the packing oil off of the pressure plate when it was new and maybe the oil has impregnated the fibrous clutch disc causing this problem.

Bad motor mounts. If the mounts are not strong enough to hold the motor down, maybe it would amplify the vibration.

Any ideas here guys? this is making me crazy!

 

[yoshisv]

I would check the motor mounts and tranny mount, Also was that a stock replacement clutch or a aftermarket replacement?

 

[mtrdrms]

Yeah the tranny mount is new but the motor mounts are original I think. The clutch was a stock replacement from NAPA.

 

[tRustyK5]

Sounds like classic clutch chatter. Any oil leaks near the rear of the pan? Also, what type of clutch did you get...3 finger or diaphram? The 3 finger clutches seem to be more prone to chatter/grabbing than the diaphram style.

Rene

 

[mtrdrms]

No leaks and I dont know what the difference is between the two clutch types. It was a standard NAPA replacement. One thing I forgot to add is that I do not have the support rods that bolt to the motormounts and the bellhouse. Also the large one that connects the transfer case and the frame is not installed. This would add to the chatter I imagine?

 

[tRustyK5]

Diaphram clutch...

Borg & Beck...

Chatter is usually cause by oil or some other contaminant on the flywheel. This can lead to heat scoring and or cracking. It could be the protectant you didn't wipe off coming back to haunt you. Mine chatters a little but my rear main seal leaks a little. Anyways, the three finger style is way worse for chatter in my experience...

Rene

 

[mtrdrms]

Thanks for the info Rene. Mine is the diaphram style. I am worried that I may end up replacing the clutch. Thanks again.

Andy

 

[theperfectgarage]

I'm with Rene, sounds like clutch to me.
Pressure plate and flywheel need to be super clean if you do a new clutch. make sure you have the flywheel ground also. Cheap compared to the PITA of clutch replacement. Clean your parts with simple green and rinse well. Don't use brake cleaner or solvents.

 

[goldwing2000]

Don't use brake cleaner? Why not?
Isn't that what it was made for?

 

[theperfectgarage]

Don't use brake cleaner? Why not?
Isn't that what it was made for?

First, let me just say that most of us ( including myself ) have used brake cleaner for years to clean rotors, drums and flywheels with no noticeable Ill effects. Most of us have also on occasion had comebacks for no apparent reason. This is what I learned.
About five years ago I took a one night " refresher " class on ABS brakes and brake systems in general. I take classes like this pretty regular 'cause no matter what I " know " tech. marches on and I like to keep up. This class cost me about a hundred bucks with dinner and was put on by Raybestes brakes. One part of the evening focused on brake job comebacks re. chatter and grabbing. They explained that even though the brake cleaner appeared to do the job it would leave residue on the rotors/drums and can cause probs. The recomendation was diluted simple green or even dish soap to clean and rinse well/airdry. The brake cleaner was for hosing down the entire brake assemblys ( calipers and behind the drums before complete disassembly ).
Now if you build engines you know that after boreing, honing operations the block should be washed with soapy water, rinsed well and air dried. You dont use chemical products. Knowing this, the Raybestes man made sense to me.
So thats why I made that post. Also, you know how fast brake cleaner goes and what it costs. Dilute simple green is a hell of a lot cheaper and saves me $$ on shop supplies.
Cary

 

[tRustyK5]

Some great tech there. I've had chatter probs after using brake clean on a clutch install... and we all know how irritating a chattering/grabby clutch can be.

Rene

 

[mtrdrms]

Thanks for all the info guys I am gonna pull back the tranny and put in a Centerforce.