A history of clutch problems

72f100 · Post by **72f100** » Thu Apr 17, 2008 1:10 pm

Here's the story, sorry it's a bit long.

My truck (1972 F-100 302 3spd) was given to me by my grandfather after he was no longer able to drive. The truck had been sitting for about 6 years so it took me a while to bring back to life.

After driving it for about 4 months, the throwout bearing started to rattle. I took the truck into a transmission shop and they told me that the throwout bearing was indeed bad, and that the clutch was at the end of it's life as well. They installed a complete clutch set.

After about 6 months, the clutch was gone. I took it back to the shop because I had a 12 month warranty. After checking everything out, they told me that they would replace everything, but because it was apparent that the clutch had been heavily abused, I would no longer be under warranty. I was sure I hadn't abused it, but saying otherwise did me no good.

Even though I treated it like royalty, the second clutch lasted only 9 months and the throwout bearing was chattering away. No longer having a warranty, I couldn't afford to take it back to the tranny shop. I instead had a friend who has a very good reputation as a mechanic install a new flywheel and LuK clutch set. It's not been a 3 weeks and I'm having starting to have some real problems.

The first few days I had my truck back, everything was smooth and otherwise perfect. It was in better shape than I had EVER had it. But unfortunately, things started to go downhill. Taking off in 1st started to become rather rough. The throwout bearing is noisy again. Yesterday, the clutch started slipping even when fully engaged. In any gear, if I try to accelerate, the clutch will start to slip and the truck hardly accelerates.

After 3 strikeouts, something else has got to be wrong but I have NO CLUE as to what that may be. I'd take the truck back to my mechanic friend, but it would be a couple weeks before he could look at it and I need my truck working properly ASAP! Anybody have any idea what might be going on?

sargentrs · Post by **sargentrs** » Thu Apr 17, 2008 1:51 pm

Did everybody replace the pilot bearing when they replaced the clutch? Commonly forgotten.

72f100 · Post by **72f100** » Thu Apr 17, 2008 2:43 pm

I can't be certain about the first two installations, but I know it was replaced this last time around...

390Nut · Post by **390Nut** » Thu Apr 17, 2008 7:24 pm

My guess is that the input shaft bearing on your transmission is wearing out.

Once it gets loose (even a tiny amount that's not really easily noticed) it begins to rattle everything loose as well. Once that happens, your clutch (and throwout bearing) wont last long because the entire assembly isn't spinning true anymore, and is off balance slightly.

There might be other causes that someone may mention for you to check into, but that's just my

guess work. I also don't know small blocks well enough to know there habits/issues in relation to the trannys.

averagef250 · Post by **averagef250** » Thu Apr 17, 2008 8:44 pm

Paul sounds right on to me. The throwout will make noise when the clutch is depressed, it will be quiet when the pedal is out. If the transmission main or counter bearings are gone you will have noise with the pedal out in nuetral and in all gears, but quieter in 4th.

BRUTUS_T_HOG · Post by **BRUTUS_T_HOG** » Thu Apr 17, 2008 11:52 pm

did they adjust the clutch free travel?

72f100 · Post by **72f100** » Fri Apr 18, 2008 11:12 pm

Yes, the free travel was properly adjusted. Paul and Dustin, if it were the input shaft bearing, about how much would that cost to fix at your average tranny shop?

averagef250 · Post by **averagef250** » Fri Apr 18, 2008 11:32 pm

More than likely more than one bearing is effected. You'd typically replace all the bearings or replace all bearings and synchros (complete rebuild). Depending on the shop if you have them R&R it a 3.03 3 speed would run $500 to $1000. All depends on the shop.

I would surely do some definitive diagnosing before having the tranny work done though.

cdeal28078 · Post by **cdeal28078** » Sat Apr 19, 2008 9:04 pm

Are the alignment dowels in place on the bell-housing?
clint

fmartin_gila1 · Post by **fmartin_gila1** » Sun Apr 20, 2008 5:46 am

Seems to me that with that many clutches in such a short time that there is something wrong besides the clutches themselves. Either, as has been mentioned before, the tranny bearings and the alignment pins could be a problem, or there could be a problem with the mounting surfaces(both front and back of the bellhousing, plus the rear of the engine and the front of the tranny. You would be money ahead to have someone set up a dial indicater to check runout in all planes, rather than wasting more clutches.
Fred

390Nut · Post by **390Nut** » Sun Apr 20, 2008 7:53 am

72f100 wrote:Yes, the free travel was properly adjusted. Paul and Dustin, if it were the input shaft bearing, about how much would that cost to fix at your average tranny shop?

Can't even begin to quote you a $ figure (never had a manual tranny rebuilt, yet), but as Dustin said, once the front bearing starts to go, it effects all the rest, including the synchros and bearings on the other shafts, so replacing just the front bearing is a temporary fix at best.

Once moving metal parts start to wear out, they usually do so at an exponential rate, and the new bearing would be quickly back to where it was. (there are and have been exceptions to this rule)

One more thing to do is to make sure all the clutch linkage is in good condition, especially at the equalizer bar (z-bar). Make sure it's greased up inside and that the felts are in good shape.

72f100 · Post by **72f100** » Mon Apr 21, 2008 5:47 pm

Thanks guys for the info. I'm honesty not sure about alignment dowels, mounting surface alignment, etc... I guess my best bet for now will be to head over to the tranny shop and see if they can figure out what's up. Thanks again!

72f100 · Post by **72f100** » Thu May 22, 2008 11:30 am

Here's another question for you guys. How would wide tires affect my clutch wear? Now that I think about it, all these problems started when I put some fancy rims and tires on my truck that a friend had given me; 265/75-R15. Do you guys think that all that added friction could have caused some serious problems for my clutch? I swapped back to 235/75 just after my previous post and even though the clutch was in need of repair, it responded MUCH better to the narrower tires. What do you think?

sargentrs · Post by **sargentrs** » Thu May 22, 2008 3:01 pm

I've been running 265/75/15's for a couple years now and haven't noticed any problems.

sargentrs · Post by **sargentrs** » Thu May 22, 2008 3:04 pm

I've been running 265/75/15's for a couple years now and haven't noticed any problems with my clutch or 3.03 tranny. That is until second gear went out in the transmission (wouldn't go in 2nd but 1st, 3rd and rev. were fine) but I don't think that was related. Sychronizers

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