Piston Slap: Automatic Decisions, Manual Trannies

Sajeev Mehta
by Sajeev Mehta
TTAC commentator hidrotule2001 writes:

Hey Sajeev,

A few months back you helped me sort out a plan of action for my Ford Fiesta transmission problems, and I have another stick-shift quandary I thought you might have some insight on.

My second vehicle is a 2003 Ram 1500 (bare bones work-truck, standard cab, manual everything), which I’ve recently been doing a lot of maintenance on (new plugs, pads, rotors, u-joints, carrier bearing, and a few other things). One issue I haven’t been able to sort out is an odd grinding/squealing I get when the car is in gear at high rpms (3000+) with the clutch peddle fully depressed (on the floor), something akin to what you hear if you come off the clutch with the shifter only part-way into gear.

Everything I can find on forums seems to indicate this is a worn throw-out bearing, but there seem to be a few things that suggest otherwise:


1) it only happens above a certain RPM (3000+), and makes 0 noise if the clutch is put in at lower revs


2) it only happens when in 1st gear, and occasionally in 2nd or 3rd (but much quieter in these cases)

I’ve had two local shops take a look at it, and neither was able to say more than it might be the throw-out bearing, or possibly some other bearing in the transmission, and they wouldn’t be able to say for sure unless they pulled the transmission out. I figure if it’s to the point that the transmission needs to be pulled, I should look at replacing the clutch (since it’s still on it’s first one, with 120k miles), and possibly some other transmission components, but that’s going to set me back a pretty penny (and it seems like throwing parts at a transmission problem is a good way to lighten you wallet quickly). I’ve also noticed that first and second gear are “clingy” and that when I shift back to neutral and/or have the clutch engaged, it takes substantially longer for the RPMs to return to idle than it does in higher gears, on the order of 2 full seconds(I’ve never noticed this in other M/T vehicles I’ve had, or if there was a difference it wasn’t noticeable). I’ve got a video where you can see the difference in time it takes to return to idle, as well as hear the grinding noise, here. I’ve also found that the problem is worst when the engine is cold, for the first 10-15 minutes of driving after starting.

At the advice of some DodgeForum member s I recently took the truck into my local independent shop to have the clutch, throw-out bearing, transmission fluid, and pilot bearing replaced, but my mechanic called back to say he was pretty sure those weren’t the cause of the issue. He’s convinced the issue is coming from something within the trans, possibly the counter shaft bearing, and was hesitant to replace components he didn’t think were causing the issue. His quote for a rebuilt transmission was 1700, with shipping and labor and a new clutch, that would end up around 2700, which is right about what the truck’s worth.

So now the question is, do I…

-Wait things out and see if they get any worse?


-Have the clutch components replaced anyway and see if that improves things?


-Have them pull the trans and hope it’s something easy to replace/fix?


-Look for a used trans and have that installed instead of a rebuilt one?


-Bite the bullet and have a rebuilt trans installed?


-Try my hand at a tranny-pull and see what trouble I can get into?

Thoughts/suggestion/voodoo-cures welcome. Thanks!

Sajeev answers:

You covered all the bases, short of learning how to rebuild gearboxes yourself. Which is usually the big problem here: nobody knows what the hell is failing until a rebuilder takes it apart and assesses the situation. I consider transmissions (of all types) to be magic boxes of horror that you must never tear apart unless you are ready for a complete rebuild. Obviously that doesn’t include accessible fail points like the clutch, torque converter, etc that aren’t encased within the gearbox itself.

Maybe you need a new clutch/throwout bearing/pressure plate/pilot bearing, but if your mechanic says no, I revert to my “magic box of horror” tranny theory.

Don’t worry about RPM hanging between gears, that’s part of the engine computer’s tuning. Not sure why it would hang more gears than others, but make sure you are driving the same way (intensity of throttle input, RPM speed before going into neutral, etc) in all gears to see if there actually is a problem. The hang in my Ranger was super annoying in all situations, so an SCT tune cured it…among other things. But I digress.

Back to your mechanic’s recommendation: let the transmission die, don’t change it immediately. Just make sure you buy a good replacement from a trusted rebuilder. If your local searches fail, get one from Jasper or a similar national distributor with a good reputation.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry.

Sajeev Mehta
Sajeev Mehta

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2 of 24 comments
  • Kmoney Kmoney on Mar 13, 2013

    Before you start replacing parts on this i would reccommend that you take it to a shop that specifically specializes in transmissions. As someone who rebuilt transmissions for several years, I can tell you that from what you describe the problem can only a throwout bearing and or pilot bearing and nothing in the transmission itself. With the vehicle in gear, clutch fully depressed, vehicle stationary, nothing in the transmission is moving. Say in first gear: mainshaft is held stationary by rear wheels being stationary, first gear is engaged holding the mainshaft to the countershaft, thereby holding it stationary, the countershaft is always locked to the input shaft, thus it is also stationary. If you google "manual transmission powerflow" this becomes easy to see. While I would never dare to say that something like this could be realistically diagnosed over the internet, I would sincerely suggest you find a specialty shop to look at this before buying parts (i just hate to see people waste money like this, as we used to get pulled in units like this from other non transmission shops where it would come in for a bearing and seal job only to find that there was absolutely nothing wrong with the unit itself).

  • Moparman426W Moparman426W on Mar 14, 2013

    Kmoney, you beat me to it. It's a no-brainer, with the truck in gear and the clutch engaged, assuming the brakes or parking brake is applied to prevent movement, absolutely nothing inside the transmission can move. Therefore nothing inside the trans can make noise, it's his throwout bearing. Throw in a new clutch, pressure plate and throwout bearing. Also replace the fluid, because old worn out fluid can make shifting more difficult, particularly when the trans is cold. The most important reason for changing it though is so that the trans will last much longer. I also suggest the truck owner start following the Engine Masters buildup series if he thinks that an LSX is better than a HEMI.

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