Car Shudders When Accelerating from Stop (MT)
 

Hello,

I discovered a new problem on my beloved '94 Accord LX MT (210k miles). When I accelerate from stop, the car shudders if I'm not extra extra careful with the clutch. I know this is a new problem because I've never had this issue before, and I've read it might have something to do with the transmission fluid? I don't have any records of when it was last changed, but based on the condition of other parts of the car, probably a really really long time ago.

A couple of things happened prior to my noticing this problem:

1) Loaned my car to a friend (doesn't know the many quirks of my car, but knows how to drive a stick shift). He drove 400 miles, mostly highway. When I got the car back, there was this problem, as well as a scrapping-type sound from the front right area (separate thread here). Also, engine is noticeable louder than before he drove it and acceleration is less smooth and less quite too.

2) Taught my girlfriend to drive my car. She has some experience with stick shift, and we were just doing basic stop-go-turn drills for the most part. Nothing fancy, nothing I would expect to be damaging in any way.


Another symptom is that one time (and only one time) there was a bit of wheel spin when I accelerated up a medium incline (15-20 degrees?). I'm pretty sure it wasn't because I gassed it too much.


Any ideas what might be the problem?


Thanks in advance!

My take. Shuddering is due to uneven wear on the clutch plate or maybe warping of one of the other clutch components.
The source is one of your friends having a v. different driving style with your clutch car than you
and/or maybe the components becoming overly hot as a result.
I've encountered it only a few times, and don't like it - so I'm pretty gentle with my own clutch
in order to avoid it.

The solution would be a new clutch, maybe pressure plate and flywheel. I'd finish the driving instruction first.
Also, me - I'd just accept it, but that's cheap old me. Maybe, I wouldn't loan my next clutch car.

Tranny fluid won't influence it if shudder only shows up before the clutch is fully grabbing (fully engaged).

Best. Tell us what happens/you do.

I'm not sure if I'm ready to invest much more money into this car considering it's on its last leg at this point. Like you, I think I'd be content with just "accepting it." Also, no more loaning this car around I guess.

Thanks a lot for the input. I was hoping it would be a relatively easy/affordable fix, but this doesn't seem to be the case. Looks like I'm adding another item to this car's "character" list.


Thanks again!!

Make sure your brakes aren't dragging. That can also make it harder to accelerate from a stop. You could get rid of two problems with one solution (cross your fingers).

Shuddering due to clutch will ONLY happen during the very short time when the clutch is slipping before you have let the pedal up all the way. If it shudders even after the clutch is engaged (after the pedal is UP), then look for something else like brakes or axles.

And maybe it would've begun doing that anyway even if you hadn't let him use it...?

Not blaming my friend or anything, but it did happen right after he used it, so I figured it might be prudent to mention it. Either way, it is as you mentioned - only shudders when the clutch pedal is at least partially depressed.

If you're going to "live with it", then try this. It'll sound like horrible abuse of your clutch...

See if you can slide the clutch at some rpm to avoid the chattering. That might polish the surface of the flywheel & pressure-plate enough to improve it. You don't even have to move the car. Rev the engine & just begin to engage the clutch. Try lower rpm or try higher rpm, until you find a point where you can slide the clutch for a minute. Then let it cool down a lot before trying again.

It's similar to bedding-in a new set of brakes. The chattering clutch (or pulsating brakes) is usually not caused by actual warping. It's caused by the friction material from the clutch-disk (or from the brake pads) getting embedded into the surface of the steel flywheel unevenly around the surface. So you're trying to even that out.

Doesn't always work, but it doesn't cost anything to try.

Interesting. I might give this a shot. Would you care to explain what you mean by "slide the clutch" though? I'm not sure what to make of that.

Set the handbrake so the car doesn't move. Say you're parked in a place where there's some empty space ahead in case the car DOES move.

Give the engine a little gas & begin lifting the clutch pedal like you're starting up. But hold the pedals just at the point where it starts straining to move the car (against the handbrake).

The tricky part is holding it there WITHOUT allowing the shuddering / vibration. That may or may not be possible. This will only work if you can find a sweet combination of RPM, gas-pedal-position, & clutch-pedal position. Hold that condition for a minute or so. Then let it cool down, probably by idling the engine in gear with the clutch completely disengaged (clutch-pedal on the floor).

What you're doing is polishing the surfaces of the flywheel & the pressure plate. If this works (a big IF) you can postpone removing the transmission to replace the clutch & resurface the flywheel.