Help diagnosing clutch problems 2008 Dual Cab

Hello

Thanks in advance for any help.

I have a 2008 Dual Cab TRD with a 6 speed. It has about 100,000 miles on it, mostly on-road. Since I shattered my clutch leg in 2011 I don't drive it as much as I used to so it spends a lot of time 'sitting around'.

Recently I have notice weird clutch symptoms. Occasionally (once or twice in an hour) right after shifting the engine will "rev ahead" of the speed of the vehicle. So, for example, I'll be at 2500 RPM, in 4th, shift to 5th, and the engine will spin 4000 RPM. If I back off the gas it'll grab and the engine will return to normal (2000 RPM) and slip no more.

Normally, I'd figure this was an indication of a fried clutch, however, I can drive the truck uphill, pedal to the metal, towing a couple thousand pounds and there is no slip.

When I have driven vehicles with bad clutches they tend to slip under load, not 'just because'.

This leads me to suspect the clutch hydraulics (master/slave).

I'm getting too old to do a clutch job by myself and I have no income so I'd prefer not to pay somebody to do it. Replacing the hydraulics is a lot cheaper and easier.

Does anybody have any other suggestions and/or diagnostic tips.

BTW: I don't tend to burn clutches. My prior truck was a 4Runner I put 350,000 km on with no issues.


Thanks

 

I hate to say it but from your explanation , the clutch is slipping .
After you let your foot off the clutch as you upshift to 5th gear , the hydraulics master cylinder and slave cylinder no longer come into play .

 

Thanks, however, if one or the other cylinder does not function smoothly then the clutch would remain 'in'.

I have read reports of people whose master and/or slave have gone and they have to pull the pedal up. Of course this may be a different failure mode than what I am experiencing.

 

Done well over 1000 clutches in my lifetime and have never seen a clutch stuck in the released position caused by a hydraulic issue .in most cases when the pedal stays at the floor , there are issues with the over center spring above the pedal or most of the fluid leaked out .

The only additional issue that comes to mind is oil on the friction disc . Its fairly common for clutches to start slipping in overdrive .
Now if I am understanding this correctly , the engine revs after you let your foot off the clutch pedal when you select 5th gear ?

 

I have noticed it in 5th gear, but it happens "now and then" and I have only been keeping track of it recently. I have run through the gears repeatedly with heavy loads, going up hills (which in my experience should cause a clutch to slip) and I can't get it to happen on purpose.

I think this truck has a limited slip differential - does that matter?

thanks

 

A limited slip rear differential allows you to turn corners without wheel hop . Once you are going in a straight line again , the rear differential drives both rear tires rather than one .With this said , the limited slip wont have anything to do with your engine revs.
I suggest looking under the truck for sources of oil near the bellhousing of the transmission . If there is no evidence of trans or engine oil , I beleive you are going to need a clutch . This may just be an early warning that the clutch is on its way out .
Happened to me as well on an F250 4x4 . 45,000 km and the clutch was done and I babied that truck .

 

This sounds like a situation where the clutch has weakened to the point where it can hold if it's engaged but cannot recover when slipping.

A "good" clutch will normally grab (or quickly synchronize speeds and then grab) as soon as you release the pedal. In this case, the clutch does not have enough friction to synchronize the transmission input to the engine output and thus slips. However, once it has grabbed, it does have enough holding force to not slip.

This is because static friction is ALWAYS greater than kinetic friction (why if you a small box or something on a piece of wood, and then start tilting the wood, the box will hold hold hold hold then fall. If you repeat the process but stop just short of where it fell last time, it will stay - but as soon as you push it and get it to start moving, it will slide all the way to the bottom. This is also the same reason why you want your tires not spinning when braking or accelerating (you impart more force with static friction).

 

I got a clutch "kit" made by a company called "PERFECTION" at AUTO ZONE for less than $150. Everything including the alignment tool. It's proven to be good quality, too. Install is no big deal. I had a tranny shop put mine in for 350 bucks.

 

Thanks for the tips/suggestions. Looks like I'm going to need a new clutch.

Anybody know how much that will cost in the Toronto area?

If I was 15 years younger I'd do it myself but I just don't have the energy anymore ...

Thanks