Problems with URD Throw Out Bearing Kit? Bad Hydraulics? Need Help

Hi All,

My Taco is in a bad way right now, and I'm completely stumped. Back in November of last year I had a local specialized yota shop throw in a URD stage 2 clutch and the oversized throw out bearing kit. Everything worked just great.. for about 4-5 months.

Fast forward to May of this year. No funny feeling to the pedal or strange noises, but the clutch pedal has to be pressed further into the floor in order to disengage (in other words, if I'm in gear and want to shift, instead of having to push the pedal 3 inches I had to push it 4). I adjusted the rod on the master cylinder about an inch and everything worked great again. A couple days later, same issue... But this time im essentially unable to put it into first, so I lengthen the rod again. Rinse and repeat another couple of times until the rod on the master is as long as it can possibly be, and the truck barely goes into gear and is very tough to shift while driving.

Throughout this process I was checking for leaks from the master/slave clutch cylinders, and the clutch/brake fluid level has also stayed completely full...

Anyway, another shop (the only one I could limp the truck over to without a tow) has just charged me nearly $1000 to try and fix this issue - They installed new OEM master/slave, new hose, and even harvested a bigger spring for the slave cylinder to give it a little more push, and at this point the truck will barely go into gear. They're telling me to take it back to the people who put the clutch/TOB kit in.

What's going on here? I've put maybe 3k-4k miles on it since the clutch and TOB were replaced. Has anyone had this happen with the URD TOB kit??

 

@Torspd @Lucario Runner
These guys may know where too look. There both geniuses on tayota trucks. One taco and the other a 4runner i believe.

Edit: Also it would never hurt too call gadget a urd who makes this kit aswell and pick his brain.

 

The first thing I would check is make sure the pressure plate is torqued to the flywheel properly. If the bolts come loose you will have this exact problem. Have someone depress the clutch pedal while you look through the hole where the fork protrudes through the transmission. Do not have the engine running.

 

Need to look at the TOB. Your answer lies within there.

 

Gents,

Thanks very much for your input - Quick update on the situation.

I took a look through the access hole under the truck with my wife operating the clutch and the plate/flywheel mate up seems fine. Also of note, no rattling or vibrations that one would expect with a loose bolt while this issue was worsening. I got ahold of Gadget yesterday, who says that with the master cylinder rod at full extension the cylinder doesn't have an opportunity to reset properly when you take your foot off the pedal..? I don't know that I fully understand, but I screwed the rod back in to around the halfway point and cycled through the gears with the truck off. Fired it up and no dice.

Alternatively, Gadget said these symptoms line up with a faulty pressure plate. I'm not in a position to drop the trans myself and have booked an appointment at the shop that installed the clutch/TOB, where their earliest available appointment is 3 weeks from now... because Alaska.

 

Eesh....things move a bit slower up there.

 

Humor me one more time and put a socket on the bolts while your wife holds the clutch pedal to the floor. If the bolts are even one turn loose it will have a huge affect. It's a pain because you can only get to one bolt at a time before spinning crankshaft via starter or socket on harmonic balancer bolt. Let me give you another comparison to show what Gadget was getting at. If you take a syringe and pull the plunger half way back and then displace the fluid you transfer half the syringe. If you pull it all the way back you displace a full syringe of fluid. In this case you only started making adjustments to the rod after you started having a problem not before.

 

I will definitely give this a try on Sunday, and would be overjoyed if we could get this worked out (or at least figured out) without dropping the trans.

I see what you're getting at with the syringe - A lot of fluid is getting sucked into the master cylinder even with the pedal at rest. But yes, the adjustments to the rod were in response to the clutch refusing to disengage. If there was some chance that the master/slave weren't resetting properly as a result of that rod adjustment, it would've been sorted out when both parts were replaced.

 

Something that hasn't been addressed here. All master cylinders need to have free play between the pedal and the master cylinder. Inside the master cylinder there is a hole in the bore goes between the reservoir and the bore. This allows fluid to freely travel between the system and the reservoir due to thermal expansion. The hole is just barely forward of the cup that makes pressure. As soon as the piston moves slightly forward, the cup goes past the hole and starts making pressure in the system. When you adjusted the pushrod longer, the cup is past that hole and you have thrown everything out of whack. When the rod is adjusted correctly, you should be able to feel a very slight amount of slack in the pedal before the rod starts pushing the master cylinder.

 

OP, do you know if the ones who put in the kit messed with the original clutch adjustment and linkage? At this point I would be tempted to return it back to the factory specs and see what happens. I also do not know what the oversize throwout bearing happens to be. Is this the one that comes with the stainless steel sleeve for the quill? If so it is in reality an OEM bearing that appeared as part of a TSB back in late 2010 that has its center milled out on a lathe to accommodate the sleeve.

 

Hey Guys! Sorry about the long delay here, I was dispatched on a surprise work trip and unable to do much of anything with the truck. That being said I got it into the shop yesterday. They did a thorough check over the new hydraulics - Pedal was adjusted correctly and the piston in the slave cylinder had adequate throw, but the clutch was still no workey.

They couldn't find anything wrong with the TOB, and from what they can tell it could only be a bad diaphragm spring. I've ordered the Competition Clutch Stage 3 kit from URD and will have it installed on Tuesday of next week... Given the circumstances here I would've preferred to go back to a stock setup, but I just don't think that's an option with the supercharger + 2.7 pulley.

 

Hey Gents - Final update on the situation. The problem was 100% bad pressure plate. I did order the Competition Clutch Stage 3+ kit from URD, but I wasn't stoked on the full-ceramic clutch disc, so I had the shop re-use the original URD Stage 2 disc (not even 5k miles on it) with the new CC pressure plate. Lo and behold, its now working better than ever. Nice stiff pedal with velvet smooth engagement.

Now it's just a matter of how much I can recoup on the warranty...

Thanks again for all the input! Though this cost far more than I would've liked, my understanding of clutch hydraulic systems and potential failure points has increased greatly

 

Apparently the new pressure plate is not the final solution. I'm experiencing the beginning of this issue again... Drove the truck about 400 miles over the weekend and it behaved normally. Started the truck up on monday and had trouble getting it into gear, with the clutch disengagement happening towards the very bottom of the pedal range. Adjusted the rod on the master cylinder a few turns and the problem is alleviated for a day.

So the pressure plate was replaced last week and the problem disappeared for about 400 miles, now the old problem is back and the failure mode is identical to before - No leaks, full reservoir, firm pedal feel, smooth engagement, but soon I will be unable to disengage the clutch. What. The. F***

 

I'm thinking I'll get some video footage tonight of the slave cylinder piston travel under different conditions.. IE engine on/off, master cylinder adjustment rod at full extension/normal length. Way too much money into this fix at this point and nobody can come up with anything definitive, so I'll just park it and gather some data points.

 

Adjusting the master cylinder pushrod arbitrarily is just going to cause you more troubles. You need a very slight amount of freeplay between the pedal and the master.

 

It's not a fix by any means - I only threaded it out because the truck wont go into gear when the rod is adjusted correctly Does increasing the length of the rod actually increase the pressure in the hydraulic system when the clutch is depressed? Should I see any more/less travel of the slave cylinder piston as a result of the adjustment?

 

See my post above on how the master works. When you adjust the push rod too long, you defeat the self adjusting feature and also the system will change with temperature changes.

 

So at a certain point, as the rod is adjusted to be longer, the head of the piston in the master cylinder is going to be above the hole/line that leads to the fluid reservoir. The system will not operate correctly at this point.

Leaving any master cylinder adjustments out of the equation here, the order of events in the last two weeks are as follows:

1. The truck would not go into gear. Period.
2. A shop bled the clutch hydraulics to ensure no trapped air and tested. They couldn't find a fault with the hydraulics, so they dropped the transmission.
3. They examined clutch disc, flywheel, pressure plate, throw out bearing and verified all bolts were torqued to spec. They couldn't find any issues or unusual wear.
4. Assuming the only part that could be to blame here was the pressure plate, that was replaced. All other parts including the clutch disc (which had maybe 5k on it) were re-used.
5. no adjustments were made to the free-play between pedal and master cylinder
6. After the pressure plate replacement, everything worked great.
7. Over the next 400 miles the point of clutch engagement/disengagement moved gradually to the bottom of the pedal travel until it became difficult to get into gear/shift.
8. As of today, one week and ~ 500 miles after replacing the pressure plate, truck will not go into gear.

If the pressure plate WASN'T the real issue, what may have happened during the transmission removal and new plate install that temporarily solved the problem? What could have changed in the last 500 miles to take the clutch system from fully functional to completely unable to put in gear, with no symptoms other than the point of clutch engagement/disengagement moving towards the bottom of the pedal range?

 

Here is a cutaway of a traditional clutch master. That red line is the small hole I mentioned. Once the cup goes past that, it starts making pressure in the system. The area to the right of the cup is no mans land. There's another cup on the far right side to keep brake fluid from dripping on your foot. If the rod is too long, that hole won't be open to the rest of the system and bad things will happen.

 

Is it possible that what's going on here is a damaged transmission input shaft? Maybe the splines are dinged up and as the lubricant gets thinner from use, the clutch disc gets jammed up on the dents/burrs and the pressure plate can't pull it off the flywheel anymore...?