6 Speed Shifting Issues

My 2005 6 Spd has been getting harder to shift smoothly. Particularly shifting into 2nd gear. I get some minimal grinding but it almost seems to hang up halfway between neutral and 2nd gear. It is however not 100% of the time this happens, maybe 80%. It also seems to be only on the up shift and almost never on the downshift. The other 20% it shifts smoothly. I notice the same hang up shifting into 3rd, but no grinding. At first i thought it was the syncros but due to the fact it is not on the downshift or 100% of the time i am starting to think it is something else out of adjustment/worn.

A friend had to move it the other day and remarked that reverse was hard to get into. I have also noticed it is sometimes hard to get into 1st from a stop, hitting that same hangup, or i get a clunk after i left the clutch pedal out after shifting in various gears. The truck does roll freely with it in gear and the pedal depressed and i never smell any burning clutch.

The truck has 170k miles on it. The clutch was replaced around 130k miles with the URD stage 2 clutch and URD throw out bearing. The TSB clutch slave cylinder and shift fork were replaced at the same time. This work was done when the frame was replaced and it was shortly after these symptoms started and have since gotten worse.

I am going to look at adjusting the pedal, but will this have a impact on how it shifts ? or just pedal position ?

The shift lever is also loose as a goose and has quite a bit of play all around and noise when the shifter is in the down position (2,4,6). Can the rubber isolator busing being shot have a effect on shifting ?

Can the mater cyl or slave cyl be adjusted ? I just want to have a line of sight before i start replacing stuff or tearing stuff apart.

 

Anyone ?

There has been alot of 6spd threads, but i cant find answers to my specific questions/symptoms.

 

I would check the pedal adjustment. I remember finding specs on here at one point for the pedal adjustment needed to function best. I also had my clutch replaced semi recently and everything was fine for a while and now I almost think that due to the clutch getting broken in it needs another adjustment.

 

i dont know too much about it, but i would adjust the pedal (maybe its not fully disengaging the pressure plate), bleed the system, change to bushing on the bottom of the shifter handle and replace the trans fluid in that order.

 

I had a MT Subaru with similar issues a few years back......turns out the transmission was leaking and I was low on transmission fluid. Only got worse as time went on.

The leak was from the transmission rusting out......if you had the frame replaced for rust issues, is there a chance you’ve got a small transmission leak too?

 

Answers below:

My 2005 6 Spd has been getting harder to shift smoothly. Particularly shifting into 2nd gear. I get some minimal grinding but it almost seems to hang up halfway between neutral and 2nd gear. It is however not 100% of the time this happens, maybe 80%. It also seems to be only on the up shift and almost never on the downshift. The other 20% it shifts smoothly. I notice the same hang up shifting into 3rd, but no grinding. At first i thought it was the syncros but due to the fact it is not on the downshift or 100% of the time i am starting to think it is something else out of adjustment/worn.

A friend had to move it the other day and remarked that reverse was hard to get into. I have also noticed it is sometimes hard to get into 1st from a stop, hitting that same hangup, or i get a clunk after i left the clutch pedal out after shifting in various gears. The truck does roll freely with it in gear and the pedal depressed and i never smell any burning clutch.

A: Based on these symptoms, this is probably the pressure plate bolts backing out. The stock torque on the pressure plate to flywheel bolts is low, especially for an upgraded clutch (15ftlbs I think). My pressure plate started backing out and I re-torqued to 24ftlbs and used red loctite. You can tighten the pressure plate bolts without removing the transmission, by putting your torque wrench through the inspection hatch that's on the driver's side of the transmission. Tightening to 24ftlbs would be a good idea anyway, even if they're not backing out.

The truck has 170k miles on it. The clutch was replaced around 130k miles with the URD stage 2 clutch and URD throw out bearing. The TSB clutch slave cylinder and shift fork were replaced at the same time. This work was done when the frame was replaced and it was shortly after these symptoms started and have since gotten worse.

A: This is more evidence that it could be the pressure plate bolts backing out. I had the same issue after I put a new 3+ clutch in mine.

I am going to look at adjusting the pedal, but will this have a impact on how it shifts ? or just pedal position ?

A: Shouldn't affect how it shifts, however if the pressure plate is backing out, the shift feel might constantly be changing.

The shift lever is also loose as a goose and has quite a bit of play all around and noise when the shifter is in the down position (2,4,6). Can the rubber isolator busing being shot have a effect on shifting ?

A: As you probably know, the shift lever is not related to the other issues you're seeing. Could take it apart to have a look, it could very well be the bushing. I bought a Hurst short shifter, it's a lot more solid and doesn't have any rubber bushings.

Can the mater cyl or slave cyl be adjusted ? I just want to have a line of sight before i start replacing stuff or tearing stuff apart.

A: No, they can't be adjusted aside from the pedal adjustment. There are ways to check if they are going bad, though, which is another possibility for the symptoms you're seeing. But honestly I'd bet on the pressure plate bolts backing out. Also, if the pedal feels mushy when you first put your foot on it, you could bleed the system first (probably the easiest of all the options) to see if that makes a difference.

 

You are referring to the bolts that hold the clutch pressure plate to the flywheel correct ? Not the bolts holding the flywheel to the motor ? If they were loose wouldnt there be a rattle/clanking when the clutch was engaged/disengaged ?

Does anyone have the information on checking the master and slave cylinders to see if they are bad ?

I do not have any leaks that I am aware of as the driveway is clean/dry, but I will get under there and check. I also do my U joints ever ~4500 miles and never noticed a leak. I am about to change the fluid anyways so if it is low it will be resolved with that.

 

You are referring to the bolts that hold the clutch pressure plate to the flywheel correct ? Not the bolts holding the flywheel to the motor ? If they were loose wouldnt there be a rattle/clanking when the clutch was engaged/disengaged ?

A: Correct, the little bolts connecting the pressure plate to the flywheel, NOT the ones connecting the flywheel to the crankshaft. Might not make any noise. I wasn't getting any noise when it happened. They backed out about 1/16" only, and that was enough to cause the symptoms you were describing. With that gap the bolts weren't vibrating because the pressure plate was still putting pressure on them.

Does anyone have the information on checking the master and slave cylinders to see if they are bad ?

A: Put vise grips on the clutch line before the slave. If you can't move the pedal, your master is good. If good, the slave is bad or you have air in the system potentially.

I do not have any leaks that I am aware of as the driveway is clean/dry, but I will get under there and check. I also do my U joints ever ~4500 miles and never noticed a leak. I am about to change the fluid anyways so if it is low it will be resolved with that.

A: Yes, check for leak underneath the pedal both on the ground and inside the cabin too. If no leaks at the slave, it's probably not the problem.

 

I would highly recommend changing out your tranny fluid to Redline MT-90! I am running it in both of my manual trans tacomas, and it has completely eliminated grinding that I've had in both of them. The shit is about 60 bucks a gallon, but it's worth it's weight in gold. The truck shifts so much smoother with it, and it is much easier to get into 1st gear while rolling/going slowly, where as before, you would almost have to come to a stop to get it into gear.

Here's a link to it. I would get the pump mechanism as well. Makes pumping it into the trans much easier. Make sure you take the fill plug out first, and then take the drain plug out. that way you can ensure you are able to refill after you drain the old fluid. Also, it only takes a couple of quarts of fluid for the 6spd 4wd. I think the 2wd models take quite a bit more. My 5spd 2wd took almost a whole gallon

$10 CUSTOM ACCESSORIES Pennzoil 36671 Pennzoil Fluid Transfer Pump - Gallon

https://www.amazon.com/gp/product/B002M589TA/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

$85 Red Line 50305, MT-90 75W-90 GL-4, Synthetic Gear Oil for Manual Transmission and Transaxles - 1 Gallon

https://www.amazon.com/Red-Line-503...pID=51H6XQEMrsL&preST=_SY300_QL70_&dpSrc=srch

 

Sorry I will make a change to my previous post about checking the master. I think the stock line is a hard line all the way from the master to the slave (I have a flexible rubber line now). So you'll have to disconnect the hard line at the slave and plug it or cap it with a silicone cap and a hose clamp in order to do that test.

 

Glad it worked for you, I didn't find it made as much of a difference as I wanted it to, BUT that transmission was almost dead anyways. I've heard mixed reviews on MT-90 overall...

 

Here is a replacement bushing made my Marlin Crawler. If you can move the shifter around in a big circle while it's engaged in gear, the bushing is likely worn out and needs to be replaced. I don't believe this should affect shifting though, besides just having more slop in the shifter. My mom has an fj with the 6spd and 270k miles and the shifter is sloppy as hell, but it still goes into gear just fine and is 100% drivable

https://www.marlincrawler.com/transmission/shifter-parts/heavy-duty-seats

 

Yeah it's worked well for me! I have noticed that it doesn't last as long as the OEM fluid before breaking down, but I am hard on my 6spd and so I change it every 5k or so. Figure I plan on keeping this truck forever, so try to maintain the trans as best as I can since I do a lot of speed shifting and im putting down more power than the stock motor.

 

5K wow! That's like every oil change. Unless you're me, I change the oil every 2k. But I think I got about 8k on the trans fluid this last time, and it wasn't terribly dark when I changed it.

 

Ha, last time I changed it, I was at 3500 miles.. really would rather spend the money on tranny fluid vs a new trans from worn out synchros though! Mine looked a little dark, but it was way worse when I changed the stock fluid out.

Do you change the oil so often just because of all the power adders you have? May start changing mine more often. I need to add a catch can

 

I agree, better to replace fluid than a transmission...

I change engine oil a lot because with the performance mods comes much richer AFR, much more often. This pushes more gasoline into the crankcase and the lubricating properties of the oil decrease, much faster. With a stock vehicle, 2000mile changes are not necessary, because you rarely hit richer than 13.

 

Interesting, very good to know, may start changing mine a little sooner too. Of course my truck runs lean as shit, so maybe I don't need to

Will probably start doing them every 3-4k with the tranny fluid. Easy preventative maintenance goes a long way for the longevity of the motor/trans

 

true, I notice with the supercharger that my synthetic oil gets darker much quicker...I go 5k intervals max with full synthetic as opposed to the 7k -10k recommended by the brand.

 

Your motor runs so lean, it cleans gasoline out of the engine oil!!

 

careful, mine ran lean too prior to the 7th injector and it toasted both my catalytic converters before my truck had 50k miles on it.

edit: actually it just toasted the front cat, but both got replaced since the 2nd one was likely not too far behind.