have had my truck a few months. It worked well for about 1000 miles and has been a nightmare ever since. without getting into all the details of all the parts I've replaced and the ridiculous number of times and ways it's left me stranded in about 3500 miles, I'll just focus on the transmission issues here: 

 

it started gradually shifting worse and worse. Initially it seemed to mostly be 3rd gear, but eventually, over the course of a couple weeks, it was all the gears. Grinds the worst and the most consistently going into 3rd  but now grinds in all the gears randomly, and the shifting in general is very hard. Can't get it into reverse without putting it into second and revving it first, and then quickly putting it into reverse.

 

so I initially tried replacing the clutch hydraulics. Got a pre-bled master/slave assembly from Oreilly's and installed it. For a couple days, it was better, and then it went back to how it was before. 

 

tried replacing the transmission fluid with Amsoil MTF, including adding an extra quart. Seemed better for about a day, then went back to doing what it was doing before. 

 

last weekend, I replaced the clutch and flywheel with new ones from Valair. for the last week, it's been driving great. shifting was significantly improved. After a couple days, I was confident I had found the problem. I went out of town for two days for work, came back today, got in my truck to drive home, and it's shifting rough again. grinding in 3rd unless I double clutch, and starting to want to grind in all the other gears again as well. again can't put it in reverse without first putting it in second. 

 

Is it possible I bought a pre bled clutch hydraulics assembly that has air in it? should I try bleeding it before I order a transmission rebuild kit? at this point all I can figure is that the syncros are going out, but it doesn't make any sense to me that every time I've attempted to fix it, it's better for a day or two and then goes back to sucking. 

 

really fed up with this truck. on the verge of selling it for a loss so I dont have to mess with it anymore. 20+ trucks and 11 motorcycles, all except one have been 20 years old or older, have had more problems with this truck than the rest of them combined. 

 

 

16 minutes ago, blacker_canyons said:

have had my truck a few months. It worked well for about 1000 miles and has been a nightmare ever since.

 

How about some history on your truck.  How many owners, how many miles on the truck, any transmission / clutch related problems before you bought the truck?  How has the truck been treated by previous owner / owners?

 

When the transmission / clutch is giving you problems, how far from the floor is the pedal when clutch begins to engage?  

 

I am assuming that when you replaced the clutch that you also replaced the pilot bearing.

 

Here are a few things that can cause your symptoms of gears grinding, hard shifting, or hard to shift into reverse.

 

  *  a dragging pilot bearing

  *  air trapped in the hydraulic master / slave cylinder

  *  worn clutch fork / fulcrum

  *  worn synchronizers / gates in the transmission

  *  wrong transmission fluid

  *  driving style

 

Any one of the above conditions or any combination of the above conditions could cause the symptoms you are describing.   This is why more detail is needed.  

 

- John

 

1 hour ago, Tractorman said:

 

How about some history on your truck.  How many owners, how many miles on the truck, any transmission / clutch related problems before you bought the truck?  How has the truck been treated by previous owner / owners?

 

When the transmission / clutch is giving you problems, how far from the floor is the pedal when clutch begins to engage?  

 

I am assuming that when you replaced the clutch that you also replaced the pilot bearing.

 

Here are a few things that can cause your symptoms of gears grinding, hard shifting, or hard to shift into reverse.

 

  *  a dragging pilot bearing

  *  air trapped in the hydraulic master / slave cylinder

  *  worn clutch fork / fulcrum

  *  worn synchronizers / gates in the transmission

  *  wrong transmission fluid

  *  driving style

 

Any one of the above conditions or any combination of the above conditions could cause the symptoms you are describing.   This is why more detail is needed.  

 

- John

 

I don't know the history of the truck. the seller lied to me about a lot of things so I don't trust what he told me and I don't care to ask him any more questions. I've never been screwed by a seller before in over 30 used vehicle purchases, but I definitely got screwed this time. the mileage is 180k, like it says in my signature. I replaced the flywheel with a valair flywheel with a new heavy duty pilot bearing already installed in it. the clutch assembly came with a new release bearing, so I also replaced that. the clutch fork was fine, it showed no signs of wear. it has the very heavily recommended amsoil MTF, which was recently replaced, like I said. I initially replaced the master/slave assembly because it always felt like I needed to push the clutch farther to disengage it, but the brand new one feels exactly the same. it's not how I drive. I've been driving manual transmission vehicles for 30 years, all of my 20+ cars/trucks/vans have been manual except for 3 of them. I've never had any issues with them, except for this one. 

 

 

Edited September 10, 20222 yr by blacker_canyons

Thanks for answering the questions and sorry I missed your truck mileage in your signature.  

 

I would try a process of elimination.  First I would operate all of the gears with the vehicle not moving and the engine not running.  See if anything feels amiss.  Occasionally you might hit gear teeth head on - that would be normal.  Do the gates align properly?  Without you hand on the shifter, 3rd and 4th should align by default.  Move the shifter to the left and 1st and 2nd should align.  Move the shifter to the right of default position (against a heavy spring for reverse) and 5th and 6th should align.  One more push to the right and reverse should align. Do the synchronizers feels about same in each gear?  First gear and reverse can sometimes hit gear teeth head on and be difficult to engage.  Out of habit I always select 4th gear before selecting reverse for that reason.  

 

Probably the most important item to address is to ensure there is no air in the clutch hydraulic system.  The first step would be to measure the distance the clutch pedal travels after it is pushed to the floor and clutch engagement begins.  Start the engine and depress the clutch pedal to the floor and select second gear.  Slowly begin to release the pedal until you hear the engine begin to load.  What is that distance?  It should be at least 3 or 4 inches of pedal travel.  

 

Something to keep in mind is that when a new clutch, pressure plate, and flywheel are installed, the clutch may engage with the clutch pedal closer to the floor than normal until all of the components wear in.  I replaced my clutch at 297,000 miles and during the first three or four weeks of driving I noticed that clutch engagement was right off of the floor and I had to pay attention to fully depressing the clutch pedal when engaging a gear.

 

I don't think there is a problem with the oil you are using nor a problem with any of the internal clutch parts you installed.

 

- John

 

 

 

1 hour ago, Tractorman said:

Thanks for answering the questions and sorry I missed your truck mileage in your signature.  

 

I would try a process of elimination.  First I would operate all of the gears with the vehicle not moving and the engine not running.  See if anything feels amiss.  Occasionally you might hit gear teeth head on - that would be normal.  Do the gates align properly?  Without you hand on the shifter, 3rd and 4th should align by default.  Move the shifter to the left and 1st and 2nd should align.  Move the shifter to the right of default position (against a heavy spring for reverse) and 5th and 6th should align.  One more push to the right and reverse should align. Do the synchronizers feels about same in each gear?  First gear and reverse can sometimes hit gear teeth head on and be difficult to engage.  Out of habit I always select 4th gear before selecting reverse for that reason.  

 

Probably the most important item to address is to ensure there is no air in the clutch hydraulic system.  The first step would be to measure the distance the clutch pedal travels after it is pushed to the floor and clutch engagement begins.  Start the engine and depress the clutch pedal to the floor and select second gear.  Slowly begin to release the pedal until you hear the engine begin to load.  What is that distance?  It should be at least 3 or 4 inches of pedal travel.  

 

Something to keep in mind is that when a new clutch, pressure plate, and flywheel are installed, the clutch may engage with the clutch pedal closer to the floor than normal until all of the components wear in.  I replaced my clutch at 297,000 miles and during the first three or four weeks of driving I noticed that clutch engagement was right off of the floor and I had to pay attention to fully depressing the clutch pedal when engaging a gear.

 

I don't think there is a problem with the oil you are using nor a problem with any of the internal clutch parts you installed.

 

- John

 

 

 

thank you, I appreciate the info. My suspicion currently is that it's the clutch hydraulics. they're just standard hydraulics from oreillys. the clutch I put in has a heavier spring than the stock one. it worked great at first but now it's not wanting to shift smoothly. if I double clutch, it's fine. 

 

 

1 hour ago, blacker_canyons said:

if I double clutch, it's fine. 

 

The reason it shifts better when you double-clutch during upshifts is because the transmission input shaft is engaged to the engine when the clutch pedal is released as the shifter is passing though neutral. This matches engine rpm to the road speed of the next selected gear.  When this happens, the synchronizer is barely used and the shift is smooth.  This is why I mention that driving style can contribute to the cause of a transmission that may seem to be hard to shift at times.

 

South Bend Clutch Products can provide you with a heavy duty master / slave cylinder system - even a system that increases the length of travel of the slave cylinder pushrod.  If you decide to go this route, be careful to adjust the additional length for only what is needed to make the clutch perform correctly.  Over-extending the slave cylinder push rod could damage the pressure plate.

 

- John

.. and hyperextending the throw out bearing through the fingers of the pressure plate. Not fond of adjustable hydraulics. More and more people think they can adjust the pedal position. It's the amount of throw on the throwout bearing. Be very careful and adjust it properly.

Edited September 10, 20222 yr by Mopar1973Man

1 hour ago, Mopar1973Man said:

.. and hyperextending the throw out bearing through the fingers of the pressure plate. Not fond of adjustable hydraulics. More and more people think they can adjust the pedal position. It's the amount of throw on the throwout bearing. Be very careful and adjust it properly.

ok thank you. what do you think is actually the problem? 

First off I don't believe in the big brand oil hype. I ditched factory spec'ed oil being they are TOO THIN I'm running Mobil 50 SAE trans fluid or Valvoline 50 SAE trans fluid which is 90 weight gear lube. Designed for Eaton Fuller 10 speeds. 5 gallon bucket cost way less than AMSOil or Redline again too thin. I'm going to dump the ATF+4 out of Thor and load with 50 SAE trans fluid.

 

Again I don't use pre bled hydraulics being most off the time I've got to pull it all back out and rebled the entire system. Happens more than you think. I don't like the adjustable hydro's as pointed out In my last post.

 

I've got Valair clutches on both trucks are dual disc zero issues. Beast is the performance dual Thor is the Quiet Towing Clutch.

Edited September 10, 20222 yr by Mopar1973Man

1 hour ago, Mopar1973Man said:

First off I don't believe in the big brand oil hype. I ditched factory spec'ed oil being they are TOO THIN I'm running Mobil 50 SAE trans fluid or Valvoline 50 SAE trans fluid which is 90 weight gear lube. Designed for Eaton Fuller 10 speeds. 5 gallon bucket cost way less than AMSOil or Redline again too thin. I'm going to dump the ATF+4 out of Thor and load with 50 SAE trans fluid.

 

Again I don't use pre bled hydraulics being most off the time I've got to pull it all back out and rebled the entire system. Happens more than you think. I don't like the adjustable hydro's as pointed out In my last post.

 

I've got Valair clutches on both trucks are dual disc zero issues. Beast is the performance dual Thor is the Quiet Towing Clutch.

ok. so you think the transmission fluid is too thin and I need to bleed the clutch hydraulics? 

 

 

fwiw i actually started out with the valvoline and it wasn't any better so I tried the amsoil. neither one helped. clutch is valair single disc ceramic rated for 600hp with the 3800 pound pressure plate spring. 

14 hours ago, Tractorman said:

 

The reason it shifts better when you double-clutch during upshifts is because the transmission input shaft is engaged to the engine when the clutch pedal is released as the shifter is passing though neutral. This matches engine rpm to the road speed of the next selected gear.  When this happens, the synchronizer is barely used and the shift is smooth.  This is why I mention that driving style can contribute to the cause of a transmission that may seem to be hard to shift at times.

ok. can you explain what non-double clutch "driving style" would make it work better? I've owned something like 18 manual cars and trucks and 11 manual motorcycles and i've never had grinding gear issues on any of them. granted, non of them were HD diesel. I've tried many different shifting styles and nothing seems to help it except double clutching into 3rd. 

Edited September 10, 20222 yr by blacker_canyons

 I replaced my clutch hydraulics about a year and a half ago. I also purchased a pre-bled setup same as you did. I had issues with it after install also. I had to re-bleed the clutch master and slave both. After that all was well. I would start there, make sure to get ALL the air out, they do not like air bubbles at all.

 Once done with that drive it and see if she shifts smooth. You may have some synchros going bad. My 3rd gear synchro is out, I've been either floating 3rd or double clutching it. 

 Mine is a stock (original as far as I know) clutch and an NV4500 (5 speed). 

 Hope this helps.

Edited September 10, 20222 yr by Doubletrouble

4 hours ago, blacker_canyons said:

ok. can you explain what non-double clutch "driving style" would make it work better?

 

Actually, I use a compromise between a single-clutch action and a double-clutch action that gives the performance and benefits of a double-clutch action.

 

Performing a single-clutch action during a shift is easier and works well with small and light duty transmissions, but, the synchronizer is doing all of the work - especially if the road speed and engine rpm are not matched for the gear being selected.  Single-clutching during an upshift will usually be fairly smooth because the engine rpm is falling during the upshift and the next higher gear needs lower engine rpm.  So, with a little practiced timing, the shifting is generally smooth, unless, of course, there is a problem with a transmission and / or clutch component that interferes with this timing.

 

I use the following technique for both upshifting and downshifting.  Here is an example upshifting from 3rd gear to 4th gear.  As the tach approaches 2000 rpm, I ease off of the throttle until there is no load on the drivetrain (nether forward nor reverse loading) and I slip the shifter into neutral without depressing the clutch pedal.  While the transmission is in neutral (engine now driving the transmission input shaft), I allow the throttle to drop to the rpm needed for 4th gear.  At this moment, I depress the clutch pedal and shift into 4th gear.  The result is a smooth shift with virtually no wear on the synchronizer, gears, or clutch facing.

 

I use the same technique for a downshift, but while the transmission is in neutral I raise the engine rpm to match the road speed of the next lower gear.

 

Cars and small pickups with light duty manual transmissions work well with synchronizers because the transmission's internal components don't have much weight, therefore a synchronizer can quickly bring a gear to speed without generating much heat.  Transmissions used for heavy duty applications (NV4500 and NV5600) have much heavier components, thus much more rotating mass in terms of weight.  Synchronizers have to work much harder for any mismatch of road speed / engine rpm during a shift.

 

Of course, any shifting technique being used will be more difficult to perform if there are malfunctioning parts involved.

 

I think first step regarding clutch hydraulics is to measure the distance the clutch pedal travels from the floor to beginning of clutch engagement (engine loading) as I mentioned previously.  In the case of my truck, the clutch pedal travel is at least 6 inches before engine loading.  If yours is similar, then there is no need to bleed the system.  If there is hardly any pedal travel, then bleeding the system would be a good place to start.

 

- John

 

 

Edited September 10, 20222 yr by Tractorman

so I did the process in this video: 

 

clutch was already really solid when I started. I cycled it a bunch anyway. 

 

last weekend I pulled my transfer case and transmission. in the process I found that there was oil on the adapter plate, so I replaced the rear main seal and gasket, as well as the clutch and flywheel. also did the oil pain gasket. 

 

got under there today and either I didn't put the rear main seal in correctly, or something else is leaking. pretty good amount of oil coming out of the bottom gap between the adapter plate and bell housing. seems like it's leaking at the junction where the rear main seal plate joins with the engine block and oil pan (really stupid design btw). 

 

so now I get to pull my transmission out again. I guess I'll plan on rebuilding the transmission at the same time since it'll be the second time in two weeks that I've had it out? 

 

yay. so glad I bought this truck. it's been so much FUN. 

 

 

 Is it possible the front trans seal is leaking? I have not had to pull my trans for anything yet so I'm not familiar with what's in there.

 Don't get discouraged, these are great trucks. Sounds to me like the previous owner may have beat on that truck and neglected maintenance and repairs resulting from abuse.

35 minutes ago, Doubletrouble said:

 Is it possible the front trans seal is leaking? I have not had to pull my trans for anything yet so I'm not familiar with what's in there.

 Don't get discouraged, these are great trucks. Sounds to me like the previous owner may have beat on that truck and neglected maintenance and repairs resulting from abuse.

it's possible, but it looks like engine oil to me, not trans oil. either way, I have to pull the trans again. 

 

everyone keeps saying that about what great trucks they are. I'm waiting for that to actually be the case. so far, every time i fix something, something else breaks a week later. i'm about ready to just sell it for a loss and move on. winter in idaho is coming and I'm not real stoked about the increasing likelihood that this thing is going to leave me stranded in sub zero weather coming back from the grocery store. 

 Is it difficult to pull the trans and transfer case other than the weight? They seem like heavy pieces.

 So, you said you had good feel to the clutch hydraulics now correct?

 Just chasing an oil leak at this point?

25 minutes ago, Doubletrouble said:

 Is it difficult to pull the trans and transfer case other than the weight? They seem like heavy pieces.

 So, you said you had good feel to the clutch hydraulics now correct?

 Just chasing an oil leak at this point?

it's a pain. it's a full long day getting it out and then back in, particularly when doing it by yourself with the truck on the ground. 

 

the clutch hydraulics seem to be ok but it's still not shifting ok, so i'm fairly certain i need to rebuild the transmission. i'm going to check the clutch fork and the pivot, etc, but i'm fairly certain i'll need to rebuild the transmission. 

 

but yes, I also have to figure out why it's still leaking oil after I redid the rear main seal and the oil pain gasket. it's also leaking fluid out of the transfer case, and for whatever reason the vacuum isn't engaging the CAD for 4x4. 

Edited September 12, 20222 yr by blacker_canyons

8 hours ago, blacker_canyons said:

for whatever reason the vacuum isn't engaging the CAD

On the plus side, this should be a much easier diagnosis than the transmission issues!

[knocks on wood]

It's possible the transmission is not the problem. There is a support system above the steering column that also has the brake and clutch pedals mounted to it. The bracket also ties into the fire wall. The bracket can crack and break which makes things sloppy. 

So your clutch doesn't have full range.

Get a light and inspect it. Move the pedals and look for any flexing up in there. Tighten up all the nuts and bolts too. Some guys do auto to manual swaps and change all that so they can sell the truck for more. Look for signs like tranny cooler parts or brackets  and plugged off heater hose parts.

FYIW, 

 

I know you mentioned a new pilot bearing was installed in the new flywheel.   What was the condition of the old pilot bearing?  What was the condition of the tip of the input shaft?

 

I'm wondering about the possibility of the new pilot bearing failing, esp since you mentioned it worked okay for a little while after you put it back together.   When you put it together, did the trans slide in easy for that last 5/8 of an inch? Or did you have to pull it in with bolts?  Also, before putting it together, did you slide that new pilot bearing on the tip of the input shaft to see if it went it tight or easy with no binding?  If it went in too tight, risk you may have damaged the new pilot bearing, hence that input shaft turning while trying to put it in gear.   Unfortunately most clutch kits come with a pilot bearing that fits too damn tight on the input shaft. You should not need to force it.  Bronze (oil impregnated) pilot bushings if set up correctly should slide on easy and are much more robust as long as you don't keep that clutch in for long times while stopped at traffic lights etc. Put her in neutral etc.

 

I'm saying this because when my pilot needle bearing failed, I had the same symptoms you described in your original post. It scored up my input shaft and the trans was not comming to a full stop when I put the clutch in.

 

Fast forward. When my pilot bearing failed, I did the right thing & installed new clutch , cut the flywheel AND installed a new BRONZE pilot bushing. I cleaned up my input shaft and that bronze bushing fit perfectly sliding on the input shaft with no slop or binding. Trans went in the truck like a dream, Did not need to use bolts to push in that last 5/8". Trans slid right into place by hand.

Edited September 23, 20222 yr by Ironforger

11 hours ago, Ironforger said:

FYIW, 

 

I know you mentioned a new pilot bearing was installed in the new flywheel.   What was the condition of the old pilot bearing?  What was the condition of the tip of the input shaft?

 

I'm wondering about the possibility of the new pilot bearing failing, esp since you mentioned it worked okay for a little while after you put it back together.   When you put it together, did the trans slide in easy for that last 5/8 of an inch? Or did you have to pull it in with bolts?  Also, before putting it together, did you slide that new pilot bearing on the tip of the input shaft to see if it went it tight or easy with no binding?  If it went in too tight, risk you may have damaged the new pilot bearing, hence that input shaft turning while trying to put it in gear.   Unfortunately most clutch kits come with a pilot bearing that fits too damn tight on the input shaft. You should not need to force it.  Bronze (oil impregnated) pilot bushings if set up correctly should slide on easy and are much more robust as long as you don't keep that clutch in for long times while stopped at traffic lights etc. Put her in neutral etc.

 

I'm saying this because when my pilot needle bearing failed, I had the same symptoms you described in your original post. It scored up my input shaft and the trans was not comming to a full stop when I put the clutch in.

 

Fast forward. When my pilot bearing failed, I did the right thing & installed new clutch , cut the flywheel AND installed a new BRONZE pilot bushing. I cleaned up my input shaft and that bronze bushing fit perfectly sliding on the input shaft with no slop or binding. Trans went in the truck like a dream, Did not need to use bolts to push in that last 5/8". Trans slid right into place by hand.

 

 

the pilot bearing was fine when I took the old one out. I was surprised because everyone I talked to was so sure it would be the pilot bearing. it wasn't. the bearing was in good shape and rolled smooth. The new bearing is much heavier duty ball bearing, it's not a thin needle bearing like the stock one. the transmission went in fine. the input shaft was fine. I really don't think it's the pilot bearing. 

Edited September 23, 20222 yr by blacker_canyons