New clutch slipping

[jwade420]

'04 2500 nv5600 135000 miles all stock. Had new clutch,pp,pilot bearing,flywheel,release bearing,fork and new hydraulics installed. All Luk stock replacement parts. It slips in 5th and 6th if you hit it hard (passing a car). Will also slip pulling a twenty foot travel trailer if you hit a steep grade and pedal it down. Could they have done something on the install that could cause it? I don't have any power adder and the stock one never slipped. Throw out bearing failure is why I went in. Am I doomed to go back in and replace with a stronger pp or new clutch? I have 5 thousand miles on it now and it has not gotten any worse or better. Am seriously disappointed as I thought replacing it all with new(while you're in there) would have me good for a long while. Now I can't even pass a car without having some distance to ease into it. I will be doing any future r&r myself as circumstances beyond my control prevented doing this one. I bought this truck with 50k on it and the clutch was always completely on the floor,the new one is much higher. It starts releasing up very high and is very easy to depress. It makes me wonder if it the throw out is applying slight pressure with the pedal all the way out thus never fully engaging the clutch. With there being no adjustment with the hydraulic unit I don't see how that would be possible.If they cut the little plastic keeper off the rod from the slave cylinder that engages the fork could that cause it? I have been all over the internet and searched this forum extensively but can't find a similar problem. Any ideas? I really only want to pull this 360 lb monster once and hate to throw any more new parts in it. I'm in it for about $1100 already.

 

[Motorhead]

Un-do the clutch slave at the transmission. Don't remove the holding nuts or bolts all the way but bring them close to being unthreaded. See if you can push, by hand, the slave cylinder back towards the bell housing. If you can only go so far, the clutch rod might be too long.
Another check is to completely remove the slave cylinder. Get a flashlight and look into the hole in the bell housing. You will see the clutch throw out fork. There should be some free play with the clutch fork. If it is solidly against the bell housing then something is not right. I can't say about the NV5600 but I read one of the articles in an older TDR magazine that an installer had left a spacer plate on the end of the crankshaft where the flywheel bolts against. This positioned the flywheel closer to the trans and fouling up the clutch geometry

 

[GCroyle]

'04 2500 nv5600 135000 miles all stock.
A. Could they have done something on the install that could cause it?
B. ,the new one is much higher. It starts releasing up very high and is very easy to depress.
C. It makes me wonder if it the throw out is applying slight pressure with the pedal all the way out thus never fully engaging the clutch. With there being no adjustment with the hydraulic unit I don't see how that would be possible.
D. If they cut the little plastic keeper off the rod from the slave cylinder that engages the fork could that cause it? .

I'm trying to break your question into individual inquiries and lettered them, I hope.
A. Could the shop have caused or created this? YES. If they contaminated the friction surface for example that would do it would be a start. And there are several ways they could do that.
B. New one is much lighter. That is a correct observation part number for part number replacement. The thinner worn disc has a heavier pedal effort than same disc with new full thickness facings. Also release bearing now slides better on guide tube, newly cleaned and greased, less friction, lower pedal effort.
C. By design the slave cylinder preload spring applies preload force to the fork, fork to bearing and bearing to diaphragm spring. No more freeplay.
D. That white strap is a shipping retainer, holds the push rod and piston recessed a bit, easier install and keeps plastic end cap installed that acts like bearing surface.

LuK was OEM supplier for your truck.

If you paid for install and the SHOP supplied parts, go back, demonstrate problem and ask them to fix it.
If you provided parts, this gets to be a finger pointing exercise.

Gary

 

[NIsaacs]

Un-do the clutch slave at the transmission. Don't remove the holding nuts or bolts all the way but bring them close to being unthreaded. See if you can push, by hand, the slave cylinder back towards the bell housing. If you can only go so far, the clutch rod might be too long.
Another check is to completely remove the slave cylinder. Get a flashlight and look into the hole in the bell housing. You will see the clutch throw out fork. There should be some free play with the clutch fork. If it is solidly against the bell housing then something is not right. I can't say about the NV5600 but I read one of the articles in an older TDR magazine that an installer had left a spacer plate on the end of the crankshaft where the flywheel bolts against. This positioned the flywheel closer to the trans and fouling up the clutch geometry

I think the spacer is only on the dual mass flywheel systems and maybe just the G-56 ones. But yes, I have read where it was left on with a single mass conversion and caused problems. I think you might be on to something in reference to the fork up against the transmission, restricting engagement. I think it is possible for the fork to be installed backwards or maybe the wrong throwout bearing or retainer. Note the difference in the fork, one end is thicker. Maybe if it is wrong, it can interfere somewhere.

Gary, can you shed some light on this?

 

[GCroyle]

NIsaacs,

Fork orientation. Facing the trans the Dodge part number stamped on the fork goes in the lower left corner.

Clip keeps fork on stud during install. Now to double check this that places the curved crown where the bearing rides right centered on the guide tube. The curved crown pushes against the flat ear on the bearing collar. If you flip it, that would put a flat surface pushing on a flat surface. Release would have a "bump" in it as it rocks on the flat fork to flat collar.

If you are a vehicle owner, this would be a case where your INCOMING odometer at the time of repair vs OUTGOING odometer reading should not be the same. If they only drove a mile or so, that's not a professional test drive. Never got up to highway speed and lit the charger for example. How could they know if it was or was not slipping w/o a serious test drive?

Gary

 

[GCroyle]

error duplication

Gary

 

[Ozymandias]

I also think about a not degreased and stoned new flywheel.
could be an error of a mechanic that is not used to stick shift transmissions.
I would ask that.

 

[johnjackson]

Sometimes they take a little while to brake in. had the same issue with a heaver than stock clutch from South Bend(who I highly recommend). They said give it a chance to break in. That was it.

 

[GCroyle]

jwade420,

Fixed? Solution?

Gary

 

[jwade420]

My apologies to all that replied with information. I thought I had replied back. Had some personal problems that kept me from checking it out right away. I tried all suggestions and it still slips if I hit it hard passing a car. I don't drive it much and haven't towed anything since this problem and thought it might have just gotten "broke in". It now has 15k on it. Went to pass a car recently and it slipped as soon as the turbo lit up. I will eventually pull it. Thanks for all the suggestions.

 

[GCroyle]

Take pic's and post.

Good luck.

 

[Gifu]

Hi guys! Having the very same issue. New clutch. Slips.

my 2006 (11/2005) has an NV5600. transmission needed a rebuild. Brought it to a (seemingly) knowledgeable shop. They scratched their heads at first because the book says that year truck should have a G56. So I guess its been swapped from G56 to NV56.
They rebuilt transmission and installed new 1 piece flywheel, Luk clutch (and pilot/release bearings), new release arm.
And clutch slips under load.
They installed the new release bearing on the old release bearing carrier... (there was a 1/8" difference)...
and clutch slips under load.
They say there is enough fork freeplay if they unbolt the slave.
the shop has had transmission out at least three times trying to correct the issued...
Now they want to try a South Bend clutch...
Truck has a very very mild tune (mostly timing), a Ryan's Tow turbo, 315 tires, flatbed with a lightweight popup Four Wheel camper. I really don't think it should need a super fancy pants clutch.

any ideas? It sounds to me like the brand new Luk clutch is defective. It's a good brand but...

 

[Motorhead]

What's the LUK built for HP or Torque wise? Once a clutch disc has been glazed from slipping, it's never the same, grip wise.
I have a South Bend OK-HD and I run the 90hp setting on a Smarty jr. Not a slip.

 

[Tuesdak]

Went to pass a car recently and it slipped as soon as the turbo lit up.

PSA: if you don't notice the clutch slipping it can get hot and shatter. Maybe parts of the flywheel or pressure plate stop in the dash after cutting your feet clean off. Perhaps a repair that shouldn't be put off.

This much slipping I suggest replacing the flywheel with the clutch - don't bother trying to turn the hot spots out of it.

Now they want to try a South Bend clutch...

Truck has a very very mild tune (mostly timing), a Ryan's Tow turbo, 315 tires, flatbed with a lightweight popup Four Wheel camper. I really don't think it should need a super fancy pants clutch.

I suggest your shop is correct to drop a South Bend Clutch in it with your mods esp. if they are not charging you 2x labor. Why should a stock clutch hold anything over stock power? Not super fancy like a double disc as just a higher holding power should do. Maybe the shop confused G56 parts with NV5600 parts.

You will need to look for hot spots on your new flywheel: maybe you got lucky. If not do you want to risk not putting in another new flywheel vs. the cost to get there. (Damage can happen really fast to make hot spots that ruin the flywheel.)

 

[GCroyle]

Gifu,

Early production 2005 trucks had NV5600. Later in 2005 the G56 was introduced. 2006 is all G56 as built. This is a verification question, where is REV on your trans. Left and back or Right and forward?

Do you have the old clutch, got pics, do you have the new clutch part number?

"They installed the new release bearing on the old release bearing carrier... (there was a 1/8" difference)."

Please clarify, was that the bore of the bearing 1/8" difference? That's a heck of a lot if it's an actual measurement. Or where was this 1/8" measured at? The NV5600 and G56 use the same clutch release bearing.

"They say there is enough fork freeplay if they unbolt the slave."

OK time to get a bit nasty. They don't understand the modern clutch hydraulic release system. They DO NOT have traditional free play like 1960's trucks did.

It's possible you have a clutch problem but not enough info yet.

Any good shop should not release a truck w/o a full test drive including a giddy up run in 5th or 6th and find out if that dog can hunt.

Gary

 

[Gifu]

Hi guys! thanks for your responses. Couple things to clarify...
the shop hasn't returned the truck because of this issue. When the test drive it... they are able to make the LUK clutch slip.
They are the ones who figured out this truck should have had (or rather did have) a G56 and has been swapped to an NV5600. I knew it was an NV5600 because cast iron case and reverse up next to 5th. They pulled the transmission for the rebuild.
The comment on the freeplay was just to confirm that the nose cone wasn't pushing the TO bearing into the clutch diaphragm. Both the shop and I understand clutch hydraulics; but we needed to make sure the fork, TO, etc. were not being subjected to forces besides the hydraulics.
My thoughts on why a stock LUK should hold up
1) I'm only running aprox 10% more power
2) the LUK clutch is 13", same size as the later 6.7 that was rated about 25% more HP
3) I'm heavier than stock... but not towing anything. My friends get away with towing 10-12K lbs with the stock clutch

At this point the truck is still at the shop. We will probably do a Southbend HD single disk something or other...

Thanks again for your thoughts and comments. I will report back.

 

[GCroyle]

Your clutch and transmission release bearing be it Getrag, NV4500, NV5600 or G56 is always in contact with the diaphragm spring fingers. It's the end result of bearing preload for a constant contact hydraulic clutch release system.

Got part numbers of the new system? Got pics of old clutch?

 

[Gifu]

Your clutch and transmission release bearing be it Getrag, NV4500, NV5600 or G56 is always in contact with the diaphragm spring fingers. It's the end result of bearing preload for a constant contact hydraulic clutch release system.

Got part numbers of the new system? Got pics of old clutch?

I keep forgetting to the ask the shop for the LUK clutch part. Next time I talk to them... (I try not to pester them more than couple times a day... as I'm just happy it's not me pulling that giant transmission in and out)
I do understand the hydraulic systems; it's similar to what we use in Land Cruisers (which I've worked on for 20 years, doing diesel conversions, V8 conversions, and the like).
Because we were dealing with an unknown "conversion" (G56 to NV5600; not something I was intimately familiar with - though I've read up on it now) and not knowing if the engine plate gets swapped, which bellhousing we had (does G56/NV use the same?), which flywheel, etc... one theory was that the TO bearing was being pushed into the clutch by forces beyond the hydraulics. But we confirmed this to not be the case by removing the slave and feeling the tiny amount of freeplay that the fork has.
Another last theory was that the hydraulics were somehow holding a little bit too much pressure when the pedal is out... like maybe the lining in the hose from master to slave was deteriorating and acting like a residual valve, keeping too much pressure on the fork/TO, and causing the clutch to slip.
But this last theory is just grasping at straws.

 

[GCroyle]

Slave cyl removed, push it in with fingers to make contact. Now pull it back until it hits trans.

How far did the fork move before it hit the trans?

Part numbers and old system pic pretty important clues right now.

 

[Darkbloodmon]

I'm just happy it's not me pulling that giant transmission in and out

Third time is the charm they say....