Slipping Clutch, under 50k?

[MichaelOverfield]

Well, something new today. I have about 49k miles, towing a 5000# trailer.. and in 5th gear on a gentle grade I get what I recognize as slipping clutch. Having had a car with a slipping clutch for quite some time before replacement, I can detect the rising RPM under acceleration that doesn't match sudden increase in speed. Has anyone had this issue with such low miles? Also clutch recommendations.. I might as well consider an upgraded clutch while I'm at it, since it seems apparent a replacement is in the near future.

 

[petersonj]

I believe that you may have a failing dual mass flywheel. The failure can have similar symptoms as a slipping clutch. This fix is to go back to a solid flywheel.

It is unfortunate for the customer that a manufacturer will make a clutch and pressure plate that can last up to 300,000 miles only to be mounted behind a dual mass flywheel that can fail as early as 50,000 miles. I know of one other person with a 07.5 truck that had the dual mass flywheel fail at 56,000 miles.

- John

 

[Brian Sullivan]

I had mine fail at 44k. Put in a south bend okhd. Has been flawless since

 

[GCroyle]

I believe that you may have a failing dual mass flywheel. The failure can have similar symptoms as a slipping clutch.

- John

I disagree with a slipping DMF as the cause on this application.

1997 and older Ford 7.3L did have an internal torque limiting friction clutch in its Valeo DMF.

The G56 LuK DMF does have a spring damper system but it does not include the torque limiting friction clutch feature.

 

[MichaelOverfield]

I had mine fail at 44k. Put in a south bend okhd. Has been flawless since

How many miles since the South Bend? It's first on my list right now. Also, other than gear noise, which won't bother me at all. Any downside to the SMF? I've seen some say that the G56 doesn't like the vibration, but haven't heard of failures associated with use of a SMF. Seems the DMF was mostly marketing from my initial investigation. I'd be really interested in the engineering considerations if there were any.

 

[MichaelOverfield]

I disagree with a slipping DMF as the cause on this application.

1997 and older Ford 7.3L did have an internal torque limiting friction clutch in its Valeo DMF.

The G56 LuK DMF does have a spring damper system but it does not include the torque limiting friction clutch feature.

Great points. It seems like the slipping clutch could not be the flywheel.. but I wonder if that flywheel face has something to do with it. In any case if I'm going to work the clutch, the flywheel will be replaced at that time, and I'm unlikely to stay with that DMF. It has had some rattle noise in neutral at idle, especially during Regen, and it has made other rattle sounds for a while. Now I think about it, this could have been a sign of a flywheel wearing out, from symptoms others have described.

 

[MichaelOverfield]

Anyone have opinions on the various Rockauto clutch options? South Bend kits are more than double cost.. are they worth that much more? Several options on Rockauto include the SMF and hydraulics.

https://www.rockauto.com/en/catalog...d,1443642,transmission-manual,clutch+kit,1993

 

[MichaelOverfield]

Anyone try a clutch from Phoenix Friction Products?

 

[Brian Sullivan]

Got mine through summit. About 12k no problems drove a manual trans for 40 plus years and first clutch ever so I know how to drive a manual transmission. You will have gear rattle. I also put in Mobil trans gear lube discussed here

 

[MichaelOverfield]

Got mine through summit. About 12k no problems drove a manual trans for 40 plus years and first clutch ever so I know how to drive a manual transmission. You will have gear rattle. I also put in Mobil trans gear lube discussed here

Thanks, I previously switched to Mobile 1 fluid. Since I have a big trip coming up, I could not wait around.. just ordered the complete South Bend Kit. The Dual disc kit was not much extra, and I decided to go with it, might be a bit of overkill for my use, but given that was enough to kill the original in so few miles. I had over 175k on my '96 Saturn clutch. Drove it hard, even towed with that car, and it began to slip.. turns out it had some transmision oil get on it, hence slip. But was not worn out. There is no reason a clutch should die a 48k.

 

[RVTRKN]

A negative to the SMF is running heavier oil to cushion harsh vibrations at low RPM's. If you run a heavier oil it retains heat easier so you need a cooler setup. Without going into the same old story read this, if it doesn't start from post #1, do so. BTW, SB clutch is the best SMF and clutch, stay away from the DD3250 unless your running at a high HP.

https://www.turbodieselregister.com/threads/246651-Transmission-oil-cooler?p=2380678#post2380678

 

[petersonj]

I disagree with a slipping DMF as the cause on this application.

1997 and older Ford 7.3L did have an internal torque limiting friction clutch in its Valeo DMF.

The G56 LuK DMF does have a spring damper system but it does not include the torque limiting friction clutch feature.

GCroyle, thank you for the information you provided. I see your point here and I agree that it is not designed to slip. But, is it possible for the DMF to slip under certain failing conditions even though it is not designed to do so?

The reason I ask is because I was involved in helping to change out a clutch that was reported to be slipping in higher gears under a load (several times). After removal and inspection I found that the clutch facings, the pressure plate face, and the flywheel face showed no indication of excessive heat. The clutch disk had only minor wear on the surface. This is why I was thinking that the DMF had failed (slipped). Unfortunately, there no way to inspect the DMF. Everything was put back together with new parts including a single mass flywheel.

So, it just seems strange to me to have a slipping clutch failure at such low miles. I have had personal experience with two other failing DMF's, one in a 2006 Dodge Cummins at 155,000 miles, and another in a VW Beetle TDI at about 95,000 miles. Neither had a clutch slippage problem and both had vibration issues. Upon disassembly, it was obvious that the DMF had failed on both vehicles.

The 2006 Dodge Cummins clutch was replaced with a Southbend organic single disc clutch kit (good to 900 lb/ft torque), a single mass flywheel, and a hydraulic kit. The clutch operates smoothly, but it does require a bit more pedal effort.

As far as being noisier than the clutch with the DMF - maybe; it was hard to tell.

- John

 

[MichaelOverfield]

A negative to the SMF is running heavier oil to cushion harsh vibrations at low RPM's. If you run a heavier oil it retains heat easier so you need a cooler setup. Without going into the same old story read this, if it doesn't start from post #1, do so. BTW, SB clutch is the best SMF and clutch, stay away from the DD3250 unless your running at a high HP.

https://www.turbodieselregister.com/threads/246651-Transmission-oil-cooler?p=2380678#post2380678

Thanks, I currently have the Fast coolers and have parts to add an external pump with thermostat controlled fan for cooling, and since I'll have a cooling circuit, plan to add a fluid filter also. Was not planning on doing all that right now, but it seems like the time to do it once I have the transmission out.

Just curious, what is the downside of the DD3250? I'm ok with additional pedal pressure. It's only about $200 more than the single disc kit.

 

[RVTRKN]

It’s noisy, and adds a harsher noise like if the input shaft has too much play in it when the clutch is engaged and idling. Release and engage the clutch again and it might center the disks quieting them, if not, do it again until it quietens. However the DD3250 holds with my EFILive on #5

 

[MichaelOverfield]

It’s noisy, and adds a harsher noise like if the input shaft has too much play in it when the clutch is engaged and idling. Release and engage the clutch again and it might center the disks quieting them, if not, do it again until it quietens. However the DD3250 holds with my EFILive on #5

Ok, interesting. Well I had the DD 3250 on order, but it can be cancelled. Would the G56-OKHD, of G56-OFEK single disc be a better choice? I also found a EXEDY Kit on RockAuto.. says it's good up to 680ft-lbs, and after $229 shipping it's about $700 or so, about $400 cheaper or more than SB. Is SB worth that kind of premium price?

 

[MMeier]

Go with what you have ordered, wont win any speed shifting contests with it, but should work just fine in your application !

 

[RVTRKN]

Ok, interesting. Well I had the DD 3250 on order, but it can be cancelled. Would the G56-OKHD, of G56-OFEK single disc be a better choice? I also found a EXEDY Kit on RockAuto.. says it's good up to 680ft-lbs, and after $229 shipping it's about $700 or so, about $400 cheaper or more than SB. Is SB worth that kind of premium price?

Is your truck stock? If not, what HP did it dyno at or future increases? These are questions for Southbend Clutch, you can call SB and they’ll advise the proper clutch for your purchase. BTW, my clutch started slipping @ 30K miles, but it was because a possible corrupted ECM update causing surging power accelerating over 2K RPM, another long story. Good luck with whatever you chose.

 

[Regcabguy]

I've got the SBC OKHD. Lately I seem to be getting more 2nd-3rd gear rattle especially when cold.
Mine's had increased noise since the conversion. I had the opportunity to drive a late '05 with the G-56. 200K. SMF and the trans was as quiet and smooth as mine was new.

 

[Tuesdak]

Ok, interesting. Well I had the DD 3250 on order, but it can be cancelled. Would the G56-OKHD, of G56-OFEK single disc be a better choice? I also found a EXEDY Kit on RockAuto.. says it's good up to 680ft-lbs, and after $229 shipping it's about $700 or so, about $400 cheaper or more than SB. Is SB worth that kind of premium price?

I have around 30K on my SBC clutch 1947-OKHD. It's smooth in all forward gears towing to the 20K max rig combo. I get some axle hop when backing the trailer attempting to slip the clutch - need a 4x4 with 4Low... When cold I do get some noise from the clutch or it's the tires slipping :-laf . It does have a heavier pedal.

Worth it? Yes. When the first shop left out a dowel pin and destroyed my first SBC I called up SBC and they gave me some warranty/goodwill credit on a replacement clutch. They also explained why I had the failures I did from that damn dowel.

You don't want too much clutch for your power level. You can call SBC and they will help you choose what's best for your truck. https://www.southbendclutch.com/resources/choosing-a-clutch/

 

[GCroyle]

GCroyle, thank you for the information you provided. I see your point here and I agree that it is not designed to slip. But, is it possible for the DMF to slip under certain failing conditions even though it is not designed to do so? - John

John,

I have disassembled the Valeo 7.3L DMF and the LuK G56 DMF. That Valeo version has an internal torque limiting clutch pack, 2 belleville springs and 2 friction surfaces. You could bolt it to a big bench, bolt a 6' angle iron to the clutch cover bolt holes and rotate the secondary and the primary stays put. I've done it. Also took the G56 LuK version apart, no friction elements internally. I think if the LuK G56 happened to completely self destruct, it would be making a racket and be undrivable. Most likely it would jam up locked and big nasty. Also cut a 2000 VW 1.9L ALH DMF apart, that was a completely different design again.

FWIW, PM sent.

Gary