2 stock clutchs in 60K miles?

[JohnJansen]

Hi

I have a 2006 Mega Cab 3500 4x4. Factory ordered new with 6 speed.

Pull a large 5th wheel, approx 14,000 lbs. Recently installed a PacBrake PXRB. Just finished a 3,400 mile trip. Truck performed well, got 11 mpg. I think the clutch is slipping again. First one went out at 39K miles and was replaced by the local dealer.

Should I go with another stock one? Seems like a non starter.

Or is there something else possibly wrong?

I never run the truck over 2,200 rpm or 1,250 on the pyrometer.

South Bend has a dealer in Tampa called Twisted Metal.

Anyone ever dealt with them?

Any reccomendations for the clutch?

I ran the entire trip "stock". Have a smarty, have never set it above "3"

Thank You

 

[CKelley1]

your truck has a dual mass flywheel. they went to this because the g56 design transmits engine noise more than any other one ever used. they picked a very poor design for the dmf. you actually are getting the average mileage out of it before failure. go back with a southbend conofe kit. the dmf has probably damaged the front seal on the g56. replace the front seal and bearing and fill the g56 with 7 quarts of pennzoil syncromesh this is one quart over full. pore it in through the shifter when installing. this is a must to cool and lube the front bearing

 

[SierraRam]

Southbend is an excelent clutch and company to deal with. Get rid of the duall mass.

 

[wcjp]

Why do you never run the engine over 2200rpm's? It sounds like your bogging the engine in the lower rpm range. Are you avoiding 6th gear while towing?

 

[CDonaldson]

Gee, I have a 2006 Mega, G56, and have 70K on the stock clutch and still functioning just fine . . run a Samrty Jr on #2 programming for towing, otherwise on #3. I tow 18K to 24K on a regular basis, clutch has never slipped . . when the time comes that my clutch needs replacement, I am going with the Valair 3800DD and upgraded hydraulics.





CD

 

[TCDiesel]

Why do you never run the engine over 2200rpm's? It sounds like your bogging the engine in the lower rpm range. Are you avoiding 6th gear while towing?

xxx2 If He's has 3:73s and 14K

 

[AH64ID]

As it's been said the DMF is the issue.

Since you have a Smarty get the South Bend Con-OFE.

As far as your rpms and pyro, you were towing on stock tuning. You need to ignore the pyro, these trucks run 1450° in stock form. That last 200° is going to keep you in gears longer, and the rpms are good for clutch holding.

Now if you are running default, or TM2, on your Smarty then 1250° is a good goal. If you don't want to tow with too much power than I suggest SW1 TM2 TQ1, or TQ2 when you get a clutch. Then drive by the pyro, but you will find you wont get to it too often.

Don't worry about too many rpms either, your not going to hurt anything and they pull alot better with rpms if the hill warrants it. I usually pulls hills at 2500 in 5th, much cooler than 2000 in 5th.

 

[tschidas]

your truck has a dual mass flywheel. they went to this because the g56 design transmits engine noise more than any other one ever used. they picked a very poor design for the dmf. you actually are getting the average mileage out of it before failure. go back with a southbend conofe kit. the dmf has probably damaged the front seal on the g56. replace the front seal and bearing and fill the g56 with 7 quarts of pennzoil syncromesh this is one quart over full. pore it in through the shifter when installing. this is a must to cool and lube the front bearing

2006 DR Service Manual calls out the G-56 for Mopar ATF+4, I thought it was the NV5600 Transmission that used the Pennzoil Syncromesh? I got 120K on my stock DMF before the bearing failed, installed a LUK replacement kit although probably could have just replaced the bearing as the clutches and flywheel looked fine, I pull 11K 5th Wheel and dump trailer w/ bobcat so have worked the truck pretty hard.

 

[fox]

As it's been said the DMF is the issue.



Since you have a Smarty get the South Bend Con-OFE.



As far as your rpms and pyro, you were towing on stock tuning. You need to ignore the pyro, these trucks run 1450° in stock form. That last 200° is going to keep you in gears longer, and the rpms are good for clutch holding.



Now if you are running default, or TM2, on your Smarty then 1250° is a good goal. If you don't want to tow with too much power than I suggest SW1 TM2 TQ1, or TQ2 when you get a clutch. Then drive by the pyro, but you will find you wont get to it too often.



Don't worry about too many rpms either, your not going to hurt anything and they pull alot better with rpms if the hill warrants it. I usually pulls hills at 2500 in 5th, much cooler than 2000 in 5th.

I know someone who believed that and now has a replacement motor!!!

Aluminum WILL melt if it reaches 1275. How much allowance are you going to give for error in the pyro?

 

[fox]

Hi

I have a 2006 Mega Cab 3500 4x4. Factory ordered new with 6 speed.

Pull a large 5th wheel, approx 14,000 lbs. Recently installed a PacBrake PXRB. Just finished a 3,400 mile trip. Truck performed well, got 11 mpg. I think the clutch is slipping again. First one went out at 39K miles and was replaced by the local dealer.

Should I go with another stock one? Seems like a non starter.

Or is there something else possibly wrong?

I never run the truck over 2,200 rpm or 1,250 on the pyrometer.

South Bend has a dealer in Tampa called Twisted Metal.

Anyone ever dealt with them?

Any reccomendations for the clutch?

I ran the entire trip "stock". Have a smarty, have never set it above "3"

Thank You

Without knowing you, and sounding like a know it all, I suggest you find a clutch guy and take him for a drive. He may be able to give you some tips. Maybe not but it is cheaper than a clutch every 30,000 miles.

 

[AH64ID]

I know someone who believed that and now has a replacement motor!!!

Aluminum WILL melt if it reaches 1275. How much allowance are you going to give for error in the pyro?

Aluminum actually melts at 1221°, but that's pure aluminum and our pistons are an alloy.



EGT's are not an accurate measurement of cylinder temps, cylinder temps are much hotter, on the order of 2500° from what I gather, at peak temp. EGT's are just the easiest thing to measure and even then it's not a set standard. Stock EGT's on the 04. 5-07 trucks run up to 1450° pretty easily and won't melt a thing, where 1450° with smarty timing is enough to melt things.



Cummins rates the QSB480 motor at 1301° continuous in the exhaust manifold and you can bet thats not anywhere near melting temp.



If something melted at 1275° it was running too much timing, had a faulty gauge, or faulty injector.

 

[fox]

Aluminum actually melts at 1221°, but that's pure aluminum and our pistons are an alloy.



EGT's are not an accurate measurement of cylinder temps, cylinder temps are much hotter, on the order of 2500° from what I gather, at peak temp. EGT's are just the easiest thing to measure and even then it's not a set standard. Stock EGT's on the 04. 5-07 trucks run up to 1450° pretty easily and won't melt a thing, where 1450° with smarty timing is enough to melt things.



Cummins rates the QSB480 motor at 1301° continuous in the exhaust manifold and you can bet thats not anywhere near melting temp.



If something melted at 1275° it was running too much timing, had a faulty gauge, or faulty injector.

The pyro reads average temps not peak temp.

That motor i was talking about ran near full throttle for 30 minutes. Pyro reading as high as 1500 for long periods.

The pistons are oil cooled which slows the heat process down.



Of course it isn't a set standard. It takes time to get the piston temps up. Pullers read well over 2000 for 30 or so seconds.

If it is heat we are dealing with, in degrees, what gave you the impression 1275 degrees is just that at any timing. Timing will change cylinder pressure.

Changes in cylinder pressure will change temps of course, but 1300 is 1300 at all timing settings.

 

[cerberusiam]

1300 is 1300 at all timing settings.

Your forgetting the combustion dwell time in the cylinder and the amount of heat transfer that happens. The 1300 and 5 degrees of advance is a lot different than 1300 at 10 degrees advance because of how much more heat has been generated.



Cylinder heat soak is the ultimate problem, not EGT's or timing.

 

[AH64ID]

The pyro reads average temps not peak temp.
That motor i was talking about ran near full throttle for 30 minutes. Pyro reading as high as 1500 for long periods.
The pistons are oil cooled which slows the heat process down.

Of course it isn't a set standard. It takes time to get the piston temps up. Pullers read well over 2000 for 30 or so seconds.
If it is heat we are dealing with, in degrees, what gave you the impression 1275 degrees is just that at any timing. Timing will change cylinder pressure.
Changes in cylinder pressure will change temps of course, but 1300 is 1300 at all timing settings.

Pyro's do not read average temp, they read exhaust temp. Timing exhibits that the best. When you advance timing for a set amount of fuel the cylinder can temperature go up, the amount of heat the piston sees goes up, yet EGT's go down.

1300 is NOT 1300 for different timing settings, as the piston sees it. Look at the Smarty SW1, it's stock fueling and advanced timing. EGT peak drops from ~1450° to 1300°, but average cylinder temps are higher. You could run stock timing at 1450° all day and be fine, do that with a Smarty on SW1 and your buying a new motor. We look at EGT's to get an indication of what's going on in they cylinders, but one setup's 1300° is not the same as another trucks 1300°.

1500° is too hot for sustained operations on any motor, unless timing is retarded well beyond factory 04. 5-07 settings. Was the motor stock or modified?

 

[fox]

Good Grief.

 

[AH64ID]

Good Grief.

Useful... care to elaborate?

 

[HBarlow]

Hi
I have a 2006 Mega Cab 3500 4x4. Factory ordered new with 6 speed.
Pull a large 5th wheel, approx 14,000 lbs. Recently installed a PacBrake PXRB. Just finished a 3,400 mile trip. Truck performed well, got 11 mpg. I think the clutch is slipping again. First one went out at 39K miles and was replaced by the local dealer.
Should I go with another stock one? Seems like a non starter.
Or is there something else possibly wrong?
I never run the truck over 2,200 rpm or 1,250 on the pyrometer.
South Bend has a dealer in Tampa called Twisted Metal.
Anyone ever dealt with them?
Any reccomendations for the clutch?
I ran the entire trip "stock". Have a smarty, have never set it above "3"
Thank You

The dual mass flywheel and clutch assembly is known to fail early and often in trucks used for towing heavy trailers but some folks have much better experiences than others. The way you engage your clutch to start the load rolling can make a large difference.

Listen to the way a big truck driver starts his load. You'll never hear a big rig rev the engine up above idle and slip the clutch. He simply shifts into the gear he needs and gently engages the clutch with the engine at idle. After the clutch is fully engaged the driver applies throttle to raise engine rpm and road speed. You should be doing the same thing. It is never necessary or recommended to rev the Cummins in our truck above idle to launch - even with a heavy load.

 

[SierraRam]

I agree with that Harvey, no throttle launch is the way to go on our trucks. Unloaded I can acheive that in 2nd gear but with a heavy load I sart from a dead stop in 1st.

 

[fox]

Useful... care to elaborate?

Well, we are seeing this from different directions.











I say the temp in the exhaust manifold is what the pyro says it is, you seem to think it is a cooler or hotter temp depending on timing. you do not make sense! And, the pyro does read average temps. Is it possible for it to read peak temps? All the exhaust is flowing near it.



It the thermometer outside my back door is 100 degrees is it hotter or cooler if I am running past it? (timing)

 

[AH64ID]

Your not understanding what I am saying.

Yes 1300° in the manifold is 1300° in the manifold, but you started talking about melting pistons and I pointed out that manifold temps are not what melt pistons, cylinder temps are. We can't measure cylinder temps, as you pointed out, so we use EGT's. But becuase EGT's don't give us average or peak temps we have to know how to interpolate them to safe and unsafe numbers. My point is this, as you advance the timing your peak safe EGT numbers drop. The EGT's are dropping becuase more of the thermal energy from combustion is absorbed by the piston/cylinder from being exposed to a longer burn prior to the exhaust valve opening, or simply put you have less heat rejection. This also (to a point) provides for an increase in power for the same amount of fuel being burned.

You made a comment that 1450° was too hot on a 06 motor becuase it's above the melting point of aluminum. My comment in return was the timing plays a huge role in the heat transfer, a bone stock 04. 5-07 motor is capable of running a 1450° and not hurting anything. The retarded timing and 3rd injection event (both for emissions) increase the EGT temp but leave the cylinder temps at a safe level. This is not like the motor in your 02, 1450° would melt things on your 02. With aftermarket tuners we advance the timing back to a more performance/economy minded setting instead of emissions based. With this advance in timing we get a substantial decrease in EGT's for the same fuel burn, again going into the piston/cylinder wall. So if one was to run a 04. 5-07 motor at 1450° with advance timing they would melt something. You also made a comment that EGT's were an average cylinder temp, again not true based on timing as explained above. Advance the timing and more heat is absorbed by the motor, thus having a lower EGT but the average temp in the cylinder has gone up. If EGT's were an average temp then every 04. 5+ motor would have melted by now, to include every 6. 7 when it goes into regen.

Here is my rule of thumb for Smarty Jr timing on a 04. 5-07. TM1 is stock. In order of least advanced to most advanced TM1, 3, 2, 4. I consider momentary a minute or two pulling a hill. RPMs and boost also play into how long I will sustain a momentary EGT for, more boost and more rpms can hold it longer and have less heat absorption by the piston, thou I have only gone over 1250° twice all summer and those were some long steep pulls at 70 mph.

TM1: 1400 max cont, 1450 momentary
TM2: 1300 max cont, 1350 momentary
TM3: 1350 max cont, 1400 momentary
TM4: 1250 max cont, 1300 momentary