04.5 Clutch reccomendations.

[Gonzo 1066]

My 04. 5 now has 140,000 miles on the original clutch, it has towed almost all of those miles at or above 20,000# up to 28,000#. It is time for a new clutch even tho the stocker has never slipped. I have 70HP injectors,a S-300 charger, Edge box, intake,exhaust ETC on the truck. . Just wondering if a dual disc is something to consider? IF the new ones do not rattle. I have a CONOFE SB in my 01 truck and have been happy with it.

 

[NIsaacs]

Since you are obviously easy on clutches I would not go with the twin disk. Since you seem to like SB products, I would go with the 1947-OR-HD if your flywheel is fine, the 1947-OK-HD if not. This clutch uses 3" lining on the disk, it looks like a dandy. The oem style, even in the HD offerings uses the shallow lining. Here is a pic of my new '01, (Sachs) notice the shallow lining on the disk. I changed it at 212k.



Nick

 

[NIsaacs]

Here is a picture of what I am talking about. It is not the SB one, but illustrates the disk lining difference's.



Nick

 

[Gonzo 1066]

Being a bit of a diesel tractor puller and a mechanic the wider facing makes more sense to me. But I would assume that there are some advantages to the narrow face?

 

[GCroyle]

Here is a picture of what I am talking about. It is not the SB one, but illustrates the disk lining difference's.



Nick

OK Nick, This is known as a wide band facing, and sure looks like the 1st Gen Getrag 13" system with the cast iron cover. This disc also included an external predamper assy that was a frequent non-survivor. The NV5600 OE type disc has the Narrow band facing, both with the 13" OD.



Question.

Which one when used with the same clamping force has the higher torque capacity? All other factors identical, facing grade, the only difference narrow band vs. wide band. We're also accepting that each cover is correct for the discs compressed thickness too. This is strictly a torque capacity question.



BTW, the OE 1st Gen clutch system made by Sachs was derived from a MB straight truck design and the cover was only one of a handful of applications (US market cars and light trucks) that was made with a cast iron housing. Some others with cast iron housings, 930 Porsche 3. 3L, Taurus SHO revised clutch version, Toyota Supra Twin Turbo, that's the ones I can think of this morning anyway.

 

[NIsaacs]

OK Nick,



Question.

Which one when used with the same clamping force has the higher torque capacity? All other factors identical, facing grade, the only difference narrow band vs. wide band. We're also accepting that each cover is correct for the discs compressed thickness too. This is strictly a torque capacity question.

Gary,



Knowing your back ground, reading all your clutch posts and getting personal advice (and taking it) I should leave this alone but being a competitve sort and liking clutches like I do, I am going to attempt to answer the question:-laf



The shallow lining will have the most clamping force per square inch of disk lining and the most torque capacity "once it is locked/engaged"... but... during engagement/dis-engagement the wide lining will have more capacity due to less clamping force but more contact during this process. It will also create less slipage heat starting from a stop or during an up or down shift. The fact that the wider contact includes the flywheel, clutch cover and disk it should make for a longer lasting, better performing clutch. So... . how did I do?



Nick

 

[GCroyle]

Gary,



Knowing your back ground, reading all your clutch posts and getting personal advice (and taking it) I should leave this alone but being a competitve sort and liking clutches like I do, I am going to attempt to answer the question:-laf



The shallow lining will have the most clamping force per square inch of disk lining and the most torque capacity "once it is locked/engaged"... but... during engagement/dis-engagement the wide lining will have more capacity due to less clamping force but more contact during this process. It will also create less slipage heat starting from a stop or during an up or down shift. The fact that the wider contact includes the flywheel, clutch cover and disk it should make for a longer lasting, better performing clutch. So... . how did I do?



Nick

Nick,



We'll this one can start a heated discussion and has even led to a few clutch industry TSB's about the topic.



I'm going from written info that I have at the office from 3 sources at least. First a dog eared copy from my 1st clutch employer, Sachs, yup 16 years with them. Met and worked a bit with the engineer that presented the Sachs 13" 1st gen system too, then a copy from Valeo and a clutch book from the SAE.



4 factors are used to calculate the torque capacity of a clutch.



1. Clampload in pounds. This is the force applied by the cover against the disc when bolted up. Note, each cover has a "gage dimension" the new disc thickness.

2. Coefficient of friction. A dimensionless number describing one materials resistance to slipping against another surface. AFAIK there is only a few companies in the US capable of testing and it has caused a lot of discussion, because one of the SAE tests is for brake friction, but it's sorta all we have along with a test known as CMET by Greening Labs.

3. Number of friction surfaces. 1 disc = 2, 2 discs = 4 etc. The multiple stacked discs is what allows some racing clutches to be soo small on the od, but the stacked discs really add up.

4. Drum roll please... ... ... Mean Radius. This is a calculation this uses the inner and outer radius to calculate that one single radius for the calculation. This calculation at least in the English inch system is a decimal foot value because we want the answer in pound/feet. Take a look at a beam type torque wrench, the handle pivots on a pin, the true length of the moment arm is fixed.



So a small ID wide band vs a large ID narrow band has by the calculation, less torque capacity because the mean radius has actually moved in, closer to the center of the shaft that the disc is actually twisting.



Insert arguments here... ... ... .



BTW a clutch as far as the friction is concerned really doesn't know its spinning when it is completely locked up. Think back to the beam torque wrench. You can hold a bolt at a certain torque with no rotation. Add rotation to torque and work is being done = the beginnings of horsepower.



To increase the torque capacity, one or more of the following must be changed:

Increase clampload.

Higher coefficient of friction.

More friction surfaces, multiple discs.

Increase the mean radius.



One or more of these factors are tweaked to increase the torque capacity. But nothing in this discussion addresses the torsion dampers role and any other drivability issues.



Narrow band systems must pass some pretty nasty durability testing, life expectancy, and all other NVH and such before the OE's sign and if they go narrow band, they save on friction material costs. I don't have any of the $ numbers associated with this often dis-believed formula. Years ago the gas engine F-Series went narrow band, here's yer bulletin.



NICK one advantage that wide band can offer over narrow, it just has a bit more meat to wear off on the facings from engagement to engagement. When the system is locked, facings are not slipping, no heat is created from the friction, they're locked. BTW, your comment about wide band making less heat at engagement, might be correct due to the larger surface area for the heat to be created on and dissipated over.



PSI doesn't enter into the torque capacity equation. I think where PSI comes in is the acceptable do not go over the "failure at X crush force" that clamps the facings hard enough, but doesn't destroy facings either. Remember, the facings that are on discs are classed as organic (I guess because the A word was "organic") but they are based on various techniques to weave and bond fiberglass into todays A-free facings. I've visited two facing producers, fascinating, even got to see how V-Lock Gold was made. Look at Class 8 truck clutches, buttons but not all the way around, the buttons can take a higher PSI load, don't need a full circle.



I think a clutch takes a lot of abuse in its normal life, now add more power, drivers of questionable skill/experience/techniques, Load the Wagon, Don't worry 'bout the Mule, it has no chance for periodic servicing (i have thought about a grease line for my bearing collar only, and SOME old Ford's had a grease fitting on them too) sure we can pull that stump, hook 'er up, naw, that engine is so strong I NEVER use 1st gear, can I borrow your truck I know how to drive stick, too many small details get over looked I'll post a pic of a trashed release bearing next week that wasn't greased, yup we ALWAYS use a lot of anti-sieze on splines it's good for 'em, get the hand grinder this F/W just needs touched up (I have a recessed Mitsubishi F/W that a guy by hand resurfaced the raised STEP with a 7" disc grinder) what air bubble in the hydros' no way the're bled.



I drive one, tow my Airstream with it AS weighs about 9K Lbs, owned a few and ordered 4 new vehicles with M/T's, installed quite a few and most importantly I enjoy the driving relationship.



NICK, thanks for the discussion.

 

[NIsaacs]

Nick,



We'll this one can start a heated discussion and has even led to a few clutch industry TSB's about the topic.



4. Drum roll please... ... ... Mean Radius. This is a calculation this uses the inner and outer radius to calculate that one single radius for the calculation. This calculation at least in the English inch system is a decimal foot value because we want the answer in pound/feet. Take a look at a beam type torque wrench, the handle pivots on a pin, the true length of the moment arm is fixed.



So a small ID wide band vs a large ID narrow band has by the calculation, less torque capacity because the mean radius has actually moved in, closer to the center of the shaft that the disc is actually twisting



NICK, thanks for the discussion.

Gary,



As usual, an awesome write up, thanks!



The "mean radius" includes outer ID and Inner ID correct? As long as both clutch types have the same outer diameter wouldn't the 13" wide band have more capacity than the 13" narrow band? I can understand the closer you get to the center the less torque is applied but if they both start at 13" OD and move to the center, wouldn't the wide band have just that much more, than the narrow band?



I also think that with the narrow band style, at least in the case of the oem NV5600 they are wasting space for a larger center hub. Since the hub is usually a weak link, they would take advantage of the room and make it bigger/stronger. Or is that just a $$ type savings and they figure it is good enough?



Nick

 

[GCroyle]

Nick,



I think I sorta left one piece of the explanation out, or not clearly presented. And I can copy and scan the formula too.



Yes, mean radius is an "average" of the inner radius and outer radius. IIRC it has a shorthand calculation and a longer more detailed formula too. One of the newbie calculation errors is using the CASTING instead of the facings for the data, wrong, got that T-shirt long ago.



Mean radius. As the formula only has one spot for the mean radius value, the higher that number, the greater the leverage of the system. Take a 1/2" breaker bar, pull at a point 1 ft. out from the axis with 100 pounds, you generated (or resisted) 100 lb/ft. Now move out 1' 3" or 1. 25 ft same 100 pound pull you now generate or resist 125 lb ft. But you didn't change anything else, just moved farther away from the axis.



I'm not sure how well this might be visualized, but instead of your hand wrapping around the breaker bar you push down on a flat surface on the bar with the palm of your hand and try to rotate the bar. You must push down to maintain and not slip, then try to pull or push to rotate the breaker bar. Now move the flat surface farther and farther out.



Formula has been presented by many OE clutch suppliers in various publications, but the SAE clutch handbook was a committee effort. The front pages list like a who's who of the clutch industry at the time they complied it AS A GROUP! Can you imagine the discussions about just nomenclature alone.



BTW, the formula only has one spot for coeffiecent of friction, clampload, and number of friction surfaces too.



Nick, a discussion about the torsion damper can be a doozie IMHO. The damper acts like a marriage counsler with an angry crankshaft on one side and a lazy input shaft on the other. Have fun with that idea.



The 1st Gen disc adapted from the MB straight truck if you get one in your hands, you'll see that German design had a real almost mid-range strength. One facing was riveted directly to a thick drive plate and the other to the lining spring. I know of no other pass car or p/u that used this design. Strong. The damper, rather simple, internal bonded to steel friction material to resist motion. The damper of a disc has springs to carry the load and most all have some type of internal friction device to try to control the dampening. Think of the relationship of suspension springs and their shocks. Shocks try to control the rate of change, not prevent it.



Moving forward, designs changed, costs are always an issue and performance went up and up. LuK has had the OE business since the 2nd Gen NV4500 and built some strong systems with their customer in mind.



Would you rather have a DMF with your NV5600? Lots of folks switching out and I think you'll find that most of the std solid F/W replacement systems are based on a version of the NV5600 disc, there are exceptions of course. And the DMF system that they offer for the G56 is the quietest system with some advantages that they should point out too.

 

[NIsaacs]

Gary,



Thanks again for your time and explanations. Yes, the picture I posted of the 3" lining is a Sach's 1st gen HD a little different than the standard version. The oem in my '91 is still going at 319k. At about 280k I pulled it and could not see a thing wrong with any part of the system so I just changed the throwout bearing and re-installed it. At that time the only offering from Napa was the 12. 3, so called upgrade of the NV4500 clutch, "NOT", so I said thanks but no thanks. If the oem would have been available on the shelf I would have went ahead and changed it. I am sure the part I could not see, the damper portion of the disk, was no doubt somewhat tired. Now that O'Reilly moved in, they are available. When I have a vehicle tore down I want parts yesterday and hate to order anything. If I plan in advance, ordering is ok



Nick

 

[GCroyle]

Nick,

The 13" cast iron is still available. We did drop the external vulnerable predamper.

Gary

 

[Gonzo 1066]

OK,, Now that I have digested most of that information,,,,,,,,,,, I know that my stock clutch had done very well with the HP of my engine, the load it has to pull and the dirver (me) of the rig. . I am a preventitive maintainence kind of guy (replace before failure) and generally a overbuilder, that is I rarely go with stock parts if there is a better built substitute available. The original question was, HOW GOOD ARE THE NEW DD CLUTCHES for drivability?? And is there a downside other than the extra cost?