Clutch Guru's a poll for you.......

[Sled Puller]

As a lot of you know, I was testing the DRE Sachs in truck pulling. (Something it was not advertised to do)



Much to my dismay, it failed miserably. Way behind an early Centerforce. Although it will handle ANYTHING, we can throw at it on the street.

Hook a sled to it, and it just spins.



Now, it has 6 brass pucks per side, 50 pounds per square inch of pressure.

This material likes to be in the 70 PPSI range to really "hook".



What I am considering, is knocking three pucks per side off, increasing the load to 100 PPSI. , sacrificing driveability, hoping it will hold at the pulls, so I can play some more this summer.



What do you think?

Gene

 

[South Bend Clutch]

MGM,



I don't know if I am a guru but maybe I can help.



Less buttons do in affect create more pounds per square inch but if you go to far it will start to work in reverse. From what we have found, it is not necessarily going to hook up better with less buttons but to create more plate load and add more buttuns in a pattern will create more clamp force. The buttons that the DRE uses are not designed for the job that you are asking of them. The product that you are useing (Meba) were designed to help prevent plate grooving and give a smoother engagement. The kind of material needed for pulling is alot more agressive. In order to get more clamp force the spring pressure has to be great. Obviously to create that kind of pressure you would not be able to push in on the peddle. What we do for the tracter pull clutches that we make (for tracters) is as follows---- 16" to 17" double disc with 12 small brass buttons on each side of each disc (not the Meba button). The pressure plate has 6 levers with 2 to 3 pound weights on the outside of the cover hooked to the levers(not ware the throw out brg. rides like the Center Force diaphram style). The pressure plate starts at about 6000 pounds and is not ran with a hydrolic thrust brg. . The higher the RPM the higher the clamp load.



The problem that the diesel pickup trucks have is lack of RPM.

Granted there is a ton of foot pounds of torque, when it is put to the extreme pulling force, more clamp load NEEDS to be created.



If you want to try and make what you have work. I would try going from the ceramic button to a brass button. Then I would add more buttons not less just smaller. Align the buttons to the outside of the disc where the most torque is created. Then try heating it up before you make your pull.



This is only my opinion, maybe someone has a better one!!!



Peter

 

[Sled Puller]

If they designed Meba for smooth engagement, they blew it!



We have tried heating the Meba, all it does is make it more aggressive leaving the pulls on the street.



What about putting a bigger slave cylinder and increasing the spring pressure?



I still can't believe the Centerforce stuck better at the track. It stunk and smoked, but I was at the 300' mark when the smoke cleared, not the 84'!!!!



Gene

 

[Jff24Gordn]

So how much does it cost for sponsership?

 

[South Bend Clutch]

MGM,



That would be a way to help the matter. The only problem that you run into is, the tempering of the diaphrams like the DRE does, only allows you to go so far. When retempering a diaphram you heat it up in an oven to take the carbon out. Raw steel runs at a 10-08, 10-10 rockwell. The OEM rockwell on a diaphram runs between 10-40 and 10-48, so, when you bring it down and then start adding carbon to raise the rockwell, the higher you go the more brittle the metal becomes. The highest that you might get it is 10-70, anything after that the diaphram will brake the first time it is depressed. At that level the pressure plate is producing around 4000 pounds of plate load. It is a very tricky process. The proper way to achieve the highest plate load is to make a thicker diaphram. Unfortunately, the cost to make a diaphram is extremely expensive. To justify the diaphram manufactures to make these for us, there would need to be a 1000 ordered to start. For someone in my position it would be a long while before I would begin to see a profit. The call is not that great at this point.





Peter

 

[Sled Puller]

Originally posted by South Bend Clutch

MGM,





If you want to try and make what you have work. I would try going from the ceramic button to a brass button. Then I would add more buttons not less just smaller. Align the buttons to the outside of the disc where the most torque is created. Then try heating it up before you make your pull.







Peter

Peter,

In this paragraph, are you calling the Meba ceramic?

What would it cost to have a disc set up like that?



What would the driveability be like with the set-up you are suggesting?



I fear even with the pucks off, revving to 2000 and letting the clutch out with a sled it is just going to spin past it again. All I will gain is worse street driving.

 

[Sled Puller]

GOOD NEWS!!!

Johnboy had his pull rained out today, and he is donateing his $10 refund to my clutch fund!!



What a Guy!

 

[Joseph Donnelly]

To take off, you give the engine some rpm and the clutch slips while getting the truck rolling. The clutch grabs when the engine rpm and trans rpm are similar, and you finish letting out the pedal. If you don't get to that point, it will keep on slipping. All clutches are a compromise. Peter just discussed some other valid compromises. I suggest working on different tires and driving styles, and getting more low end torque--I think you said your engine makes around 275 hp. Another 100 or 200 ft lb would make the truck pull better at lower rpm and you could work the rpm differential better. Fewer pucks increases psi and as I told you earlier, that will increase torque capacity, but again, the clutch needs to grab first and you aren't giving it a chance. 3-4 pucks per side gives the optimal psi for your pressure plate, the Miba brass "ceramic" pucks, and torque capacity. As we discussed a while ago, more pucks can improve smoothness, heat dissipation, and wear.



There is no clutch that will do everything you want. There are several that will do some things well and with careful driving style, they can do other things adequately.

 

[Sled Puller]

Interesting concept-BOMB the engine more to make the clutch hook.

I can't go any smaller/less aggressive tire, no traction. Did that last year. They are only 285 BFG all terrrains, not like they are boggers or something wild.



I tried comeing out of the hole easy, I got under the turbo.

It still seems like it should spin the tires instead of slipping, I mean, it is only dirt!

 

[Sled Puller]

You guys that have voted, don't be shy, post your reasons!