G-56 guys, CLUTCH UPGRADE!! No more DMF!

[Tim]

Ok, so there's actually nothing wrong with my clutch and never has been. That said, Peter at South Bend Clutch is going to use my truck as a guinea pig to build a clutch for us G-56 owners. It will use a solid flywheel. I'm likely going to go for their baddest streetable clutch, the FE.



Peter will be here to last answer any questions. I am going to drop my truck off at Blumenthal's Heavy Duty, which is the country's largest transmission parts supplier. They're in Oklahoma City, OK. I'll be borrowing their 2nd gen truck to complete my trip to Waco, Texas and picking it up 3 weeks later with a brand new South Bend clutch and solid flywheel.



Feel free to discuss BOMBed G-56 stuff at will. Oo.

 

[JCleary]

What kind of mods are you planning on to test that clutch?



On edit:



More to the point, what are you going to test the G56 with (Now that the DMF will not be protecting the trans any more)?

 

[jwilliams3]

I dont think the baddest clutch streetable clutch from South Bend is an FE.

 

[lmills]

what you should have said was single disk clutch. Most of the newer dual disks are quite street friendly

 

[Jengle]

Something you're not telling us, Lloyd?????Hmmmm... .

 

[67guzzler]

Are there going to be any performance improvements or driveability characteristics improvement or is this so that a G56 owner doesn't have to worry about future DMF failures that haven't happened yet?



I understand the intellectual argument about the reliablility and cost savings (when the time comes to replace it) of the SMF vs. DMF. But to invest any dough into going to the SMF on a "perfectly good" new G56 there has to be some driveability improvements to make it worthwhile to me.



Regardless of my criticisms regarding the slack in my driveline, the clutch engagement to is incredible on the G56. Will the SMF change that one great feature of the G56? Is there a driveability upside?

 

[Bertram65]

What will that do to your 3/36 and 7/70 warrantee for the transmission and assocated parts?

 

[RChamberlain]

How do you know if you have the g56, or does all the 05 six speeds have it. thanks.

 

[67guzzler]

How do you know if you have the g56, or does all the 05 six speeds have it. thanks.

It was a mid year model change on or around 1/1/2005. Some units after 1/1/2005 still got the NV5600. Most after 1/1/2005 got the G56.



If your reverse is as it's displayed here, it's a G56:



#ad

 

[RChamberlain]

Nope mine is the other one. is there any problems I should know about the nv5600

 

[Coyote556]

the nv5600 is tried and true. you should be good to go.

 

[hasselbach]

I wonder how those plastic gears in the g56 are going to last now that the DMF isn't absorbing the torsional vibration from the Cummins. .



This is going to be interesting... ...



Warranty? What warranty?

 

[67guzzler]

Just stirring the pot....

I wonder how those plastic gears in the g56 are going to last now that the DMF isn't absorbing the torsional vibration from the Cummins. .



This is going to be interesting... ...



Warranty? What warranty?

You guys are a riot. #ad




BTW -- I'm sure you know they've made great strides with plastics in the 20th century. #ad

 

[Tim]

What kind of mods are you planning on to test that clutch?



On edit:



More to the point, what are you going to test the G56 with (Now that the DMF will not be protecting the trans any more)?

That is their job. Blumenthal's is the largest transmission parts supplier in the nation and they are going to open up the G-56 and find out truely what it's capable of.



As to mods, if I had them, I certainly wouldn't post about it here. That is a recipie for DC to void your engine warranty completely and I will have no part in such a discussion.

What will that do to your 3/36 and 7/70 warrantee for the transmission and assocated parts?

It will transfer the responsibility to the best clutch manufacturing company in the country, and the biggest supplier of transmission parts in the country. They are responsible for anything and everything that this does to my truck. I am willing to be the guinea pig so the rest of us G-56 owners can have a product available on the aftermarket to replace/upgrade their clutch. Regardless, they will be my warranty supplier from now on, and I expect that they will cover the cost of (theoretically) clutch and transmission replacement should any of that happen.



I'm not just letting anyone tear apart my $40,000 investment and have their way with it. These are professionals. Question it if you like, but it's worth it to me.

 

[JCleary]

That is their job. Blumenthal's is the largest transmission parts supplier in the nation and they are going to open up the G-56 and find out truely what it's capable of.



As to mods, if I had them, I certainly wouldn't post about it here. That is a recipie for DC to void your engine warranty completely and I will have no part in such a discussion.

Well, that's certainly too bad. You're going to install a clutch that will hold 500 or more hp, but you're too paranoid to discuss power mods that will actually "test" the capabilities of your new clutch. Your transmission warranty would be voided anyway, so what's there to be worried about? If you crunch the transmission, SBC will get you a new one for a replacement anyway, right?



I just don't understand why they'd pick you, who won't talk about any power upgrades.



If you don't talk about your engine mods, you can't validate the capabilities and reliability of your new clutch/trans setup.

 

[South Bend Clutch]

Let me see if I can shed a little light on what we are doing and clear this up a little.



Tim has graciously offered up his truck so the after market transmission/clutch suppliers can better understand what the G-56 is all about. I think Tim should be commended for this!!!!!!!!



That being said... this is what our intentions are. Tim is driving his truck down to Oklahoma and dropping it off at Blumenthals Sept. 10th/12th. They are giving him another truck to drive while the work is being done. I am flying down and staying as long as needed. The first thing that will be done is to open up the transmission. Our goal is to compare the trans to the NV 5600 and find its strengths and weaknesses. This will show us a few things. Will the G56 be able to take added HP and Torque? What is the long term durability of the transmission? What can be done to rectify it if weak points are found? Will the transmission support a single mass flywheel? Folks, many questions will be answered with this type of R&D.



I spoke with a gentleman from Cummins and was told that it is possible to put the solid mass system in place of the dual mass system but the one thing he stressed is that there was to be no spike from the engine below 400 RPM or transmission damage could occur, hence the reason for the dual mass flywheel, to absorb the spike. We may very well find out once we open up the transmission that it must support the dualmass flywheel unless changes are made. All these questions we have will hopefully be answered in the up coming weeks. I feel confident that I am working side by side with one of the best in the field (Blumenthals) in the manual transmission industry and I will use what knowledge I have in the clutch department. Between the two of us we will be able to give you the best conclusion once the results are found.



One more thing... many of you that are wondering why worry about the dualmass flywheel. A dualmass flywheel is a two piece spring loaded flywheel that is designed to absorb the dieseling spikes from the engine and can help a transmission to live longer, it takes the abuse. They will ware out and are not cheep to replace but is cheeper then a transmission is to replace. The unit I have at the shop looks sound but only time will tell. The reason I am looking at making a solid replacement is, in the past with the Ford Power Stroke and the new Duramax the flywheels cannot hold up to horse power and torque enhancements.



Wish us luck and please applaud Tim for his confidence in our companies with his $40,000 truck to better the industry in the upcoming years.



Peter

 

[South Bend Clutch]

One more thing I would like to add.



At this point I am not worried about building a high horse power clutch for the trucks equipped with the G56. My concerns are, will the transmission support a solid flywheel. I will not build something that will eventually ruin your transmission for any amount of money. This is the reason for the exploratory actions we are taking before it is done. If it proves that it can't be done, then I will get to work on a better dualmass flywheel. LOL



Peter

 

[67guzzler]

Peter --



So I get it from your standpoint. You want to gut a G56 to check it out and see if there is a product out there that might add more value to the transmission and make it more durable.



But as a 2005 G56 owner is it premature for me to bail on the standard DMF that came with my transmission? The only issue I'm having is a difference of opinion as to the amount of driveline slack I have -- I think it's excessive -- the dealer(s) don't. But the transmission otherwise performs well. The clutch engagement is fantastic -- better than the NV5600's I test drove. It's unknown as to how the G56 and the DMF will hold up to major bombing however. Time will tell.



I guess to summarize my question -- Is the SMF inquiry based on traditional negative views of the DMF or is there tangible evidence with this G56 that converting to a better DMF or a SMF is required for bombing or heavy towing?



TIA.

 

[klenger]

Good report Peter, and good luck.

 

[hasselbach]

Doesn't it figure that the DMF is used to allow DC to use a weaker transmission (ie costs)? The spiking that peter talks about is pretty significant in a 6 cylinder diesel. Why not focus on making or improving on the DMF? There are a lot of benefits to them if they can be made to live.