installing a 'new' flywheel to the 617. - PeachParts Mercedes-Benz Forum

JDmills · #1 04-08-2009, 07:44 PM

I want to put one in an old dodge truck... and I am thinking that the stock sized clutch is on the small side.. Plus it would be easier to swap a flywheel, clutch disk, pressure plate, and transmission all at once... IF there was a flywheel that would work..

so heavier is better? How about the balancing of the rotating assembly does it matter so much in that respect?

lutzTD · #2 04-08-2009, 07:51 PM

Quote:

Originally Posted by JDmills

I want to put one in an old dodge truck... and I am thinking that the stock sized clutch is on the small side.. Plus it would be easier to swap a flywheel, clutch disk, pressure plate, and transmission all at once... IF there was a flywheel that would work..

so heavier is better? How about the balancing of the rotating assembly does it matter so much in that respect?

not sure what trans your planning on, but as far as the flywhell question. yes, the machine shaop should balance the rotating assembly including the flywheel. have them take it closer to a race balance of 5 grams or less

you should try to use a heavy flywheel too, the stock 617 flywheel weighs 38 pounds, but the true working measurement is the moment of inertia. you can get away with a lighter one if it is a bigger diameter with weight at the rim, giving it a bigger moment of inertia simply due to its distance to center

JDmills · #3 04-08-2009, 08:10 PM

I am not certain about what transmission to use as of yet.. would like to keep the first gear ratio fairly low.. and still have the option for O/D... I heard that the NV3550 is pretty robust for its size and weight.. although it only has about a 4.00 first gear if I remember correctly.. and I think originally the truck had about a 6.00 first gear..

and maybe a deep first gear would be more useful than OD, in the long run..

38 LBS is kinda heavy sounding.. maybe a flywheel for an 11 inch clutch would be better.. I am still in the deep end of the learning curve here. During the walk today, the idea popped up that I could have the whole rotating assembly balanced.. which opened up the thinking that maybe it could be done..

lutzTD · #4 04-08-2009, 08:16 PM

Quote:

Originally Posted by JDmills

I am not certain about what transmission to use as of yet.. would like to keep the first gear ratio fairly low.. and still have the option for O/D... I heard that the NV3550 is pretty robust for its size and weight.. although it only has about a 4.00 first gear if I remember correctly.. and I think originally the truck had about a 6.00 first gear..

and maybe a deep first gear would be more useful than OD, in the long run..

38 LBS is kinda heavy sounding.. maybe a flywheel for an 11 inch clutch would be better.. I am still in the deep end of the learning curve here. During the walk today, the idea popped up that I could have the whole rotating assembly balanced.. which opened up the thinking that maybe it could be done..

my take is you will have a bit of trouble mating the NV3550 to the 617. there has been talk of an adapter, but none have appeared im aware of. the flywheel weight is needed on the 617 to smooth out the 5 cylinder, and to allow it to maintain RPM between shifts. the 240D flywheel is 28 pounds, and has a annoying drop in RPM between shifts, I also believe but have not proven to myself, the heavier flywheel will help with low RPM torque vibration when lugging the motor

IndianaJo · #5 04-08-2009, 09:35 PM

look at the mercedes 617 thread of 4btswaps.com, there are a lot of people doing this and many of them are there. I believe they have determined the 617 is internally balanced, so the flywheel is round, but the expert is there, not me. If your rear end ratio is high enough to use the high rpm of the mercedes effectively, you shouldn't need a bigger clutch. I'm going to use 4.1 or 4.27:1 in my ford f150, but 9" ford rear ends have drag gears available that go all the way to 5.6:1. I'm going to use the mercedes 722 auto transmission and buy a spicer adapter for the driveshaft end. See cell's thread on this site about that.

JDmills · #6 04-08-2009, 10:49 PM

Quote:

Originally Posted by IndianaJo

look at the mercedes 617 thread of 4btswaps.com, there are a lot of people doing this and many of them are there. I believe they have determined the 617 is internally balanced, so the flywheel is round, but the expert is there, not me. If your rear end ratio is high enough to use the high rpm of the mercedes effectively, you shouldn't need a bigger clutch. I'm going to use 4.1 or 4.27:1 in my ford f150, but 9" ford rear ends have drag gears available that go all the way to 5.6:1. I'm going to use the mercedes 722 auto transmission and buy a spicer adapter for the driveshaft end. See cell's thread on this site about that.

Thanks for the suggestion to visit 4btswaps, I will look it up..
I thought about using the stock 4 speed manual initially, and still may do it.. but would like have more of truck transmission in place.. and a nv3550 seems like it is a nice light relatively robust unit... the stock dodge rear gear is a 5.83 to 1.. so maybe I can get away with 4 speed manual for a while..

t walgamuth · #7 04-09-2009, 06:39 AM

I'd recommend using some variation of a stock merecedes fw and clutch. I don't see any reason to adapt something there and face starter interface problems. adapting the tranny to the bell housing will be tricky enough.

I'd probably use a mb tranny too depending on the application.