you can drill and add heavy metal. Ive used it on SCJ cranks to get rid of the external balancer hatchet, but it expensive. be cheaper to buy a new 300D flywheel, or have one shipped from europe

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

Find one and go for it!

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Never a dull moment at Berry Hill Farm.

Just remember that with the added weight, it will suck up hp due to the engine working more to spin it.

The engine still idles fine with the 616 flywheel, what benefits (other than the engine returning to idle slower) would you find?

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My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior

i think the theory of the heavier 300D flywheel is that it helps dampen vibrations. all 4spd swaps I have seen posted here with 240D flywheels have had a buzzing vibe in the 1700-2000 rpm range. those with this fixed tend to have the 300D flywheel. the other use of the heavier flywheel would be at start of motion on first clutch release it will have more rotational inertia to take off easier. I dont have any issue taking off with the 240D flywheel, even with 2.47 gears. and the buzz is easily remedied, shift at 3200 to avoid load situations at 1700-2000 rpm.

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

That sounds like it might be a little more complicated than running a few beads of hard facing

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

ive had bad history with cast iron welds, just scares me on something turning 4000 rpm

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

Thats a good thing for a person to know, I wouldn't pick up a hot horseshoe twice either

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I wonder about that. A 617 has a completely different set of harmonics from the 616 and a little extra weight on the flywheel doesn't seem like it would change much. I always though the added flywheel weight is because the 617 has the additional mass of a crank throw, piston and con rod.

That's like telling someone to stop breathing to avoid getting a cold. Come drive mine that way sometime; it sux, trust me.

All that said, I've thought about the vibration long and hard and, have come up with these factish things:
1. On this forum, there are only a handful (say six or seven) of conversions to 4-speeds in turbo 617s
2. Of those, only one or two that I know of has reported NO VIBRATION in the 1700-1900 range. Case in point: Member TomJ did a several conversions for some biodiesel outfit in Colorado and all but one vibrated plus, I recall one other member that did a conversion who reported no vibrations. I don't believe there was any connection between vibration and flywheel weight in either of those situations.
3. Henry Schuman who has worked on more Mercedes-Benz that we'll ever see, once reported to me that in his career some cars he worked on would have a harmonic balancer device in the driveline, right behind the front flex disk. The balancer wasn't on all manuals but, similar models would sometimes have the balancer and sometimes not.
4. Mine vibrated with both the 4-speed and the 5-speed.

My (admittedly half-baked) conclusion is this:
The issue is a torsional oscillation in the driveshaft caused by one or more of the following:

1. The 617's power pulses are harmonic with the driveline length at certain RPM and some driveshafts amplify torsional oscillation when there are significant differences in durometer value between front and rear flex disks.

or,

2. The 617's power pulses are harmonic with the driveline length at certain RPM and amplify torsional oscillation when the durometer value of the front and rear flex disks is too high.

or,

3. The 617's power pulses are harmonic with the driveline length at certain RPM and amplify torsional oscillation when the durometer value of the front and rear flex disks is too low.

4. The harmonic balancer was installed at the factory on the cars that had a vibration because it was a faster solution than swapping out flex disks to eliminate vibration.

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Never a dull moment at Berry Hill Farm.

ya mean like this one? Here's the harmonic balancerBoth are in my garage along with everything else from a 617-912 mated to a four speed. I pulled them from the yard but am looking for a car with a bad tranny to put it into.

I've got one of each. IMHO, the heavier flywheel and the extra flywheel on the ds all are there to dampen the fierce vibrations of the 5 cyl 617.

Every 617 I have had with an automatic dances up and down like a jack in the box. My 240/300d with the proper 300d fw idles so smoothly you would swear its a six.

With a 240 fw on the 300 (I have one of those too, my 82 300cd) there is noticably more vibration but not enough to fool around trying to build up a 240 fw to match the weight of the 300 fw.

I will say this though, in climbing from one to the other the one with the 300d fw is much easier to shift smoothly. With the 240 fw its very difficult to shift smoothly. I think its because the engine speed drops too quickly.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I have a 4-speed with 2.47 gears and 240d fw and get very little vibration. I do agree with R Leo and the harmonic response with the flex discs, but the level of the trans mount does make a difference. I did a trial and error with the trans mount and got rid of most of the vibration (when I had the 2.88), then when I switched to the 2.47 it came back with a vengeance. I did more trial and error with the mounting of the trans mount (lowering it with washers) and effectively got rid of it again. It's not completely gone, but it's hardly noticeable.

The engine speed drops very quickly with the 240d fw. I haven't replaced the flex discs yet, but want to. I also want to see what the harmonic balance will do on the ds. I would also like to get a trans mount for a 300d manual trans. Until I can find these items, I am satisfied with what I have, and I know my motor mounts and trans mount are all trashed. They are getting replaced next week, and I can't wait to see how it feels then. Even with the way everything is now, I am not willing to deal with the loss of power to try the heavier fw, even if it gets rid of what little vibrations is left.

R Leo, I must say thanks for your write up from a few years back, I lived by it on my conversion. However I think the ds place you recommended screwed up the balance on mine.

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My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior

Thanx for the kudos.

And, I agree, Thrash driveline isn't the place it was when I did the first conversion. When I did the 5-speed, they wanted to retube my shaft for some reason. It cost me an extra $100 plus, I think they got the measurements wrong to boot.

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Never a dull moment at Berry Hill Farm.

shifting at 3200 works awesome for me, I sometimes shift at 4500. I dont think these motors are meant to be lugged. I agree there are some harmonics at play with the 617 and 4spd. I have also lowered my tranny mount with washers to get rid of most of the vibs. It got better with my rear swap to a 500SEL 2.47, nothing else changed. the shorty front drive shaft is indeed different than the 240 by about 4 inches suggesting a higher frequency harmonic potential, along with the 5 cylinder adding a cylinder at each RPM giving a pulse frequency increase. that makes sense. I have added the damper on the DS and it made no difference. if it is the DS vibrating, would adding weight to the middle of the short driveshaft be the answer to reduce the harmonic frequency?

__________________

1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

I don't think it is the short shaft because the vibration is almost the same on my 5-speed as it was on the 4-speed and the 5-speed's shaft is even shorter!

Interesting in your case that the damper (the thing I called a harmonic balancer) didn't have any effect on the vibration...so much for my theory.

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Never a dull moment at Berry Hill Farm.

from your comment above, I think you should try spacing the trans mount down some. before i did that mine was unbearable, now it revs to 4500 smooth as silk, 3200 shifts are nothing.

flywheel, vibration discussion moved here:

http://www.peachparts.com/shopforum/diesel-discussion/239847-300-turbo-manual-1700-2000-rpm-vibrations-post2044054.html?posted=1#post2044054

__________________

1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)