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  #1  
Old 09-14-2011, 12:41 AM
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is the lighter flywheel too light?

hi all,
i'm mating an '85 617 with a 4-speed and i'm not wild about trying to find in the US the heavier flywheel this is supposed to take. i have read reports that the lighter flywheel from the 616 can be used successfully. only the latter needs to be rebalanced, right? (perhaps the machine shop doing the balancing could also add weight to the wheel?)

do you guys driving a 5 cylinder engine with the light flywheel kill the engine any more often than you'd like?

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  #2  
Old 09-14-2011, 06:08 AM
t walgamuth's Avatar
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The light flywheel works fine technically. It allows the engine speed to drop more quickly between shifts and makes it difficult to shift as smoothly. The balancing issue is the same whether using the lighter flywheel or not. You need to mark the fw and crank when disassembling. then have the fw checked to see if it is neutrally balanced. Odds are it is but some are balanced with the crank and if they are and you ignore it you will be sorry. If it is not neutrally balanced the fw that is going back on the car will need to be balanced to the old fw and put back on in the same location to give a smooth running engine.
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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.
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  #3  
Old 09-14-2011, 11:27 AM
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I have the 616 FW in our 85 300D. no I don`t have any problems with killing the engine with this FW. good luck finding a 617 FW in the JY, you just have keep checking each week as they change the inventory.

You don`t have to rebalance the FW, just have it matched to the auto FW. as Tom said, mark the fw and crank before you remove it. then mark the manual FW so it can be replaced in the same location. I don`t have problems shifting with this lighter FW, but then I have been driving a stick for the past 50yrs.

Charlie
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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  #4  
Old 09-14-2011, 12:36 PM
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Like Tom says, it does affect the shifting a little - and you learn to stay on top of your shifting also. No stalling, no problem with the idle and on my switch also, I did not know the position of this engine, (The 240D) since it had a major failure and the chain was broken, I couldn't find any mark on either the starter ring gear or the flywheel, so we just put it on and it all worked out. I don't think it would be very costly to add the weight to the flywheel. That flywheel is "pan" shaped and if you could find an over size steel ring to machine it from and make it a very tight friction fit, that would be great. I think you would have to do just a little machining on the flywheel to clean it up for this "shrink" fit. For about $1000.00 you can import one from the Fatherland.
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1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!
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  #5  
Old 09-14-2011, 01:28 PM
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Quote:
Originally Posted by bricktron View Post
hi all,
i'm mating an '85 617 with a 4-speed and i'm not wild about trying to find in the US the heavier flywheel this is supposed to take. i have read reports that the lighter flywheel from the 616 can be used successfully. only the latter needs to be rebalanced, right? (perhaps the machine shop doing the balancing could also add weight to the wheel?)

do you guys driving a 5 cylinder engine with the light flywheel kill the engine any more often than you'd like?
Nice topic!

Something to mull over in the forthcoming winter months.

When is a flywheel too light?

Science project sources of information include:-

http://en.wikipedia.org/wiki/Flywheel

http://www.botlanta.org/converters/dale-calc/flywheel.html
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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #6  
Old 09-14-2011, 03:42 PM
Geezer
 
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Quote:
Originally Posted by Army View Post
...When is a flywheel too light?
When there is not enough inertia to keep the crankshaft rotating from the beginning of combustion of one cylinder to the beginning of combustion in next cylinder in the firing order?
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  #7  
Old 09-15-2011, 12:39 AM
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OK, sounds like i have a couple of options, thanks guys. i'm wondering how to calculate the time you have with clutch disengaged before the engine stalls with each flywheel but i'm sure i don't need to do that to get the job done. i have only been driving a stick for 11 years but hoping that suffices to make me comfortable with the quicker changes. i did notice that the throw on the shift lever was larger than in other cars i've driven; is a short shift kit helpful in this situation or have you all grown to like the long motions?
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  #8  
Old 09-15-2011, 02:32 AM
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Location: Out in the Boonies of Hot, Dry, Dusty, Windy Nevada
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There really isn`t a shifter kit, but you can modify the shifter levers.
http://mercedes-190.co.uk/topic/6528449/1/

http://mercedes-190.co.uk/single/?p=145837&t=227265

Shifter bushings can make it sloppy. here is one making some bronze bushings. and the dimentions.

http://mercedes-190.co.uk/topic/217321/1/

http://mercedes-190.co.uk/topic/6585129/1/

Charlie
__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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  #9  
Old 09-15-2011, 02:42 AM
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Join Date: Sep 2009
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Quote:
Originally Posted by Jim H View Post
When there is not enough inertia to keep the crankshaft rotating from the beginning of combustion of one cylinder to the beginning of combustion in next cylinder in the firing order?
Yes I think so too - but I'm guessing it is also related to engine health. If this winter turns out to be terrible and I can't work on the car I think I might break out the maths books and work out some numbers - make some graphs - have some (geek) fun.
__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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  #10  
Old 09-15-2011, 05:59 AM
t walgamuth's Avatar
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That is one definition. There are practical reasons for a flywheel too such as providing a place to put a ring gear. The weight of them though I believe mostly is determined by a want to make the engine run smoothly.

On my formula ford the stock flywheel was about eighteen pounds on a little 1.6 motor. We are allowed to lighten it to 15.5#. I don't expect to be able to feel any difference but it should make the engine accelerate and decellerate a little faster, which in a race car of course is desirable. In other sanctining bodies a lighter flywheel is legal so I have seen aluminum ones offered at 6#.

The factory 38# 617 flywheel makes the 617 idle and accelerate like a six cylinder (smoothly). With the 28# flywheel there is a little more vibration but it is still smoother than the 617 with an automatic which hops around like a jumping bean at idle.

More cylineders make a heavy flywheel less necessary too. My old Ferrari v 12 had an aluminum flywheel that (speaking from memory now) may have weighed abuut eight or ten pounds. That engine would wrap up and down like a race car, but it still was pretty smooth. When you drove it though there was a definate feel to each power pulse which gave an eager feel to the motor.

A heavier flywheel would have dampened this and made the power flow like an electric motor, which would be desireable in a luxury car. In a sports car the idea is to make it a sensory experience and exciting.
__________________
[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.
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  #11  
Old 09-16-2011, 01:31 AM
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this is getting esoteric.... but... it seems to me that the measure of weight itself is of less concern than how far off-center that weight is. i think it's with good reason that the flywheel has a heavy outer lip (apart from the gearing for the starter) - it can have more rotational intertia than another weight of the same mass but different shape would. this has to do with the leverage exerted by a mass turning at some radius, right? so wouldn't we be doing better to talk about the foot-pounds (m-kg) of a flywheel?
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  #12  
Old 09-16-2011, 01:53 AM
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replacement bushings sound smart. i don't mind getting them machined, but getting just the shifter bushings would be a lot simpler than the other flanged types pictured. can anyone speak from experience about the effect of the replacement bushings?

- thanks for the links charlie.
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  #13  
Old 09-16-2011, 02:27 AM
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I'm using the flywheel from a 1972 220d with an om617. I think this flywheel is even lighter than the 240 flywheel. It has stalled because of the light flywheel a only twice that I can remember in the 2 years I've been running it.

One other thing worth mentioning is that the crossmember and shifter rods both bolted up to the w123 with no modification.
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  #14  
Old 09-16-2011, 04:28 AM
1985 190d
 
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Does anyone know the comparative weights of a 601 flywheel compared to a gasser 190 equivalent fw?
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  #15  
Old 09-16-2011, 06:07 AM
t walgamuth's Avatar
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Quote:
Originally Posted by kahea View Post
I'm using the flywheel from a 1972 220d with an om617. I think this flywheel is even lighter than the 240 flywheel. It has stalled because of the light flywheel a only twice that I can remember in the 2 years I've been running it.

One other thing worth mentioning is that the crossmember and shifter rods both bolted up to the w123 with no modification.
I can assure you that it did not stall because of the light flywheel.

__________________
[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.
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