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+--- Thread: Match Balancing (/showthread.php?tid=6116)
Match Balancing - Biocruzer - 01-07-2015
Happy New Year, all.
I'm converting a 1981 300D from auto to manual, and the glitch of the moment is match balancing. From the terminology, it sounds like the balance of the flexplate is determined, then the flywheel (off a 240D) is matched to that, marked at TDC and returned to the crankshaft. Am I right? If not, what is the process? The local blokes either need (they say) my crank, or a 240D crank to do the deed, and some even say I need to supply rods and pistons. Isn't there an easier way?
RE: Match Balancing - zeeman - 01-08-2015
(01-07-2015, 11:42 PM)Biocruzer Happy New Year, all.
I'm converting a 1981 300D from auto to manual, and the glitch of the moment is match balancing. From the terminology, it sounds like the balance of the flexplate is determined, then the flywheel (off a 240D) is matched to that, marked at TDC and returned to the crankshaft. Am I right? If not, what is the process? The local blokes either need (they say) my crank, or a 240D crank to do the deed, and some even say I need to supply rods and pistons. Isn't there an easier way?
If you marked the flywheel location to the crank before you took it off, they should be able to match balance it.
RE: Match Balancing - F.R.A.S - 01-08-2015
There are stock balancing if we may call it that and then it's performance balancing.
In the stock car they have individually balanced parts to quite high tolerances. So they don't have to look for the right flywheel and so on, they just grab one and fit it.
When going higher revs or higher power output you need a better balanced engine. Therefore you weigh match all pistons to be maximum 1-gram between the most heavy and the lightest one. The rods you weigh in both the little end and the big end (the total rod weight should also be within 1-gram). Then you straighten the crank and balance it together with your front "thing" (I can't remember the name in English now), flywheel and clutch setup...
How ever if your engine is stock internally you can just zero balance the flywheel and be done with it.
Hope this helps you mate.
RE: Match Balancing - raysorenson - 01-08-2015
Zeeman, are you saying the flywheel isn't neutral balanced?
RE: Match Balancing - Petar - 01-08-2015
(01-08-2015, 08:20 AM)F.R.A.S There are stock balancing if we may call it that and then it's performance balancing.
In the stock car they have individually balanced parts to quite high tolerances. So they don't have to look for the right flywheel and so on, they just grab one and fit it.
When going higher revs or higher power output you need a better balanced engine. Therefore you weigh match all pistons to be maximum 1-gram between the most heavy and the lightest one. The rods you weigh in both the little end and the big end (the total rod weight should also be within 1-gram). Then you straighten the crank and balance it together with your front "thing" (I can't remember the name in English now), flywheel and clutch setup...
How ever if your engine is stock internally you can just zero balance the flywheel and be done with it.
Hope this helps you mate.
While this is true for most engines it isn't for the 617 since the crank and the flywheel are balanced as a unit.
(01-08-2015, 08:50 AM)raysorenson Zeeman, are you saying the flywheel isn't neutral balanced?
He says that if you marked the flexplate in relation to the crank that you can take the flexplate and the flywheel to a machine shop and have them match balance the flywheel to the flexplate.
However if you just removed the flexplate without marking it's position you are in trouble since you don't know how it goes back and it can go back in 12 different ways
RE: Match Balancing - raysorenson - 01-08-2015
(01-08-2015, 10:33 AM)Petar While this is true for most engines it isn't for the 617 since the crank and the flywheel are balanced as a unit.
Where did this info come from? Does this apply to the 616?
Other people have not had this experience on the 617, myself included. I stuck a zero balance Fidanza on a 617 with no resulting vibration problems.
RE: Match Balancing - w123love - 01-08-2015
+1 here on zero balancing. Just balanced the flywheel alone, and had no issues on a 617 4 speed swap.
RE: Match Balancing - raysorenson - 01-08-2015
And here it is: http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/617/03-440.pdf
Hopefully the link works.
Quote:.....a new flywheel must be brought to the same balancing condition as the removed flywheel
Maybe I'll do it that way next time....
RE: Match Balancing - F.R.A.S - 01-08-2015
How do you know this? Know anyone working at Mercedes in the late 70's and early 80's?
(01-08-2015, 10:33 AM)Petar While this is true for most engines it isn't for the 617 since the crank and the flywheel are balanced as a unit.
RE: Match Balancing - Petar - 01-09-2015
(01-08-2015, 11:24 AM)raysorenson(01-08-2015, 10:33 AM)Petar While this is true for most engines it isn't for the 617 since the crank and the flywheel are balanced as a unit.
Where did this info come from? Does this apply to the 616?
Other people have not had this experience on the 617, myself included. I stuck a zero balance Fidanza on a 617 with no resulting vibration problems.
(01-08-2015, 11:28 AM)w123love +1 here on zero balancing. Just balanced the flywheel alone, and had no issues on a 617 4 speed swap.You just answered yourself
(01-08-2015, 12:57 PM)raysorenson And here it is: http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/617/03-440.pdf
Hopefully the link works.
Quote:.....a new flywheel must be brought to the same balancing condition as the removed flywheel
Maybe I'll do it that way next time....
Some 617 engines are neutrally balanced, some aren't and there is no way to tell apart which is which. 616's are all neutrally balanced i think.
(01-08-2015, 01:15 PM)F.R.A.S How do you know this? Know anyone working at Mercedes in the late 70's and early 80's?
(01-08-2015, 10:33 AM)Petar While this is true for most engines it isn't for the 617 since the crank and the flywheel are balanced as a unit.
This info comes from the internet and MB factory service manuals. I apologize if something i say isn't correct.
RE: Match Balancing - raysorenson - 01-09-2015
Yeah, you were right. It's there in the WSM in black and white.
I have not seen or heard of a 617 that is externally balanced in the sense that the crank was manufactured to have a flywheel with a heavy counterweight to keep the engine in balance like the older "small block" Fords and others. The counterweights are so heavy on those flywheels that if you get the indexing wrong, you'll be scared to even let it idle. The amount of balancing on the 617 flywheel, if any, is orders of magnitude smaller.
There are simply too many people installing zero balance flywheels without tearing up bearings or feeling vibrations. Of course, the better the balance the better, but very few 617's see high rpms. It would be a waste of money to have the rotating assembly balanced just because the indexing was lost on the FW.
RE: Match Balancing - swampmonkey - 01-09-2015
ive heard the same, some swap flywheels without problem, and some swap and the engine sounds like it tearing itself apart.
mark it before removal, take it to a shop, get it balanced, and if uneven, get the new flywheel balanced to match that.