More balancing questions: 4 speed swap W123 - PeachParts Mercedes-Benz Forum

jcwells · #1 04-08-2006, 10:45 AM

I have read through the other balance threads and still have some questions regarding the balancing of these drivelines. I converted my 1982 240D from auto to stick and completed a restoration at the same time. A portion of the restoration is recorded in this thread: http://www.peachparts.com/shopforum/showthread.php?t=77190. Today, I drove it for the first time for about 60 miles mixed highway and city. The car has been off the road for 3 years, so I must say it is hard for me to remember exactly how “smooth” these cars are, but I do think it has picked up a rumble at some RPMs (unknown since I don’t have a tack). I know I have far fewer issues than those that convert 300D’s to stick but none the less I was looking for some conclusive comments so here goes.

When I reassembled the engine and tranny (about 1.5 years ago) I had not read about the witness marks on the crank and flywheel and so I just bolted up the flywheel at a random orientation. Its no big deal to remove it and align it but:

1. Are the witness marks always at the same location on the cranks from different engines and vintages? If they are not always at the same position, matching marks from different engines is pointless. My engine is a 1982 and the donor flywheel and tranny are from an 84.
2. Were the automatic equipped engines balanced with just the flywheel (drive plate) or with the flywheel and torque converter? If the latter, having a shop match the 2 flywheels would also seem pointless.
3. If the answer to 1. is yes, and I just simply match the marks, I am hopping that the balancing needs of my 1982 engine match those from an engine made 2 years later. Is this not unlikely?

Maybe we just have to live with balance problems with these swaps.

Comments please.

Thanks,

John

Here’s a photo of the almost complete project. The wheels are not my first choice but they were free. Notice how it rides high. It’s due to the lighter tranny and the removal of the A/C system.

R Leo · #2 04-08-2006, 11:25 AM

Nice work! That's a great-looking paint job.

1. Are the witness marks always at the same location on the cranks from different engines and vintages? If they are not always at the same position, matching marks from different engines is pointless.

Who knows?...while assembling mine, I made an effort to find and match the witness marks, thinking all the while, that there was no way it would make any difference since the crank and flywheels are supposedly match balanced before going into the engine. I now think that the witness mark is for consistent reassembly of the same crank/flywheel set and has little bearing on replacement flywheels. I can rev my engine to over 4000 rpm in neutral or, with the clutch disengaged and detect no vibration other than those made by the engine before the swap.

2. Were the automatic equipped engines balanced with just the flywheel (drive plate) or with the flywheel and torque converter? If the latter, having a shop match the 2 flywheels would also seem pointless.
Don't know. Considering the Teutonic mindset, they probably balance the converter/drive plate/crank as an assembly.

The car has been off the road for 3 years, so I must say it is hard for me to remember exactly how “smooth” these cars are, but I do think it has picked up a rumble at some RPMs (unknown since I don’t have a tack).
That rumble could be any number of things: worn u-joint in the driveshaft, worn center bearing, axle wear, etc.

The problem I'm having is a distinct buzz...like an orbital sander. I think a couple of others on the forum have this but at different rpms.

Notice how it rides high. It’s due to the lighter tranny and the removal of the A/C system.
My wagon was the same way after the conversion. I addressed it in this thread. Since you have a 240, the 'proper' spring should be obtainable (there are a staggering variety of springs and applications in the FSM..you owe it to yourself to look at the manual and determine what you have/need). Swapping spring pads for the thinnest ones will bring the front down but not much. If all else fails, you'll need to have some springs made. Check for threads by Brian Carlton for discussion about his new rear springs on his SDL...lot abotu getting springs made in there.

Good luck, glad you got your ride back on the road too!

#3 04-08-2006, 07:00 PM

1. "Are the witness marks always at the same location on the cranks from different engines and vintages? If they are not always at the same position, matching marks from different engines is pointless." Each engine is balanced different. Even more so using a flywheel from a four cylinder on a five banger. The only time you need a witness is if you plan on reinstalling the flywheel on the same engine. You MUST have the flywheels match balanced. If you have no other choice (like I did) then just install the 240 wheel heavy-side to -heavy side. Look at where they drilled the most metal off the wheel for balance on the auto wheel. install the manual wheel with all the drill points as close as possible to where the other was bolted. If you do this, you should get it fixed ASAP or you risk taking out the main bearings.

2. "Were the automatic equipped engines balanced with just the flywheel (drive plate) or with the flywheel and torque converter?" Only the drive plate is balanced. The fluid neutrally balances the Tq converter automaticly (pun intended).

3. "If the answer to 1. is yes, and I just simply match the marks, I am hopping that the balancing needs of my 1982 engine match those from an engine made 2 years later. Is this not unlikely?" As I said, the chances of finding two flywheels balanced exactly the same is 1:1,000,000. I was not able to match balance my wheels due to time constraints. While it does not shake the engine out of the car, it does have a noticable vibration at idle and specific highway speeds. I don't plan on fixing this because my engine idles like cr@p and smokes when cold. When this engine finally decides to go *boom* (from the internal mystery tapping) or refuse to start one day, i'll balance the wheel to the replacment engine.

BTW, i love the body color and rim combo.

mikemover · #4 04-08-2006, 07:11 PM

I can't answer your balance question, but you can easily lower the ride height in front by changing to the thinner coil spring pads and/or changing the springs themselves to the ones that came on factory 240D manual trans cars. The parts can still be ordered from MB.

Nice looking restoration, by the way!

Mike

Stevo · #5 04-08-2006, 08:36 PM

Nice job, the euros and white marker lights really look nice.

I have swapped a couple of manual trannys into auto 240Ds, and have always lined up the witnes marks which are found on the auto tranny cranks too (gota really look close). I have no idea what woulda happened

had I not, but i have never had any viberation problems. I assume you marked the driveshaft if you pulled it apart?

t walgamuth · #6 04-08-2006, 09:02 PM

converted an automatic equipped car to stick (technically i used a crank from an automatic car). we looked and looked and couldnt find any marks to suggest where and how to install and finally just put it on at random. the car was extremelty smooth at any rpm.

i now have a 240 fw loose that i had checked for balance and it is neutrally balanced.

the fsm says you should match balance a replacement flywheel cause they are balanced together but i think the most you should do is just have the fw checked for neutral balance. many folks have done the conversion and just stick it in there without any negative results.

if it were me, i wouldn't tear it out to check it. i recommend driving some other stick 240s and see if yours is rougher than those. i bet you are fine and if you have vibration it is from something else.

tom w

R Leo · #7 04-08-2006, 09:09 PM

Quote:

Originally Posted by t walgamuth

the fsm says you should match balance a replacement flywheel cause they are balanced together but i think the most you should do is just have the fw checked for neutral balance. many folks have done the conversion and just stick it in there without any negative results.

tom w

That's been my experience (40k miles worth). I honestly believe that if there had been a flywheel balance problem with my conversion, it would have manifested itsself by now.