M52B30 stroker using single mass flywheel with a vibration

[Franky goes]

Thanks everyone for helping me with this issue. Much appreciated.
I will update as soon as I have the car on a lift.
I had asked the shop to do this but they (Understandably) fixated on the Vanos noise so they missed the otter vibration.

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zellamay
Did you get your flywheel and PP out to balance them an it fixed your vibration or you are just living with it ?
If you are living with it can you describe the noise / vibration ?
Mine sounds like something metallic is loose and past 3,000 RPM I can feel the vibration in the steering wheel while driving.

[zellamay]

I think only the FW was in another car. ..... Also, even if the PP was also that other car, were they marked before disassembly, to ensure same relative locations?

[Franky goes]

The flywheel and the PP were in the other car and the relationship between the two was not maintained a I assumed they were both balanced.

zellamay
Did you get your flywheel and PP out to balance them an it fixed your vibration or you are just living with it ?
If you are living with it can you describe the noise / vibration ?
Mine sounds like something metallic is loose and past 3,000 RPM I can feel the vibration in the steering wheel while driving.

[zellamay]

The flywheel and the PP were in the other car and the relationship between the two was not maintained a I assumed they were both balanced.

zellamay
Did you get your flywheel and PP out to balance them an it fixed your vibration or you are just living with it ?
If you are living with it can you describe the noise / vibration ?
Mine sounds like something metallic is loose and past 3,000 RPM I can feel the vibration in the steering wheel while driving.

I also assumed mine were balanced when I put them in. They weren't. I took them out and had them balanced together, so I don't know which one was out of balance (or both?). That fixed the vibration. It's not as smooth as my wife's E90, (which you can't feel at all), but it's pretty good. There was never a metallic sound, just a solid-feeling vibration that directly tied to engine rpm. I don't remember it in the steering wheel, so if it was there it was minor compared the shifter and floorboards.

[Floxer]

past 3,000 RPM I can feel the vibration in the steering wheel while driving.

Only vibrating at 3k rpm while driving or in neutral at 3k rpm, too?

[Franky goes]

Floxer,
The high frequency vibration starts in the 3000 range and stays as the revs go up. I think it increases in frequency with the revs but it is so high frequency that I can't confirm it changes with revs.

[Franky goes]

The plot thickens.

i was unable to recreate the metallic vibration on a lift. I tried accelerating in third gear while applying the brakes to recreate the street condition but failed. I then took a rubber mallet to everything and found a metallic rattle in one of the exhaust pipe in front of the cat... Should have started with the easy stuff first... Someone else on the forum had a bad vibration under load that got fixed with a new cat.

The exhaust was installed at the same time the engine was modified. It had been in storage for 10 years. I cannot remember if it had that vibration when I removed it.

I re-installed the exhaust that was on the car last year after checking that it does not vibrate when assaulted with a rubber mallet. All good. Start the car and go for a spin. Everything is quiet. For the first time I can feel the new set-up without the metallic vibration and the Vanos rattle. It still has a high frequency vibration past 3000 RPM. It could conceivably be the single mass flywheel that is unable to absorb the normal rotating assembly vibration. It is the kind of vibration I would not have noticed when I tried this set-up in the stripped race car.

So I decide to keep driving and take the car on the highway. On my way to the highway the car misfires (#6). I go back home and switch 2 coil packs. the misfire remains in #6. I swap two sparkplugs and the misfire goes away. It does not follow the sparkplug ? And does not come back in #6. So far this remains a mystery. Not sure it is related to the vibration as it vibrates with or without the misfire.

Listening to the block at idle it is noisy at the head and the oil pan along the length. It's noisier than normal but nothing I would normally worry about if I was not already chasing every little noise.

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Does a cat going bad usually sound like a wrench is loose inside the exhaust pipe ?
I have a third exhaust I can try but I'm starting to wonder if the cat rattling is a symptom, not the cause of the vibration.

[Floxer]

For the first time I can feel the new set-up without the metallic vibration and the Vanos rattle

So it never was the vanos that rattled, but the exhaust?

[Franky goes]

Everything is affecting everything. I'm not sure what the source is at this point.
I need to find an exhaust system that does not rattle so I can continue troubleshooting.

[Franky goes]

This thread is paused while I decide how to fix the exhaust rattle.
You will find that conversation here : https://www.bimmerforums.com/forum/s...6#post30855256

[Franky goes]

While I'm waiting to get my hands on a good section of pipes to get ride of the metallic rattle in the exhaust I decided to clean my workbench and guess what I found ?
IMG_0693B.JPG.jpg
I started with 24 of those clips and I can account for 12 on the pistons I removed plus this one. So if this clip did not land on my workbench with the help of the tooth ferry it means that 11 are presently in my engine.

There must be a tooth ferry because the engine has ran at least 10 hours. It should have grenaded already.
I'm positive I triple checked every pistons before installing them. Heck on a warm engine I have above 205 PSI compression on all 6 cylinders and approximately 5% leak down. I can't see how that would be possible on a 300,000 miles block with one of the piston going up and down crooked.
I should have gotten this by now :
https://www.youtube.com/watch?v=-_hAsTxd9bA
This makes no sense...

[pbonsalb]

Might not have worked its way out yet or maybe you put a used one in?

[Floxer]

Will you take it apart to check or will you live with it. This would make me crazy, not knowing if the clip is there or not.

[pbonsalb]

Will likely ruin the block once it works its way out. Could that tiny part affect balance and lead to vibration?

[Franky goes]

I'm like you. It is driving me up the wall.

I put over 10 hours on this engine.
Even if it is a remote chance that I forgot one clip I'm tearing it down. I figure another 10 hours is not going to make a difference at this point.
Never did bearings from under the car. That should be lovely.

pbonsalb,
I doubt it would contribute to a vibration as it would mean the piston is half destroyed. Who knows. Maybe it is.

I'll report once I get the pistons in my hands.

[Pavlo]

I have been all through this one a few times now. In short, it is the flywheel/clutch combo. You can go heavier and/or lighter and it will likely go away, but I’d advise going back to a dual mass. The noise is harmonics, it will be ok for a long time but will also rattle things like oil pump and oil pump nut off (especially if you track it). ATI dampers help, but a DMF is half the price and way more effective.
The start of this problem starts with overall inertia of the rotating things (note that weight doesn’t always mean the same inertia), when you change it you move the natural frequencies of the system around and the combination that you have is just not happy. I’ve even had a rod bolt rattle out on one of my S54s because of this. When you lighter in weight, these harmonics go up, so goal would be to go very light and move it above redline. Stock dual mass actually places the natural frequency of the system below idle usually, which is pretty cool as it’s never a problem.

A well designed flywheel will have a low inertia vs its weight (material located closer to the center) and companies like LUK really do know what they are doing. In my S54 car I now run a chromoly 20lb single mass (minor rattles, but ok). My two S52 cars use dual mass only now. One of my S50s I went through nearly the same thing as you and oil pump was coming apart every time I dropped the pan.

Another thing I found is that clutch pressure plates are not balanced well, unless it’s LUK. Literally every single other brand I’ve had issues with, even Sachs. Even brand new clutches I usually have my machine shop balance them for me, just prevents a potential re-do.

Good luck!

[Franky goes]

Thanks for sharing your experience Pavlo.

I think we all agree that this is where I'm going eventually but in the mean time I'm testing to understand the degree of vibrations coming from different places. I do not believe I mentioned it before but the frequency of the vibration is fairly high but not the second order stuff that kicks in above 7,000 RPM. I believe this is where the ATI damper shines. The vibration is not as 'slow' as an imbalance would be on the flywheel either. It hums and vibrates many small plastic parts in the cabin.

So next step was to go check if I had missed a clip on one of the piston...
I'm happy to report that I did not. So that clip on my workbench can only have landed there with the help of the tooth ferry !
For those considering changing pistons with the engine in the car here is my setup:
IMG_0734.jpgIMG_0733.jpg

Installing con rods on my back was even more enjoyable than I had feared. After multiple misses trying to get the angle torque procedure, I threw away all the OEM bolts and installed ARP bolts instead.

I also had the chance to revisit all the choices I had made in the build and made some changes:
1. I removed the splash guard as it was pretty close to the pump pick-up tube.
2. With the likely residual vibrations going forward I decided to install an upgraded shaft oil pump from VAC that I had in stock.
3. I also changed the primary and oil pump chain and sprocket back to what was in the car from the factory. Well used but known to be good.
4. I installed an E46 330 vibration damper.
4. Biggest change was replacing the second compression rings because one of them was damaged when I removed the piston.

I suspect I damaged it on the install as I struggled on some cylinders. I had worked extremely hard to insure the rings went back in the original position but that died when I replaced those rings with new. The crosshatch was still good enough that it will not matter much but I will obviously loose some efficiency with a slightly lower compression all around. To hone, even roughly, meant taking the engine out of the car and that was absolutely not in the card.

I'm curious to see if the E46 damper will make a difference as it is 4 to 5 pounds heavier than the E36 one and tuned to a different frequency. After all everything else in the rotational assembly is from the E46 330. Why not use the correct damper...

I should have the engine fired up sometimes next week and will definitely update.
Thanks again to my support group LOL

[pbonsalb]

I did the rod bearings on the S65 in my E90 M3 using stock bolts. For that motor, the instructions require repeating the 3 step process 3 times for each bolt and the final movement of the 3 step process is angle torque. Including the loosenings, that is 176 movements total with 48 of them bring angles. I helped a friend do his and he used ARPs — 3 step process with no angles and no need to repeat the process 3 times for each bolt so only 48 movements total.

Interesting the S52 crank with smaller pistons uses a heavier damper. Could there be a difference in rigidity between the iron and aluminum blocks? The rare aluminum M52 may use the S52 damper but the M52 crank has much less stroke. Let us know what you feel.

While disassembling the motor was no fun, you did find and fix a problem — the damaged ring.

[Franky goes]

Here is a picture of the 2nd (Napier) compression ring that failed on my first install.
Looks like fatigue failure even though it failed in a period of 10 hours.
IMG_0732 rog.jpg

[Franky goes]

The car is back together. As predicted by some of you nothing has change except the vibration in the primary chain is back. Most likely because I replaced the ATI damper with the E46 330 OEM damper. Same vibration in the steering wheel past 3000 RPM. The sound of the engine is rough (to my untrained ears). There is a faint knock around the oil pan.

Moral of the story is that a single mass flywheel is perfectly fine for a track car if you don't mind the extra wear and tear on the rotating assembly. It's OK for the street if you are not too obsessive compulsive. I have obsessive compulsive tendencies so the single mass flywheel is coming out. Dual mass flywheel is on order and going in this week. I will report back.

Thanks.

[pbonsalb]

So much work, but it’s great you found that piston ring before it did any damage. I don’t have OCD — I like to do things right but if I understand the reason for NVH and know it is not doing any harm then I am OK. I have that situation now with a GS6-53 swap, but after a couple of years with loud gear noise at idle, I think I want more civilization since my M3 is a street car and am considering other options but need 600+ lb rwtq capacity so I can’t use the ZF320 — broke a couple of those. Either a better GS6-53 conversion or maybe a T56 Magnum. Also want to get away from the 1 piece driveshaft.

[spyderg0d]

Reading the first few posts it sounds like a misfire from improper fueling. Maybe bad injector throwing a cylinder off in mid throttle or rev range.

[Franky goes]

Back from the dead !

Back in June I did what I said and re-installed a stock LUK DMFW and PP.
Things improved but there were still too many vibrations for my taste. Still vibrations in the shifter and steering wheel linked to RPM and a low frequency shake under acceleration and a cling clang at constant 30 mph speed.

At that point my girlfriend started putting pressure on me to drive the car into a lake. I must admit I had 2 seconds of weakness when I seriously considered it. But walk away on a failure ? Nope.

I put the car on blocks and ran it in gear. That was a symphony of metallic sounds especially at constant speed. It felt like there was 1 inch of backlash in the differential. Upon further inspection (Removing the heat shield) it turns out the two U-joints of the driveshaft were completely shut. I think that tightening everything else made the last worn part in the system very, very, unhappy. Rookie mistake ! The shaft came out and replacing it was a project in itself. Here is the thread : https://www.bimmerforums.com/forum/s...l-E36-328-1997

Summer is racing season so that project got shelved.

The decision was made from Pavlo, Pbonsalb and others comments to balance the flywheel and PP assembly. Found a local guy that actually balances everything as an assembly. Damper, crank, rods, pistons, flywheel, and PP. The engine is not coming out of the car so I decided to bring him a spare crank with the Flywheel and PP. He balanced my spare crank alone, then the Flywheel bolted in, than the PP bolted to the Flywheel. I don’t know how much I can trust the numbers he gave me, but they are scary. The flywheel was off by 30 grams and the PP by 20 grams. If by a fluke I aligned those two imbalances that would be 50 grams. For reference, typical wheel balancing weights are 2.5 or 5 grams. That is the equivalent of a 10 self adhesive wheel weight imbalance… Odds are I did not have these two imbalances aligned. Odds are I also did not have them facing each other either, so this represent a large imbalance at probably 15 to 25 grams when they are vector combined. Ouch.

The new drive shaft and the balanced DMFY/PP assembly were put back in the car last week when I received the drive shaft.

Improvements from the drive shaft fix:
The cling clang that was shaking the exhaust pieces loose is gone. So is the shaking under acceleration. I now realize it was on its way out for a long time before the upgrade. I just been reacquainted with the ultimate driving machine I bought 18 years ago. What a difference !. Tight and solid through the gears.

Improvements from the flywheel balancing:
The vibration that was shacking every plastic part in the cabin is gone. No more vibration in the steering wheel and very few in the shifter when the engine is revved below 3000rpm. I’m floored by the difference. Maybe it was off by 50 grams after all…

There are still some vibrations in the shifter above 3000 rpm but I tested my E46 330 for vibrations past 3000 rpm and the stroker has the same pattern but actually less vibrations that the E46. I never realized how much the M54 engine vibrates. The worst is at 3000 and 5000. It dips at 4000. I did not test to 6000 but it felt like the vibrations would be comparable to the 5000 values.

I’m tempted to try the E36 damper on the stroker to see if it will diminish those remaining vibrations but that is project for the spring… I will update if I try it.

I want to thank everyone for their help. I might have driven it into a lake without it. You guys sharing your experience was a difference maker. Very much appreciated. I hope this thread can help someone else eventually.

Take care.