harmonic balancer help

[s50b30]

I have a m50 stroked with a m54b30 crank.

i have problem with crankpulley/harmonic balancer bolt keeps coming loose.
New bolt everytime, loctite, and the right torque is used.

so I think its a matter of wrong harmonic balancer.
First it came loose with the standard m50 pulley, then I switch to m52.
and the same thing happened.

the frequency of the m54 crank is 275- 305hz
so that would be ideal, but the standard balancer is missing the trigger tooths.

m52 is 390-430 hz
Dont know the m50 frequency.

is there any other harmonic balancers that may have a similar frequency?
I know vac/ati has a custom damper, but not sure if its gonna work. And its pricey as hell.

thanks for inputs.

[daandaman]

Harmonic damper

And the way these things truly work is still 50% a mystery to me. I'M sure though that it isn't about the own/resonant frequency alone...

What I did was buy the vac/atI one and hope for the best... there are no alternatives AFAIK anyways

[mike radowski]

What are you torquing the bolt to?

[s50b30]

410nm.

isnt there any other options from other engines?
1000$ is alot of money for a pulley l.

[mike radowski]

What rpm are you spinning the motor to? Also, do you have A/C installed?

[Nutzy]

How did you work out those frequencies?

[s50b30]

Frequencys are stamped on the damper.
7500 rpm. too much for vanos head.
No ac.

[Nutzy]

Oh snap! OK, so I am about to use an M50 damper on a M52B28 crank in an M50 block. Bad idea then I presume.

[s50b30]

Might be.
I think my problem might me the long stroke crank + m20 (lighter) flywheel.
might be a bad combo, but those frequencies are black magic to me. So who knows.
I would suggest m52 damper anyway.

[BimmerBoy]

Just incase you didnt check, but maybe need new woodruff keys?

[s50b30]

Woodruff key is new.
it Broke last time the bolt came loose.

[nzbimmer1]

Hi there,
I just found this old post and ive got the exact same issue on my M52B25 stroked with M54 3ltr crank and internals in my track car.
Engine goes great, but the crank bolt keeps coming loose. did you ever find the answer to this issue? or did you change to M52B28 CRANK?
any help you can provide will be greatly appreciated.

i'm thinking the difference in front pulley thickness might be a possible issue in that the bolt isnt actually being torqued fully ( bottoming out?) ? haven't measured it yet though.


Cheers
Andrew
New Zealand

I have a m50 stroked with a m54b30 crank.

i have problem with crankpulley/harmonic balancer bolt keeps coming loose.
New bolt everytime, loctite, and the right torque is used.

so I think its a matter of wrong harmonic balancer.
First it came loose with the standard m50 pulley, then I switch to m52.
and the same thing happened.

the frequency of the m54 crank is 275- 305hz
so that would be ideal, but the standard balancer is missing the trigger tooths.

m52 is 390-430 hz
Dont know the m50 frequency.

is there any other harmonic balancers that may have a similar frequency?
I know vac/ati has a custom damper, but not sure if its gonna work. And its pricey as hell.

thanks for inputs.

[s50b30]

I changed to m52b28 crank after the engine destroyed itself. (not related to damper)
Most people I know of in scandinavia that runs the m54 crank in a race engine, uses the ati damper. Seems to work well, but its quite expencive.
That or less rpm.

[zemaestro]

I changed to m52b28 crank after the engine destroyed itself. (not related to damper)
Most people I know of in scandinavia that runs the m54 crank in a race engine, uses the ati damper. Seems to work well, but its quite expencive.
That or less rpm.

The Scandinavians are morer smarterer than most Americans....

[gdavid]

The harmonic balancer OEM part number is the same for the all of the M52 and S52 engines, I didn't check m50's. Since the S52 has the same crank as the M54, I'm not sure how a stroked M52 would be any worse than a S52 engine. I am not planning to track my car but I am planning to use the stock M52 balancer.

I can see and would certainly expect the expensive aftermarket units to perform better but I suspect the failed stock units are the result of hardened elastomer material due to age.

[JOMARO]

Hi there,
I just found this old post and ive got the exact same issue on my M52B25 stroked with M54 3ltr crank and internals in my track car.
Engine goes great, but the crank bolt keeps coming loose. did you ever find the answer to this issue? or did you change to M52B28 CRANK?
any help you can provide will be greatly appreciated.

i'm thinking the difference in front pulley thickness might be a possible issue in that the bolt isnt actually being torqued fully ( bottoming out?) ? haven't measured it yet though.


Cheers
Andrew
New Zealand

I second this with my M50b30 stroker with M52 Damper

[nzbimmer1]

Thanks for your comments.
Pretty much every M54B30 stroker engine ive heard of here has had this issue. maybe the ATI damper is the answer, but its damn expensive...
I think i will try going back to M54 damper with internal crank trigger.
cheers

[gdavid]

Thanks for your comments.
Pretty much every M54B30 stroker engine ive heard of here has had this issue. maybe the ATI damper is the answer, but its damn expensive...
I think i will try going back to M54 damper with internal crank trigger.
cheers

Does the M54 damper have the same diameter at the front crank seal? Are they interchangeable without replacing the seal? I am going to use the internal trigger wheel, so the teeth aren't a concern for me. I also don't understand why S52’s don't have this issue, same crank and balancer combo.

[Bke36Is]

I had this issue on an s52 once. The fix was to replace the crank bolt with a new one torqued to spec and used plenty of red loctite on the bolt. It never backed out again after that..

Sent from my SM-J727T1 using Tapatalk

[5mall5nail5]

I had this issue on an s52 once. The fix was to replace the crank bolt with a new one torqued to spec and used plenty of red loctite on the bolt. It never backed out again after that..

Sent from my SM-J727T1 using Tapatalk

It never came out intentionally again either :P

JK...sorta.

[gdavid]

I just test fit mine and the damper hits the timing & oil pump chain sprocket before snuggling up on the taper. I plan to turn some material off of the inside of the damper and shim the belt pulled out to offset it.

[ryanshamal]

is there anyway to use a m52b28 harmonic on a m52b30 with a lightweight chromoly flyweehl without balancing it? worried about my main bearings. Debating whether to use the m54b30 rotating assembly or just stick with the m52b28.

All help is appreciated. thanks

[Corky325]

Were the rotating assemblies balanced?

I miss-shifted my car years back and re-used the bolt and had it loosen up on me (twice). I then got a new one and torqued it to spec (no loctite) and did not have an issue.

[nzbimmer1]

Mine was all balanced.
I've also heard of someone using eh M50 damper and hasn't had any issues, although he did tighten it with a 3 foot bar on the end of his socket..
Just stripped my engine down and everything else is fine, apart fro the bolt coming loose..
I think the M54 damper with M54 crank (even though i need to do some mods to access the trigger wheel at the back of the crank ) is the only way to go here. + new bolt + loctite + big spanner...

[gdavid]

I am going with a M54 damper and a loctite product sold for such applications (648). I believe the diameter spec for the s52/m54 crank is the same as the m50 & m52 cranks, however in reality it is smaller. The difference is very evident when test fitting the m54 damper on the m52b25 crank I have.