M20B23 harmonic balancer /damper

[JuhKu]

Hello mates!
I need information and technical lesson about the M20Bxx harmonic balancers.
I far as i know at the moment:
M20B20 has the 200mm damper size (right?) (later models without the triggering teeths)

M20B23 has the 235mm damper size(right?)
And which other models have the same damper size as M20B23?

The problem is that i build my E21 323i race car and solved out that i have wrong damper (200mm) on it. Raced my first race and damper felt loose and pop out. I think it is not because the wrong damper size, better the M8 bolts which i put there without thread lock glue(?)
And does it cause engine failure if i use smaller 200mm damper? Excessive vibrations, crank broke, crank bearing wear or something like that?
B23 stroke is 10mm longer so is that the reason to use bigger damper also?
Parts are interchangeable so i would use both sizes if it is ok but i might its not.
Car hasnt high revving engine, max rpm is there about 6500-7000rpm in this setup.
But i think that track use is the issue why its load the damper. More than normal use.

I know here is lots of knowlegde in this forum so im pleased any kind of help.
Preferably based on facts

Br,Juha

[uwbuurman]

My damper almost flew off, after putting it om my freshly overhault engine. I used the wrong bolts, be sure to use the 10,9 bolts, torque them correct and use Locktite. After my roundtrip Eifel, where I encountered this problem, I changed damper and pulley, since they both had worn out holes, no proper fit any more.

my engine is a 2.7i based on de b23m20. Using a Schrick cam, reving up to 7k rpm. I have the b23 damper. But the smaller damper is also used on e28 with autobox and m20.

[Jeroen]

be sure to use the 10,9 bolts, torc them correct and use Locktite

+1! Defo torque them, make sure there is no dirt or excessive paint in between, and always replace all 6 bolts.

[JuhKu]

I used the wrong bolts, be sure to use the 10,9 bolts, torque them correct and use Locktite.

Really? I think factory manual says 8.8 bolts if i remember right
So now i got there M8x16 8.8 bolts with loctite 243 which i think is original bolts.
As fact i wrestled with my self which ones i use 8.8 or 10.9. When those softer 8.8 were on my stock i used them
Which kind of washers did you use under bolts?

Probaply i have to find and pickup somewhere 10.9 bolts and change them.

How about those damper issues? Are they common in these M20Bxx engines?

Did you have B23 damper there first also when the vibration starts? Or did you change it later and now your long stroke is harmonic balanced

[uwbuurman]

If ordered at the dealer, with the right partnumber, you will get 10.9 bolts. My damper ran loose, don't know why. But it is not a common problem.

I used the b23 damper both times, so no difference there. Would have used the original again if the holes hadn't worn out

[BertjeConti]

I think paint or dirt on the mating surfaces causes this problem of running loose.

I always re-used the original bolts and tightend them to the right torque, 22Nm, and no locktite. Never had any issues with it.

Every time you do a timebelt change this balancer needs te be removed, so using locktite would be a strange option.

[Jeroen]

With clean surfaces tightening on torque should suffice with new bolts. Have experienced bolts upon refitting or during track use so I always have a bunch of spares here. THey are not that expensive so better replace. I personally never use loctite on these, it just wasn't necessary. It helps preventing bolts from coming loose but I believe the cause should be sought elsewhere (like dirt or paint).

[JuhKu]

I think paint or dirt on the mating surfaces causes this problem of running loose.

I always re-used the original bolts and tightend them to the right torque, 22Nm, and no locktite. Never had any issues with it.

Every time you do a timebelt change this balancer needs te be removed, so using locktite would be a strange option.

Yeah, i think you're right this stuff between connecting surfaces. It might be so that i didnt clean surfaces well enough. But now i did when i re-new my damper.
But as my original thinking was, can the smaller 200mm damper cause the vibration differently than 235mm then it get loose?
About the Loctite. The Loctite i use is medium(blue) so the joints could be dismantled with normal tools. No heating or else needed and threads remain ok. And if there is some Loctite remainings i think i can use M8 tap to clean threads.

[JuhKu]

With clean surfaces tightening on torque should suffice with new bolts. Have experienced bolts upon refitting or during track use so I always have a bunch of spares here. THey are not that expensive so better replace. I personally never use loctite on these, it just wasn't necessary. It helps preventing bolts from coming loose but I believe the cause should be sought elsewhere (like dirt or paint).

So you have track use with your car without any damper issues?
That is also little relief to me that probaply there was problems due my assembly when you and others dont have any issues
But still have to pay attention that i have wrong damper there first which might have something to do with this issue.
How long sets at one time did you drive. I'll try to figure out to myself and compare that how much engine braking and " shocking" rpm changes etc. you have done without any problems.
Mine last few dyno sets and four practice sessions(approx.80km).
(The same amount what mine brand new Spax adjustable front shock absorbers )

Those quick rpm changes is the biggest one which loads the damper(?)

And yeah, i will buy/order few sets of bolts to stock and qood to know that new bolts are 10.9 as my old ones are 8.8

By the way, if there is any dampers, hubs, king bolts, waterpumps pulleys available in the forum im interested. You can offer yours. Needs to be sended to Finland also.