Harmonic balancer/damper ... replace, rebuild, reuse?

I was just reading about how the rubber in the harmonic balancers (front pulley) of the A series engine gets broken down by age, vibration and oil etc. And was trying to decide the best way to go with renewing this part?

I'm in the midst of a careful engine rebuild and it seems silly to reuse a potentially less than wonderful part on what is otherwise an essentially brand new engine.

Moss has them listed for $117, but i have also found a place on the web out in California (www.damperdudes.net)that is supposed to really good for rebuilding them for $99+ $40 core charge. I can't decide which way to go

just ordering one from moss has the convenience factor because i wouldn't have to order, ship them the old one and wait for the core rebate... but I don't know if these are remanufactured units or new and whether they are equal in quality to a rebuild original. OR should I just put a coat of paint on the old one and proceed?

Thanks

I have heard very good things about Damper Doctor www.damperdoctor.com

Also, whilst on the subject, get Jeff Schlemmer's timing pointer kit www.advanceddistributors.com


Peter

Oh I have Jeff's kit (although an oil leak wiped out the sticker when the adhexive failed. i still have the pointer) It is well worth the almost negligible cost for what you get! I am actually thinking of reprodroducing the markings of the sticker in paint along the edge of the damper when i re-install. If i had the tools to engrave the tick marks and numbers (like you see on some of the TR dampers i have seen) I would do that.

P.S. I'll check out the Damper Doctor site too, Thanks Peter!

Okay, now Peter or anybody, I've thought about this harmonic balancing act from time to time--how do you know you need to have your harmonic balancer renewed or replaced? What are the symptoms? And if I had to can I replace mine without doing a rebuild?

Peter--Quarter Ponder?? With cheese?? I guess you will be rooting for the Patriots on Sunday... not the Giants? 8-)
Charlie

The one advantage to the one Moss has is it is made out of steel, not cast iron like the stock one, which are famous for cracking. The steel one Moss sells used to be alot higher, but recently the price was reduced, assuming it is the same one they sold for awhile now, it's gotten to the point buying that one is a better choice IMHO, then rebilding.

If what Hap suggests is true I would tend to agree that a solid or fluid filled would be better than rebuild of 80 year old tech. I just don't know how something solid can actually "dampen" a harmonic vibration.


Gotta go with the old franchise as I almost always must. Those upstart AFL teams are sill teething imho. Chuck, the parlance in Wisconsin for "Quarter Pounder" with cheese = a small cheese brat with the mandatory Miller or Pabst 12 ouncer.

The timing marks bouncing around when you have the strobe on it are more than likely what is called 'spark bounce,' a condition traced to slop in the distributor drive, worn bushing in the distributor housing, sloppy points and other mechanical elements of the ignition system. Going to a pertronix will fix much of this, going to distributor-less will eliminate it. I have Mega-jolt distributorless on my street BE and Electromotive crank-trigger on the racer. Timing marks are steady as a rock when checked -

yes michael that can also cause timing marks to seem to wander. In this case we are talking about the appearance of spark bounce that you can get if the outer part of the pulley is able to move too much in relation to its center because the flex joint between them is breaking down. the symptom can be the same but the cause is not.

Chris, on my inhouse rebuilds, I always make top timing pointer, bascily, it could be reshaped nail, and that exactly what I used for a long time, but as late use 1/4 round stock, get the right lenght, sharpen a simi dull point on it and weld to to timing cover, and then find TDC with the head off, with a dial indicator on magnetic base on set on the piston top to find TDC. Then if I'm starting from scratch, meaning no marks, which is normally the case, I find TDC, mark it on the pulley with a Sharpie marker, then use sharp chisel and hammer to make groove across the pulley for the new TDC mark, I also then paint it a constrasting color so it's easy to see, I never bother with degreeing the various timing marks, as most folks today use dial timing lights, so all you need is TDC marked. Hope this helps.

Mike is right, alot of old and worn lucas distributors will scatter alot, but if you go with a good distributor set up, it can be rock solid, thats the case with my Mallory Unilite dizzy on the vintage race car, it is every bit as steady as my SCCA Electromotive ignition race cars were.

I did an extensive study on this subject when designing a damper for my TR6 that would use a serpentine belt instead of a v-belt and found out some interesting things.

First, the rubber is there to act as a "spring" that transmits force from the "damper" to the crank. If the rubber becomes hard enough to crack it probably should be replaced. The damper is the outer part of the assembly, the inner is only a hub. The center of gravity and density at a point and distance from that cg is very important to maintain. A heavier damper is better than a lighter one. The reason is that the lighter one will not dampen the crank vibrations as well and could lead to a broken crank. Some mistakenly believe a lighter damper will increase acceleration. This is not necessarily true and could cause crank failure. If a weight reduction is desired make an aluminum hub for your pulley or install an electric fan. Even though the fan might not be mounted on the crank it will still effect the rotating force under acceleration.

BTW - the correct damper will actually increase performance by reducing unwanted vibrations.

Hi Robert, This is one of the sources I investigated. Dampers

Pages 4 and 5 will answer some of your questions about the different types of dampers.

A solid piece on the crank is not a damper and has little if any damping effect.

Note the "lagging torque" on page 7.

Also in the TR6 crowd we had been experiencing problems setting timing on some cars. We discovered that some of the dampers had hard rubber and that it was allowing the damper to slip on the hub causing the timing marks to move.

Hey what about me, guys?

I wrote:
[quote]I've always wondered about this harmonic balancer. I don't even know where to look to see if the rubber is cracked.

A timing light on my mark bounces around a bit.
A vacuum gauge on my intake manifold bounces around a little too
I have a randomly timed miss, maybe every five seconds or so. I have tightened my exhaust manifold gasket.

But, Jeff rebuilt my distributor so...

What do youse guys think? It doesn't seem to hurt anything.
Charlie

Charlie, the rubber is in the groove between the hub and outer ring(damper).

I doubt it is causing your problem but that doesn't mean that it does not need replacement.

Charlie, here's an unpainted picture that shows a better view of a damper with cracking rubber.

eeeeeeeeeewwwwwwwwwwwww

oh that's not a picture of mine, just a good pic i found to illustrate the extremes to which it can go. Mine has some cracking, but not yet as deep or wide as those.

Jumping timing marks are most likely due to ignition issues. A "permanent" dislocation of timing (i.e. you discover that motor TDC is actually 10 degrees - or more, most likely - BTDC on the pulley) is a failed damper. A damper that "jumps about" is in all liklihood one that is about to fling off the crank and impact something else in a fat hurry!

If I was building a street car with "normal" rpm range, I'd pick a damper that did not show any shift in the timing mark and be happy.

If I were building a hot street car or race car that saw high rpm use, then I'd go with a solid "damper."

Yes, solid dampers do too damp vibrations by having an inherent harmonic that is tuned to mitigate whatever bad harmonic the engine produces. This is by mass in and of itself and by carefully "unbalancing" the mass, if you have a Vee motor.

All in-line engines (especially sixes) are inherently balanced, i.e. "stable" and don't require "dampers."

Vee engines were a packaging idea, not balance! Have you seen the lengths they go through to balance them?????

Rick, or anybody, what qualifies as an 'early' A-series engine? The 1275 in my BE, which seems to date to about 1967 would not, correct?

948 - early
1275 - late
1098 - ??? :)

Rick

FYI the ealiest 1500 B-series also had the magic o-ring "tensioner."

Volvo used Soy-plastic timing gears (no chain) in their "b-series" motor.

Dunno 'bout the Honda "b-series..." Probably OHC

;)

WE used to be aqble to get and sell the Romac balancers on the A series engien, but they have since quit making them, they were super nice, SFI rated, and killer reliable.

On the MGB race engine we went with the Pro Sport unit Moss, sells it is also SFI rated and really nice, but they don't offer one for the A series, it was like $275 bucks, but for a race engien, a smart choice. At one time I was able to sell the A series Romac unit for $165, and that was the deal of a lifetime.

I did check into a ATI fluid dampner for the MGB, it was going to be alot of work, and needed a custom made adapter, it was going to easily crest $1200 for the customer to get it on and set up ::o

Huffaker did do a fluid dampner set up for the A series, of course it was set up for SCCA full prep racing, meaning carnkfire ignition, dry sump, a gilmer pulley, it's like a $1500 set up. Most SCCA full prep racers using dry sump oiling, use no balancer, everything is of course tightly balanced due to the high rpms the engine, and would running just the gilmer pulley for the dry sump pump at the crank.

I think for the street engine, it's hard to go wrong at $117 for the unit Moss sells.

A photo of the Romac A series balancer that Hap mention, billet steel, graduated and very nicely put together. I was lucky to have found mine, they are like hen's teeth.