Harmonic balancer/damper ... replace, rebuild, reuse? : MG Midget Forum : MG Experience Forums : The MG Experience

Harmonic balancer/damper ... replace, rebuild, reuse? #1
73midget Chris Edwards Texas, USA 1973 MG Midget MkIII	Posted: January 31, 2012 04:29PM Registered: 2 years ago Posts: 1,010

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

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #2
PeterC Peter Caldwell Madison Wisconsin, USA	Posted: January 31, 2012 04:36PM Registered: 7 years ago Posts: 2,125

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

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #3
73midget Chris Edwards Texas, USA 1973 MG Midget MkIII	Posted: January 31, 2012 04:51PM Registered: 2 years ago Posts: 1,010

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!

Edited 1 time(s). Last edit at 01/31/2012 04:52PM by 73midget.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #4
NYCCharlie Charles Linn Lawrence, Kansas, USA	Posted: January 31, 2012 10:10PM Registered: 3 years ago Posts: 949

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? eye rolling smiley

Charlie

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #5
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: February 01, 2012 05:42AM Registered: 7 years ago Posts: 20,311

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.

Hap Waldrop
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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #6
PeterC Peter Caldwell Madison Wisconsin, USA	Posted: February 01, 2012 09:33AM Registered: 7 years ago Posts: 2,125

In reply to # 1972673 by NYCCharlie 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? eye rolling smiley

Charlie

Charlie..... Giants fan this weekend. They deserve it, they beat us winking smiley

(also, I'm from joisey)

The symptoms seem to be wandering timing marks at speed... but there can be other causes as well.

Peter

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #7
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: February 01, 2012 09:51AM Registered: 4 years ago Posts: 13,090

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.

Regards,
Robert Kirk
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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #8
73midget Chris Edwards Texas, USA 1973 MG Midget MkIII	Posted: February 01, 2012 10:01AM Registered: 2 years ago Posts: 1,010

In reply to # 1972673 by NYCCharlie 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? eye rolling smiley

Charlie

just looking at it visually, i can see cracking in the rubber that joins the pulley to the hub. The rubber joint is I believe supposed to absorb vibrations to keep the crank balanced while rotating. The loss of integrity of the joint is what makes timing appear to wander, etc.

So here's the next question: According to the catalog the new balancers from Moss don't have a timing mark... what's the best way to permanently mark on steel? I suppose using a file to place a notch like the original? ...but i'd really like to be able to make it more clearly like the one in this picture (which is off a TR6) in some way that can't scratch or peel off. I have the pointer kit from advanced distributors so timing marks can be seen from above.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #9
mmacquee Michael MacQueen College Park MD, USA	Posted: February 01, 2012 01:53PM Registered: 2 years ago Posts: 105

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 -

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #10
73midget Chris Edwards Texas, USA 1973 MG Midget MkIII	Posted: February 01, 2012 02:11PM Registered: 2 years ago Posts: 1,010

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.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #11
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: February 01, 2012 02:12PM Registered: 7 years ago Posts: 20,311

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.

Hap Waldrop
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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #12
NYCCharlie Charles Linn Lawrence, Kansas, USA	Posted: February 01, 2012 03:18PM Registered: 3 years ago Posts: 949

In reply to a post by Robert 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.

12 oz. = 3/4 of a pound. But I get your drift. smileys with beer

So true about the Patriots. Still on formula.

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 too
I have a randomly timed miss.

But, Jeff rebuilt my distributor so...

What do youse guys think? It doesn't seem to hurt anything but my pride.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #13
tomshobby Tom Smith Windsor, Wisconsin, USA	Posted: February 01, 2012 03:41PM Registered: 3 years ago Posts: 883

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.

Tom Smith
1974 Midget
1976 TR6

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #14
PeterC Peter Caldwell Madison Wisconsin, USA	Posted: February 01, 2012 03:46PM Registered: 7 years ago Posts: 2,125

In reply to # 1972956 by kirks-auto 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.

Aye Cap'n.... an I think you have to click on my avatar to get the joke....

<hint, the Vike's QB for a while was Ponder>

Gees.... maybe Iowa needs a pro football team......

........ nah, better not, then Illinois will want one.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #15
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: February 01, 2012 04:20PM Registered: 4 years ago Posts: 13,090

In reply to # 1973248 by PeterC
........ nah, better not, then Illinois will want one.

Mr Caldwell....youse is kinda pushing it with that remark.... moon

And yes Pete and Chuckles, I "caught" the factious Pounder remark eye rolling smiley

I am a fan of all the black and blue conference...ViQueens to Lions but only those 4. My favorite team has always been any beating Dallas and of course "DA Bears". The legacy of Lombardi, and a small midwestern meat packing community make the Pack a close runner up to my favorites.

Now that we three have collectively derailed the thread, I am still unclear about what Hap mentioned to a "solid" dampner to which the wise and scientific Mr Smith, did not exactly clarify to me.

I know some of the heavy abusers of automobiles claim a liquid (?) clutch pack is a good dampener as well. My understanding is on a straight 6 and no doubt any in line motor, there is a tremendous barrier of vibration at a calculated rpm....part of the reason Ford and later others, opted to a V configuration and why for a radial engine the problem is almost non existent...

Anyone able to clarify?

Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #16
tomshobby Tom Smith Windsor, Wisconsin, USA	Posted: February 01, 2012 10:30PM Registered: 3 years ago Posts: 883

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.

Tom Smith
1974 Midget
1976 TR6

Edited 2 time(s). Last edit at 02/01/2012 10:42PM by tomshobby.

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #17
NYCCharlie Charles Linn Lawrence, Kansas, USA	Posted: February 02, 2012 10:31AM Registered: 3 years ago Posts: 949

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

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #18
tomshobby Tom Smith Windsor, Wisconsin, USA	Posted: February 02, 2012 11:03AM Registered: 3 years ago Posts: 883

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.

Tom Smith
1974 Midget
1976 TR6

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #19
73midget Chris Edwards Texas, USA 1973 MG Midget MkIII	Posted: February 02, 2012 11:11AM Registered: 2 years ago Posts: 1,010

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

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Re: Harmonic balancer/damper ... replace, rebuild, reuse? #20
PeterC Peter Caldwell Madison Wisconsin, USA	Posted: February 02, 2012 11:17AM Registered: 7 years ago Posts: 2,125

eeeeeeeeeewwwwwwwwwwwww

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