"Harmonic" Damper

[JConstable]

A simple question.....
I see three options to fixing my existing "Harmonic" damper in which the "rubber" insert has started to degrade and I need some guidance:

Option 1. Use a professional service to rebuild the existing damper with a new "rubber" insert. This damper has a somewhat chewed up key way (mid-priced option).

Option 2. Buy a new cast iron damper from BHJ or similar company (most expensive option).

Option 3. Buy a light weight alloy damper from Rootes Post Vintage Spares (much the cheapest option). Communications indicate that they do not stock a cast iron damper with the rubber insert.

I am really wavering between #2 and #3, although I like the price of #3, I am having trouble reconciling that a lighter mass alloy will have the same damping characteristics as the greater mass iron. I presume that selecting the correct damper mass is vital for effectively counteracting crankshaft twist. Similarly, I see the forces imposed on the softer alloy at the key way may affect the damper's durability. Am I making a mountain out of a molehill? All comments appreciated. John

 

[Jim E]

You can run a chevy balancer with the chevy timing cover seal mod just to add a 4.

If the key way is chewed up I would think it is junk, do not see a way to keep it from getting worse.

The alloy damper that is a copy of the stock unit seems ok to me have used a couple, now the alloy unit that is not a copy of the stock late cast piece I have seen fail.

The BHJ piece is nice other than the timing mark issue I had with one.

By the way the earlier cast pulley units with no rubber I believe will also fit and bring to question how important the mass and rubber bit are over all.

 

[jumpinjan]

Your only valid option is #2, get a new one from BHJ. Option #3 is NOT valid because it's torsional pendulem mass has changed and its all wrong. That metal ring is made from steel for a reason....because of its mass. (BHJ has some background material on the physics involved).
I purchased the BHJ crank pulley and its awesome....great workmanship!
Jan

 

[husky drvr]

Your only valid option is #2, get a new one from BHJ. Option #3 is NOT valid because it's torsional pendulem mass has changed and its all wrong. That metal ring is made from steel for a reason....because of its mass. (BHJ has some background material on the physics involved).
I purchased the BHJ crank pulley and its awesome....great workmanship!
Jan

Jan,

Did the TDC timing mark line up?

 

[robertg]

Jim is right, the two BHJ I bought (including the one Jim is talking about), the timing marks are not accurate. Other than that they seem to work fine.

bob

 

[jumpinjan]

The one that I just bought lined up perfect.

 

[robertg]

Good news Jan, maybe Jim's phone call made them take another look. They are a beautiful piece.

 

[howard]

I had mine rebuilt- cost close to $100.00 IIRC. Guy did a great job. But if your keyway is compromised, it's really not an option.

 

[jumpinjan]

Yeah, I have no more good useable ones and about 5 or 6 that have cracks and the spiral groves are all gouged. They are junk
Jan

 

[RootesRooter]

I've run out of room for acronyms in my brain. "BHJ" stands for....?

Does Rick still carry repros? The one I bot from him several years ago works great. The tolerance is much tighter than the stock damper, which used to practically flop around on the crank.

 

[jumpinjan]

BHJ said that they were the vendor that supplier Rick. Rick supplied a blueprint of the pulley to them.
Rick is out of stock of these......that's why we are all talking about them.

 

[ForzaDesign]

Advise needed!
On a slightly different note. I just got my car back from Smitty's Sunbeam after he did the final fine tuning after the restore. He mentioned to me there was a bad vibration coming from somewhere. I mention this after reading some of the comments here about different balancers. I installed one of the aluminum balancers from Rootes in the Netherlands. Has anyone seen vibration issues with these balancers? Other comments on vibrations from alpines?

Thanks,
Jim

 

[Alpine Bob]

Yes, I also have one from them, I noticed a chunk has broken out of it, maybe thats where my vibration was coming from.

 

[Jim E]

Bob's is the super lite wieght version, not the alloy copy of a SV type unit. His lost a chunk out of the part the belt rides in that is as big as a quarter at least.

 

[Alpine Bob]

Jim,
Which one would you suggest I get to replace the broken one if it was your engine?

 

[JConstable]

Wow, a surge of responses - its amazing what happens when your absent from the site for two days...., even got a PM in response. I think that jumpinjan hit on the terminology that I was looking for "Torsional Pendulum Mass" to express the idea that the steel mass is there for a purpose. I think I'll pass on Rootes Post Vintage Spares although they have provided excellent service in the past and plan on getting an old unit with a smooth key way and rebuild (Damper Doctors in Redding CA was recommended) or go with the clean and smooth BHJ. As usual I get a lots of good thoughts and advise - thanks to all. John

 

[bernd_st]

Call it "torsional pendulum mass" or just "vibration damper" it is said that Rootes Engineers experienced bad high frequent vibrations around 4000 rpm which they intended to countermeasure applying the specific factory damper. Talking about a proper replacement we also experienced an issue with the Rootes part Holland damper. In one of our cars the outer ring totally separated and flew away with a big bang after only a few hundred miles. Appearantly there are tolerance issues- something new with the usually good quality reproduction parts coming from this source. I´m using fully aluminum version on all my cars remade by John H. in the UK which performs georgously. Never had any trouble with these even after thousands of miles. Appearantly the alu provides enough dampening to even withstand heavy race useage. If anybody is interested we can order a few and have them sent over. They are not particularly cheap (at 75 Pound each plus VAT & p&p ) but can fully recommend them...

 

[puff4]

I had a look at the "Damper Doctor" website... seems an interesting link to keep, particularly as they also rebuild motor mounts - more and more mounts are going NLA these days.

One thing made me really cringe, though... they listed the cars for which they rebuild balancers, and amongst them was the "Austin Martin". (ouch!) Geez, you think they'd know better? Or that some irritated Aston Martin owning customer would have clued them in?

The only Austin Martin I know of is dead.

 

[howard]

Oh. I thought they were called that because they were made in Texas.

 

[rickra]

aluminum balancers

I also bought one of the aluminum balancers from Rootes in the Netherlands, it lasted two years before it flew apart! I got a BHJ one and am VERY happy with it!