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The Anti-RUB
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I'm an engineer by training/trade, so I'm one of those guys who likes to know how things work...

I've been researching different Automatic Primary Chain Tensioners, and the top three I've found are the HB-125, the Hayden M6 and the "new" HD tensioner. I'm currently leaning towards the HB-125.

Now, I have not had the opportunity to actually play with any of these tensioners to see how they work. So I'm working entirely off what I've read and my understanding of physics. So I might be wrong here. If I am, please let me know.

From what I understand here's a basic explination of how they work:

Hayden M6 is basically a spring that moves the guide plate up and down to keep constant tension on the chain. Simple and proven, but due to its spring design it can be suceptable to harmonic osilation (rythmic bouncing).

HB-125 is essentially the same as the Hayden M6 in that it uses a spring to move the guide plate to put tension on the chain, except that it uses hydrolics to dampen the "bounce" in the spring. Kind of like a shock obsorbers in your car. The up/down movement of the spring/plate causes a plunger to move up/down causing fluid to be sucked in/out of the base (like a hydrolic pump) dampening the springs movement. The hydrolics don't surve to put presure on the chain at all. Its just to dampen the spring. As long as the base is submerged in fluid it should work fine.



Now, for my questions:

With the HB-125:
With the 26oz of fluid in a Softail Primary, is that enough fluid to keep the hydrolic inlet/outlet ports submerged? Also, after changing the primary fluids, how long does it take for the "pump" to get primed again? Would just pushing up/down on the guide plate, after new fluid has been added, be sufficient to re-prime the "pump"?

With all tensioners (even the stock one):
How often do the plastic guide plates need to be replaced? 15-30k or more? I asume milage varies on that.

Thanks alot for any info...
 

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I just put in my H-b 125 a few days ago. Very noticeable improvement!
I did a bit of playing with it before I put it in the bike and the hydraulic mech really doesn't need a lot of time to draw in the oil.
Even at the VERY high adjustment I have mine set to, because of the 24 tooth comp sprocket with a 36 tooth clutch shell, it is decidedly in the oil.
After about 2 min of riding the bit of primary whine I had was gone as was all chain lash.
 

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petrock, are you a "hydrolics" engineer? haha couldn't resist, most of the engineers I work with can't spell either, LOL.
I've had an HB125 on my WG for almost 3 years. The bottom of the unit where the oil inlet is sits at the very bottom of the chaincase so, yes, it is submerged. If I recall, the instructions tell you that you can prime the unit before you install it to hasten the pump-up. As Stogie said, it doesn't take long and I didn't prime mine. I believe that the hydraulic action does contribute to the tension on the chain, it's not just for damping.
http://www.sohotbikes.com/downloads/instructions.pdf
 

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I've installed several "M-6's" for friends. I've found that due to variability in the inner primary casting, it doesn't always fit flush against the primary face and requires some clearancing on the bottom inner corner. I had to grind a radius on mine to get it to fit perfect. Didn't find out till I reopened the primary to inspect shoe wear/normal service and noticed some uneven wear on the tension shoe. Fixed the problem, turned the shoe around and the odd little noise I had was gone too. I called the folks at M-6 and they confirmed that this is a common problem. Makes you wonder why they don't clearance the back plate corner if they know about it....

DLR
 

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M-6

Cant speak for anything else, but put M-6 in my ultra 3 yrs ago, absolutely love the thing!! Smooth as silk shifting, no clunk! Reasonably easy to install. Jireh had it for 25$ less than retail. It would be tough to beat the M-6 in my opinion.
 

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skinnyass said:
Cant speak for anything else, but put M-6 in my ultra 3 yrs ago, absolutely love the thing!! Smooth as silk shifting, no clunk! Reasonably easy to install. Jireh had it for 25$ less than retail. It would be tough to beat the M-6 in my opinion.
I agree. Very simple design. Been running mine trouble free now for over 15k.
 

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I've installed both the HB125 amd the M-6. I think that they both work as advertised and are a noticeable improvement. I have had to replace broken inner springs on a couple of the M-6 units, but only on bikes ridden by maniacs that tend to hit the rev-limiter while downshifting! I have the HB-125 in my Softail and am very satisfied with it. Hundreds of passes at the track with no problems.....Bill
 

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24 tooth comp sprocket?

StogieC said:
I just put in my H-b 125 a few days ago. Very noticeable improvement!
I did a bit of playing with it before I put it in the bike and the hydraulic mech really doesn't need a lot of time to draw in the oil.
Even at the VERY high adjustment I have mine set to, because of the 24 tooth comp sprocket with a 36 tooth clutch shell, it is decidedly in the oil.
After about 2 min of riding the bit of primary whine I had was gone as was all chain lash.
FOR STOGIEC - Where did you get the 24 tooth comp sprocket? I'm assuming you have a flht with the stock 36 tooth basket. I bought the one Drag Specialities advertised for Dressers but the nut when on with only a threads, so I called them and they said it was a miss print and it was supposed to be for softails. So, I'd like to get the one your using. Thanks for any info.

2002 flhtcui
95"
Woods tw6hg
s+s reed
power commander usb
SE 10/5to1 forged pistons
SE Performance heads(modified)
roller rockers
SE rocker support plate
HB-125
sampson 2 into 2
 

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I had an HB125 on my '03 FLSTFI and it made a big difference.

I took the install oppurtunity to do a full inspection of the primary etc. It also gave me an excuse to use the chrome hardware kit for the primary.

It is a good thing I talked my buddy into the HB 125...when we opened his primary we found the stock tensioner shoe was cracked down the middle and it was just a matter of time before it broke off and starting winging around inside the primary:crying:

I did have my neighbor who designs hydraulic equipment look at the HB 125 and he was both impressed and a little jealous he didn't come up with it.
 

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petrock said:
With the HB-125:
With the 26oz of fluid in a Softail Primary, is that enough fluid to keep the hydrolic inlet/outlet ports submerged? Also, after changing the primary fluids, how long does it take for the "pump" to get primed again? Would just pushing up/down on the guide plate, after new fluid has been added, be sufficient to re-prime the "pump"?

With all tensioners (even the stock one):
How often do the plastic guide plates need to be replaced? 15-30k or more? I asume milage varies on that.

Thanks alot for any info...
I've had a HB-125 for about 2 1/2 years now. Really like it.

When installed, it sits low enough in the chaincase to stay submerged in oil. It won't need priming again after changing the primary oil. The spring will keep the chain from pushing the cylinder down and draining it. I primed mine when new by using a small hand pump oil can and squirting primary oil into one of the holes on the bottom of the hydraulic cylinder, but it's not critical. I don't know how long the plastic shoe will last, but I would figure long enough to essentially not worry about it. If it starts to feel like the chain is too loose again, then I'd open up the primary to take a look. Overall these things are really nice to have.
 
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