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 Posted: 05-25-2019 06:13 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 572
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Chris,

A 'thin' wrench is easier to bend, and easier to use in the tight space. And torque capacity isn't a factor for simply turning the eccentric to tension the belt. It's not like tightening the retaining nut to 25-30 lbf-ft, which requires more of a 'real' wrench. A 'service' wrench, or a bicycle wrench is a good starting point for a 'bent' wrench.

Turn the eccentric COUNTER-clockwise to tension the belt, and the tensioner will hold it's setting in service. If you erroneously turn it clockwise to tension the belt, then there is a real risk that it will back off in service. Clockwise & counter-clockwise are as viewed from the front, looking back at the front of the engine.

As the retaining nut is tightened to 25-30 lbf-ft, friction will drag the eccentric along with it, changing the tension setting a little. Set & tighten once, then check the tension and note how much it changed. The re-set the tension higher than you intended by that 'change' amount, and re-tighten. That should put the end result pretty close to where you want it to be.

Stray Note: If you remove-replace the cam or auxiliary sprockets, torque-tighten them to 25 lbf-ft.

*~*~*~*~*
The standard BLACK belts (early HCR & later HSN rubber) should be tensioned to:

For Installing a NEW belt:
97-100 if you have a Burroughs gauge (BT-33-86J, or BT-33-73F)
53 - 55 if you have a Krikit KR-1 (use the POUNDS scale).

For Re-Tensioning a USED belt:
95 if you have a Burroughs gauge (BT-33-86J, or BT-33-73F)
52 if you have a Krikit KR-1 (use the POUNDS scale).

New black belts stretch initially. Proper procedure is to monitor a NEW belt's tension frequently over the first 1000-1500 miles (until the tension stabilizes), re-adjusting it as required. That's a bit of a pain in the butt. An alternative that works is to set a NEW belt's initial tension a little higher than spec. Then continue to 'check' the tension periodically over the first 1000-1500 miles... but you shouldn't have to re-adjust it. Typically, as the belt does it's initial stretch, the tension will settle down to the target 'used' setting.

Long term, 95 Burroughs or 52 Krikit KR-1 (pounds scale) is what you want. The NEW-belt 'high' settings are just an expedient to eliminate the potential PITA work of re-adjusting the tension during the first 1000-1500 miles.

When you periodically check the black belt's tension...
90 Burroughs / 50 Krikit KR-1 is the normal minimum-limit tension... re-adjust it.

*~*~*~*~*
For the current HNBR rubber BLUE belt (Gates Racing T104RB):
83-85 with a Burroughs gauge (BT-33-86J, or BT-33-73F)
34-35 with a Krikit KR-1 (use the POUNDS scale).

One benefit of the Blue belts is that they're very stable... they don't stretch. Continue to check a new belt's tension periodically, as noted in the service schedule; but once tensioned when new, you'll rarely, if ever have to re-tension a Blue belt... they just don't stretch. Therefore, there's no difference between the tension specs for NEW Vs USED Blue belts.

Note that the BLACK-belt tension spec given in the original J-H Workshop Manual is out of date, and too low. Use the above tension specs instead. And the Blue belts ARE different, and require a different tension.

Regards,
Tim Engel

Last edited on 05-25-2019 09:08 pm by Esprit2