Belt tension rule of thumb?

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garlicbreadman

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Hello, i am going to do my timing belt(first time) this month along with the accessory belts. Ive read/watch a lot of tutorials and feel confident doing this job.

I am going to feel the current tension with what's on there now and try to make it the same tension. Any general rule of thumb to check for proper tension on the timing belt and accessory belts?

Car is a 2001 acura integra with 167k miles. I will take valve train pics for bitog
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parts madness!!
 
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The timing belt changes from car to car, and you want specific instruction, not a rule of thumb.

Accessory belts aren't as important. I've heard that you should be able to twist by hand, 90 degrees, the longest side of a V-belt. But if you go too tight, you wreck bearings. Go loose and retighten after they run in for a couple weeks.
 
There is no rule of thumb. You must first find the specs for your car. Once you find the specs, use the following method if the specs are in given in force units (lb etc.) rather than deflection (inches or millimeters):

(Deflection of belt) = (0.25)*(span length of belt between the two pulleys where the force is applied)*(perpendicular force applied on belt midway between the two pulleys)/(belt tension)

Thread describing the practical application of the above formula (link)
 
In these types of discussions, I have always contended that the results of 'rule of thumb' are different between a 90 lb. weakling vs. a 250 lb. gorilla (no insult intended with weakling/gorilla terminology....credit sensitivity training
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Tension on the timing belt is kind of automatic. It's taken care of by the tensioner. The only place that I have ever come across a timing belt tension spec is for a belt-driven Ducati. However, read your FSM just in case.

For the accessory belts, I've never used any kind tension gauge. I tension the belts by deflection; essentially feel developed from four decades of replacing belts on mine and customer's vehicles. I've not had accessory bearing failures from the belts being too tight or belts getting flung off or squealing because they're too loose.

Bando!
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Do you also have the correct crank pulley tool and a large breaker bar? Or a powerful impact gun? The Honda crank pulley bolt is notoriously difficult to break loose.
 
Originally Posted By: chrome
Do you also have the correct crank pulley tool and a large breaker bar? Or a powerful impact gun? The Honda crank pulley bolt is notoriously difficult to break loose.

Im to see if my 1/2 inch dewalt 20v impact can take it off, however I do have two 1/2" breaker bars with extensions. I am going to rent the pulley removal tool from oreillys.

Originally Posted By: JamesBond
Where did you get your parts?

I got the accessory belts, gates timing belt and koyo tensioner from amazon. I got the NPW japan made waterpump from ebay. The front camshaft and crankshaft seals, rear camshaft cap seal and lower motor torque mount are from benardi acura.

Originally Posted By: eljefino
The timing belt changes from car to car, and you want specific instruction, not a rule of thumb.

Accessory belts aren't as important. I've heard that you should be able to twist by hand, 90 degrees, the longest side of a V-belt. But if you go too tight, you wreck bearings. Go loose and retighten after they run in for a couple weeks.


I heard about the 90" degree as well.
Originally Posted By: paulo57509
Tension on the timing belt is kind of automatic. It's taken care of by the tensioner. The only place that I have ever come across a timing belt tension spec is for a belt-driven Ducati. However, read your FSM just in case.

For the accessory belts, I've never used any kind tension gauge. I tension the belts by deflection; essentially feel developed from four decades of replacing belts on mine and customer's vehicles. I've not had accessory bearing failures from the belts being too tight or belts getting flung off or squealing because they're too loose.

Bando!
01.gif


Heard good things about bando. Infact, the accessory belts now on my car are all bando. These new bando belts seem to use a furry foam like material where the belt meets the pulleys. The ones in my car look to be rubber.

Thanks all for your replies. Can't wait to tackle this
 
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Originally Posted By: garlicbreadman
Originally Posted By: chrome
Do you also have the correct crank pulley tool and a large breaker bar? Or a powerful impact gun? The Honda crank pulley bolt is notoriously difficult to break loose.

Im to see if my 1/2 inch dewalt 20v impact can take it off, however I do have two 1/2" breaker bars with extensions. I am going to rent the pulley removal tool from oreillys.


The new generation cordless impacts are quite powerful, would be interested to know how it fares against the crank pulley bolt on your Acura. Please do report back on how well it works.
 
Originally Posted By: Chris142
My 700ft lb mac gun wont do it.I have to use my 1000ft lb 3/4 gun to remove that crank bolt. Your electric will just bounce around on it.

Im sure that's going to be the case since these pulley bolts are torqued to 130ft lb. What makes them so stubborn is the thick large washer. There is a lot of mating surface. When i had my timing belt done at 80k, my mechanic was very surprised how easily it came off with his 1/2" impact using an air compressor. This is a california car so that helps a lot.

Originally Posted By: chrome
Originally Posted By: garlicbreadman
Originally Posted By: chrome
Do you also have the correct crank pulley tool and a large breaker bar? Or a powerful impact gun? The Honda crank pulley bolt is notoriously difficult to break loose.

Im to see if my 1/2 inch dewalt 20v impact can take it off, however I do have two 1/2" breaker bars with extensions. I am going to rent the pulley removal tool from oreillys.


The new generation cordless impacts are quite powerful, would be interested to know how it fares against the crank pulley bolt on your Acura. Please do report back on how well it works.

i agree, i have this:
http://www.dewalt.com/tools/cordless-impact-driverswrenches-drivers--wrenches-dcf880hl2.aspx

It's been wonderful and has taken off everything i've thrown at it. The crank pulley bolt will be a true test.
 
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Originally Posted By: paulo57509
Tension on the timing belt is kind of automatic. It's taken care of by the tensioner. The only place that I have ever come across a timing belt tension spec is for a belt-driven Ducati. However, read your FSM just in case.

For the accessory belts, I've never used any kind tension gauge. I tension the belts by deflection; essentially feel developed from four decades of replacing belts on mine and customer's vehicles. I've not had accessory bearing failures from the belts being too tight or belts getting flung off or squealing because they're too loose.

Bando!
01.gif


Kind of? Perhaps, but the tension on the timing belt is not really automatic. You still need to adjust the idler (tensioner) pulley so that the deflection is to the specs -- for example 6 - 7 mm at 4.4 lb for my engine. Spring constants change over time and the pulley may need adjustment.

Deflection for a given vertical force depends on the span length of the belt and you either need my formula above or some conversion table (that lists the results of my formula) to get the tension right. You can't just assume half inch or quarter inch is always right.

Bando, along with Mitsuboshi (not Mitsubishi), is an OEM for Toyota. So, they must be good.
 
Originally Posted By: eljefino
The timing belt changes from car to car, and you want specific instruction, not a rule of thumb.

Accessory belts aren't as important. I've heard that you should be able to twist by hand, 90 degrees, the longest side of a V-belt. But if you go too tight, you wreck bearings. Go loose and retighten after they run in for a couple weeks.


Exactly how I tensioned it. There are gadgets with a weight on it used to apply the proper tension.Over tension is worse than loose. I even heard stories where someone tensioned it like an accessory belt and eventually snapped his cam.If the water pump is driven by the timing belt, change that at the same time.I would also replace the tensioner pulley.
 
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Originally Posted By: Chris142
Any news on the electric impact vs the Honda crank bolt?


Going to tackle it this weekend
 
Originally Posted By: Chris142
Any news on the electric impact vs the Honda crank bolt?


If the impact won't break it loose, I have used a breaker bar, positioned against something ( ground, frame)and bumped the starter and that has always broken it loose for me.
 
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