Timing Belt installation...
Discussion
Hi,
Trying to avoid the heated debate on the other thread. Nonetheless, I have received numerous offlist msgs. asking more about the Twist method of tightening the timing belt.
Lest there be no more confusion, this Twist method is a method for checking the tension on the timing belt, not for tensioning it! It is simply too subjective, and one needs to have done this several times to acquire the feel. A first-timer will unboubtedly get it wrong!
Any timing belt installation should be done using an objective measuring device such as a Burroughs Gauge or a Kriket KR1 gauge. Be sure you know how to both use and calibrate these tools for proper installation of your Timing Belt. Additionally, be sure you thoroughly understan the Timing Belt installation procedures before attempting the change a belt for the first time.
One lister followed the instructions I posted here and decided that it wasn't necessary to hand turn the motor several turns before starting up the car because everything lined up, the cam marks matched, engine at TDC, belt tension ok etc. Hand turning the engine is absolutely necessary to seat the belt and wind any slack through the belt. It turned out that he didn't have the belt properly tensioned, but because the slack did not exist between the intake and ignition pulleys, he was unaware of this. Had the engine been hand turned, this slack would have shown up. He started the car which turned less than one revolution before slipping and damaging 2 intake valves and three exhaust valves causing him to re-do the head. So, if you do not know what you are doing, proceed cautiously and follow all directions completely, consult those who have done it, or leave the job to a pro.
A Burroughs Gauge is available for about $250USD from Kent-Moore Tools - [url]http://kent-moore.spx.com/[/url]
A Krikit KR1 gauge is $10USD-$15USD and is available through any seller of Gates Rubber Hose and Belt products. Ask the retailer to order one through their Gates Distributor, usually takes 5-10 working days, or order one yourself from the manufacturer at: [url]www.hmc-international.com/krikit.htm[/url]
Happy Motoring! Jim'85TE
Trying to avoid the heated debate on the other thread. Nonetheless, I have received numerous offlist msgs. asking more about the Twist method of tightening the timing belt.
Lest there be no more confusion, this Twist method is a method for checking the tension on the timing belt, not for tensioning it! It is simply too subjective, and one needs to have done this several times to acquire the feel. A first-timer will unboubtedly get it wrong!
Any timing belt installation should be done using an objective measuring device such as a Burroughs Gauge or a Kriket KR1 gauge. Be sure you know how to both use and calibrate these tools for proper installation of your Timing Belt. Additionally, be sure you thoroughly understan the Timing Belt installation procedures before attempting the change a belt for the first time.
One lister followed the instructions I posted here and decided that it wasn't necessary to hand turn the motor several turns before starting up the car because everything lined up, the cam marks matched, engine at TDC, belt tension ok etc. Hand turning the engine is absolutely necessary to seat the belt and wind any slack through the belt. It turned out that he didn't have the belt properly tensioned, but because the slack did not exist between the intake and ignition pulleys, he was unaware of this. Had the engine been hand turned, this slack would have shown up. He started the car which turned less than one revolution before slipping and damaging 2 intake valves and three exhaust valves causing him to re-do the head. So, if you do not know what you are doing, proceed cautiously and follow all directions completely, consult those who have done it, or leave the job to a pro.
A Burroughs Gauge is available for about $250USD from Kent-Moore Tools - [url]http://kent-moore.spx.com/[/url]
A Krikit KR1 gauge is $10USD-$15USD and is available through any seller of Gates Rubber Hose and Belt products. Ask the retailer to order one through their Gates Distributor, usually takes 5-10 working days, or order one yourself from the manufacturer at: [url]www.hmc-international.com/krikit.htm[/url]
Happy Motoring! Jim'85TE
Jim:
I know this is an old thread, but could you please clarify one thing for me: In earlier posts you have made about the tension of the cambelt, you say that the twist degree should be 45 degrees, but now you say that it should be 90 degrees ??? In one thread you say it´s 45 degrees, in another it´s 45 degress in both directions, and now it´s 90 degrees...
Could it be that you and Lasse means the same thing, you just measure it differently ?
I know this is an old thread, but could you please clarify one thing for me: In earlier posts you have made about the tension of the cambelt, you say that the twist degree should be 45 degrees, but now you say that it should be 90 degrees ??? In one thread you say it´s 45 degrees, in another it´s 45 degress in both directions, and now it´s 90 degrees...
Could it be that you and Lasse means the same thing, you just measure it differently ?
Hi,
It should be a total deflection of 90°, that is, 45° in either direction.
However, that having been said, this method involves a great deal of subjectivity. You develop a 'feel' for it over time. There may be some people, not counting me amongst them, who possess sufficient hand/arm strength to muscle even an overtightened belt to 45°, but that wouldn't mean their belt is properly tensioned.
Consequently, this method should never be used as anything other than a spot check when gassing up or changing oil.
If installing a new belt, the initial tension must be set using one of the two gauges mentioned above. Then once properly tensioned, try this method and you will develop sufficient 'feel' for it to employ it as a spot check.
There is also the possibility of using an accoustic gauge such as a Clavis gauge or some have even adopted guitar tuners and the like to the task. But, this method is much more complicated and can yield widely varying results unless a strict, complex, set of circumstances is observed such as ambient temperature, belt temperature, degree of engine rotation etc. Happy Motoring! ...Jim'85TE
>> Edited by lotusguy on Friday 2nd April 23:03
It should be a total deflection of 90°, that is, 45° in either direction.
However, that having been said, this method involves a great deal of subjectivity. You develop a 'feel' for it over time. There may be some people, not counting me amongst them, who possess sufficient hand/arm strength to muscle even an overtightened belt to 45°, but that wouldn't mean their belt is properly tensioned.
Consequently, this method should never be used as anything other than a spot check when gassing up or changing oil.
If installing a new belt, the initial tension must be set using one of the two gauges mentioned above. Then once properly tensioned, try this method and you will develop sufficient 'feel' for it to employ it as a spot check.
There is also the possibility of using an accoustic gauge such as a Clavis gauge or some have even adopted guitar tuners and the like to the task. But, this method is much more complicated and can yield widely varying results unless a strict, complex, set of circumstances is observed such as ambient temperature, belt temperature, degree of engine rotation etc. Happy Motoring! ...Jim'85TE
>> Edited by lotusguy on Friday 2nd April 23:03
lwasson said:
Hi Jim
My '83 Turbo has round toothed pulleys. Are these OEM? The parts manual shows the timing belt as trapezodal(sp?).
I was finishing the engine assembly and setting the timing that's when I noticed the belt and pulleys didn't match.
Thanks,
louis
'83 Turbo
Louis,
Mismatching the belt profile and pulleys is a recipe for disaster. Which tensioner do you have?
Many people have swapped the trapezoidal belt, pulleys and semi-automatic tensioner for the HTD belt, pulleys and eccentric tensioner. It's no problem as long as everything is set up for and running the proper belt profile.
I question the wisdom in this switch as it's really 6 of one, half a dozen of the other, no real advantage to either. I do prefer the semi-automatic tensioner because it will account for a stretched belt, but it is somewhat more prone to failure, or rather, you have to be more diligent in seeing that it works properly.
Whatever you have, since swapping all the hardware is pretty spendy, I'd just get the proper belt to match. Happy Motoring! ...Jim'85TE
Hi Jim
The tensioner is the original factory unit. A907??????
(no parts manual in front of me at the moment). From your comments there was a swap of pulleys sometime in the cars past. When I received the car it had the trapezoidal belt. I never paid any attention to the pulleys until yesterday.
On the parts lists on FactFile a Gates T188 fits an '88 Turbo. Do you know if this belt is round toothed and will fit my car?
Thanks again,
louis
'83 Turbo
The tensioner is the original factory unit. A907??????
(no parts manual in front of me at the moment). From your comments there was a swap of pulleys sometime in the cars past. When I received the car it had the trapezoidal belt. I never paid any attention to the pulleys until yesterday.
On the parts lists on FactFile a Gates T188 fits an '88 Turbo. Do you know if this belt is round toothed and will fit my car?
Thanks again,
louis
'83 Turbo
lwasson said:
Hi Jim
The tensioner is the original factory unit. A907??????
(no parts manual in front of me at the moment). From your comments there was a swap of pulleys sometime in the cars past. When I received the car it had the trapezoidal belt. I never paid any attention to the pulleys until yesterday.
On the parts lists on FactFile a Gates T188 fits an '88 Turbo. Do you know if this belt is round toothed and will fit my car?
Thanks again,
louis
'83 Turbo
Louis,
First make sure all four of your pulleys (crank, Aux., Int. & Exh.) all have the same profile and that someone didn't just pick up a couple 104 pulleys on eBay without checking compatability. Once sure all your pulleys match, get the matching belt.
I am not familiar with the Gates belt you describe. If in doubt get one from one of the familiar sources, they'll see to it that it's the right belt. It's too expensive to be wrong on this one. Happy Motoring! ...Jim'85TE
Gassing Station | Esprit | Top of Page | What's New | My Stuff