Belt tensioning and Pano article (long)
07-13-2004, 08:16 PM
#1
Burning Brakes
Thread Starter
Belt tensioning and Pano article (long)
Wow, an article in Pano on the 944 - what a delite!
Anyway, for a layman like myself, I found the Pano article on Cam and Balance shaft belts very interesting. Usually the tech articles we use give a procedure to follow, but dont necessarily tell us why to do it. My fear in doing my own work is that i never fully know the theory behind some of the procedures.
The article cites tensioning as a critical component of belt durability and lifespan. That proper tensioning requires the engine (oil) to be cold (cold defined as at ambient temp.) - (I already new that thanks to my able PM)
The article states that this is often overlooked by technicians and a properly tensioned belt will yield years of service life, while loose belts degrade rapidly.
My question is: the relativity of "ambient temp."
does tensioning a belt in december vs. july have any bearing on this matter? Temp swings here in Charlotte could be as much as 40 degrees (now you might say it doesnt matter as the expansion over 40 degrees is not enought to matter - i dont know)
In the article, Porsche determined that the belts should be inspected every 15k, tensioned and replaced if necessary. I guess there is no disagreement with that, as that is what we are already doing via re-tensioning.
Do the exteremes of ambient temp (seasonal) affect setting belt tensioning
and is there an optimal temp. when this should be done?
Also, since the cost of re-tensioning a belt is little more than an oil change at the shop, should tension be checked several times during the year, considering both mileage interval and seasonal temps?
I hope this makes sense and I'm not asking some really dumb questions?
Anyway, for a layman like myself, I found the Pano article on Cam and Balance shaft belts very interesting. Usually the tech articles we use give a procedure to follow, but dont necessarily tell us why to do it. My fear in doing my own work is that i never fully know the theory behind some of the procedures.
The article cites tensioning as a critical component of belt durability and lifespan. That proper tensioning requires the engine (oil) to be cold (cold defined as at ambient temp.) - (I already new that thanks to my able PM)
The article states that this is often overlooked by technicians and a properly tensioned belt will yield years of service life, while loose belts degrade rapidly.
My question is: the relativity of "ambient temp."
does tensioning a belt in december vs. july have any bearing on this matter? Temp swings here in Charlotte could be as much as 40 degrees (now you might say it doesnt matter as the expansion over 40 degrees is not enought to matter - i dont know)
In the article, Porsche determined that the belts should be inspected every 15k, tensioned and replaced if necessary. I guess there is no disagreement with that, as that is what we are already doing via re-tensioning.
Do the exteremes of ambient temp (seasonal) affect setting belt tensioning
and is there an optimal temp. when this should be done?
Also, since the cost of re-tensioning a belt is little more than an oil change at the shop, should tension be checked several times during the year, considering both mileage interval and seasonal temps?
I hope this makes sense and I'm not asking some really dumb questions?
Last edited by fezz; 07-13-2004 at 10:50 PM.
07-13-2004, 08:39 PM
#2
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Rennlist Member
Rennlist Member
Fezz- Call Jim Burton at Eurowerks. His shop is down off Independence headed towards Monroe and he's also on the board.
I can see your point, but for me, if it's cold enough to matter that way, I'm not out working on a car. I grew up in Charlotte and have done wrenching out in the driveway with temps in the teens. There is no way I'd do a timing belt and balance belt under the same conditions.
I can see your point, but for me, if it's cold enough to matter that way, I'm not out working on a car. I grew up in Charlotte and have done wrenching out in the driveway with temps in the teens. There is no way I'd do a timing belt and balance belt under the same conditions.
07-13-2004, 09:19 PM
#3
Burning Brakes
Thread Starter
Dave, thanks
Jim is my PM and I would only have him do my engine work. I try to do alot on the car, but I will leave engine and tranny to him. That is what I know him best for, given our conversations.
Actually, I'm hoping he, keith, socal, danno, et al will post a reply.
Jim is my PM and I would only have him do my engine work. I try to do alot on the car, but I will leave engine and tranny to him. That is what I know him best for, given our conversations.
Actually, I'm hoping he, keith, socal, danno, et al will post a reply.
07-13-2004, 10:03 PM
#4
Burning Brakes
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So, years ago when training started "engine cold to do timing belt adjustments" meant ambient in real life. However it was also explained to me that textbook terminology meant room temp was 70 F. So, in the lab they expected you to have the temp at 70 Degrees. However , look at it like this. The safest way to service a satellite is to do it on the ground. Some things you just can't help. We were taught that a fully warmed 944 motor at running temp grew 4 mm from cam to crank Which explains why belt tension cold is so important . so ofcourse it only gets tighter as the engine runs. Rule of thumb cool to touch.
07-13-2004, 10:11 PM
#5
Burning Brakes
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We were also taught by another mechanic that crossthread is better than locktite . Our instructor taught us porsche philosophy. Measure with a micrometer, measure with chalk and cut with an ax.not that we practice this, but I just thought it would be neat to mention.
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07-13-2004, 10:45 PM
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Burning Brakes
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lol, over the years I bet the 2 lb hammer I bought from some tool stand at the fairgrounds for $5 has definately been dollar for dollar the best tool I ever bought.
)