6.0-928S

Wondering. When installing the Gates racing belt do you tension it at the same level as the stock belt on installation since it stretches less?

Thanks, Hammer

Dave928S

Exactly the same. The difference will be less stretch during initial run-in period, and consequent adjustment, and less dynamic stretch during normal operation.

docmirror

Not asked, but I would strongly recommend removal of the small idle wheel cartridge below and around the crank pulley. I had a racing belt on and had some interference from those. It's a very, very close fit, maybe they will interfere with the back side, and maybe they won't, but mine did.

GregBBRD

Unknown.

Gates apparently claims the cold adjusting tension should be the same.

Obviously, if the belt stretches less as it gets warm, the warm tension is going to be higher....and the ending "warm cam timing" is going to be slightly different. Logically, it would seem that both of these factors should be compensated for.

However, I've heard of no ill affects of adjusting to the factory tension, so it is possible that the tension difference is moot.

There is an "Internet myth" that premature cam gear wear comes from over tightening the belt, whereas just the opposite is true....premature cam gear wear occurs from the belt being too loose. Drive sprocket failure and cam nose failure occurs from the belt being too tight.

If I use a Gates Racing belt (very rare), I back down the cold tension about 5%....just because it makes more sense, to me.

GregBBRD

While being respective to Doc's experience and opinion, I would never do this. I believe the small idler is essential to help keep the belt from jumping cam timing should the engine turn backwards (especially when cold), in rare instances.

I would not operate one of these engines without the lower roller, regardless what belt tensioning device is used!

That being said, I have had issues/noise from the "double roller" and only use the "single roller", in my engine builds.

928NOOBIE

I'll say that last time we did TB/WP (last year) the shop identified the roller referenced on my car as needing replacement and thus we did so.

While being largely stationary and it's purpose being to prevent teeth jumping...You can still look forward to paying over $200 for the part...Merry Christmas

FYI I run the factory tensioner technology on my car...although when I bought it...the previous owner had not performed TB/WP maintenance so we decided a new (reverse)tensioner was needed in 2010...they cost more than a $200 roller....they cost more than several of them in fact...

ROG100

The bearing for the lower roller/rollers is easy and cheap to replace at $7.25 each.

All the Gates Long Life/Racing belts are tensioned exactly the same as the standard Gates belt.

GregBBRD

Update.....

Like I said, this entire "belt" tension thing.....aftermarket tensioners without any data on how tight the belt is run (and thus no idea of what is happening to the cam timing), aftermarket belts with different stretch rates and without any data on how tight the belt actually is (and no idea of what the cam timing actually is)....greatly interests me.

I grew wary of rumors, guessing, and marketing....I like "hard data" when I consider changing something. (I therefore almost exclusively use the stock belt and the stock tensioner....around which I know Porsche researched and formed all of their data about belt tension and cam timing.)

I was going to undertake this study on my own, but Roger said anything I would do would not have any credibility, without someone independent standing there and making sure that I was telling the truth.

I'm not going to focus on how perplexing that statement was, to me.....coming from an engineering background and always dealing with everything I do with a 100% focus on reality.

At any rate, this "project" (knowledge) regarding belts is progressing forward...from an major engineering concern.

While my desire was to only know what was happening with 928 belt dynamics, initial discussions and basic research showed that there were other engineering "voids" in belt drive systems....which amazed everyone concerned that was looking at what I was trying to accomplish.

It appears, that Roger's thought that I might "lie" about what I learned, is turning out to be a potentially huge thing!

ROG100

Wow Greg where on earth did that come from?? I have never EVER said you would lie anywhere never. You have my utmost respect and always will have.

I do remember that you were trying to prove a point to some of the NOT GB fans and I said an independent observer would ensure that you would not be open to cheating in THEIR eyes. Where in that statement did I call you a liar?

ROG100

If you have the ability and the knowledge to make the slight adjustment to the Long Life/Racing belt tension as Greg suggests based on his experience & knowledge that would be a good thing.

The manufacturer, Gates, states to use the standard tension - has worked in the majority of cases so far.

john gill

Play nice you all its Christmas time after all.
I have a gates racing belt installed and running since the first release of them through roger. The only difference in them is they stretch less , I through trial and error use 1 degree difference between them, to allow for thermal growth of the metal parts. and set the tension at stock levels .
I believe them to be more accurate as in the last belt run through roger, I have ordered few spares . My cars do lots of track work , I check the position of the cams by then finally checking the compression of the cylinders , as if the camshaft timing is set correctly , when hot all cylinders will have even compression .

Merry Christmas

docmirror

I have only one case to remark from. It was a double roller cartridge. I had a well tensioned racing belt. There was sufficient interference to cause the 'belt tension' warning lamp to light during a long distance trip, which required me to retention the belt in a gas station parking lot, and subsequently remove and replace the belt when I got home, where it showed serious wear. The rollers were skidding by the time I took it off.

While I understand the reason behind the rollers, and appreciate that they do an important job, be advised that in my ONE case, it caused interference. Leave them, remove them, I'm only providing info on my one case. And finally, while a belt jump is a serious event, in the case of a well tensioned belt, with standard Porsche tensioner, the probability of a jump is microscopically small. Further - should a belt jump, some microscopic % of the jump occassions would result in a jump sufficient to cause an interference. A jump of one, or two teeth will result in poor performance, but not interference. A jump of more than 2 teeth I believe might result in an interference, but I will leave it to those with more knowledge of cam timing.

GregBBRD

I've had a couple of instances where the right hand roller (on the double roller) hit the belt very hard....and made terrible noises.....since they are tiny bearings and not meant to rotate all the time.

I just gave up and decided to only use the single roller, after having these experiences. I've actually been cutting the second rollers completely off of the casting....turning them into single rollers.

GregBBRD

I went back and read that thread.

Of course, you did not call me a liar....and I didn't mean that in the literal sense.

More of an impression. The idea of needing a third party to monitor what I found out was what caught my eye.....inferring that I might not tell the truth, for some reason.

Pretty high standards to jump through....that no one else needs to do. Even the people that build things and make outlandish unsubstantiated claims don't have to do this.

No big deal. Just changed my course of action.

ROG100

Merry Christmas Greg it was never my intention to offend you in any way - far from it.