Avar928

Speaking of a Porken tension alarm: https://rennlist.com/forums/928-foru...ing-light.html

Imo000

I never said they don’t fail, I wrote I never heard of it.

Neglected factory tensioner systems fail but so do the Audi units if they are left neglected. Since Ken’s Audi tensioner is recommended to be changed every timing belt interval and the factory system is also recommended to be fully refurbished (this means change every wearable part) during every timing belt interval but Ken’s deletes the warning system then, this isn’t an upgrade but a degrade in my books. My only two issue are the deletion of the warning system and the fact that the factory system does perfectly what is designed to do, nothing more.

If Porsche made the tensioner non rebuildable but a part that would require replacement, the number of parts between the Audi tensioner and the Porsche one would be substantially less. BUT since it isn’t, every part of the serviceable Porsche tensioner is counted as an individual part when compared to the Audi non serviceable sealed unit.

I guarantee that if the Audi system was on the 928 from the factory and today, someone would invent the one that the 928 came with (that has a warning system), people would be calling the inventor a genius.

Jim M.

Roger stated "we tightened the belt half a turn" well I was doing my best flashlight holding and "we" only tightened it one flat, which is much less than half a turn. Everything else looked good, no fuzz or fraying on the belt, minimal wear on the cam gear and no leaking trail from the tensioner. Oh, and that guy from Texas was the main supplier for the PO, but even with that it could have been a Conti belt. We'll find out when the PK tensioner goes on, and if it is a Conti you can be sure it won't be when it's back together.

69gaugeman

What is the failure mode of the factory system? How many failures have you seen?

Porsche could have changed the system over the twenty years they made them. They didn't. Why?

SeanR

Plenty of failures from the bushings being worn out to the bearings in the rollers being bad. It's not rocket surgery.

And yes, Porsche changed the system many times. You are the engineer, take a little bit of time and look at PET and see all the different set ups they did.

69gaugeman

Dude. Seriously. Bearings are in kens system too. If you never replace the bearing it will fail on his system too. And it will not let you know. The bushings are cheap and easy. If you don't do it at the timing belt change that is your fault. Not the design. Other than stupidity of the user, the Porsche system is perfectly designed for the task required.

DKWalser

This ignores one of the major benefits of Audi-type tensioners, which is to maintain proper belt tension throughout the the vehicle's operating range. The stock tensioner does NOT do that. It merely increases tension (slightly) as the engine warms up to compensate for the belt's heat expansion. It does nothing to combat belt-slap from rapid changes in RPM. Nor does it compensate for any stretch in the belt (which is why the stock system requires the belt be re-adjusted a 1,000 miles or so after it's first installed). Audi-type tensioners address all these issues (assuming they work). The belt is never too tight nor too loose. Nor are the components subject to sudden changes in tension. In theory, this should result in less wear on the cam gears and less wear on pulley bearings. Being under constant tension, the belt is less apt to skip a tooth and the components should last longer and be less likely to fail suddenly.

So, the two parts do not do the same things. You might not find the additional things done by the Audi-type tensioner valuable or you might find it's lack of a warning light to outweigh the benefit from the additional things that it does. Viewing the two parts as doing the same thing (one with a sensor and one without) misses the true nature of the decision by a country mile.

Chalkboss

Here we go again.

ROG100

The antiquated tensioner system is in my humble opinion exactly that. Does it work - yes sort of!!! Needs at least annual maintenance and checks.

Had my car been fitted with a PKensioner none of the above (first post) would of happened.

If you like the old original tensioner stick with it and stop trying to justify its existence to those of us who prefer the more modern system.

PKensioner Black - is the new updated bracket from Ken. It is actually black to differentiate from the previous design. More later.

69gaugeman

Yes they do do the same things. At some point the differences become mute. The tension at operating temperature is pretty constant in that once all components are up to running temperature it is running in the correct range. One could possibly argue that during cold start up the tension might be different, but how much difference is debatable as NO ONE knows. There is ZERO evidence that this system is better. Or even better enough to make the change. Once that evidence is there I will accept it as a necessary change. Until then it is just people saying it should be better, therefore it is. Which in my book is not enough.

To be fair Roger there would be no warning when the belt breaks or the bearing fails or the water pump seizes or the cam starts to crack with Ken's system. You would just be quietly doing a top end engine rebuild.

The factory knew about Audi's (at least Audi was running it) before the end of production. It would have been an easy change for them to do. Yet they didn't. Why?

SeanR

Geezus, you just don't like what others have been telling you for years.

Porsche stopped R&D on the 928 in 91/92. Look at the 968 tensioner, it is very similiar to the Audi one. On a car that had R&D that went on longer than the 928.

Nothing is going to convince you otherwise so why do you keep spouting the same **** thread after thread after thread. We all know you wont use.

69gaugeman

Definitely not the same reason you keep spouting the **** you do. And there is something that will convince me. It's called data. You show me that it is better and I will become the number one promoter of the system. Of that you can be sure.

I prefer to educate rather than use scare tactics. But that is me.

Make a claim? Back it up with data. Otherwise I will call you on it.

I never said don't use kens tensioner bracket. I just say (and still do) that the Porsche tensioner is more than adequate for this vehicle. If it helps you sleep at night, great. Go ahead and use it. But DO NOT say it saves engines, causes less wear, is better than the factory system. You do not have proof of that. You are the one spouting lies.

SeanR

You will be hard pressed to find me, anywhere, using "scare tactics". You also will never find anyplace where I have said it saves engines. Go for it, find it. I will say it does reduce wear by keeping the tension static........the same over all circumstances. Can you honestly say that it does not? That the factory one does? No. You. Can. Not.


I also don't tell people what to use, I let them decide on their own. That's the beauty of it, they have the choice to use a more modern set up that is used on virtually every (similiar) belt driven car on earth. Not the one designed in the 1970's with minimal improvements over the years that is only used on our car, which had no R&D spent on it after 1991.

For me, and others that have chose this, it is the BETTER choice. Sorry you don't feel that way.

Prove I'm spouting lies ********. Go for it.

DKWalser

In my original reply, I toyed with making explicit something I thought was implicit: I'm NOT arguing that the Audi-type tensioner is superior to the stock tensioner. Like you, I don't have any data to support or refute that argument. My point is that the two units are designed to meet the same goal -- keep the belt on the cam gears -- in different ways. The stock unit compensates for expansion of the belt as the motor heats up. The Audi-type unit is designed to dampen any changes in the belt's tension from heat, rapid changes in RPM, or anything else. That is, the Audi-type unit acts like a shock absorber to keep the belt on track. Does the Audi-type unit work as designed? I don't know. I do know that the Audi-type unit is designed to do things that the stock unit does not do. As I said in my original reply, you (or anyone) might not find those things valuable. You might even prefer to leave those things undone. Fine.

Some Harley riders prefer a hardtail; some prefer a softail. Both suspensions try to keep the rear tire on the road. They don't approach that task in the same way. Saying hardtails and softails "do the same thing" is only accurate from a distance. Looked at in detail, it's easy to see that the softail does things a hardtail does not. The same is true with the Audi-type and stock tensioners.


That line of argument goes both ways, doesn't it? The Audi engineers knew about the Porsche design and did not adopt it. Worse, from your viewpoint, Audi has stubbornly refused to accept the superiority of Porsche's design for close to 30 years. (Porsche only had a few years to adopt an "improved" design while Audi has had decades.) As you asked, why?

69gaugeman

Clearly you need to calm down. I am sorry you are having a bad day. I can send you an e-hug if it will make you feel better.

You are free to express your opinions as am I. If you don't agree with my opinion or the facts I present, feel free to discuss why in a polite manner. No need to be rude.

There is more than one reason to choose one system over another. You also have to keep in mind that Audi uses steel gears and not aluminum ones. There are so many differences in the two engines that one cannot take any one factor and draw any conclusions. They chose what they did for multitude of reasons.

In fact, I will say that from an engineering point of view if you look at the single value of dynamic tension it would APPEAR the Audi one is superior. This is of course only one factor. The biggest issue is the difference between the two systems. Is the change in tension significant enough to warrant the use of a different tensioner? If the belt life is the same it means you are doing the same work with no benefit. If it extends the life of the belt then that would be easy to quantify. But to be clear, Audi recommends belt changes from 125,000km to 150,000km , so even theirs doesn't do that. Is it enough to warrant the change? Some think yes. I do not.

On top of that, there are other weak points in the system that warrant a low tension alarm system. This overrides the (in my opinion) very small benefit of dynamic tension benefits.