mark kibort

Belt looks fine, last changed when i replaced a suspect water pump back in the very beginning of 2005. so far, 3 full racing seasons. Is that a long time?
(prior belt was almost exactly 3 full racing seasons too before the change out, and it looked good when it came out. If you remember, it had skipped 2 teeth in my last WC race at laguna in '04)

probably only about 10,000miles total, although many of those miles on the race track.

thoughts? How often do the other racers run the timing belt?

Mk

atb

I think Veninger changed his last one after about 37 minutes?
(Hope your in a good mood JV )

Jim M.

From what you've described in the past, you never hit the rev limiter, rarely if ever shift at red line, and you drive it to and from the track; so how is it that much different than a street car driven hard? If the belt maintains tension and is still flexible then keep driving it. The factory says 5 years or 60K miles. For a race car you could cut that in half, so 2.5 years or 30K miles.

Just my $9.28 worth of advice.

John Veninger

always

I would change the belt every two years and check the tension before every race weekend.
I might do mine a bit more often

mark kibort

probably good advice.

going to get one on order and change it after this race. what the heck!

Mk

justin

I would change it every 5-6 races, but thats just me.

mark kibort

thats probably when it gets most stable.

mk

PorKen

I would think that a raced 928 engine would benefit most from an adaptive tensioner system...

Fewer parts to fail, better valve timing, less belt shock, etc. You can even change the belt without removing any tensioner parts, if you want to do more frequent, belt only changes.

Maybe Roger will give you one if you put a 928s-R-Us sticker on your car.

drnick

ken, are your belt tensioners going to be available via roger all the time?

PorKen

Nick,

That's the word on the street!

He can supply the Audi parts too, at a great price.

marton

In that case why touch it?

about That was a recommendation that came out fairly late (like 1991?).

Before then the recommendation was to only to visually check it at the annual service.


on the other hand if I had a race car & enough money I would rebuild everthing after each season.

Marton

JPTL

Mark, sorry if I'm taking this off topic slightly, as I realize that you're talking about the effects of extreme use & not lack of use and/or time on belts.
That said, I haven't seen/heard of too many stories of t-belt problems due solely to an aged belt. It seems like it's w/p failure, tensioner problems, and/or cam gear issues that seem like the overwhelming cause of belt failure as opposed to age.
Reason that I say this is that I just pulled a 10 year old belt from a clean, leak free low mile engine. W/P seemed healthy, tensioner & rollers looked good and cam gears show no wear. Hardly any signs of wear or deterioration on the belt. I couldn't see a single crack or fraying. When comparing it to the new belt, it didn't seem to have stretched much either. If I had cleaned it up a bit, the smooth side could have passed as a new belt.
Maybe a belt that's ready to fail isn't apparent to the naked eye, but I'd bet that this belt could have gone for another 10 years without any contributing factors (like those listed above).
I'm in no way suggesting that anyone should try it, or that this is true - since I'm a newbie when it comes to timing belts.
Just my observation.

mark kibort

I think i hear you. Actually, just went to check the tension, both with my peek hole and the kempf tool. it really checked fine! I dont think ive touched the tension in the 3 seasons the belt has been on. (with the new water pump)

There was no sign of any cracking, and the belt did look brand new.

I think you might be right about the other factors having more weight.
Im leaning toward another season with the belt.

Ill get one on order. Maybe when its time to change it, the new engine will be going in!

mk