[Charles Geer]

Hey guys, I know most 968 owners change their belts every 15,000 miles or two years. Did'nt know if this racing adds any additional stress to the belts.

HOW OFTEN ARE YOU CHANGING YOUR BELTS?

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[Jim Child]

I've been changing mine every other year, running an average of about 25 track days per year with very few street miles.

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[Eric_K]

I agree, every two years. Sooner seems like overkill unless you are in there for other reasons. Mine still look fresh after 2 years but it is cheap insurance.



I thought a good street use interval was 30k or 4 years. ?



Eric

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[Charles Geer]

When I bought the car last year the belt broke at the secong event (DE). The belt was four years old....been parinoid ever since. The timing belt window remains open so I can look at it. The belt is 8 months old with 8 events but I can see a distinct roller pattern on the outside (non-ribbed side) of the belt. Again I'm abit parinoid but you guys have been grinding on these cars longer that I have so it is comforting to know that the belt will hold out for 2 years.



I do not believe we changed the rollers when we changed the belts but I am going to double check with my mechanic for good measure.



HOW WELL DO THESE ROLLERS HOLD UP?



Thanks,



Charles

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[flash]

i'm gonna catch a lot of flack here, but here goes:



it really comes down to how competitive you want to be - it's been my experience that most competitive guys tear the entire motor down every season, and trannie down at least every other season



if you think of it in hours and load, the math works out pretty well, at least for the belts - the street interval is a max of 60k, and generally accepted as 45k - if you figure that equates to 900 hrs at an average speed of 50mph, and further figure that the loads on a race car are every bit of 5 times that of a street car, that works out to 180 hrs of track time - that's about as far as you should go on a race motor if you want to win - if you just want to go out and play (finish, but not trying to take home the regional championship), you can probably double that



all that being said, it could be worse - these motors run a lot tighter for a lot longer than what i am used to - to tell you how bad it can be, we never got 100 hrs on a race motor in the MGs without measureable power loss

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[Charles Geer]

Boy, take me back to the days of Warped heads and Lucus electronics...I feel your pain, X Triumph TR7 owner. I don't believe my street car ever ran 100 hours.

I realize that every car and every owner has different luck with their race cars.

I owned a 993 Supercup that was the pace car for the 94' F1 season (Yep 993s were built in 94' along side the extremely rare wide body 3.8 964s) . I ran the cup car in DE event's (OK, so I tried to beat the living crap out of the car). When I sold the car to Ken Lubell of New York we had Peter Dawe leak down the motor. Even though we never kept an hours log on the car, when I sold it it had 10,000 Kilometers of redline shifting race miles on the motor. I't had a 2 % leak down on every cylinder the day I sold it in 2004.



On the other hand, My good friend who owns a 95 Cup Car has had to rebuild his motor every 80 hours for it a little bit of power every time he runs it.



The moral of this story... Air cooled 911''s (the king of reliability) will have a lemon ever once in a while, and they still can't hold a candle to the 968's in the twisties.

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