Carrera Mike

I've read a European Car magazine article by a porsche shop in CA that they recommend replacement of the twin distributor belt at 50K miles.

I was wondering if it's solely dependent on mileage. my 993 is now 6.5 years old. Is there a recommended replacement after number of years? I would think it would get brittle in time.

Steve Weiner-Rennsport Systems

Hi Mike:

I recommend that the belt should be replaced by 60K miles. Its much cheaper to deal with this proactively, rather than deal with the consequences of not recongizing a broken belt immediately.

Greg Fishman

Steve,
What time frame would you use before you replace the belt on a car that is used 100% for track time?

Carrera Mike

Thanks Steve. Appreciate your advice. My other concern though is, what of I don't reach 60K miles in 10 years, is the belt still ok?

Steve Weiner-Rennsport Systems

LOL,......Well, we are somewhat uncharted terrritory here as I've seen plenty of broken belts in cars with factory vent kits from new.

Based on that, I'd recommend a 6-7 yr replacement cycle or 50K-60K since the consequences can be spendy.

viperbob

Greg,

If it were me, I replace the belt every season. BTW, the tow hooks are on the way. I finally came out from under the holiday barrage...

Greg Fishman

Thanks Bob. Let me know when and I can pay pal you the funds.
I will put the belt replacement on my to do list for the pre-season work. Car only has 19K miles on it but the last 6k are track/race only.

Steve Weiner-Rennsport Systems

FWIW,... I think replacing the distributor drive belt every year is overkill and simply not necessary based on experiences with the 3.6-3.8 litre engines since 1989 in street and competition usage.

viperbob

Steve,

In general I agree. In racing, I have always found it best to replace those items that can put you out because they "don't break that often". Can it hurt anything? It is not like tearing down your engine. I consider things like this CHEAP insurance. If it did break, you are screwed.

Steve Weiner-Rennsport Systems

I'd surely agree about not leaving things to chance but much like changing clutch discs 8 times a year, its overkill,......

IMHO, based on what I've seen with these engines, even in RSR's which run well above 7500 RPM, the belts hold up very well; its just not an issue.

Porsche A.G., a particularly detail-orientated outfit that is prone to be anally-retentive about some things, make no such recommendations in all of the maintenance and shop manuals which I have here,.....

After racing these engines since '89, I've gotten a pretty good "snapshot" of what goes wrong or wears out on these things by now. There are LOTS of other parts on these cars that people should change frequently that never are done (for economic reasons) that concern me a lot more.

viperbob

Yes Steve, there are a number of components that should be on the list of peoples "items too watch".

Specifically in racing which was the question, I include those items as you say do not wear as much on a seasonal level. Sometimes you can lose track of when you "changed it last". With a little attention at the beginning of the season, there is no issues to you need to be concerned with. Especially with a small item like a distributor belt. What could hurt not to do this? And what happens, albeit a small chance, if it breaks?

I change most of the bearings, belts, a lot of the rubber components, and many other consumables before I begin a new season. I am not changing the clutch 8 times, but I know the condition of my car as I personally drive it around the track at high speeds. I am my own mechanic and the driver, so I tend to be on the safe side of every decision.

Steve Weiner-Rennsport Systems

We keep very detailed maintenance logs of all our race cars. Each and every component is tracked for miles & hours and are replaced after so much time, determined by past history and experience.

LOL,....I've never relied on my memory about what components should be replaced or not. Its akin to my aviation activities; using detailed checklists has kept me alive after 30 years of flying, even during a war,.....

Its NOT cheap, but it prevents mechanical DNF's.

viperbob

Steve,

We are talking about the average racer here.. Not a factory sponsored Cup Car with hords of mechanics tracking more stuff than can be analyzed. How many average Joe's keep such detailed logs tracking every component, hours, miles, and **** probe temperature readings?

All I am saying is that for most people, changing these little items on a schedule is simple, cheap, and can potentially keep a bad day from occuring at a low cost. That's all I'm saying here.

Jim Morton

Bob:

Speaking as an average amatuer racer, i.e. no sponsors, etc. I can say that the ONLY way that I became successful, i.e. winning events, was to keep detailed log books on my car, my engines, lap times at every track, interval times for tracks and all those "****" things, etc. This is the key to a sucessful racing program, amatuer or otherwise !

Seriously and directly to your point... If you changed every component that could lead to a DNF at an event, the cost and time of performing all of those checks would greatly out weigh the benefit for most every amatuer. For items like the dual distributor belt, this is an item that is not only a royal pain to do, it is not known to fail at any specific interval to suggest an annual change. Check...maybe, change...not necessarily.

One needs to rely on sources such as Steve, and/or others, with the many hours (years) of exposure to the car you are campaigning in order to make good judgement calls and reduce the maintenance items to those things resonable to perform between events and those to do annually. This lets the amatuer stick to things that keep the car competitive at some sort of sane budget and develop the car and the driver's skill set on a well paced, programmed path.

$0.02 worth.

Steve Weiner-Rennsport Systems

Hey Bob:

We are surely on the same page here; I am not talking about professional level racing. I refer to amateur level racing executed on a professional level, if you see the difference,....

DNF's are expensive no matter what and where you race. Entry fees, gasoline, tires, lodging (and your time) are all down the drain unless one eliminates mechanical failures as far as is humanly possible. I think this applies to Club racing as well as ALMS, Grand-AM or what have you,.....

One relies on experience to guide you and help focus on where your efforts are best utilized and my only point was that changing that distributor drive belt annually was NOT an efficient use of resources: money or time. I'm simply offering the benefits from building 911-based race cars and engines for a long time,...LOL.

Given the limited resources our customers have, I'd rather they spent their hard-earned dollars where it counts the most,...