Corrosion weak spots...
- Thread starter AlexG
- Start date
metric_thumbs
New member
OK, OK, OK - understood.
(I could explain corrosion at the molecular level - no, OK - I'll be getting my coat then ....... )
(I could explain corrosion at the molecular level - no, OK - I'll be getting my coat then ....... )
Guest
New member
AlexG did ask "Any other model specific gotchas ?"
and Geoff contributed > "On the 2 litre cars timing belt relacement is simple and nowhere as essential as in the 2.5 litre engine because a broken cambelt on a 2 litre car usually means that the engine stops - whereas on the 2.5 (944) lump it almost always means a new engine."
It has certainly prompted me to contact Gates and/or Continental in the near future and see if they have anything to say re Porsche belts.
Peter Morgan in 'The Porsche 924/944 Book' has this to say :-
"The failure, when it has happened, has usually been tooth breakage as a result of insufficient tension, ......"
"From 1985 .... a new stronger belt was offered. .... routine checking of the tension is advised every 12,000 miles. The belt is claimed to last the life of the engine."
"If you have the older, pre-1985, belt fitted ...... condition and tension should be checked every 10-12,000 miles and it should be replaced around 30-35,000 miles by a new belt of the new type." End of quotes.
This is radically different from saying the new type also needs changing at just 30,000 miles.
and Geoff contributed > "On the 2 litre cars timing belt relacement is simple and nowhere as essential as in the 2.5 litre engine because a broken cambelt on a 2 litre car usually means that the engine stops - whereas on the 2.5 (944) lump it almost always means a new engine."
It has certainly prompted me to contact Gates and/or Continental in the near future and see if they have anything to say re Porsche belts.
Peter Morgan in 'The Porsche 924/944 Book' has this to say :-
"The failure, when it has happened, has usually been tooth breakage as a result of insufficient tension, ......"
"From 1985 .... a new stronger belt was offered. .... routine checking of the tension is advised every 12,000 miles. The belt is claimed to last the life of the engine."
"If you have the older, pre-1985, belt fitted ...... condition and tension should be checked every 10-12,000 miles and it should be replaced around 30-35,000 miles by a new belt of the new type." End of quotes.
This is radically different from saying the new type also needs changing at just 30,000 miles.
AlexG is quite happy with all this techie stuff - even if is ever so slightly off topic (and some of it I have studied at a basic level) [
]
I have gathered quite a bit of useful info from this thread, and will continue my search (...tomorrow!) had a cursory look at a car mid last week, going to have closer look (armed with additional knowledge thanks to your good selves) tomorrow morning!
...but the lure of the dark(turbo)side is strong, plaese stop the 'sensible' arguments[&:] .
]I have gathered quite a bit of useful info from this thread, and will continue my search (...tomorrow!) had a cursory look at a car mid last week, going to have closer look (armed with additional knowledge thanks to your good selves) tomorrow morning!
...but the lure of the dark(turbo)side is strong, plaese stop the 'sensible' arguments[&:] .
vitesse
Active member
Metric_thumbs,it was said "tongue in cheek",hence the smiley.It is still my opinion that textile reinforced "rubber" belts in this application fail from fatigue and the mechanism is little different from a metal component.All items have electrons and depend on current flow for their behaviour,even bones.I won't bore you with my qualifications but "my dad is bigger than your dad" syndrome is a bad sign.[ORIGINAL: metric_thumbs
Oh come on!!! I am not picking on you - I providing the correct explanation of fatigue in metals. I will learn from what people will post here - and I hope others will pick up useful information I post. It so happens one of my degrees is to do with materials and their engineering performance. So I reckon I can add something here.ORIGINAL: VITESSE
That's the trouble with this forum,you always get picked on your contributions however well meaning they are meant to be[:-].I think in fact the general premise of fatigue failure and its' relationship to no's of cycles applies to all materials inc metals,plastics,timber,textiles and rubber,including combinations of them as composites or arrangements.
With a toothed belt,the flexure of the tensile textile reinforced flat back in both directions over toothed pulleys and flat tension pulleys coupled with the shear force applied to the moulded teeth and a combination of the two between the back & the teeth results ultimately in fatigue failure.Okay,materials have different physical & chemical properties but the general result is the same.A chaindrive would also fail ultimately from fatigue but actual length extension due to wear limits its' life to around 15,000hrs.
Lecture over.[
Of course other materials fail in extended life cycles but their failure mode is different from metals, because metals are err, well metals (flow of electricity, sea of electrons and stuff)
I could explain in very fine detail but will leave that until I can stop you from escaping.
][].In reply to Muddy,without saying so,my comment was related to enclosed comparable chain camshaft drives running in oil,not on a Frazer-Nash,basically running in a field.[
] Just seen the new threads & apologise for the response.
When I fitted just new belts to our 924S at 76,000 miles(previous change at 36,000),they were in excellent condition showing no signs of distress.At about £39,it was peace of mind for a car doing 5000 miles or less a year but based on their age(over 10 yrs).The new balancer belt was a wide one(as the cambelt) compared to the one I took off,so there has been some noise associated with the wide belt running on
the pulleys,previously polished(worn slightly ) by the narrow belt.
Well I looked at and bought a 924 NA on Sunday. It's a 1980 car with what appears to be a genuine 60,000 on the clock. It is no concours winner but seems pretty solid.
Highlights:
Highlights:
- Completely split free dash!
- No sunroof
- Electric windows and mirrors (which surprised me)
- Original unmarked 14" wheels (though finding decent tyres could be an issue?)
morris944s2john
New member
That would make a good project for someone who can weld, do body work and paint, provided the car was mechanically sound and cheap enough.
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