Discussion
Watching a part of an old documentary on Youtube, regarding the Cosworth DFV. I noticed that it was entirely gear driven. This got me thinking, I know a few cars which are chain driven (i think all of my BMWs have been) but why is it that most engines use cambelts for timings, rather than gears? Is it a cost thing, or is there a benefit for a non-racing engine of having a belt?
Google didn't seem to turn up anything helpful with my searches. Pretty sure there will be a good reason, just curious what it is.
Google didn't seem to turn up anything helpful with my searches. Pretty sure there will be a good reason, just curious what it is.
jayemm89 said:
Watching a part of an old documentary on Youtube, regarding the Cosworth DFV. I noticed that it was entirely gear driven. This got me thinking, I know a few cars which are chain driven (i think all of my BMWs have been) but why is it that most engines use cambelts for timings, rather than gears? Is it a cost thing, or is there a benefit for a non-racing engine of having a belt?
Google didn't seem to turn up anything helpful with my searches. Pretty sure there will be a good reason, just curious what it is.
My Touareg had gear drive and was one of the only parts of the engine that didn`t suffer some sort of malfunction.Google didn't seem to turn up anything helpful with my searches. Pretty sure there will be a good reason, just curious what it is.
there are some engine with both belt and chain and I can think of at least one engine with chain,gears and belt,mental!
Quiet and can do the same job, Gear driven would be noisy, a Essex V6 with steel timing gear tends to sound supercharged, A lot of older especially German cars had chains with no issues apart from getting rattily when needing adjustment, would of always preferred chain but there's a lot of modern chin driven engines that seem to give trouble BMW/mini ect
Gear driven Looks pretty tho
Gear driven Looks pretty tho
Edited by BigBo on Thursday 18th December 20:38
Edited by BigBo on Thursday 18th December 20:40
Most modern cars with timing chains are not problem free, crank and cam sensor phase issues usually stem from a stretched chain, as for gears i've had both essex and cologne engines self destruct due to gear drives shattering at under 60K most timming belts will last 60K and are easyer and cheaperr to replace and they are quieter in general but that never stopped the pinto from sounding harsh at high revs (or even medium revs come to that) 
paintman said:
Was that with the standard timing gears - fibre or nylon toothed - or the full steel ones?
The standard factory fibre ones, i tried the steel ones in an Essex but they whined more than the wife Belts are the best way to deal with infrquent oil changes IMHO as it has no impact on them unlike gears or chains, one less thing to be affected by an owners tightfistesdness, the downside is that same tightfistesdness can destroy an engine if a belt snaps but i find people are more inclined to take a hit in the wallet every few years for a belt shange rather than every year for a service! i see a lot of cam belt changes that really REALLY need an oil change but talking a customer into a belt change is easyer than an oil change
warnings of a destroyed engine works better than warnings of a worn engine in a few years (when somone else will cop the hit as they've sold it on by then).I do work in a backstreet garage frequented in the main by numptys, tightwads and people who honestly think it's my fault their car needs 3 new tyres for the MOT cos they are bald as monks tonsure (and most of them drive thier children in them daily) so my veiw is tainted somewhat
S0 What said:
The standard factory fibre ones, i tried the steel ones in an Essex but they whined more than the wife
Belts are the best way to deal with infrquent oil changes IMHO as it has no impact on them unlike gears or chains, one less thing to be affected by an owners tightfistesdness, the downside is that same tightfistesdness can destroy an engine if a belt snaps but i find people are more inclined to take a hit in the wallet every few years for a belt shange rather than every year for a service! i see a lot of cam belt changes that really REALLY need an oil change but talking a customer into a belt change is easyer than an oil change warnings of a destroyed engine works better than warnings of a worn engine in a few years (when somone else will cop the hit as they've sold it on by then).
I do work in a backstreet garage frequented in the main by numptys, tightwads and people who honestly think it's my fault their car needs 3 new tyres for the MOT cos they are bald as monks tonsure (and most of them drive thier children in them daily) so my veiw is tainted somewhat
Isn't there afew different types of Fibre gears, then there is crap nylon ones and silly loud steel ones, have been researching this as I'm nearly done with the body of a 3.0s and timing gear is one of the last pieces for the engine build needed, steel seams best but some are v loud, Belts are the best way to deal with infrquent oil changes IMHO as it has no impact on them unlike gears or chains, one less thing to be affected by an owners tightfistesdness, the downside is that same tightfistesdness can destroy an engine if a belt snaps but i find people are more inclined to take a hit in the wallet every few years for a belt shange rather than every year for a service! i see a lot of cam belt changes that really REALLY need an oil change but talking a customer into a belt change is easyer than an oil change
warnings of a destroyed engine works better than warnings of a worn engine in a few years (when somone else will cop the hit as they've sold it on by then).I do work in a backstreet garage frequented in the main by numptys, tightwads and people who honestly think it's my fault their car needs 3 new tyres for the MOT cos they are bald as monks tonsure (and most of them drive thier children in them daily) so my veiw is tainted somewhat
as for cars needing oil and tyres the customers always right eh?, we put a engine supplied by the owner in a b16 civic, told owner it needed a clutch and would be as well to change the belt for peace of mind, insisted he new the car it came from and as it ran well it'd be grand till the next payday, 2days later its stuck at the side of the road getting no-spark as the belt snapped, I don't think there is a completly flawless way of timing just well designed arrangements, its usually tensioners or guides that cause problems
also watching the recent Jay leno vid on the s600 they refer to the DFV as a benchmark for tappy engine because of the chain
Edited by BigBo on Saturday 20th December 00:23
BigBo said:
Quiet and can do the same job, Gear driven would be noisy, a Essex V6 with steel timing gear tends to sound supercharged, A lot of older especially German cars had chains with no issues apart from getting rattily when needing adjustment, would of always preferred chain but there's a lot of modern chin driven engines that seem to give trouble BMW/mini ect
Gear driven Looks pretty tho
that's a jewel it should be in a carriage clock case.Gear driven Looks pretty tho
Edited by BigBo on Thursday 18th December 20:38
Edited by BigBo on Thursday 18th December 20:40
I wonder how much parasitic loss it has compared to a belt drive though.
garagewidow said:
that's a jewel it should be in a carriage clock case.
I wonder how much parasitic loss it has compared to a belt drive though.
good question? that's a SR20, I believe they done it as its the best way they found to keep the timing accurate above 10.000rpm and its more accurate/precise also like engine-pornI wonder how much parasitic loss it has compared to a belt drive though.
konark said:
Nothing wrong with using a rubber belt, what's the worst that can happen if it snaps.....unless you use it on an interference engine, but that would be crazy....wouldn't it? Oh, hang on....!
That's 1/8th of a mil lolDont think I'd trust a service interval of 125k, but even 60-80k for most is no big deal.
Unless it's a total nightmare to change.
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