Gear Drive, Quiet vs Noisy? - Page 2 - Team Camaro Tech
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post #16 of 26 (permalink) Old Aug 3rd, 00, 02:47 AM
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I'm running one because I'll have about 300 lbs spring pressure on the seat and about 750 lbs open. I like the fact of having a link between the crank and gear that won't distort or give. Maybe I'm stupid, but like I said, I've had really good luck out of mine. People can say what they want, and I'm not telling ANYONE to buy one, I'm just saying they work for me. The backlash that I-man is reffering to is of no consequence, because when the engine is running, the large idler gear is pulled into the mesh. The small gear is under no load when the engine is running. When you turn the engine over on the stand, the large gear is tightened into the mesh. Now, I'm not saying this is better that a single, fixed idler gear, but it is a lot cheaper, and the key for me is that it fits very easily under the stock timing cover. My race engine is reverse-cooled, so I have enough water lines and vacuum pump lines on the front of my motor, without trying to work around the timing gears. I've rebuilt enough SBC with decent spring pressures to know that the chains (even the GOOD ones), get pretty sloppy after a good season at the strip. This slack retards the cam, and I know the gear will never do this. Just my 2 cents. I'm not trying to convince anyone here, just telling you my experience. Take care.

P.S. If some of you have the book "Power Secrets" by Smokey Yunich, read what he says about timing chains. He put a clear timing cover on with a light mounted behind it, then he ran the motor on a dyno. He said something about it looking like a snake above 7000 rpm. He also states that he has used a DIRECT gear link between the crank and cam (turning the cam backwards), and in fact recommends this method. He does state, as I did, that the singled, fixed idler is better than the dual idler set-up. Very interesting reading. Take care.

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[This message has been edited by 69SSRS (edited 08-03-2000).]
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post #17 of 26 (permalink) Old Aug 3rd, 00, 03:17 PM
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Of no consequence...Oh, really?? Well, thinik about this, EVERY Pro-Stock engine used today is running either a Jesel belt drive or a common duoble row timing chain set, every one. What the actual real racers found is that the gear drives actually had too much harmonic distortion transfer from the crank to cam and valve train.

Now, Pro-Stockers run cams with between .900 and 1.100 valve lifts through the rocker arm ratio, and $1,700.00 a set titanium valve springs they change in 15 runs. When these same valve trains were run with a non-daqmping timing system, the valve springs lived 7 tp 8 runs. Since a Pro-Stocker is normally aspirated (PULLS mixture into the cylinders), harmonics is a very important issue, as it disturbs the intake flow and carburetion/jetting.

Dual idler gear backlash is seen as the engine is on steady rpm output, and at deceleration, and allows the cam and valve train to chatter and have erratic operation, even in acceleration mode. This ain't good for notin' in the valve train, and is vitally consequential.

As the dual idler jobs get loser, the amount of harmonics and vibration gets more intense, with growing adverse effect. Eventually, the idler gears get so loose the contact of the teeth get twords the limit of strength, and the teeth begin to chip and will fail shortly after this.

There were lots of roundy-round racers in Merced, where I had a speed shop, and they drive of choice was the Junkson dual idler nightmare. The cars that consistantly won came from my oir another shop, and always had chains on them, the ones that always had cam, rocker, spring, valve train problems used the dual idler junk. Once the racer saw the light and went chain, he began to get a season on a chain and sprocket set and began to not have the valvetrain problems and could actually tune the engine, something that wasn't possible with the gear drives.

Blower alchohol and nitro engines run gear drives, but they only use cams with lifts through the rockers at or very near the .700 levels, and, since they vibrate the daylights out of themselves, not much damage is done from them as far as harmonics. Since the mixture is pressurized into the cylinders, the harmonics become moot in those supercharged powerplants.

Of no consequence-for a normally aspirated engine?? Makes every consequence, bet your life it does. Ask any real and knowledgeable cam or carb person about distortion and the prblems it causes in the valve train and/or intake tract, you'll hear the same thing, vitally important not to have any. You won't hear any of the real truth in the big-time hype ads for this junk dual idler garbage.

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post #18 of 26 (permalink) Old Aug 4th, 00, 02:53 AM
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Quote from before: "People can say what they want, and I'm not telling ANYONE to buy one, I'm just saying they work for me."

I was asked why I ran one, and as a courtesy, thought I would answer, but should have known I would get bashed for my opinions.

I don't like nitrous, but you don't see me bashing every guy that likes to run the stuff, do you? To each his own. You run what you like, and I'll do the same. Until someone donates over $500 to my racing fund, a belt drive is not #1 priority. Sorry if that bothers you, but I'm not Warren Johnson, and never will be. I'm trying to build a $20,000 engine on my own income, without any sponsorship or donations, so I do what I can. Take care.

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post #19 of 26 (permalink) Old Aug 4th, 00, 06:00 AM
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69SSRS, nobody, including me, is "bashing" you. Just relating FACTS about the dual-idler gear drives and their problems/drawbacks from over 30 years of fighting with Pete Jackson and pleading with him to make them better, without any positive results.

Now, it seems to me that if you have to defend the drive simply because you bought one or haven't used it hard enough to make the problems many, many others have had, then that is your problem, not anybody else's.

I posted proven facts, you countered by saying my findings were inconsequential, I responded with more PROVEN FACTS, and you couldn't handle it, so you say I'm bashing you, not even close.

The facts I posted weren't all just moine, but well over 500 of other people's Pete Jackson/Edelbrock dual-idler drive experiences, and mine.

Sorry you felt bashed, you weren't, FACT.
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post #20 of 26 (permalink) Old Aug 4th, 00, 09:36 AM
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I was just curious as to why people used them as most I have known didn't like them. I appreciate the responses from 69SSRS and IgnitionMan and didn't want nor expect it to go this route. I am sure each has its own advantages and disadvantages in different situations so I wouldn't think either is wrong. Is a three inch dual exhaust on a straight six Camaro a good choice? No of course not. But great on a 502 blower motor in the same car. I put down the gear drive because I don't see a need for it on a street driven commuter car. Maybe up to some level the gear drive is good and past that level to a all out racer the belt drive is the way to go. I really don't know. Price and usage have to be two big factors. If belt drive is so good then why doesn't the manufacturers put them in from the factory. Its probably because its not cost effective or overkill. Not because its inferior to a chain. I have to believe your both right to some extent and not that you have to go with one or the other or your making a big mistake.
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post #21 of 26 (permalink) Old Aug 4th, 00, 09:59 AM
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Belt drives are used on plenty of engines produced today, overhead cam engines, foreign and domestic. Great way to do a cam drive, but none are produced in mass quantities for earlier pushrod american engines, and yes, the Jesel drive is really expensive, but well worth it in a racing situation.

A single idler gear drive is much more accurate, will live lots longer and perform much better than a dual idler setup, that's why the fuel and alchohol people use a single idler plate mounted gear drives only, and they buy and use what works. They don't use dual idler stuff.

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post #22 of 26 (permalink) Old Aug 6th, 00, 08:51 AM
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If a roller chain or a direct drive breaks there can be alot of damage, like valves smacking pistons. Bob
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post #23 of 26 (permalink) Old Aug 6th, 00, 04:29 PM
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And, when a Junkson dual idler drive breaks, the same valve damage happens, and you get the luck of breaking the front of the cam off as well, and all that gear scrapnel in the bottom end past the front main cap. MMMMM, let me run right out and get one, they're soooooooooo good-NOT.
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post #24 of 26 (permalink) Old Dec 27th, 14, 08:49 PM
 
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Thumbs up Re: Gear Drive, Quiet vs Noisy?

I was Racing Director at a Texas dirt track for 13 years and can attest to a conversation I heard one night. I was in the pit area one night when a car owner came up to ask one of the top drivers(who was later on written up in SPEEDWAY Magazine) if his car (rear end) was broken for the night. The driver replied that it was indeed broken. The car owner asked if the driver would like to drive his car the rest of the night. The driver asked if the car owner had a timing chain or gear drive in the motor. The owner answered "it has a chain". The driver replied that he would not drive his car because he would break the chain and ruin the motor because of the jumping on the accelerator so suddenly that no timing chain would hold up to that type of action. He had driven race cars for thirty years and over that time had made the conclusion that when he destroyed an engine it was due more often by that cause.
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post #25 of 26 (permalink) Old Dec 28th, 14, 03:14 AM
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Re: Gear Drive, Quiet vs Noisy?

Gear drives are cool. I heard a '55 chevy with one at the parts store. If you like that whine up front, I say go for it. They are probably as reliable as a good chain.

As far as what Smokey says about chains above 7k rpm. If anyone here is winding their SBC above 7k, I salute you!

The important thing here is that you ask me what kind of car I've got. "I've got a BITCHIN' CAMARO"
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post #26 of 26 (permalink) Old Dec 28th, 14, 05:37 AM
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Re: Gear Drive, Quiet vs Noisy?

Not bad for a 14 year old thread. I've run SBC's above 7000 rpm for miles and had no problems with a timing chain. I rode in a gear-drive car once for about 50 miles and couldn't wait to get out, the noise became distracting and annoying.

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