Timing Chain

Okay. Why?

What's wrong with the existing designs?

Gear driven at this time and is very noisey.

Well that doesn't say much of anything useful.

Take the exhaust system off. You never notice the timing gear whine.

Not helpful ... I did not write about the problem to entertain you ... maybe you have something else to do, but be facetious.

batt

A pitch of 6.35" is one helluva big chain.

6.35 mm pitch ... made a mistake

Why a chain and not a belt? Is this a roller chain?

Why would you use existing castings in a "redesign"?

You cannot expect auto manufacturers to give you their designs.

I'd join the SAE, tomorrow and ask them for help.

If you don't know what the SAE is, good luck.

I dealt with JT ASAHI CHAIN Products - YUMINASHI DIRECT SALES in another life. Talk to them.

Originally was going to use belt but client preferred chain ... has too much input from others but he pays the bill ... so I do what he teels me.

Because they a replica engines and must look like the original from the outside.

Just wanted to know what standard ... we would have to make the sprokets to suit .. maybe not ... whenever I do layouts I specify every think I can.

SAE ... cannot see a listing for the chain ... DIN 8190 and 8191 list down to 9.525 mm but not 6.35 mm.

Yes I do know SAE and have used their standards when I designed a range of radiator caps.

Had a look at the link you have suggested but they did not have what I needed.

Thank you for repling

Batt

That's the problem with clients...
They are often idiots.
Del

use a belt then

I've owned many used cars until recently. The only one that gave me trouble with the timing mechanism had a chain that broke. When belts were used for driving the camshaft(s), I was worried about the possibility of the belt slipping and messing up the timing.

Never had any trouble with the belts, and a few of the cars had close to 100,000 miles on them when I sold or traded them.

I have had chains strip,and belts strip.The belts did not break,the teeth simply shed off.

Most of the 1970 decade American made cars had a plastic coated gear set to minimize noise.

When they stripped out,the oil galleries had to be cleaned out and I always replaced them with an all metal gear set.

The nylon coated gears were designed to run for the length of the warranty period only.After that ,you are on your own.Typical Corporate attitude.

Insofar as gear-to-gear timing,a brass to steel,(ie; Porshe,VW)oil bath pair was nearly indestructible.

Never saw a set worn out or stripped.

With improvements in materials,today's timing belts will outlast a chain,but must be replaced at recommended intervals,although I have seen some running at 200,000 miles,twice the recommended interval.

A side note:

The quietest engines ever built were the flat heads,IMHO.

use a tensioner

I think you are in over your head.

I did not understand your comment ... I do not know how you would be able to make that assesment.

batt

Unfortunately we get a lot of people here wanting to redesign things that do not have the technical knowledge or skills to pull of what they are wanting so when someone new comes in with an idea people tend to be a bit standoffish and skeptical of the persons real abilities.

That and we also see a lot of people wanting to way over engineer a simple design that in reality likely has a far more practical and effective alternative that could be used instead.

In your case you say you want to use chain drive to replace noisy gears in replica engines. In my experience noisy gears are from straight cut teeth which are easily replaced with a gears that use a helical design.

The main problem with the gears was that the engines were built when centre pitches ( could vary .015" ) and the gears were not machined acurately so they came up with slightly tapered gears which were assembled with shims to reduce the backlash.

They have tried Helical gears but that did not solve the pitch problem.

The weight of the gears was a bit much ...

Also the client wants to get away from the gears as some people that already have engines ( where the pitches are not accurate ) and they should be able to retro fit this change into engines tat already exsist.

I hope I have explained that well enough.

Batt

but if you put the gear in your pocket for 15 minutes then remeasured your measurement would change

I know! that was the whole point. Make the lab project to such tight tolerances that it fell way below the minimum repeatable accuracy of the hand held measuring devices the lab instructors used!

If the specs sheet called for +- .003" aim for +-.0003 " being that doing any accurate measurements below .001" are rather hard to do quickly and accurately on a semi complex machined part.

In all reality though once the gears we cut got installed in the old machines they were designed for I have doubts anyone of them had much under +- .01" tolerances at best once they were properly worn in.

Precision gears on sloppy old worn shafts held in place by sloppy old worn out bearings and bushings tend to take on a lot of tolerance losses as they wear in to match everything else. Especially if the gear it had to mesh with looked like it was lubricated with gravel for the last half of its life.

PTO gear set from our old MF 2745 that got wiped out last summer and a typical representation of what we got way back then in machining labs as the projects we had to replicate.

Honda used 'split' gears with spring preload between the gears to eliminate the backlash. Expensive to manufacture two very thin gears, but they must have thought it was worthwhile to get rid of the 'rattle'. My 1983 V45 Interceptor had split gears on the clutch basket. Helical gears are another possibility but now you have to design for the thrust loads as well.

Later model year Interceptors used gear drive for the cams. You might want to buy one of those from a junkyar . . . recycling facility and tear it down and look how they did it.

Maybe a noise deadening material for the timing chain covers is a 'better' solution?

idle away with a hummmm

Thrust loading on a camshaft drive is pretty light being the total power to drive the valve train is quite low.

For one example I am personally familiar with IH and Farmall tractors were running helical cut cam drives back in the 40's with nothing but a single brass thrust washer between the engine block and cam gear to counteract thrust loading even on engines that had live hydraulic pumps driven off the timing gear set.

Output is directly related to input. Little or no usable input gets you little or no relevant output.

Unfortunately, it's shown itself to be a very hard concept for way too many people in the world to follow though.

You gave little useful input about the application other than what could be assumed to be an engine of some sort that had noisy timing gears so from that the simplest solution I can find is to make something else louder so that the timing gear noise is covered up.

Thank you for the advice which is good, but where do you start and stop explaining all the parameters of the job.

My main problem is that I could in the end say "" buy this from so an so " but how do I detail what it is on my layouts especially if they want to change buyers or that supplier goes out of business.

Batt

Probably from the trail of bubbles reaching the surface of the swamp you are in.

I would listen to Solar Eagle and Lyn about automotive stuff if I were you. But I am not you, so I won't listen to them either.

Can't you buy the chain components and make the 6.34 mm pitch chain yourself? Why so small? You do realize chain is going to make even more noise than the gears did, right?

If these are supposed to be "original" reproduction engines, why in hell are you changing anything at all from the "original" as built engines? That sounds like crazy talk to me.

You have my total permission to tell your boss he is a moron and an idiot head on top of it.

what do you really think?

Comment censored! Just have the freaking gears made to tight tolerance as per TCMtech's instructions, and all will be well.

The equivalent of 6.35 mm is 0.25"; various chains may be designated xx25. Most any drive chain supplier's catalog should have what you want.

I can design the sprockets for roller chain, but I do not have a understanding or data to design the tooth form for the inverted tooth chain ... the main reason for wanting to use inverted chain was the small pitch and not the roller chain because of chordal speed variation when using sprockets below 25 teeth.

I have lots information about the inverted chain shape but not the sprocket shape to engage with it.

Batt

Web search "timing chain sprocket profile"; get gazillions of results.

Try inverted tooth chain sprocket ... ordainary timing chain no problem ... the din standard only goes down to 9.525 mm and does not show 6.35 mm

Batt

Then use a scale factor of 2/3. Or just go to 3/8" chain.

https://www.google.com/patents/US8672786

http://www.iwis.de/en/engine-systems/products/technical-information/

http://www.ramseychain.com/prod_sc.asp?gclid=CjwKEAjw1qHABRDU9qaXs4rtiS0SJADNzJisnwhUwOd6EKX6ywc8vR4vGpDvGFrO_xNz0ahWTpXBPhoCkgrw_wcB

http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1572214

Have read the screed ... thank you very much.

batt

There are a lot of patents on google which are supossed improvment on the 60 deg flat flank inverted tooth chain but I would be wary of using any of the data attached.

Have corresponded with IWIS but they do not reply to queries.

The ramsey and morse chains are what are called rolling pin joints which are made from two parts which fit a special shaped hole in the link and are generally called hy-vo which are used for transmission.

The inverted tooth chain for timing engines has a solid round pin and is called a silent chain.

Batt

What flat flank? Why would you be wary of data you don't even read?

Anybody who leaves a stone unturned, is not really looking...

The chain from manufactures I have seen has a included angle of 60 deg

Tsubaki makes 6.35 and 8 mm pitch silent chain. Their site shows guides and sprockets. If they can't supply them, surely they could provide the information to design them. Or is this one of the companies that won't talk to you?

On enquiry by email the answer was product and heip unavailiable as they are 100 per cent committed to their oem clients.

batt

I thought you represented an OEM. Sometimes email is not the communication channel of choice. BTW, what kind of volume are you representing?

It sounds to me that you are representing an OEM client. Ask them why they don't want a NEW oem client. I can't believe any manufacturer doesn't want new clients. Or, is your client their opposition?

My 1962 Pontiac 389cu engine used this sort of timing chain. GM engineers had some sort of nylon coating on the inverted tooth faces. Clearly it to was noisy.

The problem was this would embrittle over time, break off, then get sucked past the oil pickup tube screen, then hold the oil pressure relief valve open.

I learned about not reusing the old chain during my first ever engine rebuild where this was installed into a 1962 Pontiac Safari Station Wagon (first car from my parents ~1971).

There comes a time when one has to say "No". And I believe this is the time.

http://www.ebay.com/itm/COMP-Cams-Timing-Chain-and-Gear-High-Energy-Link-Belt-Iron-Sprockets-Ford-BB-FE-/390978181456?hash=item5b081d9950:g:NNcAAOSwPYZU~619&vxp=mtr

http://www.regalpts.com/products/drive-components/chain-and-sprockets/inverted-tooth/Pages/default.aspx

Nice article about cam drives...

http://www.enginebuildermag.com/2011/11/cam-drives-and-timing-components/

Sounds to me like you need to switch to a helical cut gear set.

Quite and durable.

Just a point of idle curiosity, your existing timing gear set has an intermediate pinion so the chain drive won't reverse the rotation direction...

Go on and google sprocket and chain calculations