Lotus Elan

Timing chain

PostPost by: 2cams70 » Mon Nov 13, 2023 9:20 am

I’d be particularly interested in differences between the pins and also the bushes the pins run inside of. Wear here determines how much the chain stretches. Personally I don’t believe whether the rollers are perfectly round or not makes much difference to the life. Unlike a roller ball bearing an open chain is hardly a precision device. All the roller needs to do is support the load and rotate on its axis to even out the wear. It’ seems that since you have them on hand that you have unknowingly (or knowingly) already been using split roller IWIS chains without incident.
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PostPost by: JonB » Mon Nov 13, 2023 9:23 am

While we wait for Rohan’s pictures, I’d like to ask what the expected service life of an original Lotus chain should be for normal road use?
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PostPost by: rgh0 » Mon Nov 13, 2023 9:46 am

I dont know what an original service life of an orignal Lotus chain was back in the 60's but engine rebuilds were around 60k miles or 90 k kms back then and I presume the chains were replaced as a routine service item when rebuilding an engine. What chain is required now to meet this sort of life I dont know as lubricants are much better these days. I just know a solid roller / solid bush chain is dimensionally more stable and has a better chance of a longer life especially as it probably has better materilas and better oringinal tolerances.

Microscope photos will enable me to tell more in a few days, that I can see with an eye glass currently but is hard to demonstrate

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PostPost by: nmauduit » Mon Nov 13, 2023 10:16 am

rgh0 wrote:I dont know what an original service life of an orignal Lotus chain was back in the 60's but engine rebuilds were around 60k miles or 90 k kms back then and I presume the chains were replaced as a routine service item when rebuilding an engine. What chain is required now to meet this sort of life I dont know as lubricants are much better these days. I just know a solid roller / solid bush chain is dimensionally more stable and has a better chance of a longer life especially as it probably has better materilas and better oringinal tolerances.

Microscope photos will enable me to tell more in a few days, that I can see with an eye glass currently but is hard to demonstrate

cheers
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A key issue would be price difference between solid bushing vs. split bushing in assembled chain for our favorite LTC engines I suppose... I realized via this thread that there would be a qualitative difference in lubrication at the split in the bushing (hence wear, hence reliability) between the two options (I used to naively rely on my favorite suppliers purportedly educated best selection before), but remains to quantify lifetime for an engine that remains of moderate performances, even in its tuned versions.

Image

https://www.nitrochain.com/solid-vs-split-bushings
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PostPost by: HCA » Mon Nov 13, 2023 12:39 pm

email from Renold this morning:

Morning Hal,

Apologies for the delay, I was on annual leave from Monday last week.

Yes, when specifying Renold chain, please refer to our “Blue box” brand which is made in Germany.
This version is made with solid bushes and solid rollers.

Most of our suppliers are familiar with this brand.

Best Regards,
Michael



Lots on the internet, but do not see anyone saying they will especially rivet a 120 link endless 06B-1 chain - someone will though.
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PostPost by: alanr » Mon Nov 13, 2023 1:18 pm

That is very good news Hal.
All we now need is to find out where we can buy a 'Blue Box' Renold chain made up for a Twincam.

Thanks,

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PostPost by: HCA » Mon Nov 13, 2023 1:44 pm

From what I can gleen from a few engine builders, it is expensive for a manufacturer to make up lots of small chains for stock due to the myriad of lengths and types, so they prefer to sell longer lengths to a stockist for individual onward sale as and when needed. Makes sense. So, yes, you/we need to find a chain stockist who will make up an endless 06B-1 chain to the marque demanded.

I think this is why Cross and Morse replied that they stopped making chains for the Lotus as per my question, so I have gone back to them asking for the part number of the bulk chain they make with seamless rollers.

As for IWIS, I have asked my friendly engine builder - he is ex Cosworth and looks after three racing Lotus Cortinas and numerous FFs - what chains he uses (I know it is IWIS but not the type), however, his speed of communication is diametrically opposed to the speed of his cars! watch this space - you will be the first to know!
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PostPost by: JonB » Mon Nov 13, 2023 3:04 pm

rgh0 wrote:I dont know what an original service life of an orignal Lotus chain was back in the 60's but engine rebuilds were around 60k miles or 90 k kms back then and I presume the chains were replaced as a routine service item when rebuilding an engine. What chain is required now to meet this sort of life I dont know as lubricants are much better these days. I just know a solid roller / solid bush chain is dimensionally more stable and has a better chance of a longer life especially as it probably has better materilas and better oringinal tolerances.

Microscope photos will enable me to tell more in a few days, that I can see with an eye glass currently but is hard to demonstrate

cheers
Rohan


Thanks for that, Rohan. As I feared. With my S4 at a genuine 64000 miles, it looks like I’m following this thread a bit more avidly. :roll:
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PostPost by: Donels » Mon Nov 13, 2023 5:33 pm

Great discussion and I can understand Rohan’s point about solid rollers for racing, but has anyone ever experienced or know of a TC timing chain failure and if so where do they fail? Unlike toothed belts which do have a specified life time I have never come across a life for the chain. I suspect they are just changed because of wear and noise etc.

I have heard of chain failures at high mileage on some BMW engines where the timing chain is at the rear of the engine. It would be interesting to know the failure mode.
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PostPost by: nmauduit » Mon Nov 13, 2023 5:51 pm

HCA wrote:email from Renold this morning:

Morning Hal,

Apologies for the delay, I was on annual leave from Monday last week.

Yes, when specifying Renold chain, please refer to our “Blue box” brand which is made in Germany.
This version is made with solid bushes and solid rollers.

Most of our suppliers are familiar with this brand.

Best Regards,
Michael



Lots on the internet, but do not see anyone saying they will especially rivet a 120 link endless 06B-1 chain - someone will though.



thank you, looks like the Renold A&S series has solid rollers and bushings...

https://www.renoldfrance.com/media/165444/A-and-S-REN20-ENG-09-11.pdf

https://www.renoldfrance.com/produits/cha%C3%AEnes-%C3%A0-rouleaux/cha%C3%AEne-g%C3%A9n%C3%A9rale/cha%C3%AEne-de-transmission-as/

I would hesitate to cut and rivet myself one into a 120 link loop though... maybe I'm not as game as I used to be, what could possibly go wrong ?
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PostPost by: HCA » Mon Nov 13, 2023 7:17 pm

Co-incidental you say this. I was thinking earlier why not buy a few metres of quality chain, a handful of links and a rivet tool and make chains at cost for anyone on the forum.

It is not difficult to count to 120, grind off the rivet head, press out the rivet and disconnect the length of chain then join with a master link… what can go wrong?

I’d be happy to do it, but with the UK being the dominant market, I might fall foul of the brexshit impositions - but I’d be willing to give it a go.
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PostPost by: reb53 » Mon Nov 13, 2023 7:33 pm

[quote
I would hesitate to cut and rivet myself one into a 120 link loop though... maybe I'm not as game as I used to be, what could possibly go wrong ?[/quote]

That is ,essentially what I did when I thought it was time to replace the chain.
Used a chain breaker on the old one, attached the new chain to one end with a ( temporary) split link, carefully wound the new chain right around and then joined the ends together with a rivetted link.
Bit of a fiddle winding the new chain around as needed to keep good tension on it to avoid it jumping teeth and upsetting the timing of the valves and distributor. And didn't want a valve/piston contact cock up.......
Much easier with the plugs out of course.

I had realised the makers don't make chains in a continuous loop, they obviously rivet them.
So I decided I could do the same, and it was no problem.
Rested a large lump of steel as an anvil behind the chain, slipped on the outer part of the link and a couple of smacks with a flat punch and job done.
Lots of rags in the top of the timing case as I didn't want anything accidentally falling down there !
This was years ago, and admittedly only 25K miles ago, but so far so good !

Looking at my old notes I used a "Renolds Synergy" chain.
I recall it being pretty pricey compared with others.

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PostPost by: Phil.C60 » Mon Nov 13, 2023 8:08 pm

Almost all the sixties/seventies manufacturers that fitted endless chains at the factory supplied chains with split links for in service replacement. Mercedes in particular, who supplied chains without the usual spring clip but with two tiny circlips instead for both the 6 cylinder engines and the V8s - as a previous poster suggested you ground off the rivets, split the original chain, joined them together and fed it round. Also, back in the day one could buy Reynolds chain in various sizes "off the roll" from Edmunds Walker! I fitted plenty of each and never ever had an issue. Back in my youth, every motorcyclist had a chain splitting/ riveting tool in their toolbox and carried a spare split link in their tool roll! Anyone remember " the little fish swims up the river*? Unless you are hardcore racing like Rohan, I would venture to suggest that on the limited mileage most of us do frankly any chain from a decent manufacturer with a reputation to protect and with or without a correctly fitted split link will do just fine!
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PostPost by: 2cams70 » Mon Nov 13, 2023 11:44 pm

Whenever I read people claiming "it's cheaper to manufacture therefore it's performance is worse" I smile to myself. For anyone involved in product development it is well known that "cheaper to manufacture and performance is better or equal to" can indeed be possible. Many important innovations throughout history have occurred as a result of that philosophy.

I think it would be appropriate to ask IWIS at this point a non accusatory open ended question something along the lines of: "We have noticed some of your chains used in engine timing applications now have a split rather than solid roller. What are the advantages and disadvantages of such a configuration?" That way you may get a non-hostile response that gives you the information needed. They are the ones who have done the R&D and what we are discussing here is really just conjecture.

rgh0 wrote:The side deflection tells you a lot about the clearance between the pins, bushes and rollers, its not important in terms of deflection during operation. A new quality twin cam chain with unworn components has about 5 mm deflection over 30 cm. The used solid roller IWIS chain I measured had about 10mm and the used split roller chain had about 15mm deflection. I would prefer a chain with minimal deflection showing consistent tight clearances on the components. What is ideal I dont know but clearly it increases with wear even when stretch length increase is not signficantly measurable.


What is more important is how much the pins and bushes wear over time (i.e how durable they are). Whilst it may be good to have minimal clearance initially in service the chain operates under tension so the initial clearances are taken up.

Donels wrote:I have heard of chain failures at high mileage on some BMW engines where the timing chain is at the rear of the engine. It would be interesting to know the failure mode.


Timing chain failure is pretty rare in modern engines and usually caused by something else - eg. chain tensioner failure. Chain tensioner failure isn't uncommon!
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PostPost by: rgh0 » Wed Nov 15, 2023 9:41 am

Got my digital microscope so here are a few photos and comments on the details

Microscope photo of stamping for JWIS split roller chain and JWIS solid roller chain. Its strange that the script for the split roller changes is not as clean and is slighly different in detail as major companies like IWIS are very careful with the brank mark details and differences like this is how you spot fakes in many brands like NGK and mitutoyo who are copied by cheap fakes often. Not saying this split roller JWIS chain is fake its just odd that the stamping is different ?? Perhaps IWIS can explain

Split roller chain link , not heat treated, centre punch rivet

WIN_20231115_17_35_27_Pro.jpg and


Solid roller chain link - heat treated, shoulder punched rivet

WIN_20231115_17_45_43_Pro.jpg and



Microscope photos of split versus solid roller. Wear at the split area clearly visible I would not want this sort of discontinuity hitting the sprockets 1700 times a second at 6000 rpm even in a road engine

Photos of JWIS split roller showing wear and distortion especially at the split seam but also on the edges as it has worn into a barrel shape.

WIN_20231115_17_39_24_Pro.jpg and


WIN_20231115_17_28_22_Pro.jpg and


WIN_20231115_17_40_01_Pro.jpg and




Photos of JWIS solid roller much less wear and distortion as no split seam

WIN_20231115_17_41_55_Pro.jpg and


WIN_20231115_17_42_21_Pro.jpg and



I know which sort of roller I want in my engines either competition or road which was my basic position when this discussion started. These rollers hit the sprockets at 1700 times a second at 6000 rpm What you put in your engine is up to you but look at the photos and think about the wear and noise due to this split roller distortion.
I need to do some futher analysis of pins and bushes and will post when this is done.

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