Cam chain guide material ??

[Turborick]

I need to make some cam chain guides for our race engine, what material would be best.
I looked at Delrin but the working temps seem to low

Rick Yacoucci Nebulous Theorem II #988
Fastest 4 cylinder Bonneville 2 way average 352.525 mph
Nebulous Theorem III #788 Fastest Unblown Flathead 280 mph

http://www.bonnevillestreamliner.com

 

[patprimmer]

Heavily hear stabilised Stanyl nylon 4.6 from DSM Engineering Plastics is far and away the best material for this.

I normally recommend a selection of suppliers, but for nylon 4.6, last time I looked there was only one manufacturer.

The most common material used for this is graphite and molly filled nylon 6.6 as it is a lot cheaper than nylon 4.6, however OEM automotive companies specify Stanyl when and if the 66 fails life cycle tests. They get typically 3 times the life and up to 9 times the life from the Stanyl parts over nylon 6.6 parts.

Because of the very high crystalline nature of type 4.6, it does not respond to the molly/graphite like 6.6 so there is no point in the additives in that case.

Regards
Pat
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[Turborick]

Thanks for the quick reply
I have some Nylatron GSM some Nylatron 901 and some Nylatron GS.
Would any of those be comparable to the nylons you speced?

Rick Yacoucci Nebulous Theorem II #988
Fastest 4 cylinder Bonneville 2 way average 352.525 mph
Nebulous Theorem III #788 Fastest Unblown Flathead 280 mph

http://www.bonnevillestreamliner.com

 

[patprimmer]

Some Nylotron grades are nylon 66 graphite and moly filled. The graphite and molly filled has a very dark gray pearlescent look to it. It should be specified in their data what it actually is.

Nylotron also does nylon 6 which has a lower melting point so is not so suitable.

I think Nylotron also has a grade based on nylon 4.6

Regards
Pat
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[Tmoose]

I made some "nylatron" wrist pin buttons for a Norton in place of the virgin Teflon we normally used. They wore away rapidly and formed Nylatron wool in the process. Nylatron seemed to work OK for the inlaid piston skirt buttons in vogue at the time.

 

[Turborick]

What type of Nylatron did you use?

Rick Yacoucci Nebulous Theorem II #988
Fastest 4 cylinder Bonneville 2 way average 352.525 mph
Nebulous Theorem III #788 Fastest Unblown Flathead 280 mph

http://www.bonnevillestreamliner.com

 

[TVP]

Turborick,

Nylatron GS is PA6,6 + MoS₂. I agree with Pat that one of the Stanyl PA4,6 grades have the best temperature capability and hence durability, but out of the three options you listed, Nylatron GS seems to be the best.

 

[patprimmer]

I am not speculating.

Many production engines have for very many years has graphite and molly filled nylon 6.6 as timing chain tensioners. More recently some moved to nylon 4.6 as oil temperatures and engine speeds and expected life all increased to the level that 6.6 was giving unacceptable life. In 1995, Saab, MB and BMW all had some engines with type 4.6 tensoners.

I have also personally run graphite and molly filled nylon 6.6 buttons in many engines including my ski race boat that ran hundreds of hours, my friends circuit race boats, some every day drivers and we supplied them to a friend who built engines for many professional race teams including cars well placed and class winners in the famous Bathurst 1000 km race. WE never ever had a nylon button fail. They had to be fitted right and with a domed end to continue to match the bore dia as they rotated. They do fibrilate a little from the machine marks until they burnish as the wear in.

Regards
Pat
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[patprimmer]

An important point.

From memory, nylon 6 melts at about 215 deg C, nylon 6.6 melts at about 256 deg C and nylon 4.6 melts at about 295 deg C

Also, the higher the melting point, the more they retain their physicals as they approach the melting point then the more sudden the change.

Regards
Pat
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