Plastic vs Metal Chain Rails
 

As I was just looking at the upper timing chain rails for the 380sl on several websites, -- e.g., http://www.mercedes-benz-parts-direct.com/epc-items.asp
and http://www.thebenzbin.com/parts/?N=11159+4294966701+1668+7281) -- I happened to notice that there are plastic rails made by Swag for $4-5@ and metal rails made by Meyle for close to $20@. However, I did not realize this when I changed my rails several years and app. 40-50k miles ago. So, I used the plastic rails. Of course, had I known then that there were metal rails, I would have used them instead -- considering how crucial they are to the engine's timing, and the plastic ones' tendency to crack with age.

I was therefore wondering if the metal rails are new, and if other people have also replaced their rails with the plastic ones -- either because they didn't realize that metal ones existed, or because the metal ones don't have a big advantage for some reasons.


I also happened to notice on the Benz Bin's website that the tensioner rail requires a rubber lining, but I don't recall whether the tensioner rail I used came with a rubber lining on it or not. Does anyone happen to know whether they typically do or don't?

Thanks very much for the feedback.

Bill

Thanks very much for the info.

Bill

The OEM rails for my 280 SL (M110) are metal, lined with rubber.

Been told the metal are better, plastic were the common replacement but had some long term issues, my replacements are plastic, and long term seem just fine.

So, I guess Mercedes was using the rubber-lined metal rails made by Meyle, and switched to the plastic ones to save money. I'm just wondering if the metal rails had a tendency to break over time, like the newer plastic rails, and if MB therefore prescribed changing the metal rails every 100k miles? If not, it seems to me it would make sense to switch back to the metal rails when it comes time to change them, to avoid having to do it over and over again.

seems logical

I sent an email to Meyle, and here is the response I received:

"Actually the design comes from the earliest version produced by Mercedes that were used in the M116 and 117 motors from the early 1970's. The idea to reproduce the chain rail and an OE sample of the original was supplied by a Mercedes Benz repair specialist in Bellevue, WA in 2003. He supplied us with the rail and was the first to get a production sample and approve of the design.His name was Frank Schmidt but he has recently sold his repair shop and retired due to health reasons.

In 2002 MEYLE Products purchased their own rubber to metal products production facility and hired a number of rubber to metal engineers from OEM manufacturing companies to design and over see the production of all of the rubber to metal products offer by MEYLE Products. See www.meyleusa.com for information on the different HD products offered by MEYLE. . . Close to 400 pieces of this chain rail were sold in 2007 to different warehouse distributors on the USA. . . Since the release of this version of the chain rail 3 years ago I have not received any complaints that the rubber separated from the aluminum. I have not received any complaints at all for that matter."

I'm just very surprised that very few people have apparently ever used or even heard of these rails, given the tendency of the plastic rails to crack, and the cost and difficulty of replacing them every 100k miles.

I removed the plastic upper rails (original) from my '86 420SEL after 150,000 miles and 21 years and they were yellowed but not cracked and barely worn. I felt comfortable replacing them with plastic rails then, although I had considered the metal rails after reading all the horror stories. I replaced the tensioner with an OEM unit although mine seemed to work OK and the tensioner rail with a like unit although it too looked good. I think that if your tensioner is working and you don't run with a weak one the rails are probably not stressed much and will be OK. It's hard to argue with their success in my car. Of course, some second/third owners run the cars in the ground and they have, shall we say, problems. Good, old "run-to-failure" maintenance usually ends in...failure.