SC tensioner part # info?

SCadaddle · 11-15-2012, 09:47 AM

Fellows,

Looking to rebuild the chain tensioners in my '82 SC. The part number of my tensioners are 930.105.501.0R and I'm finding rebuild kits that indicate they are for the "049 and 053 tensioners".
I've searched this forum as well as the technical forum to no avail. Any help would be appreciated!

Flat6pac · 11-15-2012, 11:14 AM

Thats a casting number.
The basic difference in the tensioners is the width of the top that resides on the large pin. The earlier part has about 25mm and the later part has less than half of that. The change was made about 1982 with the idler that had brass bushings and a wider stance on the large pin. If you needed a new tensioner in the day you would get the thinner support tensioner and a washer to fill in the space to your idler.
Why rebuild an item that if it fails you loose the engine. Much like rebuilding a brake master cylinder...are you ever really sure. Be sure to use the fail safe guards.
Bruce

SCadaddle · 11-15-2012, 12:07 PM

Thanks Bruce,

As the car and all associated parts are 85 miles distant to me, I made a phone call to my mechanic for the part number on the tensioner and he's really busy on other things for the moment. The car was built in 07/81 so it's an early 82. The tensioners have already had the collars fitted and I definitely intend to re-use the collars.
I'm in the process of going back together after replacing the lower head studs and a complete top end job. The tensioners, as far as I know, were functioning fine. But since they are out I figure I might as well try and put a rebuild kit in them. Like you say, I do realize they are an extremely critical part, however, and I also realize this may be 180 degrees out from "conventional wisdom", I'm just not sold on the carrera tensioner update for a car that will be very seldomly driven. While I do understand the mechanical tensioners "will fail in time" and the carrera tensioners "might fail", either fitted with the collars I would hope would deter catastrophic engine failure. I'm on the fence, and it's a very slippery slope whichever way I fall. The difference being when I get up and dust myself off I might still be holding on to about $1200.
But still at the bottom of the hill.

ajwans · 11-15-2012, 01:24 PM

You'd do well to check that you have the wide chain wheel support arms behind the tensioners. These seem to be an important factor in the tensioner failure story. If you don't have them install a set while the engine is open.

andy

Flat6pac · 11-15-2012, 01:59 PM

The Carrera tensioners are not bullet proof, that was found out in the early 90s when they started to fail. Dollar wise, if you dont have Carrera oil fed tensioners already, its hard to justify the upgrade when a set of collars properly installed will save the engine and its less than $.10 on the dollar.
If the tensioners are holding pressure, I wouldnt rebuild them, I would just reinstall them. The guards are suposed to sit up about 3mm on the shaft so they can change with temperature and expansion.
Bruce

BURN-BROS · 11-16-2012, 09:30 AM

Tensioners are a service item and I always recommend rebuilding them. Most of the long term failures are the upper oring for the reservoir. Servicing them lets you inspect the bore and shaft for damage etc. Plus I wouldn't want to run a tensioner that has 15 years of old oil trapped inside. The PH level of oil changes throughout it's life causing corrosion.

the rebuild kit will work for the 82 tensioners, just install the collars after inspection and rebuild.

Henry Schmidt · Henry Schmidt's Garage

A great number of tensioner failures can be attributed to idler arms friction/ galling.
Use either Carrera idler arms or Supertec up-dated arms.