A call to the experts...tensioner explanation
 

The tensioner debate will rage on forever as to what's best- that's understood. I've read all the threads, but I've become confused because I'm not quite sure I understand what the all the options are, especially when talking of the "930" tensioners and collars, idler arms, etc....so, can someone please break it down for a newbie like myself? I have a 73.5 that I would like to have updated for piece of mind, but I want to stay away from the modifications associated with the Carrera tensioner update (pressure fed/oil-fed?). I was told the 930 tensioners avoid all the modifications and simply add collars. So what's the difference between getting collars put on my current tensioners and getting the 930 tensioners?

As always, thanks for all the help and input...

Before the pressure fed tensioners came along in '84 there were numerous iterations of the older oil filled and sealed design. As I recall the last version was called the "930 tensioner". Any of the older models up to and including the 930 could also be fitted w/ a coller that prevented total collapse of the tensioner in the eventual loss of an oil seal. This provided a small saftey margin that let you drive slowly to a repair faclilty.

An other mod that actually preceded the pressure fed tensioners was the '80 up style idler arms w/ incorporated a wider base bearing support area.

the idler arms you want are
930.105.509.00 left
930.105.510.00 right

the general rec is to use 5 black ramps and 1 brown(lower right)

but on the earlier engines(thru 2.2 and maybe 2.4) these will be noisier so some use all brown.

A data point for you.
Not knowing the history of my car,I just opened my 79 sc to do the oil fed tensioner install.
The po had installed saftey collars on the mech. tensioners and replaced the ramps as well.
So, what to do?? Install the oil fed tensioners with spacers for $500.00 or button it all up and leave the old tensioners in with safety collars.
I opted to put the oil fed tensioners in with spacers and also add the oil line restrictors in the cam housings.I checked the cam timing, inspected sprockrets for wear and buttoned it back up.I did not install the updated idler sprocket arms due to cost.
So, I now have an engine with improved oil pressre, oil fed tensioners valve adjust,and peace of mind that I am not running the risk of tensioner failure due to ignoring the avice of many owners on the bbs board.

Bottom line in my mind ..select the degree of p.m. you are comfortable with and do it. If you decide to go with the collars,I have a set that are yours for $20 p/s. If you go oil fed with spacers or new idler arms may the force be with you! Either way you have addressed a known potential failure point,corrected it and now can "just drive it" as the good dr. intended.

Bill,

Sorry to dredge up an old thread....I just pulled the ramps off my 71' 911T (2.2)and I have 5 blk ramps and 1 brwn ramp ready to install but you give me pause...

Last night, when I pulled off the existing ramps I noticed, that although the color was black, the 5 ramps had the height profile of the new brown ramp I'm ready to install-and they were all in new condition with the exception of the one that was causing all the noise (it had a very worn end). I thought the PO's wrench just used what ramps he had lying around....then i read your post.

So, should I go ahead and install the 5 black and 1 brown, or should I get all brown?:confused:

instead of collars you can look into "spacers" put inside the tensioner... J. Woods does this. Cheap and no way they can get loose. A bronze spacer from OSH fits perfectly - just cut and sand to length... so I have pressure fed, oil line restrictors and internal spacers - hoping that keeps the cam chains happy.

Your question has already been answered by the other posters, but let me add my own decision based on the exact car and desire you have.

My 73.5 was running fine, but with a bit of chain noise, when I bought it. When opened up, the tensioners had the collars installed (by the PO), but one had come loose and the chain was slack. I replaced the tensioners with the pressure fed, new sprockets (worn), new chains (they were stretched), spacers and ramps. Cost a tidy sum, but I wanted the peace of mind.

My point: Several ways to go, but pressure fed is most reliable (though not 100% fail-safe.) Once you open up the towers, you may find several other things to change out to ensure reliability--don't scrimp, if in doubt, replace.

I can throw in my own limited experience here and hope it helps... My barn find 72 911T had tensioners with collars from the PO. By my estimate, both tensioners had basically failed. One had seized and the other was mushy. The collar on the mushy side was hammered so much by driving while in total failure, it snapped the smaller end of the collar. I guess the PO missed the part about gently driving it to the nearest Pcar mechanic as Bill V pointed out. I fished the larger pieces from the chain tunnel and luckily found the smaller piece with accompanying bolt in the sump strainer.

The Carerra update kit allowed me to kill two birds with one stone. I got to ditch the Mg, gently warped, tunnel covers while getting new tensioners. I too, bought the spacers to keep the old sprockets.

Knowing what I know now, and again, I stress my limited experience here, I like the Carerra update solution compared to the collar option.

Meanwhile, I plan to rebuild the old tensioners, put my new collars on them, and park em' for now.

Sounds good but...........
When replacing sprockets, the important ones are the chain sprockets on the I-shaft because they're the drivers.
It means splitting the case.
These Dual-chains don't really stretch, the rollers wear and the sprockets wear and that combination gives the impression of chain-stretch.
If new chains are used, ALL sprockets need to be replaced.
If you only replace cam sprockets and idler sprockets, the chain sprockets on the I-shaft still have the worn out pitch and this will happen:

http://forums.pelicanparts.com/porsche-911-technical-forum/200267-new-chains-without-new-sprockets-read.html