Idler Arm Repair

[Porsche_monkey]

As expected the idler arms from my high mileage 74 2.7 show the same wear as photo 6-12 pg 160.

It is a bit unclear to me how to tell the difference in the 'old vs new'. I think the newer style has the bushing, but no other difference?

I have the oil-fed tensioners, but I have no bushing in the idler arms. Can I not bore out the idler arm and bush it to suit (I am quite capable of doing that), or are there other mods/benefits that are not mentioned?

[Tim Walsh]

PBH,
The difference between the old style and new style idlers is the extra bushing material. If you look at a new set the bushing portion is longer to prevent any snaging or binding. You will either need a new set of idler arms or a set of spacers

[Porsche_monkey]

So I can bush it and put a spacer in the rear? I do not have a new one to look at and the book has no clear photos.

[Tim Walsh]

I'm pretty sure there's a picture of the spacer. I'll look when I get home.

[john walker's workshop]

you don't bush the old ones, you buy the updated, bushed ones. then there's no spacer used.

[Porsche_monkey]

Those of us living in Soviet Canuckistan don't have a Porsche dealer on every corner. Sometimes we just want to get the thing finished and not order any more parts and try to forget about how we were stupid enough to over-rev the engine the first place. (Not that I'm bitter about any of this).

Soooo, can't I bore out the old one, bore out the spacer too, (which I just discovered I have in my parts box), and bush both of them with a long bushing, and get on with the job?

Feel free to answer curtly, ie that would be stupid and I'll place my idler arm order with Pelican ASAP. Then spend the weekend moping about and waiting for more parts....

[911pcars]

IMO, a rebushed early idler arm is better than a factory unbushed arm. The '81-on idler arm is a better choice than a rebushed early arm (more bearing area). Take your pick.

Sherwood

[Wayne 962]

Old and new idler arms are clearly compared next to each other in Figure 4-7 on Page 79 of the Engine Rebuild Book.

-Wayne

[Porsche_monkey]

Thank-you Wayne, once again you are correct.

[power]

Ummmm.....I'd take John's advise on this one, the $140 to replace the arms to the newer style is worth it considering the consequences of an arm binding. IMHO

[hcoles]

you don't bush the old ones, you buy the updated, bushed ones. then there's no spacer used.


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john walker's workshop

Have you noticed that the idler sprocket can move fore and aft +/-0.060 inches. Wouldn't it be an idea to install some sort of spacers to limit this travel to some extent? I quite sure the cam and intermediate shaft don't move around this much. I also have some strong evidence that the arms may not float as well as people think they do.

Also, if I want to install new arm bushings what is the exact bushing material I want my machine shop to use?

Thanks,

-Henry