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Tim,
Thanks very much. I too am afflicted with being a mechanical engineer. Such is life....it seems to be keeping food on the table....
Anyway...I'll see what the new "stock" bushing cost and probably go that route.

I tend to agree with you that properly bushed narrow style should give good service....considering all however I would certainly not do that in my own engine, I would find another area to save some bucks. I'm nervous as a cat just using the good wide type and soon to be new bushings with honing with a proper tool at a machine shop. I went to 4 places today to see who would put in new bushings and hone to fit....you'd think I was asking for someone to build me a space shuttle.

I was thinking a bit like you....get some good bushing material and throw it in a lathe....then hone then press in.

One place said they had a hone of the right size and would do it if I brought in the stock bushings. So that's one out.

I was initially thinking I'll find some killer new bushing material and have someone put it in there....at this point I don't think I will have enough time and energy to get to that point. It's a shame....as there is now so many new types of bushing material available compared to the original stuff.

E.g. GRAPHALLOY®? and there are bunch of other things to look at...

BTW - should I post a picture of wear markings on the end of one of the tenioners? I like to see what comments would come back.


-Henry
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1989 3.2 coupe, DIY top end at 77k, now 112k
Old 04-08-2005, 11:50 AM
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Henry, lets see the pics. I cannot imagine why your arms failed unless they were installed over previously damaged shafts. How many miles on the arms? There is hardly any movement on the shaft so short of moisture induced corrosion after a very long nap, I would guess that
the new style arms were installed by a PO over damaged shafts? No matter, the bronze should prevent any galling that leads to seizure (which leads to loose chains due to tensioners that no longer can advance to apply tension).
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Old 04-08-2005, 12:19 PM
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Tim,
The person that started this thread I think was the person that had a noticable issue. My car didn't have any type of cam system failure just a intake guide that got a mile wide for some reason. So while fixing that I'm going over other parts of the engine. As mentioned before I'm taking a harder look at the idler/tensioner system for the cam chains.

I don't like the look of the bushings so I'm now going to replace them. Just today I got bushing stock from my machinist and will make new bushings and he will let me use his Sunnen hone machine to hone to size/etc.

I was just reminded that "they" don't sell just the arm bushings.

So I'm in good shape now assuming I can get the bush material sized for pressing in and ready on the ID for honing. I'll probably aim for 1/3 of the way up from the bottom on the spec. in Waynes book for the clearance during honing.

Here are a couple of pictures. One of bushing and one of a mark on top of a tensioner.

After talking to my machinist it is now the plan to make and place spacers for the arm to limit fore and aft travel to some extent....not the current allowed +/-0.060 inch.

-Henry



Old 04-08-2005, 04:34 PM
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Quote:
Originally posted by Tim Hancock
(By the way, I also admit to re-ringing my Alusils instead of buying new P&C's. 2500 miles thus far w/ no smoking!)
It's not the first 2500 I would worry about, but the miles after about 10,000...

-Wayne
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Old 04-09-2005, 06:42 PM
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Point taken Wayne. I guess time will tell. (I followed your break-in procedure in your book which obviously must work well for seating the rings initially.)
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Old 04-11-2005, 04:53 AM
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Tim,
I started a new thread containing:
1-rebushing idler arms, I machined some SAE 660 cast brass, I'm still investigating if this material is close to proper for this application - I need to talk to a bushing engineer.
2- shimming of idler arm so they don't move fore and aft so much
3- Jerry Woods slugs inside the tensioners
4- my homemake torque wrench tester, I think you will like it
Thanks for all your posts and conversation
-h
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1989 3.2 coupe, DIY top end at 77k, now 112k
Old 04-12-2005, 09:13 AM
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Henry, most commercial bronze bushings are made of SAE 841 (oil impregnated, sintered) and SAE 660 bronze (not sintered). The SAE 660 is a bit harder and shows a higher load at rest rating. I would assume in this application, one does not need to be concerned with velocity (rpm) as these see hardly any motion. By all means, consult a guru on bearings if you can find one. I used 841 (660 IMO would be even better if you think you are see deformation) and after pressing into place leaving holes undersize, I reamed with a 15mm reamer and ended up with a very nice fit.
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Old 04-12-2005, 12:33 PM
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Tim, thanks for the reply.
I'm checking more into. SAE 660 or other being good for this application. My machine shop skills along with a bad boring bar bit is making things a bit difficult. I'll see if I can use the lathe at my machinist instead of the one at work. I should be able to get the parts ready for the hone. Is 2-3 mils too much of a press fit for these bushings? Since there is not much load either way and seeing how easy the original ones pressed out...any way I could always try it or find my mechanical design books and look it up.

Anyway if you want to follow along...I started a new thread so that people won't think my arms look like the ones at the top of this thread. I think it may have led to some confusion.

Thanks again,
-Henry
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1989 3.2 coupe, DIY top end at 77k, now 112k
Old 04-12-2005, 01:54 PM
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Tim,
I found a bushing engineer at Reliable Bronze that talked to me for awhile and after considering all of what I explained he thought SAE 660 was a very good choice. It is used inside engines in a varity of places very commonly. It is hard but not too hard and will take pretty large loads and since it is lubricated we don't need to consider an oilite type bronze which has lower load capability. So I can now move forward with the machining.
-Henry
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1989 3.2 coupe, DIY top end at 77k, now 112k
Old 04-12-2005, 02:12 PM
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