Upper control arm bolts - Page 2 - Alfa Romeo Bulletin Board & Forums
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post #16 of 20 (permalink) Old 06-26-2018, 10:39 AM
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Quote:
Originally Posted by barboncino105 View Post
they are M10. now, ossodiseppia has me worried! my notes do not show anything specific on them... as i recall, they are class 8.8... but not as confident in the recall these days. in any case, the heads will be marked, just get the same thing.
I don't know *****. What I do know, is I have a bunch of suspension fasteners that I removed from a couple of Alfettas. Neither parts manual I looked at had the specs of the screw.

We just need to match the original one that is on your car with one of mine. Many that I have are 8.8. The ones I posted a picture of are the ones I assumed are correct.

Brian __________________________________
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post #17 of 20 (permalink) Old 06-26-2018, 07:38 PM
Del
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Usually, the bolt end caps have letter and numbers on them to identify what grade they are, esp with higher grade versions.

Are there any on these?

Del

Seattle

1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
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post #18 of 20 (permalink) Old 06-26-2018, 09:14 PM
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Use some WD40 and Scotch-Brite to clean off the existing bolt heads to confirm the grade (my educated guess would be grade 10.9, which is the norm with critical suspension fasteners).

It is interesting that the threads would be fine-pitch. This is the norm with a bolt that is used to fasten a highly-stressed component (think CV bolts, flywheel bolts, etc), that requires a higher-clamping force (which loads the bolt in tension as Ed pointed out). Perhaps Alfa engineers determined that properly-torqued fine-thread bolts/nuts would be less likely to come loose when subjected to the constant twisting motion exerted by the movement of the control arms. In any case, fine-thread fasteners will require a higher torque value than a coarse-thread fastener of the same size (check the manual).

I am not sure if I have posted the following in this forum yet (I am known to do it on the Porsche and BMW forums that I participate in), but anyone who touches a wrench, either as a hobbyist or professional, needs to buy this book and read it cover to cover:

https://www.amazon.com/Fasteners-Plu...ith+nuts+bolts

It is deeply informative and will help you to determine what is necessary in a case where there is no manufacturer-provided bolt or torque spec.

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!

Last edited by cda951; 06-26-2018 at 09:19 PM.
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post #19 of 20 (permalink) Old 06-26-2018, 09:59 PM
Del
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"In any case, fine-thread fasteners will require a higher torque value than a coarse-thread fastener of the same size (check the manual)"

Usually, finer thread bolts are made with material of a much higher tensile stress allowable, allowing a higher installation torque in order to develop a higher assy preload, with better torque application control.

Interestingly, I've seen very fine rolled thread 4340M bolts of 275-300 ksi tensile allowable on aircraft, something a car will never see. Trouble is with those materials is that they are like glass, in that if there is any defect, grinding nick, whatever, they crack almost instantly due to an absurdly low fatigue life. Undamaged, however, they have superb high load service life.

Del

Seattle

1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 06-26-2018 at 10:07 PM.
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post #20 of 20 (permalink) Old 06-27-2018, 09:39 AM Thread Starter
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Again, thanks for all of the input, I succeeded in getting the threaded end free via hacksaw, it is an M10 1.25 thread. The head of the bolt is buried for now in the impossible to see recess of the unibody. It will be liberated this evening (thank you hack saw). I am pretty positive that it will read 10.9, all of the other bolts that have come off the front suspension so far have been. In any event, new 100mm bolts are ordered, and Adrenalina should be back on the road pdq! Thanks everyone!
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