Torque Spec for Upper A-arm Cross Shafts?
Thread Starter
Safety Car
Joined: Jul 1999
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From: Marianna FL
Torque Spec for Upper A-arm Cross Shafts?
I cannot find this in the FSM. Anyone know what they should be? One side was fairly tight and the other was not when I disassembled them.
Team Owner
Joined: Sep 2003
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I imagine it's NOT included in a FSM because bushings and shafts were never 'service parts' by GM SPO. Do any of the bushing suppliers supply assembly instructions and if they do, does it vary brand/product/material? There could be some interesting responses. What brand/product/material are your bushings or are the arms 'stock'?
Drifting
Joined: Jul 2004
Posts: 1,358
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From: MA
This is from the Ridetech instructions, they are Delrin bushings installed (35-40 lb-ft). I used a bit of red Loctite on the threads too just to make sure they didn't back off. I know the factory used a thread locker that required a bit of heat to remove those nuts.
Last edited by grandspt; Nov 18, 2021 at 05:39 PM.
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Drifting
Joined: Aug 2009
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The bolts that secure the cross shaft to the chassis or the giant nuts on the ends of the cross shaft that secure the control arm? If the latter, not in the FSM. I went with 80 ft lbs and Loctite. Almost 5 years, haven’t thought about it since.
https://www.corvetteforum.com/forums...verhaul-5.html
^^See post 81
https://www.corvetteforum.com/forums...verhaul-5.html
^^See post 81
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
I attached the Energy Suspension instructions I had. But you can see they just say "tighten nuts to factory specs"...which don't exist. So thanks for nothing, ES! There are a couple factors at play. First, those cross shafts are aluminum so you can't torque them anywhere near as tight as a steel bolt that size. Second, your goal in torquing the nuts is to capture the inner metal sleeve with the washer so that when the control arm pivots, the poly bushing rotates on that inner sleeve (and not within the outer sleeve). So I would try to tighten the nuts to 30lbs and see if you get that desired rotation. Then adjust the torque as necessary to get that accomplished.
Race Director
Joined: Jan 2012
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From: United States
Years ago, did VB&P poly graphite type bushings. I did 35#'s using a calibrated torque wrench, per research back then... I used red loctite too. Only one has backed off. I put a sharpie mark on it..
Team Owner
Joined: Sep 2003
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That I don't believe could/should be used for the OP's question regarding the nut's on the control arm shafts. For 'most all other' fasteners it could be considered 'appropriate' BUT always check for a more appropriate specification for specific applications.
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
No! Again, these cross shafts are made of aluminum instead of the various grades of steel that typical fasteners use. If you default to the standard fastener size torque spec...well, have fun shopping for new cross shafts.
Racer
Joined: Apr 2016
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From: San Antonio TX
Aluminum? Really? I know that the control arms are forged aluminum, but the shafts? I've seen them dozens of times working on the car, but always assumed that they were plated steel. It is interesting that there is no published, official torque value for them though. My experience is that if a fastener requires a torque value other than the normal value for its size or a special torque procedure such as torque-to-yield, that is highlighted prominently in the service manual.
Last edited by NavAir; Nov 23, 2021 at 07:19 PM.
Race Director
Joined: Jan 2012
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From: United States
As posted about 15 years ago, its 2024 Aluminium, and Non Serviceable via GM. Buy the whole arm, and deal with it.
Or, use what most people have come to agree on, around 35 ft/lbs.
Global West said 10 ft/lbs for their bushings.
Best I could find for a recommended calculation is this. Its a 15mm bolt, 30 mm nut correct?
They dont have the specific material 2024, but two aluminums come up 6061 is what I chose. 40.88 ft/lbs
https://www.extreme-bolt.com/fastener-torque-specs.html
And if you are feeling froggy, try Nasas recommendation, which does have this metal in there.
https://ntrs.nasa.gov/api/citations/...0170003491.pdf
Or, use what most people have come to agree on, around 35 ft/lbs.
Global West said 10 ft/lbs for their bushings.
Best I could find for a recommended calculation is this. Its a 15mm bolt, 30 mm nut correct?
They dont have the specific material 2024, but two aluminums come up 6061 is what I chose. 40.88 ft/lbs
https://www.extreme-bolt.com/fastener-torque-specs.html
And if you are feeling froggy, try Nasas recommendation, which does have this metal in there.
https://ntrs.nasa.gov/api/citations/...0170003491.pdf
Racer
Joined: Apr 2016
Posts: 336
Likes: 93
From: San Antonio TX
Thanks for the citations. The NASA one is especially interesting. I didn't ask the original question, but I was surprised that there wasn't a published spec for the torque value in the service manual. After all, Chevy must know what torque they set their nut drivers to on the assembly line...
Race Director
Joined: Jan 2012
Posts: 17,062
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From: United States
Global West bushing was 10ft/lbs per instructions.
https://lib.store.yahoo.net/lib/yhst...g-kit-1059.pdf
Ride Tech says 37ft/lbs
https://www.ridetech.com/instructions/11569500.pdf
I guess the propertys of the bushings determine some of the torque to to keep from binding up?
https://lib.store.yahoo.net/lib/yhst...g-kit-1059.pdf
Ride Tech says 37ft/lbs
https://www.ridetech.com/instructions/11569500.pdf
I guess the propertys of the bushings determine some of the torque to to keep from binding up?
Team Owner
Joined: Sep 2003
Posts: 25,406
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Thanks for the citations. The NASA one is especially interesting. I didn't ask the original question, but I was surprised that there wasn't a published spec for the torque value in the service manual. After all, Chevy must know what torque they set their nut drivers to on the assembly line...