C4 Upper Control Arm Shaft Torque
Thread Starter
Instructor
Joined: May 2004
Posts: 105
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C4 Upper Control Arm Shaft Torque
The good news is that I am just about done rebuilding my 1984 C4 front suspension including upper and lower ball joints, tie-rods, and poly bushings. The bad news is that I can't find the torque specification for the upper control arm shaft end nuts. These are the two very large nuts that keep the upper arm bushings in place and had to be removed in order to replace the bushings. If they are too tight they will likely bind up effecting handling and I don't even want to think about the consequences if they are too loose...
Anyone know what these should be torqued to? If not is there anyone with a C4 and a torque wrench that could run out to the garage and figure out what theirs is set to?
Anyone know what these should be torqued to? If not is there anyone with a C4 and a torque wrench that could run out to the garage and figure out what theirs is set to?
Burning Brakes
Joined: Apr 1999
Posts: 754
Likes: 0
From: Lehighton PA
Re: C4 Upper Control Arm Shaft Torque (Lister)
hi,there are no torque specs in the factory book for the shaft nuts,did mine last year and used the red loctite on the shaft nuts and had the car on the ground and tighten the hell out of the shaft nuts.hope this helps ,good luck greg84 :cool:
Drifting
Joined: Aug 2000
Posts: 1,521
Likes: 0
From: West Islip New York
Re: C4 Upper Control Arm Shaft Torque (Lister)
The bad news is that I can't find the torque specification for the upper control arm shaft end nuts.
GM never intended them to be repaired, hence no specs...
Burning Brakes
Joined: Jun 2003
Posts: 827
Likes: 1
From: Henderson NV
Re: C4 Upper Control Arm Shaft Torque (Lister)
Upper control arm shaft nuts (per service manual) to 37 lb. ft. It's tricky to find, but it's in there. And this makes sense to me; too much pressure on the bushings will make it very hard for them to wrap and relax. They are meant to "give" a bit. And yes, I would definitely use loctite on all suspension nuts and bolts.
Thread Starter
Instructor
Joined: May 2004
Posts: 105
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Re: C4 Upper Control Arm Shaft Torque (vetteseniorcit)
vetteseniorcit,
Not that I want to seem like I am doubting you but there seems to be a bit of disagreement here and I want to be absolutely certain before I put my life on the line. Can you please quote the sentence from the manual that claims 37 lb ft and supply the page number? If what you say is correct then you have helped a lot of us out and some folks should go back and re-torque theirs to spec.
Thanks
Not that I want to seem like I am doubting you but there seems to be a bit of disagreement here and I want to be absolutely certain before I put my life on the line. Can you please quote the sentence from the manual that claims 37 lb ft and supply the page number? If what you say is correct then you have helped a lot of us out and some folks should go back and re-torque theirs to spec.
Thanks
Burning Brakes
Joined: Jun 2003
Posts: 827
Likes: 1
From: Henderson NV
Re: C4 Upper Control Arm Shaft Torque (Lister)
I'm sorry, I misread the model year on your car, thinking it was a 94. Ok, I doubt that much changed in this respect through the years. In my manual on page 3C-4, Figure 3 - UPPER CONTOL ARM INSTALLATION. Last paragraph on the page under INSTALL OR CONNECT, there is a wrench icon, TIGHTEN.
"Control arm nuts to 50 N.m (37 lb. ft.) I certainly don't blame you for double checking. If you are uncertain about that figure, do as the other fellows did, "tighten the hell out of it!" Worst case, it will harshen the ride a bit and also stress the control arm somewhat. We're not absolute experts here on the forum (probably some are); I looked up what I could and read what was there. :)
"Control arm nuts to 50 N.m (37 lb. ft.) I certainly don't blame you for double checking. If you are uncertain about that figure, do as the other fellows did, "tighten the hell out of it!" Worst case, it will harshen the ride a bit and also stress the control arm somewhat. We're not absolute experts here on the forum (probably some are); I looked up what I could and read what was there. :)
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Thread Starter
Instructor
Joined: May 2004
Posts: 105
Likes: 1
Re: C4 Upper Control Arm Shaft Torque (vetteseniorcit)
Thanks for the extra effort in verifying this for me. I recently read somewhere that the upper control arm did change enough so that the early and late models are not interchangeable and it was primarily due to simplifying the production process for this component. I would imagine that the torque setting would be very similar for both since they are of the same basic design and function. I agree with the torque needing to be fairly light since the aluminium suspension needs to move and the lower control arm handles most of the load. Thanks again.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: C4 Upper Control Arm Shaft Torque (Lister)
Just to add to the confusion, the factory service manual for my 87 says to torque the upper nuts to 48 ft-lbs. and my 92 manual says 37 ft-lbs. And my cheapie generic C4 Haynes manual specifies 63 ft-lbs!! There is always a possibility that different torque values are required for different years based on any number of factors. FWIW, there have even been some threads about discrepancies in the factory manuals, so check carefully.
You should invest in the factory service manual for your 84. You can usually find them on eBay or order them from http://www.helminc.com
You should invest in the factory service manual for your 84. You can usually find them on eBay or order them from http://www.helminc.com
Melting Slicks
Joined: Oct 2002
Posts: 3,193
Likes: 1
From: Cincinnati Oh
Re: C4 Upper Control Arm Shaft Torque (c4cruiser)
I want to add to the confusion too:
when the manual says "upper A-arm nuts" or whatever, could they not be referring to the bolts that tie the A-arm into the support tower/crossmember (the bolts with your shims on them)? Or is there a different spec for those as well?
:cheers:
when the manual says "upper A-arm nuts" or whatever, could they not be referring to the bolts that tie the A-arm into the support tower/crossmember (the bolts with your shims on them)? Or is there a different spec for those as well?
:cheers:
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Re: C4 Upper Control Arm Shaft Torque (Ramanstud)
I would think these lower torque values are for the small bolts that hold the upper A arm to the frame....the ones your alignment shop would loosen to add or remove shims for the camber adjustment.
37-45 seems waaaaayy too loose for those big nuts on the shaft (man, that sounded obscene :lol: )
37-45 seems waaaaayy too loose for those big nuts on the shaft (man, that sounded obscene :lol: )
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: C4 Upper Control Arm Shaft Torque (Frizlefrak)
In my 87 manual, the pics for the upper control arm bolts with the torque value of 48 ft-lbs are on a different page than the pic for the bracket to frame rail bolts and those have a torque of 37 ft-lbs.
The 92 manual doesn't show a torque value for those smaller bolts. These bolts appear to attach the "Drivetrain and suspension frame" to the chassis. You're right that 37 ft-lbs doesn't sound anywhere near tight enough for these bolts.
The 92 manual doesn't show a torque value for those smaller bolts. These bolts appear to attach the "Drivetrain and suspension frame" to the chassis. You're right that 37 ft-lbs doesn't sound anywhere near tight enough for these bolts.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Re: C4 Upper Control Arm Shaft Torque (Lister)
There IS no spec in the 1984 Helms manual. And there shouldn't be. The A arm bushings are NOT serviced by GM. If one wants to renew the stock A arm bushings, new A arms are required. Since it was never intended by the factory that these bushing be, independently changed, there was never a need for a torque spec for those nuts.
RACE ON!!!
RACE ON!!!
Race Director
Joined: Dec 2000
Posts: 17,551
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From: El Paso Texas
Re: C4 Upper Control Arm Shaft Torque (CFI-EFI)
There IS no spec in the 1984 Helms manual. And there shouldn't be. The A arm bushings are NOT serviced by GM. If one wants to renew the stock A arm bushings, new A arms are required. Since it was never intended by the factory that these bushing be, independently changed, there was never a need for a torque spec for those nuts.
RACE ON!!!
RACE ON!!!
What needs to be done is to reverse-engineer this process. If we could get a C4 that has never had this bolt off and measure the torque it takes to break it loose, and then just reset it to that torque value. Too late for me, I did it by the old armstrong method.
Again, 100 ft lbs. My suspension moves just fine, no unusual noises or binding, and I've never had one come loose. As for metal fatigue, get back with me in 10 years and I'll give you an analysis.
Thread Starter
Instructor
Joined: May 2004
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Re: C4 Upper Control Arm Shaft Torque (Frizlefrak)
I'm not sure that the break-loose torque would provide the same reading or not. I figured that if someone could use a beam-type torque wrench and tighten the bolt until there was very slight movement of the nut, that would be a fairly accurate reading. Another method would be to set the torque wrench (clicker type) to a fairly low value (say 30 ft lb) and see if the nut exceeds this reading, if not then bump it up 5 ft lb and try again, and then repeat until the nut has slight movement. Anyone want to give it a shot?
Race Director
Joined: Dec 2000
Posts: 17,551
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From: El Paso Texas
Re: C4 Upper Control Arm Shaft Torque (Lister)
Yeah, you guys are right. Breakaway would give a skewed reading. Lister, I'm thinking you have the right idea.....Take a cherry vehicle and keep bumping up the clicker in 5 lb increments until the nut budges forward. This isn't going to be 100% accurate either, but it should give a good ballpark of where the factory set it.
CFI-EFI, you willing to guinea pig yours? Would make a nice tech article.
CFI-EFI, you willing to guinea pig yours? Would make a nice tech article.
Drifting
Joined: Jan 2002
Posts: 1,608
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From: I Hate Tourists FL
Re: C4 Upper Control Arm Shaft Torque (Frizlefrak)
I can steal a torque wrench and crowsfoot kit from work. The wrenchs are calibrated every month within .5 lb-ft so its pretty damn accurate. Mine is a 93 so I dont know how much of a difference there will be in the difference of the cars but if you need me to do it I can.
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Re: C4 Upper Control Arm Shaft Torque (FSTRNU)
I can steal a torque wrench and crowsfoot kit from work. The wrenchs are calibrated every month within .5 lb-ft so its pretty damn accurate. Mine is a 93 so I dont know how much of a difference there will be in the difference of the cars but if you need me to do it I can.