Loose suspension nut... Options

[MikeM]

Hi all...I'm referring to the inner nut on the suspension ear ,inner end of pivot shaft.
Can anyone tell me why this nut always seems to loosen? Every time I put a wrench on it I can tighten it by about 1 turn. It tightens up, then a week later it's loose again?
Car is a 74 2.0 liter, I have Eric's bushings in the trailing arm.
Thanks!!
Mike

[Rob-O]

Have you changed the nut? It's a one-time-use nut. Kind of like a nylon nut, but without the nylon. Instead, the factory cut a tiny slot on the side of the nut. It's supposed to help the nut compress at different torque ranges and produce an effect similar to double nutting a bolt.

It probably has lost it's locking ability because it has been pulled off and put back on a number of times. Now, you can tighten it, but every time you drive the car the suspension is moving up and down. The 'up' movement would cause that nut to loosen (imagine looking at that nut straight on as the suspension is moving up and compressing the shock absorber, it would cause a lefty-loosey effect).

Hope that makes sense.

[JamesM]

Hi all...I'm referring to the inner nut on the suspension ear ,inner end of pivot shaft.
Can anyone tell me why this nut always seems to loosen? Every time I put a wrench on it I can tighten it by about 1 turn. It tightens up, then a week later it's loose again?
Car is a 74 2.0 liter, I have Eric's bushings in the trailing arm.
Thanks!!
Mike

My guess is you didnt get it torqued properly. I have only had problems with them loosening when they haven't been tightened enough. I forget the spec but those things are supposed to be torqued down to something pretty ridiculous.

[bdstone914]

Hi all...I'm referring to the inner nut on the suspension ear ,inner end of pivot shaft.
Can anyone tell me why this nut always seems to loosen? Every time I put a wrench on it I can tighten it by about 1 turn. It tightens up, then a week later it's loose again?
Car is a 74 2.0 liter, I have Eric's bushings in the trailing arm.
Thanks!!
Mike

My guess is you didnt get it torqued properly. I have only had problems with them loosening when they haven't been tightened enough. I forget the spec but those things are supposed to be torqued down to something pretty ridiculous.

I checked the factory manual and the torque is 87-103 Ft Lb. I does not say to replace the nut. I have seen them get damaged and loose the locking properties. You should also look at the splines on the end of the pivot shaft. They may be worn smooth if the nut has repeatedly come loose. Have some one look at the outer end of the shaft to see if it is turning when you tighten the inner nut. The shaft may be turning and you would not be getting proper torque.

Bruce

[MikeM]

Bruce...it does tighten, just doesn't stay tight.
With the heat exchangers I have no idea how I'd get a torque wrench on that!!
It's difficult to get ANY wrench on it.

[MikeM]

Rob-O....Are you sure this is a one use nut?
What you are saying does make sense....

[brant]

its a symptom of chassis ear flex
do you have wide sticky tires or drive under a lot of G-loads?

when we first started tracking... those nuts would come loose daily
next thing that happened is we ripped the console out

fixed it and ripped it out again, in a matter of a hundred miles.

the true solution are console braces.
those nuts never came loose again in 20 years once the bracing was installed.

brant

[MikeM]

Please tell me more about console braces. Stock tires and wheels, mostly drive it like an old lady....mostly.

[914_teener]

If you installed new bushing and didn't grind back the bushing to expose and make sure the serration on the pivot shaft engages the ear......it will get lose.

Did you do that when they were installed?

[Rob-O]

Rob-O....Are you sure this is a one use nut?
What you are saying does make sense....

Pretty sure. I don't remember where I saw the information. If Bruce says it's not in the factory manual, then maybe it says it in the PET.

[ClayPerrine]

The shaft is not supposed to move. The bushings are supposed to move on the shaft.

I would suggest a dab of locktite and the proper torque to make sure it doesn't back off again.

[914_teener]

If you got the hard replacement rubber bushings from PMB the bushing will sit "proud" of the control arm enough to be longer in OA length to the pivot shaft.

If you didn't grind them back to less than the pivot shaft length then the pivot shaft will have a hard time staying stationary relying just on the torque on the nut and the surface of the new bushing against the chassis mounting points.

The serrations of the pivot shaft end are intended to lock against the suspension ear and the outer mount near the side valance.

It could also be the "ear flex" but if you haven't done the above.....I doubt it.

[MikeM]

Awesome....this means I get to pull it all apart again.
Excellent news....

[914_teener]

Well.....IF.....you think that is the problem....why couldnt you just drop the front
of the control arm down and just grind the face of the bushings...measure the
OA against the pivot shaft? That way you don.t take everything apart

Just a thought.

[Steve]

According to the factory manual:
Control arm bearing on control arm.
Inside = 87 ft. lbs
Outside = 108 ft. lbs
Both Self-locking hex.nut
Threads M 14x1.5 Grade 8 G

[MikeM]

Steve...thanks for the torque specs. Are you saying I should replace the nut?
Mike

[MikeM]

914 teener...it's a good thought but with the heat exchangers just under the trailing arm, I would think that would be impossible. I can hardly get a box end wrench on it to tighten it!!
Mike

[914_teener]

914 teener...it's a good thought but with the heat exchangers just under the trailing arm, I would think that would be impossible. I can hardly get a box end wrench on it to tighten it!!
Mike

You can break the nut with the HE's on. I've done it. You may need to remove the shock IIRC. I used a box wrench and with the car jacked up high enough...wasn't much of a problem.

Then just break the three nuts on the mounting pedestal...remembering how many shims are there and in what positions.

Not sure if you need to just unmount the rear caliper and take off the e-brake cable with the one clip. I think you do.

You should then be able to muscle out the pivot shaft from the chassis ear.

Then just tap the pivot shaft through the bushings.

[Steve]

Steve...thanks for the torque specs. Are you saying I should replace the nut?
Mike

I just use locktite and tighten it as best I can. I have never had the inside one come loose. Only the outside when it wasn't torqued down. When it slipped it would make a klunking sound.

[914_teener]

Here's a pic of what it should look like.