Mechanic said he didn't torque lower control arms at curb weight

[2.7taudi]

He told me that torquing the lower arms at curb weight or load is not necessary. Is he right? I met him yesterday to get a friends passat done and I asked him and he said he didn't put load on them when he did mine.

I have been running the new arms for 3k miles. Is it just about given that my arms will fail prematurely?

This is on a 2.8 fwd even tho all of them use the same arms.

[FCPEuro]

He told me that torquing the lower arms at curb weight or load is not necessary. Is he right? I met him yesterday to get a friends passat done and I asked him and he said he didn't put load on them when he did mine.

I have been running the new arms for 3k miles. Is it just about given that my arms will fail prematurely?

This is on a 2.8 fwd even tho all of them use the same arms.

Not tightening the arms with the suspension "preloaded" will indeed cause premature failure. With the suspension hanging there the bushings and ball joints are not in their natural position, so when the car is put on the ground the bushings/ball joints want to twist, but if they are tight they will not be able to move and all the strain will be put directly on them. This eventually leads to cracked bushings, and torn/worn ball joints and boots. I can't say that this happens EVERY time, but I would say that about 95% of premature failures are caused by improper installation.

Nick@FCP

[2.7taudi]

Not tightening the arms with the suspension "preloaded" will indeed cause premature failure. With the suspension hanging there the bushings and ball joints are not in their natural position, so when the car is put on the ground the bushings/ball joints want to twist, but if they are tight they will not be able to move and all the strain will be put directly on them. This eventually leads to cracked bushings, and torn/worn ball joints and boots. I can't say that this happens EVERY time, but I would say that about 95% of premature failures are caused by improper installation.

Nick@FCP

Doh!

Does this include torqueing the upper at curb weight? I don't think there might be enough arm space for any one to do so at curb for the upper arms.

[bw86]

torque everything with bushings at ride height.

If you don't have room - just take the wheel off put a jack under the knuckle and bring it to ride height.

[M-Hood]

torque everything with bushings at ride height.

If you don't have room - just take the wheel off put a jack under the knuckle and bring it to ride height.

Exactly, the car doesn't actually have to be on the ground to do it since the suspension just needs to be compressed.

[walky_talky20]

Just to clarify, the damage is done to the circular bushings at the inner end of the control arms. They are "twisted" well beyond what they should be and thus are apt to tear the rubber. The ball joints and their boots are really not affected one way or the other. In other words, "proper" installation is done to save and extend the life of the circular bushings, specifically.

[00SantorinS4]

I have FCP Lowers I just installed last week and did not torque with load (uppers I did last year I did torque properly). I'll gladly be the test to see how long until the bushings go to crap.
Either way I'm willing to bet I don't even have the car anymore by the time happens--if it does, FCP lowers cost me about $120 for all four. I'll gladly install another set at that price.
FCP LOVE!

OP I wouldn't stress over it, my inner bushings on my OEM lowers were pretty shot but it was the actual ball joints on my lowers that produced the knock over bumps..
Those didn't even have the boots remaining with 110k miles on them LOL

[MadAudi]

Your mechanic is a retard.

[AudiNFS]

I know people that haven't had there's torqued at curb weight and they're still going on 1.5 years with a daily driver on a lowered car.

[walky_talky20]

Indeed, they will still be "going". The damage to the inner bushings is not as noticeable as a worn out ball joint. Worn ball joints cause a knocking/rattle over bumps which is very noticeable and discernible play which will cause the vehicle to fail a safety inspection. Torn bushings, on the other hand don't usually cause any clunking or anything. They are full-circle mounts and are completely filled with rubber. About the worst they can do is cause somewhat degraded or "mushy" handling that is a gradual onset and not nearly as noticeable. Over time it can become more severe and cause alignment issues and mild "thunking", but only when they get extremely bad. The damage done is not tragic. It is somewhat minor, but needless damage nonetheless.

Basically, a car with correctly installed arms will have optimum handling for longer, and the arms will probably not be replaced until the ball joint goes bad. A car with incorrectly installed arms may begin the descent to sloppy handling earlier and the arms may need replacing because of worn bushings, while the ball joint is still good. Obviously YMMV.

I would say that 75% or so of Audi control arms are installed incorrectly at repair shops. Few mechanics who are trying to beat the clock will take the time to load the suspension to prevent a failure 30k miles later. Nobody has died in spite of this (probably). The slight degradation in handling over time is surely only missed by the enthusiasts in any case.

[M-Hood]

I know people that haven't had there's torqued at curb weight and they're still going on 1.5 years with a daily driver on a lowered car.

That is fine if the car is lowered with no compression travel to the point that the bushing never has to rotate that direction, but still has plenty of rebound to rotate downward like the arms were when they were installed. If you install it that way on a car that has plenty of travel on the compression side then the bushings are going to tear quickly since they are going beyond their rotation.

[AudiNFS]

Interesting. I didn't know all of this. So the lower control arms should be torqued with the car on the ground, or something to simulate that effect. *What if* the control arms were out of the car, torqued to what they needed to be, and without the curb weight torquing were tightened by relatively strong guys so that they couldn't spin tighten any more? Basically what I'm trying to understand is if it is *possible* to torque it relatively close to the proper way of torquing things without actually having the car on the ground, or something of having the car on the ground.

[walky_talky20]

The thing you are addressing when torquing them "at ride height" is the control arm bushing "zero point". That is, the point where the bushing is completely relaxed and not twisted. That "zero point" should be the point at which the bushing rides at most often: ride height. As the suspension fluctuates in either direction (compression/droop) the bushing is twisted, which is normal. However, if the zero point is set at full droop (ie: on a lift with the wheels hanging at full droop limit), then the bushing will almost never be relaxed. It will be very twisted at ride height and during compression (hitting a bump, fast turn, etc) it will be twisted even further - far, far beyond the amount of twist that it should ever see.

Key item = the "zero point".

So you can tighten the inner bolts with the wheels on the ground, or on an alignment rack. Or on a regular lift with a jack under the upright. You could even measure the angle of the control arm at ride height (your car's specific ride height) and then duplicate that angle upon install, tighten the inner bolt, THEN connect the ball joint to the hub assembly. However you want to do it, as long as the zero point gets set reasonably close to the actual ride height. The bentley manual even shows the specific angles for a stock car when doing the upper control arms. Of course that all changes if you've lowered it.

[2.7taudi]

Your mechanic is a retard.

LOL dont worry he's not my usual "engine" mechanic. This guy's shop is right next to work so i gave it to him so i would have it back by the time im off work. He usually gets chevys and ford in his garage and their lowers are not individual lowers like ours. Maybe thats where he messed up. Unless ALL cars are supposed to be torqued at curb weight.

Any way i got somewhere around 3-5k on them. dont remember exactly. Should i bring the car back to him? its been over 3 months.

[MadAudi]

Whenever you do any work to your suspension, everything should be tightened down at ride height. I'd take the car back.

LOL dont worry he's not my usual "engine" mechanic. This guy's shop is right next to work so i gave it to him so i would have it back by the time im off work. He usually gets chevys and ford in his garage and their lowers are not individual lowers like ours. Maybe thats where he messed up. Unless ALL cars are supposed to be torqued at curb weight.

Any way i got somewhere around 3-5k on them. dont remember exactly. Should i bring the car back to him? its been over 3 months.

[J. Daniel]

I'd say it would be instructive to watch your bushings as the steering is turned lock to lock. There is not only the normal twist of the bushing about a horizontal axis as the suspension moves up and down but a tremendous amount of twist about a vertical axis as the steering is turned. Only cars with individual arms and two outer balljoints (Audi and BMW to my knowledge) have this vertical twist and it really gives the bushings a workout.
Bearing that in mind I'd be doing everything I could to reduce bushing deflection.

[walky_talky20]

^That's true, there is twist in both directions.

There are other control arm designs have that same type of deflection in a bushing. For example Toyota Camry lower control arms (Macpherson suspension) use a full circle bushing like that. It sees that "vertical" type of twist as the control arm deflects up and down. The bushing is installed perpendicular, as compared the Audi bushings:



They end up failing like this:



(Photo of Subaru control arm, but same design)

[Lornnn]

give 'em a year like that before you start hearing them.