How to tighten the thrust arm

[Kibokojoe]

I am replacing the lower control and thrust arms. I know you have to load the front end before tightening the nuts and bolts, question is??? Can I leave the bolt/nuts loose and then drive it up on a pair of ramps and then tighten them or do I have to have the front and back end level? I suppose I could drive the car up on the ramps and then level the car using a jack and stands. Will that work? The other question is do I really have to load the fenders to the correct weight before I tighten or will the weight of the car suffice? Is this really that critical?

[Ross]

No problem driving it onto ramps with the bolts loose. I'd get it as close to level as possible since the idea is to have it at static ride height when tightening to prevent preloading the bushings. Bounce the suspension a few times to settle it before tightening.

[Kibokojoe]

Ok good will give it a go. Someone had told me it was necessary to place weights on the fenders???

[philbyil]

To do it properly, the car needs to be level and sitting on its tyres. You can run it up on ramps, jack up the rear then drop it onto stacked blocks or ramps of the same height to get it level.
The car needs to be at spec ride height before you torque down the bolts. In addition to a full tank of gas, you need about 150 pounds in each front seat, 150 pounds in the middle of the back seat, and 45 pounds in the trunk. You can get the proper ride height measurements from your Bentley manual. Can't help you as I haven't got it at work!
You then torque down the bolt holding the bushing side of the thrust arm to the frame to 110Nm (81 ft-lb).

Done......



I am replacing the lower control and thrust arms. I know you have to load the front end before tightening the nuts and bolts, question is??? Can I leave the bolt/nuts loose and then drive it up on a pair of ramps and then tighten them or do I have to have the front and back end level? I suppose I could drive the car up on the ramps and then level the car using a jack and stands. Will that work? The other question is do I really have to load the fenders to the correct weight before I tighten or will the weight of the car suffice? Is this really that critical?

[Ross]

That's great advice if you typically have two passengers, a full tank and a bag of sand in the trunk.
I used to go through all that hoo ha(much to the dismay of the alignment shop)when it was alignment time myself. Since it's usually just me or the wife I wonder if it isn't the reason I always seem to have alignments redone at least once.
Next time I just let 'em have at it.

[Tiger]

Geez! That's alot of spec and I bet you 90% of the time, it is not done that way... Hell, maybe 50% of the time, they tightened it right on the spot while in the air.

[Robin-535im]

I did the math once - free body diagram and sum of forces, etc. (flashback to freshman year in college...)

IIRC - a 50 lb bag of sand on each fender was equivalent to the load you see when loaded per Bentley. The displacement is minimal though, so as long as you're loaded and level you should be fine. If you're up on ramps there will be less load on the front end than normal so I would put some big sandbags over the fenders to load it a little more... but that's just me.

[Kibokojoe]

All these calculations...makes me want to press out the standard bushings and put in powerflex. Press them in the arms (no aligning :)), copper grease them up and torque them down and forget it. I will go and pick up some 50 pound bags of sand tomorrow. With the front on ramps and the back end jacked up to make the car level this should be good I would think.

[Old Man Pete]

Last time I did mine (about 18 months) I used two people sat on the front end and it worked fine, but the bushes need doing again and I've got powerflex ready and waiting! The oem bush for the 525 really is crap is what I found.

[632 Regal]

use the M5 bushings, I would pop the stockers on the test run.
Last time I did mine (about 18 months) I used two people sat on the front end and it worked fine, but the bushes need doing again and I've got powerflex ready and waiting! The oem bush for the 525 really is crap is what I found.

[philbyil]

Geez! That's alot of spec and I bet you 90% of the time, it is not done that way... Hell, maybe 50% of the time, they tightened it right on the spot while in the air.


Well, he asked and I told him.....:D:D
Remember, I am ENTIRELY anal when it comes to maintenance items ;)

[Kibokojoe]

Arms and new tie rods in and its off for an alignment. Not to bad with my son helping me. Next time I will install Powerflex bushings so I don't have to worry about preloading the arms. Thanks to all


I am replacing the lower control and thrust arms. I know you have to load the front end before tightening the nuts and bolts, question is??? Can I leave the bolt/nuts loose and then drive it up on a pair of ramps and then tighten them or do I have to have the front and back end level? I suppose I could drive the car up on the ramps and then level the car using a jack and stands. Will that work? The other question is do I really have to load the fenders to the correct weight before I tighten or will the weight of the car suffice? Is this really that critical?