Thrust Arms 101

[George M]

Since I find myself in the midst of yet another thrust arm replacement (not on my car) and have done a number of them by now, I thought I would share a couple of lessons learned that should help the first timer tackle this daunting job. As discussed a couple of weeks ago, if not replacing the shocks and/or springs, no need to remove the strut, brake and/or rotor. Have a look at the following pics...and note I didn't use a pickle fork for any of the ball joint separations...only a couple of good pullers as part of a Murray's loaner/purchase/return kit comprised of five pullers total.
George
90 735iL/149k




Drop the upper and lower control arms attached to both steering knuckles DOWN WITH with the thrust arm tube X-mbr. Use your floor jack to bring the whole assembly down together slowly after disconnecting the lower control arms from the engine X-mbr.






With the tube thrust arm X-mbr attached to suspension arms all brought down together, now simply take the impact to the pesky thrust arm bolts. It is very hard to get enough leverage to break loose the thrust arm bolts with the X-mbr up on the car and there is insufficient room to get an impact wrench on either the thrust arm bolt head or lock nut. On a lift you can use your body fpr leverage but under the car it is only arm strength and they can be stubborn. Much easier this way. Two bolts to put the tube X-mbr back up prior to reinstalling fresh arms.






Disconnect the knuckle from the strut by supporting the rotor hat with a jack stand. Need to rotate the steering wheel to gain access to all three knuckle bolts. No need to remove the strut unless doing shock and/or spring replacement.

[MO525]

I pulled nothing but the Thrust Arms.
EVERYTHING came loose VERY easily, except for the driver's side joint.
MAJOR pain getting it loose.
The passenger side was out and in within an hour.
The driver side took at least 3 hours.

It drives SO MUCH better now.
Amazing what a difference it made and no more irritating "CLUNK" when you hit pot holes and such.

I bought the arms from BMA.
Best price around!!!! $90 each side.

[Bruno]

way too much work....
I don't want to have to drop all that. I just use pure force and a large braking bar to break all my bolts off.... yet the compressor is due for next week... Yeeeeha poower tools

[MO525]

way too much work....
I don't want to have to drop all that. I just use pure force and a large braking bar to break all my bolts off.... yet the compressor is due for next week... Yeeeeha poower tools

[George M]

hmmm...Mo525, if you change the lower control arms, you have to remove the knuckle from the strut for access to the ball joint lock nut...you only did half the job. And Bruno, I will be looking for you in the World's Strongest man competition....lol...maybe you will get it after you get your air installed. Since I have probably rebuilt more suspensions than you two guys combined, for the rest of you, trust me when I tell you this is by far the easiest way if you have air tools....I have done it many different ways to determine the easiest method. The front lower control arm bolts can also be zipped with an impact. The tube x-mbr has to be loosened for access to the rear locknuts which some use a ground down 22mm box end wrench on which isn't necessary. Loosening the X-mbr, or already having it loose for reassembly you can easily get a regular 22mm box end wrench on the rear locknut versus sliding an open end 22 into the crevice which isn't as secure when retighting the thrust arm bolts with a torque wrench. Mo525, you did use a torque wrench when you retightened your thrust arm bolts didn't you?...and retorqued the bolts with the suspension in loaded position? :-) Removing the two carriage bolts that retain the light X-mbr to the car's sub frame is by far the easiest method to change the thrust arms. You can lead a horse to water....
George

[Paul in NZ]

george you got any pics with the pullers in place?

[Mike]

George, you're da man! Your walkthrough boosted my confidence in doing the thrustarms on my own. Just not sure about the puller placement, as I only used a puller once in my life before; like Paul said - any pics of puller in action?

[George M]

when I get a little time, I will take some pics of the pullers I used and provide a couple more tips. Many different types of pullers will work, but will show the ones at least I had success with. If you check the archives, there was a good pic not long ago of a 3 claw puller that appeared to work well for one board member. My preference is always a fixed jaw puller versus a variable, adjustable claw puller because pulling force is never purely parallel to the direction of separation...a component of force is radial to
the direction of pull by the design of an adjustable jaw puller design...why they tend to slip if torqued up real high and work best for small ball joint applications.
George

[MO525]

hmmm...Mo525, if you change the lower control arms, you have to remove the knuckle from the strut for access to the ball joint lock nut...you only did half the job. And Bruno, I will be looking for you in the World's Strongest man competition....lol...maybe you will get it after you get your air installed. Since I have probably rebuilt more suspensions than you two guys combined, for the rest of you, trust me when I tell you this is by far the easiest way if you have air tools....I have done it many different ways to determine the easiest method. The front lower control arm bolts can also be zipped with an impact. The tube x-mbr has to be loosened for access to the rear locknuts which some use a ground down 22mm box end wrench on which isn't necessary. Loosening the X-mbr, or already having it loose for reassembly you can easily get a regular 22mm box end wrench on the rear locknut versus sliding an open end 22 into the crevice which isn't as secure when retighting the thrust arm bolts with a torque wrench. Mo525, you did use a torque wrench when you retightened your thrust arm bolts didn't you?...and retorqued the bolts with the suspension in loaded position? :-) Removing the two carriage bolts that retain the light X-mbr to the car's sub frame is by far the easiest method to change the thrust arms. You can lead a horse to water....
George

1. I only changed the Thrust Arms, NOT the lower control arms.
2. I don't know what Thrust Arms you're speaking of but I had NO problem accessing the 22mm nuts with a standard Craftsman combination wrench. By the way, the box end fit fine, no kidding.
3. Yes, I loaded the suspension (to the best of my ability) using my wife, my brother and my daughter for weight.
4. Yes, I torqued the bushing bolt to 94 with my trusty Craftsman torque wrench.
5. The job was surprisingly simple. Had it not been for the stubborn driver's side "joint", it would have been done in two hours.

You have your favorite method and the rest of us have Bruno's simple but effective method.

[George M]

one with little experience and not a whole lot of creativity.
Anybody who takes 2 hours to separate a single thrust arm ball joint, doesn't know what the hell he is doing....your self admission.
George