Front suspension questions

[miloh]

Hey all, my tie rod ball joints are cracked and so are my CV boots. I've been hesitant to do suspension work on my X since 2021ish when I sheared off the eccentric bolt alignment tab in the back and had a shop re-weld it. BUT now I'm wanting to get a bit deeper and conquer my fears.
I've watched a lot of videos where people, namely M539 on youtube, use ball joint (I think) and bushing extraction tools.

On RealOEM the front tension struts:
31126769717 (L)
31126769718 (R)
have listed:
2x 31126769715 (Tension Strut Bushing)
2x 31126756491 (Ball Joint)
as components that seem to be replaceable.

The FCP kit from Lemforder: E53CAKIT10PIECEL has both tension struts with bushings preinstalled, and the ball joints separate.

Same with the front wishbones:
31126760275 (L)
31126760276 (R)
have listed:
2x 31121124622 (Bushing)

Both are the tension strut and wishbones are sold in the kit as the complete assembly.

Can or should I purchase the two replaceable components for the tension strut? Are there reasons to do the whole assembly over the serviceable parts? One time a shop told me you can only do replacements of some of those serviceable parts about two times. I'm not sure if that's true or not and I can't recall the reasons they supplied to me, so I wonder that also.

My CV boots are covered under a shop warranty so I'm gonna have those serviced and then start a refresh sometime soon (probably with x5chemist unless I get excited and jump the gun).

[andrewwynn]

Unless you already have the press with the right fittings it's not worth the effort to replace the bushings just replace the whole part. Be careful on assembly, they take a crap ton of torque 165 ft·lb 225 N·m! IIRC, and must be tightened when the wheel is loaded. (i lift the hub from under the steering knuckle to load the suspension; it's impossible to torque with the wheel on and on the ground).

Plastic parts in the way; i made access holes for the tension strut bolts when replacing on our E53s.

Enjoy the cost difference on the older model. I paid about 250-300 per axle for complete OEM kits from FCP on the E53s. It's double that on the e70.

I bought the Neiko torque multiplier and is my favorite tool for big suspension bolts. 165/3=55 ft·lb to tighten monster bolts.

With the relatively low torques involved you can just use a 3/4 to 1/2 adapter with existing sockets but i bought a few specific to e53 suspension initially but eventually i bought a complete 3/4 drive socket set.


–awr–

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[Fifty150hs]

Originally Posted by andrewwynn

Unless you already have the press with the right fittings it's not worth the effort to replace the bushings just replace the whole part. Be careful on assembly, they take a crap ton of torque 165 ft·lb 225 N·m! IIRC, and must be tightened when the wheel is loaded. (i lift the hub from under the steering knuckle to load the suspension; it's impossible to torque with the wheel on and on the ground).

Plastic parts in the way; i made access holes for the tension strut bolts when replacing on our E53s.

Enjoy the cost difference on the older model. I paid about 250-300 per axle for complete OEM kits from FCP on the E53s. It's double that on the e70.

I bought the Neiko torque multiplier and is my favorite tool for big suspension bolts. 165/3=55 ft·lb to tighten monster bolts.

With the relatively low torques involved you can just use a 3/4 to 1/2 adapter with existing sockets but i bought a few specific to e53 suspension initially but eventually i bought a complete 3/4 drive socket set.


–awr–

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I jack the axles up to correct ride height with the car on jack stands when I torque the tension strut bolts. Much easier to get to and the suspension doesn't "know" its not on the ground.

[andrewwynn]

Originally Posted by Fifty150hs

I jack the axles up to correct ride height with the car on jack stands when I torque the tension strut bolts. Much easier to get to and the suspension doesn't "know" its not on the ground.

It's the only way to go. I think ideally you need to lift at the hub to get it perfect i don't have the ideal tool that is held on by the lugs to lift from the bottom. I started putting the lugs in holding the rotor tight and lift from the bottom of the rotor to simulate being on the ground. If you lift from under the spring it won't compress as much.


–awr–

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[Fifty150hs]

Originally Posted by andrewwynn

It's the only way to go. I think ideally you need to lift at the hub to get it perfect i don't have the ideal tool that is held on by the lugs to lift from the bottom. I started putting the lugs in holding the rotor tight and lift from the bottom of the rotor to simulate being on the ground. If you lift from under the spring it won't compress as much.


–awr–

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That's typically what I do. I have coil overs and have lowered my X 2", so it doesn't compress much anyway.

[BenFenner]

Originally Posted by andrewwynn

I bought the Neiko torque multiplier and is my favorite tool for big suspension bolts. 165/3=55 ft·lb to tighten monster bolts.

I purchased this same unit in preparation for removing and reinstalling the front main pulley on the E53. I haven't gotten to that job yet, but it has already come in very handy removing the flywheel bolts on my E90 M3.

A note about that math.

It is not especially accurate, but more like 165/2.46 = 67 ft·lb
See this video beginning at timestamp 7:22:
https://youtu.be/npM78T3SrH0?si=5ICmtoVTSzJ3NkIi&t=442

[andrewwynn]

Originally Posted by BenFenner

I purchased this same unit in preparation for removing and reinstalling the front main pulley on the E53. I haven't gotten to that job yet, but it has already come in very handy removing the flywheel bolts on my E90 M3.

A note about that math.

It is not especially accurate, but more like 165/2.46 = 67 ft·lb
See this video beginning at timestamp 7:22:
https://youtu.be/npM78T3SrH0?si=5ICmtoVTSzJ3NkIi&t=442

I'm familiar with that exact video. They made a big error in how they attached the reaction arm. If you want the math to work you need to apply the torque 180° from the reaction arm.

I use a jack stand to hold the reaction arm horizonal and apply the measured torque exactly opposite.

I've measured the input vs. output torque and it was spot on 3:1 in the 100-150 ft·lb output range.

Using a 1" bolt at 150 ft·lb, 50 ft·lb input it was within 3%. In fact some tests were exact. 30 ft·lb in for 90 ft·lb out to one decimal place.

I was actually going to reference that video to explain at normal human levels you will get the 3:1 torque that Neiko specifies.

I've trusted up to 225 ft·lb output doing suspension and 300+ on axle nuts i think spec was 330 so 110 on the torque adapter.

I will do another round of testing at some point but my test was this:

1/2" input with digital click torque wrench, into the multipler, 3/4 to 1/2 adapter through my 1/2" digital torque adapter that has peak reading.

First test was tighten some lubricated 1/2-20 to spec of 90 ft·lb.

30 click on the input and 90 ± 2 on the output.

Similar, used a 1.5" socket on 1" bolt "snugged" to 150 ft·lb. Was within the 2% of the input rating.

Repeated each test several times.

I was not too happy to see such a big difference in my personal experience but when you see how they used a chain at an extreme angle, the sideways force on the output shaft would be 2-3x what would happen from 180° application of force and counter force and i suspect that's why they had such a big difference.

The design is 3.3:1 gearing on purpose to make tge torque ratio easier to work woth. (3:1)

I'm happy to use the 3:1 but i will do another test at some point


–awr–

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[miloh]

Cool. Thanks for that info. Would I maybe want to do custom bushings and ball joints where I get a tool to install ball joints I think will last longer or are better quality than OE lemforders?

[Henn28]

Originally Posted by miloh

Cool. Thanks for that info. Would I maybe want to do custom bushings and ball joints where I get a tool to install ball joints I think will last longer or are better quality than OE lemforders?

Unless that type of engineering is your thing, that sounds like a lot of work and brain damage. Frankly, I’d love to be able to contemplate fabricating stuff like that, but the one brain cell doesn’t stretch that far.

I do think that the majority of the mileage you get out of your suspension bits, especially control arms, depends on the quality of the roads where you drive. My OEM bushings made it a couple years (about 15k), at most and I had resigned myself to changing cheaper OEM arms every so often. I suspect too that my small lift and the wheels/tires I’ve got on put more stress on the front suspension, as does the hunting season driving I do on unimproved roads.

A couple years ago I decided to try a set of Turner monoball uppers (they make lowers too) which seemed pretty bullet prof, but I pulled them off after a year as they were too stiff for around town driving where I live. They have been replaced with poly bushings that I really like, but started squeaking within 6 months on the grease they sent with them. I pulled them again and lubed them with plane old white lithium grease. So far so good. I had a local shop press out the OE bushings and press the metal cups for the poly ones in.

As Andrew says, it takes a huge a of pressure to get the bushings in/out. Until this poly set though, I’ve always bought complete sets since I don’t have a press, and when time is considered buying replacement OEM arms made sense to me. I know Turner makes monoball uppers and lowers and you can buy the bushings or complete arms. More expensive, but they feel amazing on good roads. My switching to the monoball and now poly bushings was really just out of curiosity if they would last longer on my modified X5.

Long story short, I had gotten pretty fast at replacing control arms and aligning with string in the driveway (thanks to an education by Factory6speed), so I leaned towards buying OEM arms every couple years. The right tools are a must and will make life a lot easier and the job much faster. I resisted buying single use tools for years and wasted so much time and energy on axles, ball joints, etc.

Now I’ve got two ball joint separators (large and smaller) for the arms, a big three leg press to push the axle out, the special puller to pull it back into the hub, and a 40” breaker bar to get the axle nut set. It’s mostly Amazon junk, but saves me so much time. I think the ball joint separators are from ECS:
https://www.ecstuning.com/b-schwaben.../008959sch01a/

That torque multiplier sounds like a great tool Andrew. Definitely better than guessing for the really high torque fasteners.

[miloh]

Originally Posted by Henn28

Unless that type of engineering is your thing, that sounds like a lot of work and brain damage. Frankly, I’d love to be able to contemplate fabricating stuff like that, but the one brain cell doesn’t stretch that far.

I do think that the majority of the mileage you get out of your suspension bits, especially control arms, depends on the quality of the roads where you drive.

Ok that makes sense. I wouldn’t have made the ball joints from scratch, just if there was an obvious “ball joints you would have to press yourself but is superior build quality”