K-MAC rear lower control arm bushing install -- E53

RocketyMan · #1 03-16-2020, 01:04 AM

I'm attempting to install the kmac bushing kit in the rear control arms on my e53. After searching the forum, there are absolutely no write-ups nor good pictures on this issue--just people talking about it.

The issue is that the frontward bushing on the rear control arms interfere with the sub-frame. The supplier, KMAC, say that this kit is compatible with the E53 and also E60 as they share much of the same rear-end structure.

I attempted to contact KMAC as I'm sure they should be well-aware of this issue--otherwise they wouldn't have advertised having a fix for this. No response yet on their end.

Please see pictures of the frontward bushing mock-install (these are the same pictures I emailed to KMAC hoping for resolution):

What I'm hoping for in this write-up is someone to chime in with personal experience or insight. I do have a couple of ideas to try--but want to first open up a forum with wisdom that might prove more successful so that other X5 owners with concern of poor negative camber can have access to a solution with actual pictures and pertinent dialogue.

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RocketyMan · #2 03-16-2020, 01:16 AM

The instructions given with the K-MAC bushing kit is utterly lousy. In addition, they are not specific to each chassis per P/N. For a kit that costs a high premium of around $400, this is poor product delivery and communication.

Here are the instructions given with the K-MAC bushing kit. Please see the attached pictures.

K-MAC P/N: #193726J

andrewwynn · #3 03-16-2020, 01:20 AM

Are you saying the replacement bolt is too long? How does it compare with the original and will the nut just not fit because the bolt is too long?

I would consider the options of recycle the original bolt and/or nut or if it’s just a case of the bolt being too long I would cut the bolt to match the original (a bandsaw will make quick work of hardend bolts)

RocketyMan · #4 03-16-2020, 01:27 AM

Quote:

Originally Posted by andrewwynn

Are you saying the replacement bolt is too long? How does it compare with the original and will the nut just not fit because the bolt is too long?

I would consider the options of recycle the original bolt and/or nut or if it’s just a case of the bolt being too long I would cut the bolt to match the original (a bandsaw will make quick work of hardend bolts)

Correct. The replacement bolt is too long. If I were to tighten down the bolt, it would jam into the subframe. It would be MOST ideal if the bolt would be able to install on the otherside--but this is impossible given the design of the subframe.

I hope that makes sense.

RocketyMan · #5 03-16-2020, 01:28 AM

Oh..and in addition, you cannot use the previous bolt because the one designed with the k-mac is eccentric in a way that only fits with that bush.

I guess I can take a picture showing how the OE bolt is incompatible with the kmac bush.

RocketyMan · #6 03-16-2020, 01:38 AM

As far as doing research to anyone who installed this on an E53, this was the only response I was able to come up with...from ECS tuning, none-other.

Quote:

Install is rough, but worth it
Without these, my X5 (E53) was chewing through the inside edges of my 10.5" wide rear tires (315/35/20). Factory alignment settings have negative camber for the rear, but these allowed to get neutral setting.

Note though, this installation is *involved*. The bushing need to be pressed in, and you need to grind off some tabs of the rear subframe to be able to get wrenches on the nuts for the front bushings. Even with the modifications noted in the installation manual, I needed to get nylon locking washers because I could not get the nut and lock washer provided with the kit installed.

Also be sure to pay special attention to which bushing goes where. Sounds obvious, but the instructions could be a bit clearer.

All in all, these will pay for themselves in savings from having to constantly replacing the rear tires.

Posted By RickB87 on 3/21/2017 - Carlisle, PA | BMW E53 X5 M54 3.0L | Daily commuter

I'm hoping whomever this "RickB87" is on the X forum...

upallnight · #7 03-16-2020, 10:18 AM

I find it ironic that a person with the name Rocketyman can't figure how to fix this. This is not "Rocket" science. Just cut or grind down the bolt.

EODguy · #8 03-16-2020, 12:18 PM

No but it is close to Rocket surgery...

Suggest that he puts a nut or two on the bolt to the correct height and then cut so that taking the nuts off afterwards will smooth out the edges of the threads.

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RocketyMan · #9 03-16-2020, 03:36 PM

As an update, I spoke with Kevin @ K-MAC and he suggested the wrong bolts were supplied with this kit as well as the nut. In regards to the bolt, it has a tapered end that should be cut off to help accommodate the sub-frame interference. The nut is too deep, 15mm vs traditionally 12mm that should also barely squeak by since the golden-knurled washer is essential for "biting" down during torquing of the assembly.

I totally appreciate Kevin for taking my call @ 6 am ozzy-time. :Australia:

RocketyMan · #10 03-16-2020, 04:55 PM

Here is the plan to modify the sub-frame and bolt to make it work:

As a side note, the stock bushing length is about 69mm for the dowel. The K-MAC supplied one is 68mm. There is a significant gap for the bushing to sit in the housing--which is why it's crucial to torque the fasteners to the limit in order to compress the coupling to reach the knurlings in order to remain stationary.

One thing I wish came with the kit was class 10.9 fasteners instead of an 8.8 since the max torque for an m12 bolt is 100 Nm, or roughly 75 ft*lbs. The OE used class 10.9 fasteners on nearly everything suspension related.

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