CMP (or other) subframe bushings - DIY'd install? Fitment? Partially drop subframe?

[Tbonem3]

Hi, can anyone who's DIY'd the install of CMP (or maybe Turner) sub bushes tell me how the fit was and how pressing them in was, did you use a special tool, or did you throw the whole subframe into a press?

I've already had plates welded, but am thinking of switching subframe bushes out. I'm wondering if I can simply lower the subframe 6 inches like I did on my e82 128i. I guess almost everyone just drops the whole thing, my situation isn't as common.

I have a subframe press tool where the cup is about 4-5 inches tall, so I'm hoping I can get away with just partially dropping the subframe without disconnecting the driveshaft and all the other stuff.

[Arith2]

I would advise a press. Impacting press tools is not a very good option if you have the press available. There is no give on solid aluminum and I found the build quality on our subframes is pretty subpar. CMP has high quality products like most solid bushing, I just think the issue could be the subframe

[mrgizmo04]

I used the rtab tool, it actually fit perfectly.

https://www.fcpeuro.com/products/bmw-trailing-arm-bushing-tool-cta-7642?ads_cmpid=352576039&ads_adid=22972407319&ads_matchtype=&ads_network=g&ads_creative=85218275839&utm_term=&ads_targetid=aud-667196784149:pla-329388689743&utm_campaign=&utm_source=adwords&utm_medium=ppc&ttv=2&gclid=Cj0KCQjwyN-DBhCDARIsAFOELTkP0yzqTtd6XYGlP1jMdno17IYGifhtbslI7DLOn8k8CYkiY2t6VGgaAkzEEALw_wcB

For the threaded rod, I used the rod from the schwaben bushing kit, it is much more stout.

https://www.turnermotorsport.com/p-402350-schwaben-subframe-differential-bushing-tool-set/?gclid=Cj0KCQjwyN-DBhCDARIsAFOELTnp1iThFWOiN4yB-DPv6jYFF2DFM-AywLl6YCtc0c8PO9--p2rGjLoaAlOzEALw_wcB

You can freeze them overnight and they will go in easily. I didn't freeze them, just put a lot of grease on them and they went in. The CMP rtabs though...I would definitely freeze, those went on with a fight and I stripped the nut on the tool literally millimeters away from being done on the final bushing (2nd pic).



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[mrgizmo04]

Oh, on your question of lowering the subframe...unless you are going to be removing the studs (I think only the front 2 are easily removable with a hex, but depends, see below), you will need to drop the subframe down quite significantly. Then you will have parking brake, brake hoses/sensors, driveshaft etc to worry about.

Also depends on what your #3 and #7 look like https://www.realoem.com/bmw/enUS/sho...diagId=33_1076

After doing cmp topside beam reinforcements, #7 is a threaded stud without a hex like #3, so for me I had to just take everything down/apart, which was not really a huge deal because I was swapping diffs and all control arms/bushings anyway. Stock #7 is an actual bolt, so removing that is easy.

The good part about cmp bushings is they are pressed upward into the subframe. The issue is that you need to have something to hold the tool in place from the top to pull the bushing in.

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[Tbonem3]

Ah I forgot you had them, I would have just texted you.

I have an RTAB press tool too, so that's good to know. And I was hoping they'd go in from the bottom, so that's good confirmation. I probably could fab something up that would fit up top to draw bushings in.

I'll be removing rear bolts as I'll also be installing a rear GTR brace (topside), but I didn't plan to remove fronts. Are you saying that, with them (front studs) in place, they won't allow subframe to drop much? I guess removing them is fine, I'll be supporting the frame with jack. I just did one corner at a time on 128i.

Maybe I got lucky with 128i, that it was easier to lower than E46?

Thanks Stas

I really really don't want to drop the whole thing and disconnect so much as I've already redone my rear end and everything is great, I just thought I'd upgrade the sub bushes.

I'd be dropping my other car's whole rear end to pop the AKG sub frame bushes in there, but that's not this car.

[mrgizmo04]

Well, the front studs with the hex are about 3" long (if left in place), so you need to drop the subframe at least 3-4" so that the stud is out of the inner hole of the bushing so you can thread through the rod you will use to pull the old bushing out or push the new bushing in.

The problem with pushing the new bushing in, is you need a cup (or what in my pic is that golden colored u-shaped rtab tool) that is wider than the outer diameter of the bushing because the bushing protrudes at the top, it doesn't sit flush with the top of the subframe. So you can start by putting a flat plate on top to pull the bushing in 90% of the way there, but to finish it, you need a receptacle that is wider and can accept about 1/4" of depth. All of that is space you need from above...

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[ClevoCapri]

I had my subframe out when I did my CMP bushes. I had them in the freezer overnight, heated the subframe with a heat gun then just tapped them in with a plastic deadblow hammer. Easy.

[mrgizmo04]

Boom hammer them in!

Assuming the current bushings are poly 2 piece that are easy to get out.

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[Tbonem3]

Correct

So how far do you think I could drop the subframe before brake/ebrake lines are an issue?

I'll need a couple of inches at least to remove upper half of poly and get a cup and double nut on top to draw up alloy bush I'd guess.

[Tbonem3]

I had my subframe out when I did my CMP bushes. I had them in the freezer overnight, heated the subframe with a heat gun then just tapped them in with a plastic deadblow hammer. Easy.

Thanks, tapped them in upside down?

[heinzboehmer]

Fwiw, I froze my bushings as well and don't think I could have gotten them in by just tapping on them. They definitely went in a lot easier than the CMP RTABs did, but still.

Tbone, I suspect the subframe will get caught on the front two subframe bolts if you try to drop it with the driveshaft still connected (as it'll want to tilt). Why not just disconnect the driveshaft, move the calipers out of the way and drop the whole thing completely? Shouldn't take too much longer and will probably make your life a whole lot easier.

[Tbonem3]

Ya, just more work and I'm getting old. I feel like it's not worth doing if my current situation is good which it is. Just wanted to see how easy it could be to swap them out.

[Obioban]

Correct

So how far do you think I could drop the subframe before brake/ebrake lines are an issue?

I'll need a couple of inches at least to remove upper half of poly and get a cup and double nut on top to draw up alloy bush I'd guess.

What's your plan for getting the poly bushing past the stud on the front mounts?

[Tbonem3]

I'd be removing the stud if I'm working on that particular corner. So I guess now I have to visualize if I can get a wrench on the stud and get it out with the subframe in the way, which I guess is a no? On the 128i, it was 4 bolts. Maybe that's the thing that makes this impossible.

[Obioban]

I'd be removing the stud if I'm working on that particular corner. So I guess now I have to visualize if I can get a wrench on the stud and get it out with the subframe in the way, which I guess is a no? On the 128i, it was 4 bolts. Maybe that's the thing that makes this impossible.

I believe the base of the stud is wider than the hole in the bushing, so not sure that's going to work out...