Rear Upper Control Arm- weld press nut or hack it our and put a normal nut on?

[Nate_Conner]

mentally gearing myself up tackle my rear upper control arms. I made it through 2 seized pinch bolts, how much worse can this be /s

I need to remove them not only becuase the bushings are shot, but because I also need to mount the ride height sensor for the AFS headlights.

the outer bolt on the drivers side is already seized, so its gunna get cut out, but im at a impass for the inner bolt. ive not yet tested to see if it will come out without spinning the press nut, but with how rust the rest of the bottom of the car is im assuming it will.

thoughts on if i should just have the nut permantly welded to the subframe, or turn the bolt until it spins to get it loose, and just hack the whole thing apart and put in a new bolt and a nut with a actual hex on it?

or say fuck it and save myself the drama and take it shop, and instead take a kick to the wallet.

[Nizmo]

If the job I need to do is at home, without Oxy Acetylene, Welders, and it say an axle nut bolt or upper control arm that has siezed from rust, if I cannot get the bolt/nut out and I cannot drill it out I take it to the shop. I had 2 completely rusted front axle bolts, completely rusted. I attemtped until I realized without a "hack" I cannot do it.

To hack it I could take out the front spindle, axle and all. But right after the alignment I said fuck it I let them do it. $400 a side with supplied OEM axles.

Sometimes its worth it just to ask for the help. I can do anything, I just dont have the tools at home for everything.

[Jayz691]

When I did mine on the sedan, I lowered the subframe far enough to get a small pipe wrench on the nut. Just replaced it with a new pressfit nut, thinking I won't need to remove it again.
The other option is to completely remove the dif/subframe, remove the old one, and tack weld a new nut after "pressing" in with the bolt(they pull into place). Only way I'd do all that is if you think you'll have the car for 10 years, and may need to remove again.
I live in the rust belt(PA) so I had to cut almost every suspension bolt in the rear, changed all the arms. Did it outside on Jack stands before having garage access.. Wasn't fun, lol. That was about 5 years ago. Also, I'd anti seize the new hardware, so the new hardware don't seize in the sleeves again.

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[CrickiKaze]

See if you can get a nut splitter in there, I can't remember how much space is there. Can always use a dremel with an angled head to cut as well avoiding the frame and a hammer and chisel will work as another resort. Always have things like PB Blast or other anti-rust sprays to soak it in before anything else. Tapping with a hammer helps.

Don't weld the nut. leave it as a bolt assembly or its going to cost you later.

[Jayz691]

See if you can get a nut splitter in there, I can't remember how much space is there. Can always use a dremel with an angled head to cut as well avoiding the frame and a hammer and chisel will work as another resort. Always have things like PB Blast or other anti-rust sprays to soak it in before anything else. Tapping with a hammer helps.

Don't weld the nut. leave it as a bolt assembly or its going to cost you later.

Tack welding the nut helps down the road, that way ya don't need to lower the subframe to remove. You can loosen and remove the bolt easily, from the back side, without touching the nut. Just a PITA to actually do it.

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[Nizmo]

Around my area, same as Jay we actually are taking entire rear subframes out because of rust. Many will not survive the next 5 years. The owners and customers will not pay those types of repairs and many have moved on long ago. Rarity on all is going up, and value is thereafter.

Cali and Florida type states will see these cars for a bit, but up here in the north a B7 right now is rare.

Take out the rear subframe, buy a new or used rust free subframe do all new bushings, paint with POR-15 and install. Fix the body seals and underbody surface rust while out. Whilst I do appreciate 034 and Meyle control arm kits we get OEM bolts. All of them. Otherwise ANY job will suck. Period.

Edit- No plug, but props to all who know this type of work, and THESE guys specifically. You are a pro. https://www.youtube.com/@RedishMotorsportbmw

[Nate_Conner]

thanks for all the advise. the reason im leaning just welding the bolt is that i dont have the time or really the equipment (no lift) to remove the entire rear subframe.

I would love to pull the whole thing, replace all the bolts and bushings, sand blast and rust paint the whole thing, but I only get to work on the car on the weekends at my parents garage, and i have to drive my car to work everyday. i dont have a shop and spare car where i can have it sit for 2 weeks while i fight every nut and bolt off the car.

Here to hoping that i can atleast get the bold twisting in the threads of the press nut, and maybe ill just go with the vice grip method.

[Nizmo]

thanks for all the advise. the reason im leaning just welding the bolt is that i dont have the time or really the equipment (no lift) to remove the entire rear subframe.

I would love to pull the whole thing, replace all the bolts and bushings, sand blast and rust paint the whole thing, but I only get to work on the car on the weekends at my parents garage, and i have to drive my car to work everyday. i dont have a shop and spare car where i can have it sit for 2 weeks while i fight every nut and bolt off the car.

Here to hoping that i can atleast get the bold twisting in the threads of the press nut, and maybe ill just go with the vice grip method.

I (we) usually get them off eBay from Southern regions, as well as OEM but that is prohibitively more expensive.

Then you'll have the new to recondition. Sand/Grind Corrosion rust, weld new metal if damage, weld thru primer, Body seam sealer, paint/powder coating usually a 2 week process. Do it yourself or this could be a $20,000 proper job we do for RS4's.

[Jayz691]

I (we) usually get them off eBay from Southern regions, as well as OEM but that is prohibitively more expensive.

Then you'll have the new to recondition. Sand/Grind Corrosion rust, weld new metal if damage, weld thru primer, Body seam sealer, paint/powder coating usually a 2 week process. Do it yourself or this could be a $20,000 proper job we do for RS4's.

$20k to refurb a rear subframe??? Holy shit!!

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[Nizmo]

$20k to refurb a rear subframe??? Holy shit!!

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You'd be surprised what people will do to maintain the value of the car. In the case of RS4 usually 60K and up. Need get to all the seam sealers, primers, to bare metal. Surface rust and corrosion will be the killers for all cars. There are many companies who offer full restoration services to OEM.

The E46 RCAP procedure with restore is an easy 20k too. BMW guys have known this since E36 days. There are some very high value vehicles amongst us.

I wouldn't recommend the full bit for an auto B7, but for something special, like say the DTM's and Rs4's specifically for Audi.

[Jayz691]

Yeah, that's just insane. Just cuz someone will pay it, don't mean it's worth $20k.
But when paying for labor, shit gets expensive. Do it yourself for a small fraction of that.

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[Nizmo]

Yeah, that's just insane. Just cuz someone will pay it, don't mean it's worth $20k.
But when paying for labor, shit gets expensive. Do it yourself for a small fraction of that.

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That is in fact what most of the cost is. Sometimes we need panels from Audi, BMW, Lambo, Porsche. They do sell them. Removing spot welds is a lengthy process. In fairness Ive only ever seen maybe half-dozen full reconditions. Mostly it is piece-meal, like just a subframe and light recon what most will do. RACP on BMW is a warranty service, it's mostly paid through BMW and insurance but outside of warranty it is on you!