Rear Subframe Question

[Ohmess]

So, I purchased this subframe in the hopes of dialing in a little bit of negative camber using the eccentric bolt and washer that you can see inserted here:

When I looked at this subframe side by side with the one I just removed from my car, however, it appears that the outer mounting points for the trailing arms are higher on my old subframe than they are on my new subframe. (I am unsure where the original inner mounting points on the new subframe may have been because they have been modified to accommodate the camber adjustment). This change in the outer mounting point would appear to cut against what I am trying to accomplish.

Here is a picture of my existing subframe (and yes Peter -- that is yet another TX mud wasp nest on the top of my differential. I thought I had gotten rid of all of them):

Short of installing the new subframe and seeing what my rear suspension geometry may look like, does anyone have any suggestions?

 

[Peter Coomaraswamy]

Chris,

Any way to snap a picture for comparison??

An alternative would to be; clean the one you have and put in the adjusting plates- at least you will know what you are dealing with. Also, just a suggestion that this may be a good time to reinforce the rear shock towers- Texas mud wasps have been known to cause significant weakening of that area

 

[rsporsche]

in looking at the photos of the two, it looks like the outer mounts were turned upside down on the new subframe in relation to the old one. one thought - lay both of the subframes on the floor (flat) and measure the distance to the bolt holes ... and determine what the difference is. is it consistent from internal mount to external mount ... and what is the difference between the two units. just curious

 

[Ohmess]

Thanks guys -- will try to do the measurement after I remove the dif. Here are more pictures of the comparison. The trailing arms fit into the new subframe.

 

[Ohmess]

So, assuming I can get caster to spec and a little more negative camber than stock with the new subframe, the question remains...

How will moving the forward mounting points of the trailing arms downward by about an inch effect my car's behavior?

 

[rsporsche]

it looks like the holes in the inner brackets have been elongated ... so perhaps this was done to ensure that the mounting points are at the same height.

 

[Ohmess]

Scott -- thanks for your reply. Yes, the inner mount has an elongated opening which enables the camber adjustment.

There is a washer welded off center to a bolt which you can see in the first picture I posted. The threaded end of the eccentric bolt is flattened into a D shape, and that end inserts into a washer with a D shaped hole so as to equalize the eccentricity of both washers relative to the center line of the bolt. The bolt is installed into a U shaped channel welded to the mounting ears at a 90 degree angle from the elongated opening. As you rotate the head of the bolt, the washer moves within the channel so that the body of the bolt moves up and down within the opening. This raises or lowers the inner mounting point of the trailing arm, changing rear camber.

This setup is similar to the rear camber adjustment on my e39 (bolt 15 and washer 16 move within a channel on the body of the e39):

 

[Sven]

Chris,

It looks like the newer subframe bolt locations are also farther aft of the main cross frame. Or is this just an illusion? If so, it would shift the wheel position back as well so it would no longer be centered in the wheel well. Is this an e9 subframe?

 

[bdigel]

I suspect the modded subframe is from something other than an E9 , maybe an e12 ?? Another issue ( at least to me ) is if your going to change camber I would also want to fix the toe , most of the time when you change camber it will affect toe . most of time people also make the toe ADJ .

 

[Ohmess]

Damn Sven -- Good eye. The outer mounts are 5 mm farther from the subframe as well as being about 25 mm lower. I had been thinking the 25 mm lower was not a deal killer, but now I have concluded installing this subframe would not be a good idea.

Brendan -- Thanks for jumping in. Thoughts on how to accomplish both toe and camber adjustments? Ireland engineering stuff perhaps?

I wish I had started this thread before I had the subframe powder coated.

 

[bdigel]

Damn Sven -- Good eye. The outer mounts are 5 mm farther from the subframe as well as being about 25 mm lower. I had been thinking the 25 mm lower was not a deal killer, but now I have concluded installing this subframe would not be a good idea.

Brendan -- Thanks for jumping in. Thoughts on how to accomplish both toe and camber adjustments? Ireland engineering stuff perhaps?

I wish I had started this thread before I had the subframe powder coated.

You put the same set up you have on the inner pickup point on the outer except you make the slots 180 from the inner ones that are for the camber. Email me Ill try and get some pics of one of my cars

 

[Peter Coomaraswamy]

"You put the same set up you have on the inner pickup point on the outer except you make the slots 180 from the inner ones that are for the camber. Email me Ill try and get some pics of one of my cars" Absolutely!!

Chris, I think the elongation is not right, I think the camber is adjusted on the outside and the toe using the inside but I could have that wrong or it may not make a difference. You could check the Ireland Engineering site, they should have pictures of the mods I made to my sub-frame with their adjusters, or possibly some better shots. And don't worry about wasting money on the powder coat, any job worth doing is worth doing at least twice

 

[Ohmess]

Yes Peter -- I would surely have been fired by now if I were doing this for a living.

Camber is inside according to the Ireland Engineering Web site. If you happen to be in the neighborhood with your welding gear, let me know.

 

[paul cain]

Ohmess,
Thanks. I read your prior post. The powdercoated subframe was definitely out of an E3? It looks like an E12 subframe. I have not spent that much time under E3, but I will definitely get images of the subframes that we have for sale at the shop. Thanks for this follow up, Paul

 

[Ohmess]

Hi Paul - I bought the subframe from Al Taylor (Bavman here), and Al told me it was from an e3. Then again, he also told me it would fit an e9, but when it didn't he bought it back.

Al funds his racing selling BMW parts, so he's usually pretty good. I bought my five speed, shift platform, e12 flywheel and a handful of other things from him. But with Brendan and now you thinking this was an e12 part, maybe that was the problem.

 

[Markos]

Hi Paul - I bought the subframe from Al Taylor (Bavman here), and Al told me it was from an e3. Then again, he also told me it would fit an e9, but when it didn't he bought it back.

Al funds his racing selling BMW parts, so he's usually pretty good. I bought my five speed, shift platform, e12 flywheel and a handful of other things from him. But with Brendan and now you thinking this was an e12 part, maybe that was the problem.

Aren’t the e3 and e12 subframes quite similar? The e3 has a more modern (better) suspension than the e9. It didn’t fit under the e9, which was based on the existing 2000CS.

E3 rear suspension. Note the spring location:

 

[paul cain]

Reposting my reply under the correct topic name:
Jan. 27 2022

OK, I was clearly wrong.

I currently have 2 CS rear subframes. The one in Patricia Mayer's car and the shiny black one that is center image on slide 2. Both are identical.

It is very clear that Bavaria (E3) rear subframes are noticeably different. The easiest way to note the difference is the outer mounting point. On the CS the bolt center line is roughly in the very center of the entire subframe arm. On the E3's it is sunken noticeably lower to the lower edge. Slide two and three show these differences. See also BMW's part no. differences including the E12, that I shot my mouth off earlier -slide 1. That's like the 17th time this week I've been wrong . Apologies to Ohmess and the great Al Taylor for being spot on!

A tip of the chapeau to @Mike Pelly who just provided the clearest image of these differences. Note both the inner and outer bolt hole center lines. Thanks Mike!


Back to answering the original question and concern:

We have (1) E9 subframe for sale and (1) E3 subframe for sale this Saturday.

Attachments​

 

[Markos]

Thanks for clarifying. If you don’t find a buyer, I believe that the place that does the welded camber adjustments will buy it as a core.

 

[Ohmess]

No worries Paul - just trying to help those poor orphan parts find a good home.

Markos - Road Race Technologies (RRT) does race prep and custom work outside DC near Dulles Airport. They did this as a one-off for me. Unlikely they are interested in cores.

 

[Markos]

No worries Paul - just trying to help those poor orphan parts find a good home.

Markos - Road Race Technologies (RRT) does race prep and custom work outside DC near Dulles Airport. They did this as a one-off for me. Unlikely they are interested in cores.

I am referring to garagetastic. This should also inform sellers on the value of a rear subframe.

E9 and E10 Adjustable Rear Subframe Conversion - 2002, CSL

E9 AND E10 ADJUSTABLE REAR SUBFRAME EXCHANGE PROGRAM The stock E9/E10 rear subframes does not allow you to align the rear wheels. This problem carried onto future subframes like the E28 and the E30. Alignment is a critical point in how your car handles and wears tires. Especially important in...

www.garagistic.com