HP52TA

iTrader: (4)

Purchased a BMR k-member for my LS1 swap and went to install my Spohn A-arms and it is a no go. Arms install fine, but when you rotate the arm up, the Spohn cross brace hits the BMR k-member. Here are some pics of the issue.





Seems there is a reason why the BMR A-arms have there cross brace on an angle.

Anyone else run into this problem? If so how did you solve it, short of buying the BMR a-arms? The other kicker is the BMR arms are $50 more than the Spohn arms, I am assuming for the additional bump stop.

I am thinking of cutting the section out that has been marked with black pen, but am really havng a hard time cutting into a brand new k-member.



I would hate to cut into the k-member and then find the arm hitting in another location.

Anyone in need of a set of coilover A-arms, call me and put me out of my misery

thewizard

iTrader: (43)

I had a similar problem and ended up getting the interfering bar chopped out of the arms and a X configuration welded in. Not sure what brand they were; sold that stuff last year.

My issue was a little more serious than what you have pictured. I don't see anything wrong with cutting out that little section you marked off.

quickkris2006

iTrader: (2)

yea this has been brought up a few times about the spohn and bmr issue.. i would just cut it out.. or cant u just return the a arms? and get the bmr ones?

UnderCover89TBI

iTrader: (25)

I'd cut it and not fret. The nice thing about workign with metal is that you can add and remove as logn as you have a cutting tool and a welder!

TraviZ

iTrader: (2)

cut it and paint it!

gregsz-28

iTrader: (1)

Cut it.
Good to know, because I have a BMR k-member and I was going to get Spohn A-arms, since BMR doesn't offer theirs with rod ends.

//<86TA>\\

iTrader: (14)

to me, it looks like if you cut that mounting ear, you will loose a bit of strength in the mounting point. Im no engineer, but i dont like it.

UnderCover89TBI

iTrader: (25)

you could. I would cut out another piece of metal to the same shape and weld that in place to support that piece more. So basically it would be thicker.

HP52TA

iTrader: (4)

I was using the Spohn A arms with my stock k-member before I decided to go LS1, so there are no returns happening on the A arms. I was first thinking of modifying the A arm itself, but it would be a lot more work and probably look like ....

There is a lot of meat to the k-member mount in this area and I am thinking I can do a real clean job with a hole saw. I'll scope it out this weekend.

I don't think it is too big a deal to cut out sufficient room, just hate to cut into a brand new k-member. Going to go sharpen up that hole saw...

Tony89GTA

iTrader: (7)

You sure that little chunk is enough to give you the up travel your going to need? To me it looks like you might need to cut little more out then what you have showing.

HP52TA

iTrader: (4)

Well ... I went for it.

With the Spohn arm having the cross brace closer to the pivot point and being a true A arm, I feel this is the stronger of the two A-Arm designs. When shopping for the K-member, I felt the BMR was a stronger design, thus my predicament. Somewhere in my excitment to purchase, I missed the warning on the BMR website that you MUST use their arms with their k-member ... so no fault of BMR's...

As both the BMR and Spohn A-Arms extend straight out from the bushing area wth no arc in either design, the only major difference is the location of the supporting cross brace, being the major area of my concern and the point of contact.

Here are some pics for comparison.

BMR A-Arm

Spohn A-Arm


Before any cutting, I carefully measured out the radius and arc of travel of the Spohn A-Arm brace and plotted it on the bracket. The horizontal line with the "C" indicates the center of arm location when in the fully up position, with the upper horizontal line taking into account half of the 1 1/4" tubing thickness.

The other "C" being the center of the braces arc during travel.



Here is another pic showing the supporting structure around the BMR k-member rear pivot connection point.



At this point it was now decision time. My thought was with the Spohn A-Arm brace closer to the pivot location it would require less support from the k-member at the rear pivot point, than the BMR arm, due to the BMR arm's angled support brace leaving the rear half of the arm more flexable, requiring more support from the k-member itself than the Spohn arm, due to its true A-Arm design. That was my justification to move forward.

Out came the 1 3/4" hole saw. As I would be drilling at a slight angle, I first drilled a pilot hole to ensure that when I got to the hole saw its 1/4" drill bit would not run astray.



After cutting out the area, I used my Dremel tool to smooth out the cut, to prevent any possibility of cracks coming from the area. A little touch up primer and torch red paint and it was done.



Here are a few of the arm in the fully up position. As mentioned both arms are built straight out fom the bushing so with the modification, I now have the full travel with the Spohn arm as I would have had with the BMR arm. Full travel was checked and all is fine.





I will keep an eye on it and if any cracks occur, I will just add another supporting plate.

matthufham

iTrader: (5)

Looks good now. I don't think you'll have any problems.

BlueZee28

iTrader: (30)

How can you be sure you had it at the most upward position without it being on the ground, driving over bumps? The force of hitting a bump in the road is what's going to let you know if you cut enough off or not. I don't see how you can (easily) get the a-arm to pivot upwards all the way if you've got the coil-overs set up how you want them.

HP52TA

iTrader: (4)

As I mentioned, the BMR and Spohn arms both are straight from the bushing pivot location to the ball joint, without any arc to the A-Arm horizontal design. That is why the contact point in the original picture was my only area of concern.

The Spohn A-arm can now be raised up until the arm itself hits the K-member in the same location it would if a BMR arm was installed. (See second last picture above, above the rear pivot location. This is the same contact point the BMR arm would make at full up travel.)

I also confirmed full travel by installing my strut without spring and bottomed out the front suspension. All is good.

mmadden55

How much better than stock does it handle?