Horn Pin Holder and Shock Tower Reinforcements

[halboyles]

We're in between traveling to Mid-America '02 Fest (simply the best vintage BMW event in the US!) and The Vintage next week, but I wanted to introduce a couple of parts I've been working on. (We'll be driving the '74 Mintgrün to The Vintage with the tent for the 2002 Forever Chapter so please drop by and say hello.)
As many folks have discovered when they removed the steering wheel and did any work in that area, the horn pin holder self destructs if even gently touched. So I designed a much more robust holder that uses a commonly available horn pin and can be 3D printed. I'll probably just give the stl file to anyone with a 3D printer, but could also sell the complete unit if someone needs it.
The other part is a rear shock tower reinforcement that is based on the original design by Steve Hose (@Stevehose). I've added a few refinements and have had a CNC pro who was mentioned in the thread below make the first pair for testing.

Great CNC Resource

I’ve undertaken a Wilwood front brake project on my e-type. The custom caliper brackets are the first thing that requires some work and I had to find a CNC shop to make them. Many shops wanted a lot and lead times were crazy but through some vintage race buddies I found a great CNC shop owned...

e9coupe.com

I don't have time to say much more right now but will keep everyone updated this summer.
Stay well,
Hal

 

[TRIPPFONTAINE]

Nice work. I'd be interested in the rear shock reinforcements... please post when you've any updates tx

 

[teahead]

Ditto

 

[boonies]

Same

 

[HonaloochieBoogie]

I’m interested as well. Thanks!

 

[eriknetherlands]

Are these the ones?
If so then i have 4, they are identical to the part on my column. I don't need em...

 

[halboyles]

I could use a couple as models as my original was in a thousand pieces so I couldn't measure the dimensions.

 

[Bmachine]

I really like your rear shock reinforcements. The outer thickness seems fairly thick but maybe that is ok. Have you done a test fit of a bilstein in it?

 

[halboyles]

Have you done a test fit of a bilstein in it?

I won't have any time to play with either new part until after Vintage, but will do due diligence this summer.

 

[bavbob]

Erik obviously uses his horn a lot.

 

[Oldbmwcoupes]

Erik obviously uses his horn a lot.

Too funny,

I’ll stop by and meet you at the Vintage. I’m very excited as it’s the first event I’ll be attending in two years. Not due to covid, just galactically bad timing with other events and work. That despite well advanced planning. I look forward to meeting many other “coupe groupers” there, despite the fact that I won’t be in one of my e9s. Look for me in the barely legal white e28 race car

 

[kongsfam]

Hal and Steve,

I have followed the discussion on rear shock tower reinforcement and feel it is the best solution available to me now.
I have a 72 3.0CS that I have owned since the mid 1980's and it had shock tower tearing that was repaired with some minor welding by
the previous owner.
Following the coupe registry advice in the late 80's(no online forum at that time), I did the "washer sandwich" reinforcement which seems to have
prevented any further deterioration of the shock towers.
Fast forward to 2022, I decided to start restoration of my coupe and drove down from Portland to Alameda and Don Lawrence's shop. The car has
been stripped and is currently at the painters. Now is the best time to address the towers, the stars seemed to all align with this forum thread,
the coupe being in the bay area, hitting the link in your thread, and finding out that Intellectioncnc is in SF, so I sent an email to Andrew today to
inquire about availability.
I will be in SF this coming Friday to visit family and visit Don and the coupe. I also offered to visit with Andrew.
Thanks for your time and effort.

Bill

 

[halboyles]

I am glad that it all came together at the right time Bill. Please update us with pics as the installation is in progress.
Hal

 

[kongsfam]

Hal

Andrew emailed back and asked if all shock towers are identical which I responded that I assumed they are as I have not read anything to the contrary. He also asked if the first set has been test fit and any feedback as to fit/installation. I think he is being cautious, as he produced the part from supplied specs and didn't personally measure any dimensions himself. If you have any fit information, please forward to me/him. I told him I will take accurate measurements of my towers this Friday and I will compare with the measurements/pictures that forum members have provided and proceed from there.
Thanks

Bill

 

[halboyles]

I haven't personally fitted the support but the original design with the same dimensions was created by Steve Hose and he has them installed on his coupe.

 

[Markos]

Hal

Andrew emailed back and asked if all shock towers are identical which I responded that I assumed they are as I have not read anything to the contrary. He also asked if the first set has been test fit and any feedback as to fit/installation. I think he is being cautious, as he produced the part from supplied specs and didn't personally measure any dimensions himself. If you have any fit information, please forward to me/him. I told him I will take accurate measurements of my towers this Friday and I will compare with the measurements/pictures that forum members have provided and proceed from there.
Thanks

Bill

I have a shock tower that I saved and lended to @mark99.

Mark - can you ship it to Andrew? I can provide the address.

 

[kongsfam]

Hal

Want to verify that Andrew has the dimensions that you stated in reply #187 of the "Heartbreak-broken rear shock mount" thread
which states a width of 99 mm, not the profile drawn by Bmachine reply #192 with a width of 98 mm.
Steve's final width was 98 mm (reply #103), but stated a 98.5 mm width may be a more snug fit (reply #105)
Thanks

Bill

 

[eriknetherlands]

Given the dimensions above, I would opt to have a part made to the smaller dimension; that way you are (most) sure it fits, plus as it is welded in anyway, having a 0,5 or 1mm smaller diameter isn't that important.

 

[Bmachine]

I posted the accurate dimensions (of mine at least) in the main thread. Post #302

https://e9coupe.com/forum/threads/heartbreak-broken-rear-shock-mount.18208/page-16

 

[kongsfam]

Thanks again Hal and Steve for starting this thread, here is an update on my progress to date:
First pic is my sandwich repair, with bottom and top washers the total thickness is around 10mm and my bilsteins had plenty of thread length to clamp down onrubber bushings. This repair was done in 1988, about 40,000 miles ago.
Second and third pics show the current condition of the towers

I measured the diameter of the tower in 5mm increments from 15mm to 35mm. I had difficulty getting a consistent reading at 15mm because of the high rate of taper at that particular point. It is a consistent rate of change from 20mm to 35mm. So, I decided to design the replacement removing the top 20mm of the shock tower, not the 15mm in the previous versions

When I was measuring the towers the welder stopped by and we discussed the design. His recommendation was to reduce the thickness of the reinforcement to help alleviate the heat sink effect when welding different thickness metals.
I then contacted Andrew at intellectioncnc.com and he sent me the dimentional drawings.
I increased the overall diameter to match my tower measurements at 20mm below the top
The lip was moved from 15mm from the top to 20mm from the top
I increased the thickness at the shock hole from 3.75mm to 5mm. A stock bushing (E9 and E12) still will fit. This strengthens the historical weak point.
I reduced the wall thickness from 10mm to 5mm

I received the finished product from Andrew and just test fitted this week. It is solid and hefty, the outside diameter inserted into the shock tower is 99.15mm (was shooting for 99.0). The inside diameter of the shock tower at 20mm is 99.93mm. It is a snug fit and will bind if not centered, but once seated there is play, so the welders should be happy.