You can probably bolt everything together for an easier assembly, but use alignment pins if possible so there is no guesswork for the geometry. However many bolts are used to hold the OE strut bushing to the top of the anchorage will be a good starting point for how much bolt strength you will need (although the KW’s not being pressurized like the OE shocks will lessen the load on these parts).
I like this idea. I had thought about it before but didn’t know if it would be cheaper/simpler to weld everything. I spent a ton of time today in Fusion editing the part so that it could be assembled without welding.
Here’s what I came up with. It may end up being more expensive to do all that machining work just so that I don’t have to weld everything together. The benefit is that if any subcomponent has to be swapped out for any reason, like if I want to change the angle of the spring seat or if I want to make a set that’s compatible with BC coilovers or some custom shock, then I can just machine that subcomponent and swap it out.
First off, I ended up realizing that I had missing some clearancing on the top face of the mid plate. There seating surface on the car isn’t totally flat as there some sheet metal welded in a seciton that I had overlooked.
Also, I ended up splitting the upper section into two parts.
From the top to the bottom:
KW Strut Mount
Upper Section
Mid Plate
Lower Section
How everything’s bolted together:
The oem Volvo upper strut mount to anchorage is secured by three 8.8 grade M8x25mm long flanged hex head capscrews. The thread engagement is about 17-18mm. With that PDV upper strut mount, there’s only 15mm of thread engagement and it works fine. I ended up with about 15mm of thread engagement on all the fasteners in my design and used four instead of 3 to hold the “stack” together.
KW strut mount is bolted to Upper section using four 12.9 grade m8x1.25 30mm long socket head capsrews that are zinc aluminum coated: McMaster-Carr
– Didn’t use flanged hex head capscrews like oem because the flange is unecessarily wide (can’t make the whole upper section wider because of clearance issues with the chassis hole.)
– Didn’t bother with a pin, the bores through the KW Strut Mount are 8mm so the clearance around the bolts is very very minimal which should keep it aligned.
– The threaded holes are 10mm longer than the fastener needs so that they can just be tapped with a regular tap and not a bottom tap, little thing that may keep cost down.
The lower section, mid plate and upper section are bolted together using four of the same type of SHCS as above but they are 40mm long. McMaster-Carr
– I liked the idea of using the 12.9 grade aluminum-zinc coated SHCS and 40mm was as long as M8s came so I had to deepen the bore in the Lower Section on two of the four bolts so that there would be good thread engagement.
– The heads of the SHCS are recessed below the spring seating surface.
The “countersink” diameter is 14.25mm for a 13mm diameter headed SHCS as per this random chart I found: https://rorty.net/wp-content/uploads/2020/08/holes_and_counterbores.pdf
I used only one dowel pin for alignment of the lower section -> midplate -> upper section stack. Maybe I need to add a second? I am using an aluminum pin to avoid any corrosion that would occur with a steel pin as the part will be aluminum. (Also, doesn’t make much sense to have your dowel pin be harder than the material around it.) I could only find the aluminum dowels in standard sizes so it’s a 1/4″ x 1″ long pin: McMaster-Carr
All the fasteners are oriented so that they are perpendicular to the spring seating surface instead of the midplate plane. Figured this just made more sense.
A lot of boring details, let me know if any of you guys have any thoughts. Hoping all this extra machining work doesn’t make them even more impracitcally expensive haha.