Broken Shock Mounts

[red57]

Steve,

I'm curious why you treated the left & right brackets differently? Seems like they would have the same weight load, same spring rate, and same shock resistance, so the same deflection loads?

Did you find that the left one didn't need the stop bolt, so went with a simpler gusset? Or were both gussets added after your first trial - one with the stop bolt and one without? Inquiring minds want to know.

I expect your shocks are too short, but if you have any more length, you might want to make brackets like the Konis I show above, they have their own bottom plate with a 1" bar turned down at the end for the shock that extends across the bottom plate and is welded most of the way across, thereby taking advantage of clamping by both ubolts and no need for the plates to resist bending.

Dave

 

[steveg]

Steve,

I'm curious why you treated the left & right brackets differently? Seems like they would have the same weight load, same spring rate, and same shock resistance, so the same deflection loads?

Did you find that the left one didn't need the stop bolt, so went with a simpler gusset? Or were both gussets added after your first trial - one with the stop bolt and one without? Inquiring minds want to know.

I expect your shocks are too short, but if you have any more length, you might want to make brackets like the Konis I show above, they have their own bottom plate with a 1" bar turned down at the end for the shock that extends across the bottom plate and is welded most of the way across, thereby taking advantage of clamping by both ubolts and no need for the plates to resist bending.

Dave

Dave,
The stop bolt and gusset were added at the same time. The normal action of the shocks was enough to bend each mount along the axis of the u-bolt holes. I spotted this right away as soon as I'd taken my first drive. In the bottom pic you can see a slight bend at the front where my knockoff hammer didn't get it quite flat.

I'm curious how the right side Koni setup interfaces with the e-brake mechanism. The mounting stud must be longer and beefy enough not to bend under load.

--Rt side: the stop bolt was an easy fix and with the e-brake linkage, there's no room for the gusset. I have taps/dies but no in-house welding. Stop bolt was only change necessary on right side.

--Original Cape-supplied shocks were about 1" too short, as the axle was held above the frame cushions. At the time, I didn't realize this was a fatal flaw. They'd done their development work on 4-seaters and were surprised when I later sent pix of the broken and bent lower mounts.

--Lt side: solved bending with a gusset bearing against the spring box. Later I added the ear for the Cape "uprated" panhard rod, as the original setup had broken off the Healey axle mount inside the spring box, which couldn't be fixed except by removal of the axle.

--My replacement SPAX shocks aren't long enough to reach below per the Koni lowers. The distance of the outreach of the bolts is necessary due to the placement of the Cape upper mounts and the e-brake mechanism on the right.

These are my iterated Mk I mounts which are not exactly like my drawings above. The drawings are my idea of the easiest setup for a Mk II version.

 

[red57]

Thanks Steve, Makes sense now, I wasn't considering the extra stud length for the offset shock on the right side - it does require quite a bit linger stud on that side.

Interesting to hear the shocks were too short for you. I had no idea the body work was different in height for the BN6 & 7 ...I knew it was different as far as spare tire & boot but just never considered the height where the shocks mount would be different.

The Koni kit did have a longer 1" round bar lower mount to set the shock an inch or two inboard on the right side compared to the left side to clear the stock ebrake cable. I did not like the asymmetrical aspect of the different distances from the car centerline so I shortened the right shock mount to match the left side and then mounted the shock top brackets as required (the Koni are independent and not a long angle iron like your Cape set).

I made a small bracket and moved the ebrake cable mount as shown and reversed the direction the bell-crank turns - a bit weird but it works fine (bell-crank ended up near the same point but the mount and cable are moved inboard). You can also see how stable and solid the bottom mounts are (I think they are similar to the Putzke lower mounts). When you have time you might search out a longer shock and copy the Koni bottom mounts.


Dave

 

[steveg]

Dave,
My setup, using the stock e-brake position including increased brake leverage, providing for the new panhard mount and using my existing externally-adjustable SPAX shocks - works well. I've solved all my issues and been running like this since 2014.

How much heavier is it than yours? Probably a bit, given the weight of the bottom plate has to be included.

When I get my car back from the body shop (another story), I'll weigh the mounts including the lower spring plates so we can compare. When they're out I can probably drill some lightening holes.