Technical I need shock mount ideas - FINISHED PRODUCT

I am relocating the front shocks on this frame and have a couple ideas in mind for the lower shock mounts and would be interested in others ideas. For the top mount I will use a couple tabs similar to what I have shown. For the bottom I could drill the axle and use a bolt ( not my favorite idea ) would some type of plate bolted on with the u-bolts work ? would welding a threaded bung to the axle be a good plan ? would you weld a bung or tube on the bottom of the axle ? any thoughts would be great.

 

I would go bolted not welded, ( reason: different metals and people’s welding ability etc).
Or this type of thing......
https://www.roadstersupply.com/Universal-Shock-Mounting-Studs-p/soc-62004.htm

 

I'd suggest that you avoid drilling the axle if there is another option.
I also think looking at how some pickups with solid axles mount the shocks may give you an idea that is tried and proven.
I am assuming the axle will have some horizontal movement which may influence how you mount your brackets.

 

Been a few years since I owned this and don't have good pics, but it looks like mine had a stud welded. (built before me) Maybe make a plate with a hole or stud to attach with the u-bolts

 

Functional, strong and neat is good. I know your setup is overslung, but the general idea would work with some thought. Good if the bracket can pick up all four u-bolt points.
Not a super important part of suspension setup as a failure will only be shock related. The spring will support the car. Still, better to over-engineer in my opinion.

 

It's a forged axle so why not weld a mounting tab to it ? My axle on my avatar was too wide so I cut it in two and took 6 1/4 inches out of it and welded it back together . I also drilled 8 holes in it with no issues so don't overthink it.

 

I like grumpy65s idea. Or? How about a smaller version of a steel plate with a drilled, angled tab for the lower shock mount that is sandwiched between the axle and the spring? Chassis Engineering and others sold plates like that in their kits to convert buggy sprung cars in the rear to leaf springs. I had one of their kits on my 37 Fordor sedan. You might need longer U-bolts. Sorry no pix.

 

Any plate between the axle pad and spring pack will raise the ride height by the thickness of said plate (in the case of overslung as shown in @TA DAD 's pics). The idea is good but any plate/bracket would need to attach to the bottom end of the u-bolts if a change in ride height is undesirable. The principle of a "wrap around" plate under the axle and attached to all four u-bolt ends would work. I would imagine that attaching only to the front two bolt ends would be more than adequate if the plate/bracket assembly was suitably manufactured. Once again, it is a shock mount. It is not carrying the vehicle mass. That is the spring's gig.

 

Grumpy, I like that idea, my concerns with the plate were the longer bolts and having all hanging under the axle. Not necessarily a problem but I don't like the way it would look. The trouble with a stud through the axle would be that it would have to be long enough to get out past the top of the axle and now you have a long lever that will bend easier than a standard shock mount will. Plus I can build those myself. I made these rears in the photo out of 3/8 plate , I am with you on over building.

 

One other thing gnichols mentioned longer u-bolts. I have not came across a source for those. The only ones I have seen that are square have been for trailers. And I might not need them with grumpy' idea.

 

Just use the front portions of the plates tucked under the axle pad and bolted using the front u-bolt lower sections. Make sure the "pins" are out far enough forward so the shock clears the axle. Can't see it in the pic, but use a strengthening gusset behind the pins under the plate. If the plate is shaped to match the axle pad, it should match in quite well.

 

If the plate was 1/4" it looks like you would have enough thread on the u-bolts.

 

My first attempt will be to use all four mounting points. If not the two front ones may work. I like your idea of wrapping the axle and catching all four bolts the best.

 

The only problem with this approach is you are "modifying" the axle. Not so easy to reverse the process if there is a change of plan at any stage.

 

While this would be the strongest option, it may be a challenge to design/produce something that is able to slip over the axle from underneath and pick up the u-bolt tails. On closer inspection of your pics, it seems that the bottom spread of the axle may be close to the same dimension as the front to rear hole centers. I am flying blind here. Would help to have the axle to measure up, so will leave that in your court.

I still think using just the two front u-bolt tails would do the job, and maybe look more streamlined and unobtrusive. The "pin" could be in front of the axle at the height shown in the second picture in your original post. If done this way, nothing hangs below the axle. All neat and tidy.

 

@TA DAD
See added bit on my last post.

 

grumpy, I was thinking the same thing about the bracket fitting over the axle after your idea got my brain running so it might have to be two bolts. I will update as I move along. But I am slow now days !

 

Please do. I am interested in the outcome, and I am sure this will be helpful to others.
I will be watching this thread. Post pics as you go please.

 

Should be simple to build. F100's used these..



Mid fifty sells these...

 

Another version. These are rears, but you get the idea...

https://www.classicparts.com/1947-5...MI5YWXxMTA6wIVEQnnCh0bDwttEAQYASABEgIH-fD_BwE

 

Looking at the photos don’t you need to move the shock out at the bottom? I have always angled my shocks.

 

"Vertically mounted shocks will control suspension movement, but on a street rod, most shock manufacturers recommend mounting shocks at a slight angle (viewed from the front or rear). This increases handling by limiting side to side movement, which will decrease body roll during cornering. On most street rod applications a mounted angle of 15-25 degrees is preferable for great handling." [Speedway Motors]



The info above relates to coilovers, so includes the action of the coil springs as well as the shocks. I am not sure if angling just the shock is as important, but I am guessing that it is, considering that most vehicle manufacturers do it. If it were me, I would try for 15 to 25 degrees off vertical.

Another method is to imagine an arc described from the middle of the contact patch of the opposite side tire. Both the top and bottom shock or coilover mount points should fall on this arc. If one point (top or bottom) is in a set position, try and get the other one as close as possible.

 

RE the shock mounting, IMHO the angle doesn't have anything to do with keeping the suspension in place on corners. Your rear suspension should already do that - Watts links, Panhard bars, wishbones, 4 links, etc. But I do see how mounting them along the natural arcs where the axle would travel would greatly decrease any potential binding. It is also used in "packaging" stuff on the chassis, leaning them in or forward or back a little. When a shock is not mounted vertically, it looses effectiveness - more and more as it is leaned over. There are published charts that show that. Heck, Ford trucks even have them on opposite sides fo the rear axle to help control axle wrap from torque. But it looks too funny to use on a hot rod, eh?

 

The more vertical the shock is the stiffer it is. When I built my rear crossmember I put two mounting positions. One at 20 degrees and one at 35. I have a 87 Dodge D250 and the factory mounting has those at a 43 degree angle. My main concern will be going in a straight line. On my front ones the drivers side is limited due to the steering linkage.

 

This is technically a correct statement.

What angled mounting does is more related to the arc principle (last picture).
Your prefered axle mounting system (4 link, panhard bar and coilovers for example) should limit side to side movement and define your roll center. This is the point the body/chassis rolls in relation to the axle (body roll). An angled coilover/shock that is "on the arc" is working in line with the axle movement relative to the chassis, yet will be at an angle in relation to the horizontal chassis/ground level. The angle helps to work against body roll, not sideways axle movement.

I know, clear as mud, right? I hope the info I am giving is right and not too confusing.
Happy to be corrected if needed. There are a lot of guys on here with a lot more of an understanding of this than I.

 

I see the arc discussion with independent suspension. I'm not sure it applies to the parallel leaf springs on this rod?

Phil

 

Not sure about your U bolt size or spacing, but factory Chevy pickups in the 1950's used a plate with a shock stud sandwiched to two of the U bolts. Simple, and effective, and I don't think they look bad. I used them on my '39 Chevy coupe.

 

This is true if the axle movement is also vertical, as in both wheels bouncing upwards at the same time (speed hump, front on at speed). In real world driving, often it is one side or the other that is in motion, therefore pivoting the axle on the "arc" in relation to the chassis. If the mounts were on the arc, this situation would give "stiffest" operation during one wheel jounce.

I think it is a bit of a compromise between two wheel jounce and one wheel jounce. Mounting on the arc would seem to give the best reaction against body roll. Once the angle is worked out, do the compensation to vertical to determine spring rate to carry vehicle mass. Chart attached.

 

Thats the ones !!!!

 

You may be right.
Just curious Phil, would you mount shocks at an angle with parallel leaf springs or not?
It may not help, but it can't hurt.

More to the point, moving the bottom mount outwards puts it closer to the wheel. This definately is an advantage.