Rear Shock Mounts

[tcm glx]

Certainly impressive looking. That site hasn't changed much in the at least 5 or more years I've been drooling over their parts. I'm just trying to weigh cost of pre made vs. fabbed. and I can't find any prices on either of thee off the shelf rear shock mounts on the web.

Just call John and ask. A bolt in mount usually costs more than a weld in version due to it being more complicated. But paying for someones labor will always cost more than doing it yourself.

Be aware that the rear upper mount sees a lot of forces and it will break if not properly designed and gusseted. John's design is probably the most proven out there and copied often.

I can vouch for them breaking if not properly made!

[baja-chris]

My Spirit rear shock mount tore apart after a couple years. It should of been made from 4130 plate instead of mild plate. I had Complete Fabrication repair and rebuild it with 4130 plate and it's holding up fine now.

[SteveG]

My Spirit rear shock mount tore apart after a couple years. It should of been made from 4130 plate instead of mild plate. I had Complete Fabrication repair and rebuild it with 4130 plate and it's holding up fine now.

Interesting. If you have them, I would love to see pictures of where it broke.

I've said this is in other threads, but I built and broke two of my own mounts before I came across a used Autofab mount. Version 2.0 was REALLY stout and ended up in the scrap pile. I learned a lot about the kinds of forces at work back there in this process. When I was planning on building version 3.0 I was thinking about adding a triangular brace that attached to the center of he crossover tube and angled out to either frame rail. My hope was that it would eliminate any problems caused by side to side and rotational forces on the mount.

[Berne]

I've said this is in other threads, but I built and broke two of my own mounts before I came across a used Autofab mount. Version 2.0 was REALLY stout and ended up in the scrap pile. I learned a lot about the kinds of forces at work back there in this process. When I was planning on building version 3.0 I was thinking about adding a triangular brace that attached to the center of he crossover tube and angled out to either frame rail. My hope was that it would eliminate any problems caused by side to side and rotational forces on the mount.

isn't that the truth. I've developed quite a respect for shock mounts on something that really is intended to get run hard. Having seen poorly designed shock mounts "literally" break cages in half, I give alot of though to how I mount shocks on things that are going to see hard miles.
Any part of a shock mount that is setup in "bending" is eventually going to fail. Real shocks on rigs that really get driven can exert a LOT of force, and the cyclic rate can be through the roof....all of which lead to certain death via fatigue failure if not designed correctly.

Just keep that in mind.....mounting shocks the way "general use" 4x4 stuff and rock crawlers get away with will NOT last in the desert.

--B

[PaulW]

My Spirit rear shock mount tore apart after a couple years. It should of been made from 4130 plate instead of mild plate. I had Complete Fabrication repair and rebuild it with 4130 plate and it's holding up fine now.

Interesting. If you have them, I would love to see pictures of where it broke.

I've said this is in other threads, but I built and broke two of my own mounts before I came across a used Autofab mount. Version 2.0 was REALLY stout and ended up in the scrap pile. I learned a lot about the kinds of forces at work back there in this process. When I was planning on building version 3.0 I was thinking about adding a triangular brace that attached to the center of he crossover tube and angled out to either frame rail. My hope was that it would eliminate any problems caused by side to side and rotational forces on the mount.

========
Chris breaks stuff, so do I. Follow him in Baja and you will see why. Break the mounts and beef them up and don't look back. Even the Spirit front shock towers made out of 4130 have had to have cracks welded. Hard driving and 10s of thousands of whoop and washboard miles do test the parts.
Don't worry about these issues just keep looking for cracks and get them fixed.
How about a bent 9" housing/arms. They fail when you drive like we do.
Drive hard in Baja and expect maint issues.
Stock parts fail as well. Like hoods fallloff, ttb beams crack, fenders crack & craze. Enjoy the Bronco and dirve hard and fix as required.
Paul W

[yikes]

Enjoy the Bronco and drive hard and fix as required.
Paul W

I really like your thinking Paul.

One thing I always think about is the fact that springs and shocks are trying to resist 4000+lbs of dead weight. Add inertia and all kinds of other forces to that and wow! It's crazy what we put our equipment through. I'm truly amazed at the abuse some of the minimalist, well engineered fab work out there can take. I often overbuild to compensate for my weee brain. When in doubt, I add some metal. Haha!

[philofab]

Enjoy the Bronco and drive hard and fix as required.
Paul W

I really like your thinking Paul.

One thing I always think about is the fact that springs and shocks are trying to resist 4000+lbs of dead weight. Add inertia and all kinds of other forces to that and wow! It's crazy what we put our equipment through. I'm truly amazed at the abuse some of the minimalist, well engineered fab work out there can take. I often overbuild to compensate for my weee brain. When in doubt, I add some metal. Haha!

I'm always amazed when I see .065 tabs for 2.5 shocks! I worry about .120 tabs.

[shockseals.com]

I'm always amazed when I see .065 tabs for 2.5 shocks! I worry about .120 tabs.

So long as they are chromoly and the shock doesnt bottom out on itself...they should hold all day long. I would use a boss on the hole though.

Most broken shockmounts regardless of vehicle model I have seen are due to shocks bottoming on themselves.

[johncharlesb]

If building rear mounts with dom mild steel what tubing size and thickness should one use for a bronco? I know it depends on the design, but what pile of steel do you start building out of? I was planning on using .120 1 1/2" for shock mounts and gusseting. Is 1 1/2" sufficient or should one jump up to 2"? This would suppose a 14" or so and a 2.5" shock on a mild prerunner.

[Polarcub]

Mine was made out of 1 3/4 .120 mild steel. The cross member goes through the frame and plated. All welded no bolts Held up well for me now the mounts are my limiting stap points haha. I would think that 1 1/2 would be fine as long as its gusseted etc. I am sure someone else will cime in that would know better than me though.

[philofab]

Mine is 1 1/2 .120 mild steel with 1 1/4 .120 mild steel sleeved inside it. Tabs are .375 for shocks and plates going to the frame are .250 mild. I put a hole in the plates on the side of the frame and actually slid the tube through it and then welded both sides. Much like how Autofab and Perry's does it.

[gunit]

[Hard driving and 10s of thousands of whoop and washboard miles do test the parts. Don't worry about these issues just keep looking for cracks and get them fixed. How about a bent 9" housing/arms. They fail when you drive like we do. Drive hard in Baja and expect maint issues.
Stock parts fail as well. Like hoods fallloff, ttb beams crack, fenders crack & craze. Enjoy the Bronco and dirve hard and fix as required.
Paul W

Paul,
You are exactly right : "Enjoy the Bronco and dirve hard and fix as required"

I live by this motto as well.

[PaulW]

Not shock mounts but my rig is getting more fixes - repairs. I will report after they are done this summer. No way will I giveup on the thing, it just gets better ever time.

I love my Bronco.
PW
Yup, drive hard, enjoy and fix as required