Limit Straps Inside Front Coils?

[Ol'Blue]

Looking for a good place to install some limit straps and inside the coil looks like a good option. Making a mounting tab for the coil cup bolts would be easy, its the upper mount that would be tricky. Was thinking of running a clevis bolt through the upper coil mount tab.

I have Duff long arms, 3.5" coil and 1" BL, heavy duty coil cups

Has anyone done this and have comments or pics?



Thanks!

 

[bronconut73]

I have seen folks do a limit strap towards the middle of the axle. That why your axle can still articulate. But sometimes it's not enough. Something to consider though.

 

[Ol'Blue]

I have seen folks do a limit strap towards the middle of the axle. That why your axle can still articulate. But sometimes it's not enough. Something to consider though.

I'm looking to save my shocks and towers so I think mounting straps at the outer axle would be best.

My shock mount tore my frame open. Shock looks to be okay.

 

[DirtDonk]

Are you sure over-extending was the cause of that? From here it does not look like there was much penetration of the weld. If that's the case, then the mount may have failed just under the stress of doing it's job. The shock itself can put a lot of force on that area.
And your shock is relatively long travel it looks like. Are you sure it even able to top out with the given wheel travel not being limited by other stuff?

What is your valving by the way? The stiffer it is, obviously the more stress the mount takes.
Got a closer shot of the frame behind the mount? If there was good penetration then likely you're on the right track with limiting straps.
The reason a center limiter is a legitimate potential solution too though, is that when articulating and coming to the end of the shock travel, it's usually not that harsh. But when jumping or otherwise hitting a high-speed whoop-de-doo that tops out the suspension, a limiter in the middle will still help.
I think you're right still that putting them out and the ends is "more" effective, but a center mount can help at least.

Good luck.

Paul

 

[garberz]

What size travel are those 7100’s. I’m thinking they’re too short and topping out. F-250 towers can be tricky. 12” short bodies end up too short, 14’ s can be too long. Also depends on how you mounted them.

Mark

 

[toddz69]

What size travel are those 7100’s. I’m thinking they’re too short and topping out. F-250 towers can be tricky. 12” short bodies end up too short, 14’ s can be too long. Also depends on how you mounted them.

Mark

X2.

Todd Z.

 

[Ol'Blue]

Thanks for the input and questions, the weld penetration was good. The frame wall tore open, maybe too much penetration.

The shocks are 12" of travel with 360/80 valving. Rides awesome. The F250 mounts are set just about 1" low of mid travel (5" up/7" drop). With everything installed and the axle hanging under it own weight, I still have about 1.5" of extension left. The coils seem to be the limiting factor as there is no driveshaft bind, the Duff Long Arms are doing their job and all the linkage appears to have room left to extend. If I stand on the axle or press down a lot, it drops another .5" or so. Its possible the damage was just from the action of the shock on the mount, but I thought since I was in there with the welder I could install limit straps to save the shocks and mount if I ever get nutz on the woops. AND definitely add some reinforcement around those shock mounts.

Attached is a close shot of the failure.

 

[gnpenning]

Interesting that was the weak link and allowing that much damage.

Did it happen all at once or progressively?

Any details on how it happened?

 

[garberz]

Thanks for the input and questions, the weld penetration was good. The frame wall tore open, maybe too much penetration.

The shocks are 12" of travel with 360/80 valving. Rides awesome. The F250 mounts are set just about 1" low of mid travel (5" up/7" drop). With everything installed and the axle hanging under it own weight, I still have about 1.5" of extension left. The coils seem to be the limiting factor as there is no driveshaft bind, the Duff Long Arms are doing their job and all the linkage appears to have room left to extend. If I stand on the axle or press down a lot, it drops another .5" or so. Its possible the damage was just from the action of the shock on the mount, but I thought since I was in there with the welder I could install limit straps to save the shocks and mount if I ever get nutz on the woops. AND definitely add some reinforcement around those shock mounts.

Attached is a close shot of the failure.

I’d say it’s definitely the shocks limiting your down travel. I’ve seen limit straps mounted to similar shock towers, ending with the same result. Limit straps will be needed, or longer shocks. Mounting the straps near the coils sounds like a good plan.

Mark

 

[.94 OR]

I'm concerned the coil bucket might succumb to the same fate as they aren't really designed to withstand a great downward pressure. They wrap under the frame to support upward pressure from the spring. I would think a separate limiter strap mount might be in order.

 

[nvrstuk]

...and the frame is solid, rust free?

Takes a lot to tear a frame like that from "only" the weight of the housing/tires/wheels. 380#'s maybe? that's nothing. Trying to support several thousand pounds when the Bronco is airborne coming down is a different story.

You said that the shocks still had appr 1" of travel when standing on the axle.

I suggest try disconnecting the shock and see if you get any more downward travel. 12" shortbodied shock like Mark and Todd said isn't enough. I ran 14" short bodied Bilsteins but have a backhoe so I could 100% locate the F250 mount to utilize every inch of travel. The bottom of the stock F250 mounts were mounted on top of frame rail. I had extensions to give support to them along the side of the rail. 19+ years and worked hard-no issues.

Back in the '80s I tried limiting straps made out of cable mounted at the coil to the radius arms. Worked fine until the cables literally broke in half. I used 1/4" cable which is good for thousands of pounds but I think the repeated shock just hammered them. I was running air bags in the coils and probably the typical "too short" OE length shock up front-I ran Gabriel Adjustable E's back then... not many options for sure

 

[Yeller]

I'm always impressed when folks get f250 towers to survive. I have always broken the frame, with enough shock to properly control compression and rebound, those forces are incredibly high. If the shock is not bottoming out, or being over extended you need a brace at the top of the bracket over the engine. I may just be a knuckle dragging neanderthal (I've broke a LOT of stuff that is not supposed to break, I think Brian and I have a distant relative....LOL) but I can never get a F250 bracket to not rip the frame apart, even with them being installed properly with the proper length shock, tried many times.

I've done limit straps inside the coils, it works fine just use a turnbuckle at the top for fine tuning the length, where ever you purchase your straps they will have the hardware for this. Don't forget bump stops, they can be just as important.

 

[Ol'Blue]

Shocks disconnected and axle hanging I'm at 26" eye to eye and if I stand on the axle I'm about 27". The shock max is 28", so my plan is to set the limit strap at about the 27" mark depending on the length of strap I end up using. Frame is rust free.

Yeller, ya I didn't think I was being that rough on it but guess I was wrong. My welder is really going to have to do some major reinforcement on the towers and frame.

 

[Yeller]

you need more than 1" of difference in the travel, unless your mounting in the same plane as the shock, hitting the shock extended during articulation can result in the same damage. you have to take into account all of the geometry and were all of that stuff moves to during all the arcs of travel. Properly setting up limit straps is a pain but worth it for not killing your nice expensive shocks or worse, the damage that you have.

 

[nvrstuk]

Agreed (again of course) with Steve about setting up the straps. This is why I was saying you need to remove the shocks as the bushings or eyes will also limit travel... anyway...

My F250 shock towers were welded to angle iron so I had 4 separate beads all at least 2 inches apart to spread the load on my frame rails. That did the trick for a lot of abuse over a couple of decades of real world testing... lol. Many miles of 12-16" sand dunes at 35-45 mph...

Spreading the load, thats the key. I was peeeling my attachment points on my 9" housing antiwrap bar mounts till I added extra "load dispersement" . Then I snapped the .250" DOM in my track bar.

I think Steve and I should be sponsered so we can test the limits of suspension stuff and not have to pay out of our own pockets!!

 

[landshark99]

You might think about putting a small hoop from the top of the coil bucket to the frame just behind the shock tower on the outside and connect the hoop to the top of the shock tower to spread the load. You can then run a limit strap from the hoop behind the shock tower to the radius arm - maybe even the back of the shock mount on the arm.

If you go with limit straps, Your not going to need a very long one and might not have to account for much “stretch” unless it’s over 12”.

 

[Ol'Blue]

Thanks for the input. I'm beginning to think it would be best to install the limit straps outside the coil so that the shock, coil and limit strap all have separate stress points on the frame. I don't think adding the additional stress of the limit strap to the coil mounts would be a good idea.

Will look at other option tonight and post up for comment.

 

[toddz69]

Many off road racing vehicles use a weld-on clevis mount similar to this:

http://www.bajaracingsupply.com/limit-strap-clevis-weld-on-mount/

Not sure if you have space between the shock tower and the coil tower to wedge something like that in there or not, but the adjustability of the clevis is nice.

Todd Z.

 

[Ol'Blue]

Thanks for all the suggestions. I got both shock towers welded up and reinforcement added. Hopefully this will hold. I welded on a bracket at the bottom of the frame rail in-between the coil and shock towers for the 13" limit strap and ran it to the radius arm. At 13" limit, this will let my axle drop 6" before it hits the shock limit of about 7". Was up at BBBB this past weekend and seamed to work out really well. Also installed all new brake line front and rear as old ones were getting sketchy looking.

 

[73azbronco]

OK, so what were you doing to blow the weld on the tower?