4" lift and shock upgrade Bigfoot 19' - Fiberglass RV


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Old 07-14-2013, 10:26 PM   #1
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Name: Jared
Trailer: Bigfoot
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4" lift and shock upgrade Bigfoot 19'

Alright, been on here for more than 4 years, about time for my first post.


I have had my 84 Bigfoot 19 Gaucho for over 2 years now. It is a great trailer and rides extremely well but the ground clearance was not acceptable. On several occasions I have had to stop to put rocks and logs under the wheels to get through even the most minor washout on BC logging roads. I like to frequent the more remote BC rec camp sites. The trailer was also not handling the washboard on the logging roads as well as I liked. Carbonated beverages in the trailer could not be opened for a while after arriving at camp.


I decided to do both improvements at once for time and cost savings. People have done the straight axle swap and added shocks but I could not find good documentation on it so i decided to share my experience/learning. I am in no way ensuring this will work for your trailer, if you choose to copy my setup in any way it is your responsibility to verify that it will be safe for your application. Proceed at own risk.


OK, got that out of the way. First off, here is the trailer before modification (yes it needs a bath).







First step was to order some straight axles to replace the 4” drop axles. I was shocked at how affordable the axles were from our local mfg in Calgary so as long as I swapped over the brakes and hubs. Little did I know what surprises were coming (not the mfg's fault on the axles).


Next was to figure out how to get shocks on it now that Monroe no longer makes their retrofit kit for trailers and the only place that still had them in stock wanted more than $200 shipped for 2 kits not including the shocks. I can figure this out myself.


From experience on other projects tackling the hardest challenges first seemed wise -Lower mounts. After measurements and research I discovered that 60's era jeeps had the same width front springs as my trailer with a shock mount on the u-bolt plate (no sway bar mount). After receiving them I discovered that the holes on one of the plates was spaced further apart due to the differential on the jeep axle. Measured my axles and decided slotting the holes would solve this. Used a round file and it only took about 10 minutes. These plates use a 7/16” dia u-bolt which is smaller than the standard 1/2” on a 3500 axle which this trailer has, but were de-rated from the factory. Since my trailer is 2600 dry, I figured i need nowhere near the 7000 lb rating that the two axles would be rated for and would be fine.





Upper mounts were not as simple as I thought. I originally wanted to get 5/8” shoulder bolts for the increased strength as they were going to be loaded outboard of the frame walls, however they would have been much more expensive and I would have to have very accurate holes machined in the frame with threads in one side. I would have to rent a mag drill to keep them square and I know shocks do not require anything even near that level of accuracy so I went with a cruder, less expensive solution. I picked up some 1/2”dia 5” bolts with a box of washers. I still needed a spacer to bring the dia from 1/2” to 5/8” for the ID of the shock and after a lot of searching, I picked up a bronze bushing (1” to 1-1/4” long 1/2” ID and 5/8” OD). The part is actually a bearing from an electric motor. But you can pick these up from industrial suppliers. The Monroe trailer shocks came with some spacers but I had to add about 3-4 washers to gain enough clearance to from the frame. Another benefit to going down to 1/2” is that most standard drills can take up to 1/2” drill bits and the hole in the frame would not be as large. I am going to keep an eye on the bolts as they are not hardened and might fail over time.


I used the Monroe trailer shocks (there are several lengths but almost every trailer on this site would require the shortest. Online shopping saved a ton of money on these (especially in Canada).




Getting the old axles off was not as hard as I thought, even on a 29 year old trailer. Don't bother trying to unbolt the u-bolts, cut them or torch them off. You can not re-use them either as they are designed to deform under torquing and re-use could result in failure. Unless you want to remove the brakes before the axle, you will need to drop the spring by removing one of the spring boats.


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Old 07-14-2013, 10:27 PM   #2
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Name: Jared
Trailer: Bigfoot
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The brakes proved to be the most challenging part of the job. When the axles were manufactured, they did not machine enough off of the brake mounting face of the axle to get a socket on the nuts. 29 years of rust proved to be a large challenge too. I used a hole saw to machine enough off of the face to get a socket on the nuts. Some of the studs came loose so I needed to replace them with bolts (very cheap at the local Calgary mfg). When I tried this on the second axle, the hole saw was getting shredded and hardly touching the metal. For some reason this axle had a much higher hardness. I could have used a diamond hole saw, but at this point i was running out of time so I picked up some new brake assemblies for the second axle.








Putting axles back on was easy. The bolts through the spring stack will keep the alignment with the axle, so unless there was an alignment problem before the swap, everything should be fine.








The shocks mounted very quickly. Just had to make sure that the shocks would not over extend and with a double axle the negative travel can be more than it appears. Drilling the frame took a little while but with some cutting fluid went smoothly. The shock angle on the rear shocks had to be steepened a bit due to the shower drain interfering with the mounting. Loctite was used on the shock mounts to keep the nuts from backing off.




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Old 07-14-2013, 10:28 PM   #3
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Name: Jared
Trailer: Bigfoot
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Here is the trailer after the modifications and a good cleaning.







Here is why we all do this.






Happy to give back, you have provided so much good information to me.


JL
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Old 07-15-2013, 08:18 AM   #4
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Good work!

But a lot of work... I'm glad that the Monroe kit was still available for me, and that I did not need to change the axle beam. Also, although my axle was just as old, the U-bolt nuts came off with real difficulty, so I did't need to cut them.

An alternative to the Jeep plates - which were a brilliant solution - is the Dexter kit, which uses simple plates with a bent extension, and stud-ended shocks to go through a simple hole in them. The Dexter kit also includes the shocks, and a weld-on top mount. I didn't want the welding. My non-moulded fifth-wheel has the Dexter kit; it seems to be the common choice for factory-installed shocks on leaf-spring beam axles.
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Old 07-15-2013, 08:21 AM   #5
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One question:
Why put the shocks on the inboard side of the frame rails? Is there not enough clearance on the outboard side?
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Old 07-15-2013, 08:26 AM   #6
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I'm curious as to why not replace the springs also or in lieu of the shock upgrade? That may have resulted in the same improvement. Those springs look really old.
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Old 07-15-2013, 08:47 AM   #7
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Quote:
Originally Posted by cpaharley2008 View Post
I'm curious as to why not replace the springs also or in lieu of the shock upgrade? That may have resulted in the same improvement. Those springs look really old.
They're old, but they still have lots of arch. If the springs have the same 3500 lb/pair rating as the axles, they're very lightly loaded and could last a very long time. As I recall, the Bigfoot 19' we considered buying had 2500 pound axle ratings, which would be more reasonable (and ride better). With only three leaves in the pack, I suspect these are 2500 lb springs; that wouldn't explain the long life, but does help explain a lack of inter-leaf friction damping and goes with Jared's comment about factory de-rating.

Even if the springs need replacement, new springs would not make the kind of height difference that the straight-beam conversion does... but I realize Jim is asking about the need for shocks, not the lift.

Shocks do something fundamentally different from springs. They add damping which smooths the ride, in a way that even the most perfect steel spring cannot do. The only damping in a leaf spring comes from inter-leaf friction; it will never be as strong as a proper shock, and frictional dampong is poor compared to the hydraulic damping of a shock.
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Old 07-15-2013, 08:48 AM   #8
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Really nice job. It did look too low in the original pic.
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Old 07-15-2013, 09:25 AM   #9
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Great work. It's amazing how a few rusty fasteners can double the labor on any job.
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Old 07-15-2013, 10:38 AM   #10
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Did you need to adjust the tow ball height? It seems that the angle would be different after this mod (angled down more without adjustment).

BTW, thanks for sharing. I am looking at this mod, or jacking my trailer up 4 inches or so. I have absolutely no mechanical aptitude however so ...

Am I correct that these eggs do not usually have shocks as a standard item?
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Old 07-15-2013, 10:43 AM   #11
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Originally Posted by jwcolby54 View Post
.......Am I correct that these eggs do not usually have shocks as a standard item?
Shocks are rare and usually added by an owner as opposed to the factory.
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Old 07-15-2013, 10:54 AM   #12
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My scamp 16 is a 2009, so "almost new". I'm hoping that there will be little corrosion yet and thus easier to mod if I get to it immediately. I would like to lift it a few inches, install shocks, and if possible get bigger tires on it. 13" tires just seems undersized to me, and at least in the scooter world, they wear much faster than the larger tires.

So what is involved in a "lift"? Is it the shape of the axle? I.e. swap the axle out for a new one with a different shape?

Am I just nuts to even be thinking about this?
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Old 07-15-2013, 03:30 PM   #13
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My scamp 16 ...
So what is involved in a "lift"? Is it the shape of the axle? I.e. swap the axle out for a new one with a different shape?
Assuming it still has the original type of suspension, a Scamp uses a completely different suspension type from a Bigfoot 19, so what is involved in a lift is entirely different.

For the Bigfoot, yes, the axle beam goes from a shape which drops down from hub to beam at each end, to one which is just straight.

The Scamp can be lifted, too - maybe someone can point to a good choice among the many existing discussions - but it is unrelated to what Jared is showing us. Similarly, shocks can be added to the Scamp - and again maybe someone can point to a good existing discussion - but again it is not done the it is done for the Bigfoot axle. There's one thing in common: due to the discontinuation of the Monroe kits, adding shocks is an exercise in custom fabrication.
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Old 07-15-2013, 03:34 PM   #14
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Originally Posted by MC1 View Post
It did look too low in the original pic.
Yes, it looked low, but I think that's mostly the visual effect of the fender skirts, and partially the fact that the intended height was lower than is currently fashionable. For normal road use, there's lots of clearance visible between the body and the road.
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