Scamp Axle - Leading vs Trailing - Fiberglass RV
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Old 08-12-2013, 06:26 AM   #1
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Name: RogerDat
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Michigan
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Scamp Axle - Leading vs Trailing

My trailer is in the shop getting measured for a new axle. I am debating some choices and looking for advice from those that have "been there and done that". I understand the stock axle for my 1977 13 foot Scamp would be a 0 or 10 degree down angle leading arm. I'm generally a big fan of following the original design, unless I know more than the original engineer I'm not going to make it better. However things have changed in the last 35 years so...

1). Stay with stock leading arm configuration in stock location or switch to the more common trailing arm with axle welded in different location?

Any issues with a Scamp 13 positioning an axle in the different location required for a trailing arm? Is it being done that way on the newer ones?

2). Stay with the 4 on 4" rims I have or go to 5 on 4.5" rims. I have modern 13 inch rims that are 4 on 4 and am not in a hurry to spend the additional money to purchase new wheels with a different bolt pattern unless someone provides a reason better than "it's the more common style".

Will 5 on 4.5 rims fit the spare tire hanger bolts? Is there a specific advantage to changing the rims that justify the expense?

3). Down angle 10 or 22.5 degree? I would not mind the greater clearance for the front and rear edge of the trailer provided by greater down angle but don't want to put the trailer up so high that it becomes significantly less stable or DW needs a step ladder to get inside. Or make the tire look mis-matched to the wheel well cut out when looking at it from the side.

Anyone having experience with the end results of using either down angle and 13 inch tires able to share the results?

Brakes and bracket kit to make axle bolt on are a given. Bolt bracket kit is inexpensive insurance to keep cost of future axle replacement down and while I don't "need" brakes, having them is a significant safety advantage.

At one point I had considered going with a 45 degree down angle and 14 inch wheels, get as much ground clearance as possible for boondock camping. Decided that not enough useful advantage to offset needing a step, and expense of three rims and tires, plus having to come up with a different mount for the spare. Now leaning toward 22.5 down and 13 inch tire on stock 4 bolt rims, with brakes on a Dexter #9 axle.

Appreciate any feedback on helping make the best choice. Want to avoid saving a penny up front that cost me a pound later.
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Old 08-12-2013, 11:25 AM   #2
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I've done the axle 'swap' using a Dexter #9 w/brakes, leading arm. It has worked well. It's a lot of reading but if you haven't already, check these threads - http://www.fiberglassrv.com/forums/f...a-55120-2.html and http://www.fiberglassrv.com/forums/f...ics-49911.html and http://www.fiberglassrv.com/forums/f...xle-52859.html
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Old 08-12-2013, 01:34 PM   #3
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I've done the axle 'swap' using a Dexter #9 w/brakes, leading arm. It has worked well. It's a lot of reading but if you haven't already, check these threads - http://www.fiberglassrv.com/forums/f...a-55120-2.html and http://www.fiberglassrv.com/forums/f...ics-49911.html and http://www.fiberglassrv.com/forums/f54/82-scamp-axle-52859.html
Thanks for the info Harvey. I have read those threads, the lift that Kevin K ended up with was too much at 22.5 down angle. But yours looked about right from combination of de-rating to 2k but at what down angle?

Have also read that axle manufactures recommend fairly shallow angle for leading arm. I'm guessing that may be 10 degree or less. Possibly to avoid the hard braking crow hop issues mentioned in those threads or to avoid a ramming effect if running into something hard for the tire to roll over.

Had not really figured out the Dexter chart for figuring "H". I like you am at between 10 and 22.5 up angel right now, and as in your pictures my wheel well cust across the rim not the tire..

From what I can figure on the chart it looks to me like a 10 up (H = -2.0) or 22.5 up (H = -3.0) that means a 10 degree down (H = -0.1) and would give me between 2 and 3 inches of lift, a 22.5 down would give me between 3 and 4 inches of lift.

I think I'll try the suggestion of Thomas G and call Dexter regarding 22.5 degree leading arm, and having brakes with that configuration.
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Old 08-12-2013, 01:39 PM   #4
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........
I think I'll try the suggestion of Thomas G and call Dexter regarding 22.5 degree leading arm, and having brakes with that configuration.
Some time back I sent an email to Dexter asking about leading arm configuration and they said that they didn't recommend it, though I got the feeling it was a preference as opposed to a flat "do not do it" recommendation. They also stated that brakes can be used with a leading arm.

I think that I posted their exact words here somewhere.
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Old 08-12-2013, 02:07 PM   #5
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Some time back I sent an email to Dexter asking about leading arm configuration and they said that they didn't recommend it, though I got the feeling it was a preference as opposed to a flat "do not do it" recommendation. They also stated that brakes can be used with a leading arm.

I think that I posted their exact words here somewhere.
Yes you did along with the advice to call Dexter and ask, along with a phone number. Which I'm betting will yield just what you said. Can but not recommended configuration.

At issue for me is the coin toss between moving the axle and going with the current "standard" or putting a more stock replacement in same location. Looking at the frame the location of the leading arm axle looks really good. Almost as if it was made for it. <_<

Moving alxe involves changing the stress on the frame to at least some extent. Makes me nervous, and it seems that more of the people in the threads read so far go with leading over trailing. My trailer guy is a strong believer in go with the current standard of trailing, less chance of problems down the road.

I can't see changing the bolt pattern, buy rims just so I can mount the same ST175/80 13 tires? Just does not make sense to me.
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Old 08-12-2013, 02:30 PM   #6
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Yes you did along with the advice to call Dexter and ask, along with a phone number. Which I'm betting will yield just what you said. Can but not recommended configuration.

At issue for me is the coin toss between moving the axle and going with the current "standard" or putting a more stock replacement in same location. Looking at the frame the location of the leading arm axle looks really good. Almost as if it was made for it. <_<

Moving alxe involves changing the stress on the frame to at least some extent. Makes me nervous, and it seems that more of the people in the threads read so far go with leading over trailing. My trailer guy is a strong believer in go with the current standard of trailing, less chance of problems down the road.

I can't see changing the bolt pattern, buy rims just so I can mount the same ST175/80 13 tires? Just does not make sense to me.
I'm not sure what I'd do. Sticking with an original design that has worked for decades has a certain appeal, though the trailing arm has certainly become the standard.

Re the wheels, the brake drum / hubs are fairly expensive compared to wheels, so if you think that you might want to go with the 5 lug rims, now would be the time to do it. Sometimes you can get a pretty good price on mounted tires from a place like eTrailer.
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Old 08-12-2013, 03:24 PM   #7
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I'm not sure what I'd do....

Re the wheels, the brake drum / hubs are fairly expensive compared to wheels, so if you think that you might want to go with the 5 lug rims, now would be the time to do it. Sometimes you can get a pretty good price on mounted tires from a place like eTrailer.
eTrailer is where I was checking, along with a local tire store. I can purchase rims just like what I have (white spoke) but in 5 bolt for $25 plus shipping. Plus mounting and balancing. The same tires fit both what I have or what I would purchase.

I guess another question for Dexter would be is the common brake flange available for both 4 and 5 bolt hub configurations. Avoiding weird brake size would be important.

Also don't think spare mounting studs on rear of trailer will line up with 5 bolt pattern, I measured against my 5 bolt utility trailer spare studs and those are almost 1/2 inch wider.
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Old 08-12-2013, 04:39 PM   #8
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Just got off the phone with the trailer place. Was told it the front floor dropped areas are in the way of a trailing arm. So ....

Purchasing a Dexter #9 22.5 degree down angle, EZ-lube, 7 inch brakes. Staying with 4 on 4 bolt pattern so the spare tire studs on trailer will line up. Will be a trailing arm but will get turned around to be leading arm. Should get a little more than 3 inch lift (no load height) compared to what I have now.

Going to have to cut the axle mounting bracket shorter on one end to mount it where axle needs to go to put the spindle in the center of the wheel well since we will be turning "long" side of bracket to the opposite direction.

Said it made me the only person he can ever recall telling to not buy the bolt on bracket kit. Because he would have to custom cut bracket same as axle, and probably re-drill the bracket bolt holes on one end. More labor than it would cost to cut axle welds off if it needed replacing and any future replacement axle would never just bolt in since it's mount would also need to be cut and drilled.

Cost will be about $365 for axle with estimated shipping cost. Plus about $150 or a little more for labor.

At the end I willl once again have a suspension and about 3 inches of my tire up in the wheel well, as opposed to 6 inches. Yep my wheel well cuts right across my rim, top of wheel well opening is at 17.5 inches off the ground on a 23.5 inch tire.

Did suggest a digital brake controller so I could do a fine adjustment of trailer brakes to take into account leading arm axle tendancy to rise up if braked too hard. I quote "yes they do that, that is how they are supposed to act." Considering he is a third generation trailer fabricator I guess it's probably a sound observation and suggestion.

Pretty close to what others have installed as replacements, thanks for the suggestions and suggested posts for reading.
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Old 08-12-2013, 05:07 PM   #9
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Make sure you specify the weight of the axle when ordering. A #9 axle can be built to 2200 lbs. if you don't ask for it you usually get a 2K lb. axle if it comes from Redneck.
Scamp replaced a leading arm axle on a 1982 S-13 for me. #9, W/O brakes, 22.5 deg. down, W/ brake flange, E/Z lube, 4X4 lugs. They had to notch a small piece out of the mounting bracket on one side. (Door side I think.)
One other tip. Tell your installer to cut off the swing arms first thing off of the old axle. It is almost impossible to get the old axle off if you don't.
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Old 08-12-2013, 05:16 PM   #10
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Amazing good price on axle and labor. Care to share the name of the shop?
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Old 08-12-2013, 05:41 PM   #11
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Amazing good price on axle and labor. Care to share the name of the shop?
Not sure I know the name, will have to call and ask. It's not a storefront type shop with a big sign (or even a little one). It's two really big pole barns on several acres behind a house on south side of Grand River just East of Burkhart road. Maybe 2 miles East from M-59. Area around it is light industry. Always has a couple of trailers for sale up by the mail box.

Do a lot of custom trailers for landscapers and heavy equipment companies. Build utility and snow mobile trailers usually have a few built and for sale. Some custom carts and such for Auto companies. Plus repair. Place is always busy.

I'll call them and get a name and ask if they mind if I post their phone number (don't think they will ) For now I'll PM you the number I have for them.
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Old 08-12-2013, 05:53 PM   #12
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For now I'll PM you the number I have for them.

Thanks. It would be good to know of a reliable trailer shop in the area.
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Old 08-12-2013, 06:22 PM   #13
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Roger
Make sure you specify the weight of the axle when ordering. A #9 axle can be built to 2200 lbs. if you don't ask for it you usually get a 2K lb. axle if it comes from Redneck.

Scamp replaced a leading arm axle on a 1982 S-13 for me. #9, W/O brakes, 22.5 deg. down, W/ brake flange, E/Z lube, 4X4 lugs. They had to notch a small piece out of the mounting bracket on one side. (Door side I think.)
One other tip. Tell your installer to cut off the swing arms first thing off of the old axle. It is almost impossible to get the old axle off if you don't.
Eddie
Thanks for the info, I'll touch base with him in the morning on the capacity required and pass on the tip on getting the swing arms first.

So did Scamp convert from leading to trailing?

I think he orders direct from Dexter rather than a reseller but could be wrong. Know he orders things like axle tubes from them, if as he says they sell it cheaper than he can make it.
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Old 08-12-2013, 07:01 PM   #14
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The trailer was leading arm and that's how Scamp replaced it.
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Old 08-12-2013, 09:49 PM   #15
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I guess another question for Dexter would be is the common brake flange available for both 4 and 5 bolt hub configurations. Avoiding weird brake size would be important.
You don't need to ask Dexter - you can read their Application Guide, which shows all of their hardware.

All Torflex #9 axles use the same size brakes (7"). The only way to get a different size would be to go to a different series of axle, such as the #10, with up to 3500 pound capacity and 10" brakes. For each series of axle, there is a common or default bolt pattern, plus usually some alternatives. Typically, changing bolt pattern doesn't change anything else.

A #9 has a capacity of up to 2200 pounds, as already mentioned. If that's a lot more than the trailer weight, it can be built with shorter rubber rods giving it softer springing - and less capacity.
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Old 08-12-2013, 10:06 PM   #16
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Was told it the front floor dropped areas are in the way of a trailing arm.
Yes. The whole point of the original Boler chassis design - and a Scamp 13' is a Boler clone - is to be as low as possible, and that was accomplished by dropping the floor down below the frame in the middle. The axle can't go under that, since that would push the trailer back up, so the axle tube is behind the dropped section, with the arms reaching forward around it.

Switching to leading arm means putting the axle under the dropped section, on tall enough mounts to reach the frame. That raises the trailer and requires fabrication work, but you're raising it anyway and doing custom work anyway. I would see if I could get a trailing arm setup with a roughly zero or even up start angle to get about the same height without modifying the axle brackets or running the Torflex in a leading configuration. 22 degrees down seems like a lot for a configuration that works best with an up angle.
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Old 08-12-2013, 11:24 PM   #17
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That was my thought. 22* down on a leading arm axle with brakes seems scary to me.
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Old 08-12-2013, 11:52 PM   #18
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It seems like a better outcome would be to try to get a trailing arm setup even if it involves spacing the axle tube down from the frame to clear the dropped floor. Using a Flexiride axle in lieu of the Dexter would allow for ride height adjustment too. Leading arm @ 23 degrees down would act like a pole vaulter when the brakes are applied.
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Old 08-13-2013, 11:24 AM   #19
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When I touched base about making sure it was a 2200 lb. axle being ordered he told me since he was in Elkhart picking up a trailer to be worked on he had taken some pencil blue prints sketches to a different axle manufacturer Al-Ko.

Talked to someone he knows there. Was told they could manufacture axle as true leading arm and with brackets to match the install based on his sketches.

I know there is some internet debate over Al-Ko vs Dexter but there is also a pretty good chance the original axle is Al-Ko.

I also think there is much to be said for the idea of having an axle designed for leading arm install as opposed to turning a trailing arm around and making it fit by cutting off the "long" side of the bracket.

On posting the shop name and number he is going to talk it over with his brother. They really do not advertise or do much homeowner work, they primarily do commercial accounts that they have built up over generations of being in business. I was told to call back in a week to get an appointment to get axle measured, when I called it was another week before they could slip me in. I'm really only a customer because I bought a utility trailer they built.
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Old 08-13-2013, 11:52 AM   #20
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That was my thought. 22* down on a leading arm axle with brakes seems scary to me.
I'm not an expert but bearing down on the tires (side effect of trailer trying to pivot up) would increase traction up to the point where trailer tries to crow hop.

I know an old rule of thumb was 2/3 of the braking capacity was always supplied by the front wheels of a car or motorcylce because when stopping the weight shifts forward and bears down on those tires. Same as with a leading arm trailer axle. Rear wheel was losing weight (traction) during a stop which seems more like a trailing arm would act.

This behavior was one of the reasons for front disk and rear drum brakes being a common configuration in the past on motor vehicles, you got a lot more benefit from the disk brakes on the front than you did from putting them on the rear.

I don't know if one axle configuration may be much easier to control than the other or have a more sudden degradation of effectiveness and control. Sometimes the difference between working great and going south can be very abrupt, it is easier to react when there is more warning that you are getting closer to the limits of good operation.

What did the old Scamp 16's have? Leading or trailing? Brakes or no brakes? Angle might also be important if they had leading arm with brakes.

I think that was part of the reason for the suggestion of using the digital brake controller, to get that fine tuning that is a key to making that configuration "good".
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