Question re: single axle carrying weight, inner tire wear

CWKboat

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Greetings!


I have a single axle Magic Tilt Trailer currently carrying a 20.6 Larson bowrider with a Merc V-6 outboard. The dry weight of the boat is listed at 1800 lbs, so I figure with the engine and fuel I'm well exceeding the carrying weight of 2000 pounds noted on the trailer ID.


I do have the axle position adjusted to where the tongue weight is within specs, but it's obvious since I purchased this combo as evidenced by the rapid inner tire wear that the trailer axle is not well-matched with the boat.

Otherwise, the trailer is certainly long enough for the hull as the transom is resting on the end of the bunks. I think also the trailer ID emblem says 19-21.


Would it be a suitable option for me to simply upgrade the single axle to a 3500 # axle/new hubs and set of appropriate leaf springs, and trust that this will even out the tire wear? I figure this would cost app. $500 or so.


Otherwise, I guess I'd be looking at starting over with a tandem axle trailer.


Thoughts?
 

Starcraft5834

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yes!!! if you think your over weight for current axle, install a new one,, your springs are probably fine...a 3500# axle is about $150... if you install the axle yourself, make sure you install it with the camber in the right direction..."camber" means the spindle under load goes back to (zero)...most have a 1-2 degree camber.. if you install it upside down, you will double the camber and wear your tires out in the inside... how do I know this? Because stupid me did that....gee why are my tires only wearing on the inside about an inch.... once I flipped it over, new tires run straight and wear properly...
 

CWKboat

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yes!!! if you think your over weight for current axle, install a new one,, your springs are probably fine...a 3500# axle is about $150... if you install the axle yourself, make sure you install it with the camber in the right direction..."camber" means the spindle under load goes back to (zero)...most have a 1-2 degree camber.. if you install it upside down, you will double the camber and wear your tires out in the inside... how do I know this? Because stupid me did that....gee why are my tires only wearing on the inside about an inch.... once I flipped it over, new tires run straight and wear properly...


That's exactly how mine are wearing now, about 1" on the insides. Already noticeably worn after about 400 miles.


Is it possible to look at the axle and see the camber angle prior to install? I also read something about installing a drain hole in the axle? Is that just in the middle bottom to keep water from accumulating in the axle?


Thanks for your help!
 

Starcraft5834

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yes, when you get your new axle, it will come with directions showing you which end is which.. the directions will show you whether your spring pin hole needs to go up or down. that's if the axle you buy has "pre-drilled" spring pin holes. some do and some dont.. either way, there will be a sticker on the axle indicating which end is up... if you do it yourself,, jack up your trailer, if the boat is on it, that's fine,, just jack it up and put blocks (solid mortor) not cinder blocks, the 8x16 ones you can get at Lowes/Home Depot work nice,, stack them up and place under the frame, use jack stands as a back up to that...some prefer solid wood blocks, once you get off the tires, hubs, and axle off carefully measure the distance between the two spring pins.. that's your distance for spring center holes on the new axle (if you choose to drill it yourself). all you need is new tie plates "U" bolts and nuts,, get em from Eastern Marine.. or locally if you can find em.. use loctite "red" on the new U bolt threads and nuts,, (red) needs a torch to get em off,, lets face it, once you get them on you wont be messing with them again, you dont want them to get loose.. I bought a new 3500# axle last year, did not read the directions.. yea brilliant,,,,,ran it all last year and my tires wore only on very inside, this spring we took off everything and flipped it, now it runs straight and true.. the whole project will cost you about $200

forgot to mention,, measure your overall lenght of old axle too.. if your off more than an inch, you might have problems with fender tire clearance... sometimes you have to adjust your fenders too... if your new axle is same over all length, your good to go
 
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CWKboat

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That is a huge help! Thank you!


I did notice that the ones sold by Eastern Marine do not have the holes pre-drilled. I suspect I'll get everything from them. Sounds like it will be easiest just to remove the old axle first and confirm the correct length of the axle with the hubs removed.
 

Starcraft5834

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some do,,, I installed a #3500 square axle made by Tie Down... it came with predrilled spring center holes, one of them was exactly what I needed.. I live in North East PA, everything I order from them, I get next day... thats with regular shipping,,, they are in DE... remeber to use blocks, nice wide platform, at end of your trailer, on ends.. I dont trust jack stands only,, I like to know the ground is holding up the whole thing, not just the stand...have fun! after this, you too will be an expert! just do it right the first time :frusty:. not like what I did

also...I assume your going to install the new axle under the springs, as opposed to on top, or through the springs... mounting the axle so the springs sit on top give you the most clearance for your tires so they dont rub the fenders........... your welcome! fish on!
 
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CWKboat

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Hadn't even thought about installing the axle under the springs as the current setup has the axle on top of the springs, thanks for the tip!
 

smokeonthewater

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lets SLOW down a bit....... FIRST you need to determine whether your FRAME is up to the weight... most likely it is but let's see what it's made of... IE 2x3x1/16 C-channel would be way too light... next, if your axle is too light then your springs probably are also...

Your tires are possibly also under rated for the load... wheels can possibly be re-used but maybe not depending on diameter and bolt pattern.

Next, the preferred thing to support the trailer would be at least 2 quality jack stands and 3 or 4 would be nice... next choice would be wood blocks.... any sort of concrete, cinder, or mortar block is NOT designed for this application and not a safe choice...

Think through your on top/ under spring choice... ONLY mount the axle under the spring if you NEED added clearance... The lower your boat is to the ground the less you have to back it in to launch and the easier it will be to access the inside while on the trailer.. I'm not saying to do it one way or the other but that it is a tradeoff and not a no brainer.

Last consider that by the time you get done here it MIGHT make more sense to find a good used trailer and sell this one for @ the same money.
 

CWKboat

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Smoke,

I recently put 14" tires on (moved up from 13") and moved up a load rating (I think it was 1750 lbs) per tire. The wear on the inner tires continued.

Points well taken re: supporting the trailer and the positioning of the axle. I will most likely opt to put the axle on top of the spring as the boat is already not easy to climb into without a ladder. Will also check the frame dimensions, but it seems stout and has held up well in the 2 years I have towed the boat.

I'm looking at some used trailer options as well as you suggest. If replacing the axle, I'd also replace the springs.

Thanks for the food for thought and pause!
 

Starcraft5834

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let us know how it went CW.....is disagree with jack stands as primary support,, a wide safe platform from the ground up followed by jack stands as back up is only way I'd proceed...if you only use jack stands and they fail, and your under there, your likely dead....others can do as they wish, I would not do it...I agree with smoke about the springs... if they are fine, they are fine.. that's for you to determine... as for finding a good used trailer......possible.. but unlikely for the 200-300 bucks this job will cost u... be safe first....and have at it...

also, I installed a 14 inch tire that's rated 2020lb per.....as opposed to the 1750.... necessary? probably not.. nice to have just a spec more tire width? yes...
 
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CWKboat

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Imperial,


Thanks! i will definitely build some redundancy into supporting the boat with the axle removed!


Since I've already set up the trailer with new bunks, wiring, lights, etc, I'm more of the mind just to replace the axle, springs, and hubs or bearings and just invest the money for somethig I know will last a long time. It's still going to be a crapshoot somewhat with buying another trailer and getting it adjusted to the boat and dealing with any issues. I think I'll just definitely go with fixing the one I have.
 

CWKboat

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Well, to update, I received the 3500# galvanized axle from Eastern Marine along with two new 1800# slipper springs and started on it yesterday. I got the trailer/boat up on jackstands behind the axles and kept the coupler hitched on the truck.

The old axle/spring assembly came off easily and I had the axle off in 10-15 minutes. The new springs came with 9/16" bushings, but the old springs were 1/2." I wound up drilling out the existing hangers to accommodate the new springs and 9/16" shackle bolts.

I mounted the new springs, and then drilled holes in the bottom of the axle to top mount the axle on the springs. My spring seat measurement was 73 5/8."

I bolted the axle down with the tie plate kits and now just need to add the new hubs tomorrow on each side. I like the fact that the new axle has grease fittings on each end.

The trailer was very sturdy with the jackstands. I decided to stack up 2 tires/rims under each side near the rear for backup, and used a jack on the side I was working on. I didn't have any worries about the setup shifting on me as I was on a flat carport, and I pushed and pushed on it before starting and it was totally stable.

It really wasn't that difficult. Will update later to let you know how everything rides.

Thanks for all the help!
 

CWKboat

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Nice work. The new axles w grease zerks are nice..you just installed. "Piece of mind".


Thanks, I installed the hubs today. I ordered the Vortex hubs from Eastern Marine, and they also have grease fittings on the back of the hub, but I'm going to use the one's on the end of the spindle for convenience.

The trailer seems to pull straight and true, with tires now in the correct camber. I also put a magic tilt heavy duty winch stand/bow post on the trailer, so it definitely feels like a different trailer now.

Thanks a lot for your help and encouragement in sharing your experience!
 

BF

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glad it worked out... I need to replace my axle as well (previous owner had backed into curb and tweaked a spindle), so it was a good read for me. I thought (?) that springs were rated by the pair, not by the spring... but I guess I need to do some more reading...
 

smokeonthewater

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springs, tires, and axles are all rated EACH thus a pair of 1750 lb springs and a pair of 1750 lb tires work with a 3500 lb axle
 

Starcraft5834

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Thanks, I installed the hubs today. I ordered the Vortex hubs from Eastern Marine, and they also have grease fittings on the back of the hub, but I'm going to use the one's on the end of the spindle for convenience.

The trailer seems to pull straight and true, with tires now in the correct camber. I also put a magic tilt heavy duty winch stand/bow post on the trailer, so it definitely feels like a different trailer now.

Thanks a lot for your help and encouragement in sharing your experience!



glad to help...........this forum is loaded with experts ( which I am not), I did however stay at a holiday Inn express last night!! and installed an axle...:eek:
 

CWKboat

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glad it worked out... I need to replace my axle as well (previous owner had backed into curb and tweaked a spindle), so it was a good read for me. I thought (?) that springs were rated by the pair, not by the spring... but I guess I need to do some more reading...

As Imperial noted, everything is rated "Each."

I got everything from Eastern Marine, and they ship very quickly. While it may seem like a lot before diving in, it really goes pretty quickly once you get the old axle/springs off. The axle they sent me also had a drain hole pre-drilled, so it sort of took the guess work out of "which side is up."
 

CWKboat

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glad to help...........this forum is loaded with experts ( which I am not), I did however stay at a holiday Inn express last night!! and installed an axle...:eek:


LOL, I'm in the same category... Just a "shadetree" hobbyist as we call it in the South!
 
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