View Full Version : Want to convert boat trailer to car hauler, are the axles heavy enough?
09-07-2009, 11:23 AM
My dad's got a tandem axle boat trailer he's willing to give me. The cheapest car hauler I've found locally is $1600 and it needs a deck, tires, and probably brakes. I can get a new trailer for $2300 if I drive a few hours west, $2900 in town. I was quoted $700 to get a deck put on this boat trailer, to include a square section added where the frame narrows in the front. My only concern is what the axles are rated at, all 4 have brakes, and the boat it used to hold had a small block Chevy, so as far as boat trailer are concerned it seems pretty decent. How can I find out what the axles are rated at? That's really the only think keeping me from doing this.
09-07-2009, 11:27 AM
What kind of axles are under it? Bolt pattern? What kind of car are you going to be hauling?
09-07-2009, 12:51 PM
I have no idea what kind of axles. That's what I want to find out. It's a 4 bolt hub. I will primarily haul a 2400# fwd Corolla around, but my 3800# Crown Victoria is going to need a lift as well. Don't plan on hauling anything heavier than that. If they're 3000# axles (or whatever the standard is, is it 3500#?) then I should be good assuming this trailer is around 2000# itself with a deck. I don't have the trailer right now, my dad does, what should he be looking for to be able to ID these axles?
09-07-2009, 04:40 PM
Probably has a 2000 or 3000 lb axle. Depending on the maker of the axle, there might be a tag on the axle identifying it. A lot of Dexter axles have these, but I seriously doubt it would hold up for too long.
You would need to upgrade to at least 5 bolt hubs. Then you have to deal with finding tires to support that kind of weight in a single axle application.
Then you would have to see if the frame would even hold the weight.
You might be better off selling the boat trailer and putting the money toward a proper car trailer.
09-07-2009, 05:28 PM
My dad's got a tandem axle boat trailer he's willing to give me.
AxleS, plural, it has 2. That's one of the main reasons I even considered converting it. What's the weight limit of a 4 lug? If I have to swap axles, it's probably not worth it. It's an old ass trailer too, but the way I see it, if I put a grand or so into this one I'll essentially have a brand new trailer for what I'd pay for a used trailer that would still need a new deck, tires, and brakes.
Damn, looks like the 4 lug was the answer. 3500# axles only come with 5 or 6 lugs. Is it as simple as sticking different bearings on with 5 lug pattern or are the axle beams simply not strong enough?
09-07-2009, 07:52 PM
If it's 4 lug regardless of tandem or single or tandem axle, it's not heavy enough.
Quit trying to be cheap. Spend some money and get a trailer heavy enough to pull something.
When you start talking about pulling trailers safety is a real big thing not to mention insurance. Trailers can be real unsafe.
Overloading them is just plain stupid.
09-07-2009, 09:18 PM
So are the prices these *******s charge for a car trailer out here. $1600 for a 10 year old trailer with dryrotted rubber, a beat ass deck, and God knows what for brakes. By the time I fix that POS I coulda had a brand new trailer. WTF? If I can stick a different hub on the existing spindle and instantly have a higher axle rating, then why not? If not, then this project really won't be worth it in the end.
09-07-2009, 09:24 PM
My bad...I didn't see where it said it was a tandem....
What was the load rating for the trailer from the factory? What size tires and what load rating are they (how much weight can they carry)? Does it have brakes? How old is the trailer?
There should be either a plate or decal on the frame giving you the GVWR and GAWR. It looks something like this:
http://www.g4-graphics.com/images/VIN-Tags/TAG-FOIL.jpg (Large size image, or I would have embedded it)
You really need to find out what axles are on the trailer. Dexter axles (which are common) will have a metal band around the axle with the ID #. This will tell you what each axle is, its weight rating and specs. (overall width, perch to perch width, and flange to flange width).
Odds are, being a 4 on 4 hub, the axle is rated between 1000lb - 2200lbs... Dexter does not offer a 4 on 4 in the 2300 - 3500 class.
Sometimes, you can just put 5 lug hubs on, but not often. The spindles are usually smaller. You're not really dealing with the load capacity of the hub, but of the axle beam itself. The axles are designed for a certain weight, and will have a slight upwards bow to them, so when you load it down, it straightens out, instead of going into a negative camber situation. True, the camber goes positive when unloaded.
Then you will need brakes. Look to around $350 per axle to convert to electric brakes, staying with the 4 on 4 bolt pattern. If you go with the 5 on 4.5 pattern, it's about $380 per axle. That is assuming you can put a 5 on 4.50 hub on a 4 on 4 axle. You might be able to, as the kits come with the same bearings. You would have to measure your spindle (or know what bearings are in your current hubs) to see if it would work.
09-07-2009, 09:34 PM
So a new hub ups the rating for the entire axle even thought the axle itself was not made for that much weight?
Quit screwing around a buy a new trailer cause apparently a used trailer in your area is not worth it.
You are better off with over kill, then trying to use a trailer that can't carry the weight, or was never made for what you are trying to do.
You asked, this is the advise.
BUY A CAR TRAILER.
09-07-2009, 09:49 PM
Really what I wanted was a way to ID the axles, which neonhomer did a good job of explaining. It's easy for you to tell me to buy a car trailer, you're not the one who has to come up with the scratch for it. If I weren't moving this winter, I wouldn't even think of it 'till my truck was paid off. Even though I don't like the answer, I know it's the best. But if I can safely make this work, it'll be a good bit cheaper in the end.
09-08-2009, 08:13 AM
why buy a car trailer, U-Haul rents them.
09-08-2009, 09:01 AM
Because it would cost me about $1000 to rent a uhaul trailer from SD to CA to CO that's why. ****in crooks.
09-08-2009, 09:55 AM
You would have to change the whole axle and springs to get the capacity. Not just the hubs.
09-08-2009, 04:25 PM
honestly i'd think it depends on the GVW. dont haul more than what the title states that it can... and i converted a 16 foot single axle boat trailer over to a flatbed. 12 foot deck with toolbox, sides, and winch. slid the axle forward. added 5 crossmembers. we haul our midsize kubota B1550 with it and it handles fine. i can get a pic later.
09-08-2009, 04:47 PM
I just sold a 24' SSL trailer rated at 10,000LBS. Brand new deck, rubber, and brakes. 2006. For a grand.
Anyways, yeah you're going to have to get new axles under it. Go to the junkyard, see if they have anything. And I'm talking trailer axles, don't go and put pickup truck axles under it, they weren't meant for that.
Also, on the boat trailer, you'll have to move the axles forward. Most boat trailers have the axles closer to the rear, because that's where most of the weight is.
And with it being a four lug pattern, they are probably rated at 2,000LBS each, minus the weight of the trailer, and it's probably good for around 3,000 to 3,500LBS.
09-08-2009, 07:09 PM
Last time I checked, and this was a few years ago. A 5000lb Dexter Torflex axle w/ brakes was around $600. IIRC, this was circa 2000 or `01.
So a pair of axles is going to run you $1000. The first thing you need to do is ID the axle or find out the info on the trailer.
Just because it is a boat trailer, doesn't mean it doesn't have heavy axles. I picked up a trailer for my brother in law in Tampa and brought it to Daytona Beach. It was a tandem axle trailer, but the GVWR was up there... I want to say 4-5k.
That info label should tell you all. The axle tag will ID the axles. If there is no tag, look for a # stamped into the axle tube somewhere.
09-08-2009, 07:31 PM
I bought a new flatbed car hauler in Sikeston, MO with a treated deck and brakes on both Dexter brand axles new for $1,650 just a few months ago. Not happy with the paint but have hauled my Jeep 6k miles on it now, pretty good price.
09-08-2009, 07:33 PM
I have never seen a boat trailer that had anything but surge brakes unless it was built after 2006. I have towed a lot of boats and would not want to tow a car trailer with surge brakes more than across town.
09-08-2009, 11:45 PM
Even if you could convert the trailer I am pretty sure that it wouldnt be legal. The trailer is designed for a boat and licensed as a boat trailer, if you were to get pulled over or cross a state line with a port of entry and the cops run the plates on the trailer it's going to come up as a boat trailer and it's hauling a car. Your going to have a lot of explaining. Boat trailers are designed for boats and flatbed trailers are designed for hauling cars. The towing characteristics of a boat trailer and car hauler are completely different and if your traveling cross country make sure you have the right set-up for it. Being cheap isn't worth killing someone because you had an improper setup
09-09-2009, 12:30 AM
Yeah, it does have surge brakes. I slowly figured that out as he described it to me. He didn't mention there being specific registrations for trailers, he said in MI a trailer's a trailer as far as the Secretary of State is concerned, unless we missed something.
09-09-2009, 01:03 AM
Depends on the state and what they require, but also if you do get pulled over if a police officer thinks your load is unsafe then that's the law. A lot of Uhaul trailers don't have all the running lights needed for each state. I got pulled over when I was driving from Phx to Spokane and got pulled over in the Zion National park in Utah. I got pulled over because the trailer was licensed in AZ where you just have to have brake and turn signals, the trailer wasn't illegal for UTAH but since it was night the cop deamed it unsafe. I didn't get a ticket because I didn't own the trailer and I don't have a single bad mark on my driving record, he just made me take the next turn off to cross the mountains to get to I15 where there was more light. You may not get that lucky though
09-09-2009, 01:19 AM
I would think you could find a used car hauler cheaper than what you have listed. Modifying your boat trailer to use as a car hauler is just a bad idea. It was not designed to handle the weight. By the time you replace or reinforce everything that needs it, you will have more time and money in it than if you just find a car hauler. Not trying to be rude to you, just pragmatic. God forbid you had it loaded up and something failed in BFE. Used trailers are out there, just start searching.
09-09-2009, 10:00 AM
I have. $1500+ for POS that needs work. I know beyond a shadow of a doubt the Crown Victoria is out of the question, but the Corolla might not be. Believe me, the last thing I'm trying to do is ghetto rig a trailer that'll break somewhere in the Rocky Mountains and launch my precious car off the back. If the trailer is what he claims it is, there's a 4" outer C channel wide enough for the Corolla with cross members every couple feet. So if he'd get his ass out there and get me the GVWR of the trailer I'd know more. It sounds like I can bolt on decking planks on with minimal reinforcement since the Corolla is so short and wouldn't protrude up where the frame starts to come together. It's all heresay until I get the trailer in my posession. He seems to think it's under 1000# as is, I'm assuming around 1000#. That + 300# max for the deck from what I've figured so far + 2400# Corolla = 3700# which gives me a decent cushion if in fact it does have a 4000# GVWR. That's why as of right now I don't see this as unsafe. The trailer is apparently of a flatbed design already with uprights bolted to it for the boat, so there is no downward curvature in the middle thus keeping the fab to a minimum. I'm under the impression right now that a car hauler would require a suitable C channel outer frame with good cross members every 36" and a wooden deck on top of that. That is, of course, assuming everything else is rated properly.
09-09-2009, 10:15 AM
What about a standard 16' utility trailer with ramps. I know the Corolla would fit, the Crown Vic would be close. 1500 will buy you a new one. Unless you just want a flat deck. I have hauled several cars on one.
09-09-2009, 10:51 AM
You are still trying to use a light trailer and make it something it's not.
If you have 1500 dollars you can find a car hauler that will pull both.
Even if you upgrade the axle, what about the frame?
How about the surge brakes?
Start looking around even if you find a 16ft, they should both fit on that.
09-09-2009, 06:57 PM
Still, a trailer is a trailer, get it retitled. or get it titled as home or self built. here's the trailer i built out of a boat trailer. makes a hell of a nice trailer, in my opinion. i added 5 box steel crossmembers, welded in, and all of the bolt-together parts of the trailer have been welded, except on the suspension, obviously. it hauls our midsize kubota very well.
and honestly, if the GVW on the title says 3,000#, dont exceed that. yeah, the GVW on this is 2,000#, on a trailer that was completely bolted together. not a weld on the trailer. we welded every place a bolt was, plus crossmembers. i could easily see hauling a ton and a half on it with no problem.
09-09-2009, 07:48 PM
I forgot all about the different trailer designations. In the State of Flori-Duh, a trailer is a trailer. Campers are campers. They list the manufacturer, weight class, and whether or not is it a trailer.
I've seen boat trailers turned into car haulers. They usually were designed for heavy boats, having aluminum I-beam frames. They also rework the structure of the trailer to make it more square.
I also forgot about the surge brakes. My car dolly has surge brakes on it, and it is kinda jerky when you stop. Good news is that if it has surge brakes, then it should have the 4-bolt flange on each side of the axle to convert to electric brakes.
Have you given thought to having a trailer frame built? A friend of mine had a car trailer built to suit his purpose. He supplied the axles, springs, and design. A local shop welded the frame up for around $600. He then had to plank the trailer himself.
If you are going to use a car trailer often, but don't have the cash in hand for one, have you thought about financing one? I was going to buy a trailer for hauling my bike when I go out of town, but my credit sucks (I have a beacon score of -1... LOL). The shop I was buying from was going to give me a hell of a deal on a trailer that had been sitting on the lot for a while. They were going to even throw in some extras to get the sale. If my credit hadn't been bad, I would have bought it. So you might find a good deal on a trailer that has been sitting on a lot for a while.
09-10-2009, 12:00 AM
Funny you mention that. My dad found a trailer locally being sold by some old guy who used to haul his race car on it. Sounds like it could use decking and possibly tires (and likely brakes). It's a 20 footer with tire racks and crap up front for $800. Score. I move in January, plenty of time between now and then to get it ready.
09-10-2009, 10:59 AM
Chris Rock said - "Just because it can be done, does not mean it is to be done". In this case I agree. Taking an older boat trailer and repurposing it to haul a heavier dead load is potentially dangerous. I think it would be wiser to find a car hauler.
If you take it apart and reinforce everything, you are essntially building a home trailer from scrap. That puts the onus completely on you for it's workmanship. If you trust your engineering skills and you can fab it up good luck.
I think most everyone here feels that this is too much work, expense and potential for tragic failure for the outcome.
09-10-2009, 11:13 AM
I have converted several boat trailers into flat bed's. The last one I had to shorten the tounge remove all the stuff that held up the boat . It has a c channel frame all the way front to back so it is super sturdy as far as that goes. Mine was from a pretty big boat(got to dump it free a a dump day here!) But the axles are not stout enough for car hauling. I can weld and modify everything my self so when I need a cheap trailer It doesnt cost me much. If your trailer is wide enough to haul cars Im sure you could find axles strong enough to hold up used somewhere. I almost bought one from a guy with trailer house axles it was all home built. Good luck anything is possible just make sure it will hold car weight!:weld:
09-10-2009, 12:56 PM
The uprights were rated to 2100#, but still no GVWR on the trailer. I'm kinda disappointed I won't be doing this assuming it was all rated to 4k as it would have been nice and light. This 20 footer is going to be a beast, but it's rated high enough for the Crown Victoria, has electric brakes, racks and **** up front. . .
09-10-2009, 01:24 PM
The only problem with a homebuilt trailer, at least in Texas, you are limited to 4000GVW. I know different states have different rules, but it is something to check out.
09-10-2009, 11:41 PM
Wouldn't have been an issue. Would have been perfect for the Corolla. Good info nonetheless. So do some states require the orange markers all down the side? I have no idea what the lighting situation is on this 20 footer.
09-11-2009, 05:08 AM
This should answer any questions.
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