1720 lbs Harbor Freight 94564 trailer: 3000 lbs dual-axle modification

HF trailer mod

The 1720 lbs 4’x8’ Haul-Master trailer from Harbor Freight (item 94564) is a decent buy on its own with many users that rate their purchase highly.

$389 price (went up to $398 end of 2011) can be combined with HF regular 20% off coupon (or 25% off they have for the major holydays). After reading all the positive reviews, much thinking and getting too tired to clean my Honda CR-V each time I had to bring bagged concrete mix from Lowe’s, I have decided to pull the trigger and got it the spring of 2011 for a total of $311.99 tax included.

The trailer comes in 3 boxes, some are very heavy. Our local HF has the trailers stored in a large 40’ container outside and 2 store employees were able to load it into my small SUV without too much trouble (OK, one box was very long so part of it was on top of my head all the way home). The easiest way to unload was to break the boxes inside of the car and simply bring parts into the garage one by one.

1720 4x8 trailer on display at Harbor Freight

As I said the trailer is an OK thing and for most people it works well the way it comes after the assembly process. However, I wasn’t one of the happy customers. My 3 major issues with the trailer were:

1720 94564 trailer in boxes in my car

1. The trailer bed is exactly 4’x8’, with stake pockets located inside of the frame. With permanent metal walls installed like I wanted to haul gravel (or the official ugly DIY 2×4 setup with pockets used) there is no nice way to transport drywall or plywood sheets. With walls you lose about 4 inch of width and length of the trailer (effectively down to only 3’ 8”x7’10”).

2. 1720 lbs is not too much. OK, it is twenty-one 80 lbs bags of concrete (plus in US my Honda CR-V is rated to haul 1500 lbs only) but life is rough – I have plans to haul tons of gravel to finally finish my driveway and 1720 lbs minimum may be too low for my needs (a buyer of this trailer also has to remember that in 4 US states (California, Idaho, Nevada, New York – doesn’t matter if you register it locally over there or travel on the states roads – a trailer over 1500 lbs requires brakes).

3. The way it is constructed, the trailer wiring doesn’t work right. There is almost no ground coming to its end – only bolts are holding two parts of the trailer that are covered with thick layers of red enamel (I don’t think it is powder coating), so negative voltage can barely make it. Many users report that stop lights stop working after a year or so when surface rust make the rear half of the trailer totally inaccessible for 12 negative.

In Europe Honda CR-V with 2.0 liter engine (US version has 2.4L) is rated to tow 1200 kg (about 3500 lbs) when trailer is brake equipped and only 1300 lbs without brakes. As I said in US my official tow rating is 1500 lbs only (without brakes) and there is nothing Honda says in the manual about a brake equipped trailer, even if the car is clearly designed to haul more. I guess it is a part of a marketing game of Honda USA:  let’s put 4450 lbs GVWR on CR-V and offer much larger Honda Pilot to whoever has to tow more cargo, it is not Europe where Pilot is out of reach for most of the population. My problem was (except that I can’t afford Pilot at the moment) I couldn’t have predicted how many pounds of gravel my local mill is going to load with their Bobcat, not talking about shoveling it myself: 1500, 2000 or more, plus it was absolutely clear that even with 1500 lbs max load the safe stopping distance for CR-V is critically affected. So after much thinking I have decided:
1. To add brakes to the trailer and fortify the construction to safely tow (if it comes to that one day) at least 3000 lbs
2. To add permanent metal walls and still have the bed to accommodate 4×8 drywall sheets
3. To fix wiring ground issues

The trailer tires (5.3″ x 12″ Tire with 5 Lug Rim) are rated at 1050 lbs/80 PSI each and carry M rating – top speed 81 MPH. However, Harbor Freight has a printed warning on every wheel that says “Maximum highway speed = 55 MPH”. I’m not sure how a US company can legally limit a tire with US DOT M rating with 55 MPH only – my only idea is that with American legal system tires have to withstand 80 MPH  but cheap Chinese-made hub bearings are exempt, so that’s may be the case why we have that 55 MPH stamp on the wheels.

As you can see with my desired 3000 lbs trailer setup there is no way to carry the weight with the included 1050 lbs tires – we are about 1000 lbs short. We have two possible solutions: (first) to use larger wheels with stronger leaf springs and axle or (second) simply add an extra couple of wheels with another same type axle and a set of springs. After some thinking I’ve decided to take the second approach. My original idea was to order an extra axle from HF customer support with a couple of springs to use with their $49.99 12″ wheels. 15” or larger 2000 lbs wheels with a single axle do have some obvious benefits – easier setup (one set of leaf springs, one set of brakes, and no equalizers), somewhat cheaper price and a much better speed rating. But they also have a huge minus: for a small SUV like I have, to get a flat tire on a fully loaded trailer while going full speed can be very dangerous if not deadly. With dual axel setup on a tandem trailer you are still going to have working wheels on both sides, even if it is overloaded. Some other advantages and disadvantaged are listed here, but they were minor to me compared to the above mentioned.

I don’t want to describe much the initial assembly. The manual is very easy to follow. You want to level the frame very carefully and since I didn’t have a perfect spot to do that I had to use some bricks and cinderblocks. Here is Katrin standing next to the assembled frame after 6 hours.

Assembel 1720 trailer frame

After that, I had to hook up my Harbor Freight (of course) 120 Amp Arc welder to 240v and start doing the actual modification. Wired to 240V, that cheap welder works very well with 3/32 E6011 Lincoln electrodes from Lowe’s and that’s what I used through the entire job (later on the project I’ve added a small 110V fan to the welder making it work non-stop – before it was about 15 min of rest after 15 min of work).

The first part was to weld all the frame joints together. Not sure if it adds any serious strength – the metal of the actual frame is only 1/8″ so the OEM bolts are OK for it – but it fixes all the electrical ground issues.



Original leaf spring holder is cut to accomodate new central holderThe second part was to install APT5 Tandem-Axle Trailer Hanger Kit for Double-Eye Springs I’ve got  from Etrailer.com for $42.95. Unfortunately, all the equalizers and hangers I could find for any reasonable price were designed for 1 3/4″ leaf springs and the original 2″ leaf springs that came with the trailer (slipper springs BTW, not double-eye) were too wide. Based on that I’ve decided to get 2 sets of 3-Leaf, Double-Eye Spring Kit for 2,000-lb Trailer Axles, also from etrailer.com for $34.95/set. Oh well, good things do not come for free.

Here we have the frame welded and hangers installed. Notice that I had to cut the original leaf spring holders to accomodate the new hangers – they are too wide to fit inside.




Front hanger welded with an extra steel angle 

Also, you can see steel angle added under the front and rear hangers to add strength to the frame.







Original frame welded together 



The end of the day I hit the welded joints with a grinder to make them to lool a little bit better and sprayed all of them with black Rust-Oleum . So, whaever black spots you see on the original red enamel are welded joints I made.



 Reinforcing the frame





Next weekend I’ve got some more 4′ x2″x3/16″ still angle from Lowe’s. to reinforce the frame. I’ve decided to weld it into a square tube under the frame. To use four $10 (on sale price) angles may not look like a good idea, but it only what I had available at the moment. Each piece was simply placed on the frame and then welded together to create a solid 3/16″ tube. It was during that work when my cheap arch welder started taking 15 min brakes so I had to search eBay and order a small 110V fan ASAP to keep the welder cool.



Frame reinforcement - tongue





Here is the tongue area of the trailer frame with still angle added. Also, you can see a new trailer coupler welded in – I’ve got #66951 5000 lbs coupler from Harbor Hreight for $20 to replace the original one I din’t really like.







Frame with the 3/16 square tube welded together





 Here is the frame with the tube welded together.


Small 2" hitch I welded to the back of the frame








I had a 1-1/4″ to 2″ Hitch Adapter from Harbor Freight (#65023) I didn’t have any use for, so I’ve decided to cut it and weld it to the rear of the frame as a small hitch. Later on I have plans to use it with a truck  bed extender to load  12′ and 16′ wood pieces.


Spring kits are installed




Here, we have both spring kits installed on the frame. Since all the bolts and nuts were included, it was an easy task.


Trailer with axels, drum brakes and wheels installed




Here we are with axels, brakes and wheels installed. 7” electric brakes that include wheel drums and assembled brakes were $150/set on eBay, $300 total – ouch. But it wasn’t the last expense I had to face. Unfortunately, the original Harbor Freight axle uses non-standard spindles, hubs and bearings. So, common L44643 bearings that came with the new drums with their inner diameter of 1” (25.4 mm) and outer diameter of 50.292 mm didn’t fit the HF axle that is designed for some weird 30205 bearings that have 25 mm (about 0.98”) inner diameter and 52 mm outer diameter. 30205 are also about 1 mm thicker than L44643. I tried hard and was unable to find any bearings with 25 mm inner and 50 mm outer diameters and based on that decided not to get another axle from HF plus 2 sets of square brake mount flanges like I’ve originally planned (HF axles do not come with those). And I didn’t want to replace original spindles as well – they are welded very well and to remove them looked like a horrible time consuming task, not talking about spending money on all new parts anyway. Instead, I took an easy way and simply got two regular 2000 lbs axles from Northern tools for $49.99 each (item #1242) that come with proper spindles and brake flanges already mounted. Another huge benefit was that the new axles have 64 ¾” of total length vs 61” of the original HF axle – with the brake mounted 61” could be too short for the new drums. I’ve also got two extra wheels from Harbor Freight for about $40 each after their 20% off coupons.


Trailer on the ground


After much frustration while trying to lift the frame myself to put it on the ground I had to call a friend who helped me to complete the task. Brake drums have added some weight, no questions about that. Here you see the trailer (OK, now we can start calling this thing a “trailer”) with temp electrical wiring and the included light kit setup. Also, I have installed 2 sets of Curt Manufacturing bearing protector (bearing buddy clones) – paid about $26 total for those.




Cuts on the frame for the tandem equalizer to move





After drugging the trailer to the front yard and back behind my car I have immediately realized that there is a problem: the original leaf spring holder had its wall was too high to have the new holders setup on its bottom – the equalizer was moving too much on my uneven gravel driveway and spring eyes were hitting the metal walls making loud noise. Check the photo – the right spring is actually stopped from moving any closer toward the frame by the outer wall of the original spring holder. The fix was easy. To add extra way to move to the springs I have cut square holes in the original holder, like shown on the photo (the inside walls were fine since new holders didn’t go throw those). After that leaf springs could move all the way to the frame and stopped hitting it.



Taking trailer to Lowe's - the first trip



After testing the lights, I’ve decided that it is time for a real road test. Since I needed two sheets of 3/4″ 4×8 plywood to create the trailer floor, a trip to Lowe’s was a good chance to test the trailer and bring those sheets home.  No trailer brakes were attached at this time since my car needed proper wiring and a controller installed first.

The trip went very well! I was a little bit worried for not having a license plate on the trailer but, hey, how do I get a plate for a trailer that is not ready yet?  (Sounds like a poor excuse in somewhere in California or in NY I guess but I live in Alabama and there are not too many people here who have license plates on their utility trailers. So my hope was that our local cops are not going to notice my little trailer or at least would just give me a warning if everything goes bad – how do they know that I’m not on my way to DMV to register it?).



Parts to build a tandem dual-axle trailerYou may have a valid question: how much did I spend on all the extra parts so far? I’m going to put all the parts we are going to use together. However, we need to separate tandem conversion parts and parts you are going to need even if you use the trailer the way it comes. Based on the second, I’m not going to add any parts on the car side – every car is different, and some come with all the wiring in place from the factory. OK, here we have a picture of all the extra parts I had to purchase for the project:

1. 2000 lbs trailer jack, etrailer.com $27
2. 5000 lbs coupler from Harbor Freight, $20
3. Curt 4000 lb weld-on chain loops, amazon.com $12 (4 total x $3/each)
4. 5.3″ x 12″ 6 Ply Rated Tire with 5 Lug Rim, from Harbor Freight $120 (3 total x $40/each)
5. Spare tire carrier from Harbor Freight, $9
6. Trailer latch, $10 northerntools.com (2 total x $5/each)
7. Side panel kit from Harbor Freight, $110
8. Gate weld-on  hinge, etrailer.com $12 (2 total x $6/each)
9. Trailer brake light boxes from eBay.com $15/set
10. 2000 lbs axles from northerntools.com $100 (two total, $50 each)
11. Curt weld-on anchors (stake pockets), amazon.com $27 (15 total x $1.83/each)
12. Protective wire tubing from Harbor Freight, $9 (3 rolls, $3 each)
13. Tandem axle trailer hanger kit from etrailer.com $42.95
14. Trailer 1000 lbs stabilizer jacks from eBay.com, $32/pair
15. Curt 52040 breakaway kit with charger, local store, $30
16. Sway control kit, Harbor Freight, $20
17. 3 leaf double-eye spring kit for 2000 axle, $70 from etrailer.com (two kits $35/each)
18. Curt ¼” safety chains $12 from amazon.com (two $6 each)
19. 7” electric brake sets with hubs, brake wire and trailer connectors included, ebay.com $300 ($150/set)

Those prices are what I’ve paid extra, with all the coupons and discounts I was able to use. If we put everything together we are going to see a horrific price tag of $977.95 – a super add-on to the original $312 I paid for the trailer itself. Also, you need to add $40 I spent on plywood and about $150 I spent on 3/16 steel angle at Lowe’s. So, we are talking about final price of the trailer about $1500, paint and primer included. However, as I said, it is not so simple. Over $500 were spent on parts that have nothing to do with dual-axle mod (side kit, plywood, spare wheel, jacks, sway kit etc). I had about $600 I have really spent on adding brakes to the trailer and converting it into tandem (brakes, axles, breakaway kit, 2 extra wheels and suspension). Since my car insurance deductible is $500, to have $600 spent not to get into an accident is not too bad. Like I originally said, I don’t want to have a blown tire when drugging a single-axle trailer full of gravel and I want to have brakes on a trailer if it is over 1000 lbs. $600 is by no means cheap to spend on some fancy add-ons for a utility trailer, but not extremely expensive if you spend it on your safety.  Looking from another direction, I didn’t have to buy a larger SUV or a track to replace my Honda CR-V, something that I have started planning originally. In my case I’m saving thousands with this trailer, so it is an OK investment. Plus it is also a hobby project :)

The Harbor Freight trailer with metal wall kit installed and extra steel angles added for strength




 Here you can see all the extra steel angles I have used to add strength. The Harbor Freight metal wall kit for $99 was used to build walls. It was connected to the frame with revets – the metal is not very thick for 1/16 sticks I tried to use so revets were a better option.




Gate and rear anchors are welded in place





The gate hinge and rear anchors welded to the frame. You can see some extra metal on the side wall I had to use to get the extra length to have the true 4×8 bed size.












Front anchors welded in place









Front anchors. The front wall was too short as well – for the true 4×8 bed I had to add extra steel plate, you can see revets that hold it together. It is also welded to the frame and the angle on top.





Harbor Freaight trailer  with brakes, metal wall kit and dual axles installed






 Here is the trailer with the walls installed and all the wiring in place. I’m testing how the brake controller works I just placed in my car. You can see the breakaway kit near the spare wheel. There is no floor yet and the trailer needs to be painted. There are 15 stake pockets total welded to the steel angle on top the side walls, I think I paid $1.80/each delivered from Amazon. Also, you can see round 3/8″ steel rod going around the trailer welded to the pockets – the rod is from Lowes and works great to add strength  to the sides and stake pockets, plus it is also a tarp/rope holder. The spare wheel is hanging in front of the winch mount I’m building to use with a manual winch to load heavy things later on.


 Herculiner applied on trailer



With a 40% off coupon I’ve got a gallon can of Herculiner Truck Bed Liner from Advanced Auto Parts. I can’t say that $50 I paid is the best investment, but since I’m going to keep the trailer outside for now, I needed something very water resistant to cover the plywood floor. There are two layers of ¾ exterior grade plywood (expensive) that were not super easy to attach with bolts and I don’t want to replace those every year. So, after checking the cheapest options I have applied two layers of KILZ primer and then two layers of Herculiner on top of it. “HERCULINER is very difficult to remove from skin once it has dried” the manual says and they are not lying : I was wearing gloves and still managed to touch it with two of my fingers in the process – the thing staid on my skin for a full week. How does it look? Imagine millions of tiny bits of rubber dissolved (almost) in a gallon of high gloss black paint. I’d say it is very “durable” ( don’t want to use word “nice looking”) – exactly what I was looking for.


My HF trailer is almost ready, winch mount is done


Here we are: trailer is spray painted (one coat for now), has Herculiner applied twice, with its VIN number attached back to the frame to have it inspected. Trailer LED lights from HF (paid $30 for the set) are mounted and tested. I had to use caulk for some places  – that is what those white strips are. I will need to cover caulk with Kilz primer later on. You can see a winch mount I have made using some steel angle and a cheap ATV hitch mount. It also works as a spire tire carrier. Caulk was a big mistake BTW – Kilz or no Kilz it was getting wet and soft. Had to Bondo all the seams later on and it worked 100 times better.



"Bobcat" trailer


With spare tire, conspicuity (I can’t pronounce that word) reflective tape and eBay Bobcat stickers :) As soon as I went to Lowe’s two people asked me where I’ve got “nice small Bobcat” and how much did I pay for it :)




1 tonn of gravel



Here we go, one ton of gravel is loaded! Paid $18 for the ton. CRV has no problem pulling the weight, had to check that it is still there sometimes.







Unloading concrete mix. So far the maximum loaded weight was 3000 lbs. With brakes working very well never had a problem stopping. The only plan I have is to upgrade wheels one day to 13″ tires that have 45-50 PSI working pressure – the current 80 PSI take too long to inflate properly for 4 wheels and trailer is too hard on the road when empty.

Thank you for reading