I wanted to run matching tires/wheels on the trailer so that I could only carry one spare between the Jeep and trailer both and swap between either rig in an emergency if need be. With a good tire repair kit, one spare is all that is really needed anyway, so no need carrying two. It's a good place to save weight and space for other stuff. After getting my 3500# axle with electric brakes and EZ-lube spindles, and finally locating my pair of Moab rims, I came to the realization that the Moab rims would NOT bolt onto the 3500# brake drums/hubs as a direct bolt-on like I'd hoped. This meant a wheel spacer or adapter would be required to make it work. Great. I'd had the axle cut to the Jeep track width already with the Jeep spacers in mind, so my axle for the trailer is already at 63", which means my spacers or adapters for the trailer will be even wider than I wanted. Oh well, it has to be done in order to work. In the pic below, you an see why. Basically what is happening is the center bore of the 3500# brake drum hub is roughly 2 1/2" outside diameter and sticks up 1 3/4" from the WMS. The lug studs are only about 1 1/2" tall if I remember right. What happens is the center cap on the Moab rim is only 1 7/8" and the hub for the brake drum comes into contact with the narrower center cap and won't fit through the smaller hole. You can see that in the pic below-obviously the shorter wheel studs won't fit through the hole either and the WMS won't even contact:
I searched for a while trying to find an adapter or spacer that would work in order to mate the Moab rim to the 3500# brake drum. As we all know, the Moabs are 16x8 rims with 5x4.5 bolt pattern and 5" BS. It goes without saying the brake drum is also 5x4.5 bolt pattern which is a common off-the-shelf trailer axle part size, but the hard part is finding a spacer that has a center bore large enough to clear the hub on the drum. I run Spydertrax on my Jeep and have for well over 30,000 miles now, but after talking with Spydertrax direct and explaining the problem, it was determined by the Spydertrax rep that they would NOT work and they recommended I find a different manufacturer for my trailer. I could have ordered them, then taken them to a machine shop and had the centers machined out to the larger diameter and had the hub-centric ring removed and made them work, which then would have weakened the spacer and made them questionable from a safety standpoint, but why? It didn't make sense to go to the trouble and hassle of ruining and weakening a spacer making it questionable and unsafe, so the search continued. I only mention this here simply because I've seen it mentioned in other threads on other boards as a solution. It is not safe and I do not recommend it. There are other solutions that are much easier and much safer, so please, use some common sense and just buy one that fits right off the shelf.
Where do I do that you ask? Well after some searching I learned most folks are ordering custom spacers made to fit their needs. That is all fine and dandy, but is rather expensive and takes a few days to order, make and ship so it could be a while. I needed spacers now and didn't want to spend a fortune getting them. I thought I'd check one last place before going custom at a place here relatively local out in Cashmere Washington at JT's Differentials here: http://www.justdifferentials.com/
I noticed they sold wheel spacers so I called up and explained my situation, then asked if they knew the center bore diameter. Jeremy had answered the phone and said he didn't remember the exact dimensions but could I please hold and he'd go measure real quick and be right back. He was back in a matter of seconds stating that the center bore was right about 2.8". Great! the hub diameter was about 2 1/2" so this was a little more than I needed. He said I've got 1.25", 1.5" and 2" in stock, come on out if you think they'll work, I'm here till 5:00. I asked if he'd mind if I brought a rim and the drum to do some test fitting to make sure I got the right one. Jeremy said sure, no problem, bring them out with you, I'll have one of each on the counter waiting and we can test fit each to find the one that works best so you know they'll fit. Awesome, I'll be right out.
When I got to the shop, I test fit the first spacer in the 1.25" size as I wanted to keep the track width as narrow as possible. The spacer worked great! It bolted right on, everything worked fine, or at least it seemed to. No need to test the 1.5" or 2" spacers, so I just paid Jeremy for the 1.25" then was on my way back home to fit everything together, excited I finally had what I needed. The next day I got to putting the axle together, fit the spacers up then found when I put the center cap on, the wheel wouldn't fit-I was at least 1/2" too short!!! After inspecting things further, the dust cap for the axle made contact with the center cap on the rim. Crap! I didn't take that into account when I got the spacers from JT's the day before. After examining things I needed another 1/2" minimum of clearance to make this all work. JT's had a 1.5" spacer which would get me another 1/4" and I THOUGHT I could cheat another 1/4" pretty easy in another area so the simple answer was to call JT's back and explain my screw up, and ask if I could exchange my 1.25" spacer for a 1.5". Luckily I got Jeremy on the phone again who already knew my situation. I explained what happened and asked if it would be at all possible to make the swap. Sure, no problem, bring them on in, I'll have the 1.5's sitting here ready for you when you get here. Great! I was in a rush and sure enough, they were on the desk waiting when I got there so I was able to just drop them off, make the trade and go. The customer service at JT's was excellent, I was impressed with the help I got with these spacers!
The spacers themselves that you'll need are regular Jeep 5x4.5 bolt patter in the 1.5" thickness. They are made from 6061 T-6 aluminum using grade 8 hardware. JT's has these made to their specs for them. The center bore is about 2.8" so it will bolt directly on to the 3500# brake drum making it a safe, smart and easy way to make the Moab rims work on the trailer. You can get them in 1.25", 1.5" and 2" for the Jeep, but they sell other spacers for other rigs as well, and I think even for 8 lug rigs as well. Here's what I got for the trailer that was a direct bolt-on:
You'll notice the cost was right on these, which was about half or less than going custom so that was nice. I bolted them on using red loctite like I did with the Spydertrax spacers on my Jeep as I haven't had any trouble with them in over 30,000 miles now, so I expect these will perform just as well on the trailer.
more to come...
Best of Luck,