Sharp Motorsports 4600 Class Early Bronco

[LSharpNM]

I learned this the hard way on a project a couple years ago. Round tubing is not actually round, it just looks like it is. It is actually not even very close to the specific diameter either. I found that Ø1.00" round tube could vary .03"-.05" in diameter pretty commonly.

Funny that the 35 spline clearance in a D60 topic should come up. I'm in the middle of building a semi-clone of the Yukon tool. It is only a semi-clone because I will be using a Hougen annular cutter instead of their shell mill. The annular cutter is designed for exactly this kind of cut where the shell mill really is not. It is not a surprise to me that the shell mill is good for maybe two housings max before it's toast. Once I'm finished making it I'll be detailing what I did in "My Distraction" build thread on GFB. So far it's looking like it can be built for about $300 and some time on the lathe with a little drill press and welding time thrown in.

Sounds like a neat project! For what rear ends go for around here though, it isn't really worth messing with the old small spindle full-float 60 housings. For whatever reason though, late model full float Ford van rear ends haven't been showing up at the yard lately. The one I did come across, someone had cut the ends off the housing before I got to it ?:?

I can get a Sterling, 14 Bolt, or Dana 70 for the same price, and all of those are plentiful and super stout bone stock, but I don't want to deal with the weight and loss of clearance.

I had the same cancer in the rockers (along with 50lbs of body filler) and someone local had these: https://dufftuff.com/product/1-4-rocker-guards-1966-77-bronco/

so i went that way... i kept having to tell myself this isn't a restore and it will get messed up so made it easy on myself...

I did replace some of the door posts, but just made sure there were structurally sound. The pans and rear floor were really bad in the one i picked up and required replacement/fabrication...

I have no sheet metal experience so it is a good thing this isn't a restoration ;D The way I look at it, it will make for a good learning experience. I am not planning on trying to fix everything, but I want to fix the major issues.

Fortunately the major allowance for body modification in the 4600 stock class is the rocker panels. You are allowed to cut everything off below the door sill and between the tires. I am planning on cutting it all out and replacing the rockers with some box tubing.

 

[ntsqd]

For my use the D60 rear is just about perfect. I clearly need more rear axle than the existing 8.8, but don't want to get too heavy and don't really want the extreme U-J angles that a 9" would bring with it. The housing came to me nearly bare, wheel hubs and drum brakes only. Didn't even have bearing caps, so I get to fit some Mark Williams steel caps. Since I have to buy everything anyway it makes sense to buy them in 35 spline. which means I need to bore the spindles. It looks like with a pair of machined spacers I can fit an Exploder RDB kit as a bolt-on.

I've seen one of those van D60 rear assemblies out of the vehicle, they're every bit as heavy and bulky as a D80 or a 14bff. I don't see any advantage in them. For the size and weight of them there are larger, stronger ring gear rear axle options.

 

[LSharpNM]

For my use the D60 rear is just about perfect. I clearly need more rear axle than the existing 8.8, but don't want to get too heavy and don't really want the extreme U-J angles that a 9" would bring with it. The housing came to me nearly bare, wheel hubs and drum brakes only. Didn't even have bearing caps, so I get to fit some Mark Williams steel caps. Since I have to buy everything anyway it makes sense to buy them in 35 spline. which means I need to bore the spindles. It looks like with a pair of machined spacers I can fit an Exploder RDB kit as a bolt-on.

I've seen one of those van D60 rear assemblies out of the vehicle, they're every bit as heavy and bulky as a D80 or a 14bff. I don't see any advantage in them. For the size and weight of them there are larger, stronger ring gear rear axle options.

It may not be a night and day difference, but the Dana 60U is a bit lighter than rear ends I mentioned in my previous post. The big advantage of the Dana 60U over other full-float rear ends being the smooth, high-clearance casting that has no lip that hangs down to get hung up on. Additionally the advantages of a Dana 60U over the old Dana 60 full float rear ends include large bore spindles, larger 32 spline 1.4" diameter axle shafts, 3.5" tubes vs. 3.125" tubes, and disc brakes which are lighter than the old drum brakes. They also retained the 8 on 6.5" bolt pattern unlike the disc brake Sterlings. Another small benefit of the Dana 60 over the Sterling and 14 bolt is that the pinion has a smaller hypoid offset which raises the driveshaft slightly higher.

If I get my hands on a Dana 60U, I will just weld the carrier and put 5.38s in it for this season, and probably upgrade it to 35 spline down the road. I would be worried about stock 30 spline shafts, but the stock 32 spline shafts are probably just as strong as the 4340 shafts I am running in the front axle.

 

[ntsqd]

Yeah those drums are really only good for holding down my shade tent. The Exploder parts should get me a much lighter rear axle assembly.

That is a downside to this housing that I have, although it is not going under a crawler I expect to be spending a little time with one of these: https://www.lenoxtools.com/pages/lenox-metalmax.aspx and a respirator "tuning up" the bottom of the casting.

 

[LSharpNM]

I drew up some fixture pieces in CAD to make a jig for the axle and had a buddy print them out using his 3D printer. They work great and it was waaay easier and cheaper than trying to make something out of metal. The big donut-looking pieces bolt in place of the carrier bearings, and the thinner sleeves with the tapered ends slide into the axle "C"s to keep them concentric with the carrier bearings. I designed everything so I could use a piece of 1.5" DOM I bought for my cage as an alignment bar. Ideally I would have used a larger OD tube for an alignment bar since 1.5" is a little on the flexible side, but the pieces of original axle tube that I am sleeving to have a 1.75" ID which precludes using anything larger.

I also finally go around to installing my 50amp 220V outlets so I can run my welder and plasma set to "Kill" instead of running them on 110V. 175' of 6/3 armored cable isn't cheap

I finally pulled the trigger on some internal pneumatic bead locks so I could get to mounting the tires and wheels I bought last year in anticipation of the build. I went with internal pneumatic bead locks instead of more traditional bead locks for several reasons: they are significantly lighter, they lock the inner bead as well, they help protect the wheel and give some run-flat capability, no bolt torquing, and with wheels, they were cheaper than just about any traditional aluminum bead lock wheel. For wheels,

I went with some 16"x8" Procomp 1069s for that classic 8 hole polished look that is timeless on an early Bronco. I need 16" to clear my brakes, and I looked into swapping my brakes to be able to run a 15" wheel for more sidewall, but all the 8 lug 15" wheels are steel, and I am not willing to step down to 5 or 6 lugs. They were one of the lower cost wheels, but had one of the highest load ratings of anything out there (3,500Lbs.). They are cast instead of forged, but it seems like every traditional wheel under $200/ea and beadlock under $500/ea is as well, so hopefully they hold up. The only thing I really don't like about them is that the valve stem is in a really vulnerable spot, but I think that has as much as anything to do with my sizing (0 offset) which doesn't have a very deep outer lip.

For tires, I bought some 35/12.50-16 bias Trepadors (non-sticky since I have to run a DOT non-sticky). I have had good luck with Maxxis in the past, and the bias Trepador is a mean-looking tire that lots of other competitors in rock sports have been running with success (albeit sticky versions). Justin Reece has won two KOHs on the radial versions, so they should have what it takes.

The install however was a pain in the ass. Here are the highlights, although Coyote Enterprises has a very detailed installation video if you want to get into the nitty-gritty details.

First, you need to sand the inside bead edges of the tires so that they don't cut the inner tube. I used a 1.5" 50 grit drum which worked pretty well.

Then you need to figure out where you are going to put the valve stem hole in the wheel for the inner tube. It needs to be 6-8" clockwise of the normal valve stem hole to help balance the webbing overlap on the bead lock casing. I decided to put the hole on the inboard side of the wheel for protection and since it lined up better with where the inner tube valve stem naturally wanted to be. I mocked the wheel upon the hub, rotor, and caliper to verify clearance before drilling.

After center-punching the location, I drilled into it with a small pilot bit. Then I switched over to a step bit to finish it off which has the nice benefit of making a small chamfer for the O-rings to seat simultaneously.

Next you need to mount the inside bead of the tire and powder up all the bead lock components with talcum powder. Then wrestle everything into place and mount the outside tire bead. This part was a major pain in the ass. It might be easier with wider wheels and tires, but I had a hard time trying to stuff it all together while making sure nothing was pinched or twisted up inside.

Finished product:

The tires weigh about 68 Lbs. each, the wheels 21 Lbs., and the bead lock components 5.5 Lbs. The total for each wheel and tire assembly was ~94.5 Lbs. Not bad considering that most people are well over 100 Lbs. per wheel and tire with traditional bead locks.

After mounting everything up, the tires just looked kind of small to me, so I measured them up. Even brand new at 45 PSI they only measured 34 5/8" tall I was hoping they would be closer to a true 35" tire or maybe a little bigger since the 42" bias Treps measure just under 43".

 

[LSharpNM]

Hmm, none of my pictures are working anymore, I guess I'll have to figure out what is going on

EDIT: The pictures started working again, I am not sure if there was just a problem on my end

EDIT2: So apparently the site where I host my pictures is having issues after a software migration, so I apologize for the completely random and unrelated pictures that are showing up in my last post They are working on fixing the issue and asked us not to edit or delete any pictures at the moment.

EDIT3: The pictures should be working again now

 

[ntsqd]

I learned the hard way that round tube isn't all that round when I tried to use it for large hinge pins. I'll suggest that you look at McMaster-Carr for some 1.5" linear bearing shaft. It isn't too badly priced, is solid bar, has a hard surface so it won't ding easily, and is really and truly straight. I had a section bookmarked when I was thinking of changing to 14bff spindles, but I've since deleted it.

Yeah, 3.5" Back-spaced 8 lug wheels that look correct for the vehicle aren't easy to find. That's my current challenge.

 

[markw]

Going back to your rusted rockers: Maybe consider cutting them off, trimming your fenders and run rock skis. Gives you more clearance and you can tie them in to the frame and roll cage. What we did with my NORRA Bronco. Downside is weight.

 

[markw]

Here’s a quarter view

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[LSharpNM]

I learned the hard way that round tube isn't all that round when I tried to use it for large hinge pins. I'll suggest that you look at McMaster-Carr for some 1.5" linear bearing shaft. It isn't too badly priced, is solid bar, has a hard surface so it won't ding easily, and is really and truly straight. I had a section bookmarked when I was thinking of changing to 14bff spindles, but I've since deleted it.

Yeah, 3.5" Back-spaced 8 lug wheels that look correct for the vehicle aren't easy to find. That's my current challenge.

I am not concerned about using the piece of tubing; DOM (A513 Type 5) tubing has much tighter dimensional tolerances than other types of tubing and is plenty straight for a front axle housing. Now HREW on the other hand you can visually see is not perfectly uniform

Going back to your rusted rockers: Maybe consider cutting them off, trimming your fenders and run rock skis. Gives you more clearance and you can tie them in to the frame and roll cage. What we did with my NORRA Bronco. Downside is weight.

That is exactly what I am planning to do. I am still debating on how complicated I want to make it for myself. I am thinking I'll either weld in some rectangular tubing flush with the bottom of the door jamb, or alternatively some fairly thin (~1/8") angle with a heavier plate (~1/4) spanning the legs to make mini "boat sides" and cut down a bit on overall weight. I'll have to calculate the weight difference when I get to that point to see if it is even worth worrying about. The mini boat sides would only gain about 1.5" of clearance at the outside edge and be a lot more welding.

 

[LSharpNM]

Here’s a quarter view

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Looks good! I am curious on how you tied the cage into the sliders; it is always nice to steal other people's ideas ;D

 

[markw]

Thank you! The skis I have are American Bronco Company. No longer made from what I know. They are robust but really heavy. I use them for jacking points as well. They are tied in with brackets extending in to the frame at the A and B roll cage tubes. The down tubes are bolted through those brackets.
I'd use your A idea. B is way too much work. You'll find the details will bury you and the further you go in the project the more details become evident. The rabbit holes can become deep, slow and expensive. If there's a lesson I've learned in all of this it's KISS.
Been following your build, can't wait to see it and meet you at an event some day!

 

[ntsqd]

......

Funny that the 35 spline clearance in a D60 topic should come up. I'm in the middle of building a semi-clone of the Yukon tool. It is only a semi-clone because I will be using a Hougen annular cutter instead of their shell mill. The annular cutter is designed for exactly this kind of cut where the shell mill really is not. It is not a surprise to me that the shell mill is good for maybe two housings max before it's toast. Once I'm finished making it I'll be detailing what I did in "My Distraction" build thread on GFB. So far it's looking like it can be built for about $300 and some time on the lathe with a little drill press and welding time thrown in.

In case anyone cares, the write-up on making a D60 spindle boring tool:
https://www.gofastbroncos.com/forum/viewtopic.php?p=154702#p154702

 

[LSharpNM]

In case anyone cares, the write-up on making a D60 spindle boring tool:
https://www.gofastbroncos.com/forum/viewtopic.php?p=154702#p154702

That's a pretty cool tool you built, but for that level of effort and expense, why not just weld a set of larger bore spindles (or unit bearing flanges) on your housing? Are you planning to be boring out a lot more spindles in the future? How much lighter do you think a standard full float Dana 60 housing is than a Dana 60U?

I am not knocking what you did, it is certainly a good design and seems to work great, I am just trying to understand the reasoning

 

[ntsqd]

No idea what a 60U weighs. My best reasonable guess is that this axle assembly with Exploder RDB's will be about 350-370 lbs. Which according to "internet" axle weights that I could find isn't much heavier than the drum brake 8.8 in there now.

The one E-350 D60 axle (D60U?) that I looked at was not even marginally a two person lift. I'm not sure that the bare housing would have been. Based on physical size I'd estimate it's casting to weigh twice what this housing's casting does.

There is at least one other D60 (in MISF's K5 crawler) that needs this done to it.

It was more effort than it was expense. This is a hobby so I'm not worried about the time involved in making or using the tool. Were I building a crawler or a race truck I wouldn't have bothered with a 60 in the first place, I'd have gone straight to a 14bff, D80, or perhaps a Sterling 10.5

I first looked at going with different spindles and either Solid Axle hubs or JY 14bff hubs. None of the axle housing guys that I've found in the area can do full float housings. Looking into what I'd need to buy to make my own housing alignment tool would have cost about the same as this tool, but the parts cost (Rough Stuff spindles, SA hubs, etc) would be much more.

 

[LSharpNM]

Not much of an exciting update since I've been out of the house the last 3 weekends and been waiting on some parts to show up, but I figured I ought to keep the thread alive. I have been trying to get gears and upgrade parts for my Dana 20 from Jack O'Brien, but it's like the guy is allergic to money or something %) If it doesn't work out with him, I am not sure what I am going to do for a transfer case since I need better gearing than a stock Dana 20 provides and an Atlas won't clock above the bottom of the frame rails (not to mention they are $$$). I suppose I could still go the NWF integrated doubler route, but first gear would be stupid low in double low for an automatic (104:1). I would also worry about the strength of a stock Dana 20 gear set behind a doubler (Jack O'Brien claims his gears are ~50% stronger than stock). Both the atlas and doubler route would be heavier than an upgraded Dana 20; the Atlas has 40 Lbs. on a Dana 20, and I am not sure how much weight the doubler would add.

I finally bought my link material for the 3 link. After much deliberation I decided to go with 2.5" OD 1/4" wall DOM lowers since everyone bends 2"OD 1/4" wall DOM. I could have gone with heavier wall tubing such as 2.125" or 2.25" OD with the same 1.5" ID, but the 2.5" OD 1/4" wall was stronger, lighter and cheaper; although, I had to buy some new tubing bungs which ate up all the cost savings. I also considered heat treated 4130 and 7075-T6, but they were way more expensive and I was concerned about running aluminum links since aluminum "sticks" to the rocks worse than steel, and I am going to be doing a lot of sliding over rocks on 35" tires.

Here's a table I used to make my decision based on numbers generated from the Link calculator and prices from Midwest Steel and Aluminum and Bent Fab AZ:

Here's the obligatory beer can comparison between a beer can and 1.25" rod ends with both 1.5" and 2" ID tubing bungs:

The 2" ID tubing bungs are from Rockwell Offroad since they had the best pricing I could find and hex ends. The nice thing about jumping to 2" ID bungs is that there is a lot more meat in the threaded area, so you don't have to worry as much about warping the threads when you burn them in.

I also made a material rack for my tubing so I could stop tripping over it

I finally managed to score a set of decent used tires for my race spares since I don't have a baller tire sponsor that sends my free tires It took me almost six months to find some tires that weren't roached with the seller asking for 75% of new price %)

 

[LSharpNM]

I figure I should add in a few pictures I haven't posted previously just so people know that this build still has a pulse

I used a propane weed burner to preheat the axle housing to ~600ºF prior to welding and ran some .035" ER70S-6 in my Millermatic 211 cranked to kill. I did some post heat after welding prior to wrapping the housing in blankets and it seems to have worked out; no cracks or warpage

Not the prettiest welds since I was rushing to get it all welded up before the housing lost too much heat.

Looks like a body :-X

Stealing the C4 out of the '75

 

[LSharpNM]

I wish I had more to update, but I have had to many things going on lately and haven't had the time I need to focus on this thing and make some serious progress (I am going to be out of town this weekend too %)). If anyone is local and wants to be a part of the race effort, let me know; I need some people who are willing to get their hands dirty and not just show up on race day.


I have my C4 with the guys over at Dynamic Race Trans right now getting their "Competition Plus" build which includes a hardened input shaft, partial rollerzation, and a forward manual valve body. I also had them add their C4 low gear set to the build which convert 1st and 2nd gear to 2.90 and 1.60 from 2.46 and 1.46 respectively. They claim this build should be good with over 500 HP and is what they recommended for my use even though I'll probably only be around 350 HP at the flywheel for the first race season, and maybe closer to 450 HP in the future.

I also ended up ordering an Atlas 3.0 ratio transfer case after all after wasting way too much time trying to do business with Jack O'brien to build the Dana 20 %) Jack O'brien finally gave me the price on the gears after literal months of back and forth ($2,217.32 for just the gears for those wondering), and with the cost of a twin stick kit, modified shift rails, and a 32 spline rear output, it would cost considerably more to build out the Dana 20 than just buying an Atlas Not to mention, there is no 32 spline front output shaft available for the Dana 20, and the factory 26 spline front output shaft from full-size Dana 20 applications are impossible to find now. Unfortunately, the lead time over at Advanced Adapters for an Atlas is currently at 20 weeks It is going to be cutting it close to KOH, so I am going to build with the Dana 20 for now and hopefully have time to swap it in before I need to head out for the lake bed. The crawl ratio is going to suck at 38:1 if I end up having to run with the Dana 20 :barf:

I am going to start working on the engine next, but I need to make some room since all three of my engine stands are occupied at the moment. The plan is go .030"over and stroke it out to 347ci and run about 10:1 compression. I've got an Explorer top end (GT40P heads and GT40 intake), accessory setup, and coil-on-plug ignition system. I am thinking I am going to run a Comp XE264HR cam which has .512"lift on the intake and exhaust and 212/218 intake/exhaust duration at .050" since the GT40P heads don't have any additional flow above .500"lift and I want to maintain strong low and mid RPM torque and don't plan on revving it out past 6,000RPM. I also want to be able to run as low of a torque converter stall as I can get away with to avoid having to battle high tranny temps. If anyone thinks I am way off base with the cam selection, or has a recommendation for a better cam for my application, I am all ears!

I still haven't had luck finding a disc brake Dana 60U for the rear and have been kicking myself for not grabbing one of the drum brake versions I came across earlier. At this point, I can't keep waiting much longer, so I am going to grab the next Dana 60U that shows up at the yard regardless of the brakes it has and I'll just spend the $350-$400 for a brake conversion if I need to.

 

[ntsqd]

I've been slowly working out how to mount an Explorer RDB system to my D60. The rotor will need to be machined and I'm not too excited about that. Then I need to make two adapters. One that bolts the rotor to the backside of the wheel hub's flange, and another that centers and correctly spaces the backing plate / caliper mount relative to the housing flange. I think for a street driven truck on 35's or less that this RDB system is a good choice. For taller tires on the street it may not be.

For really tall tires (let's say 40"+) on a hard core crawler I'm pretty sure they won't be. At that point I'd look at the typical RDB kits that use the GM 'Metric' caliper (ala some of the "Cadillac Kits"). These appear to use the front rotor from a K20 or something like that. Just don't expect an actual, functioning parking brake from such a brake set-up because it either isn't going to happen or it isn't going to last.

 

[jmart52]

Looks like a good project! If you still need a hand during race week I would probably be able to help. I crewed on Andrew's KOH rig also.

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