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After missing any wheeling this summer due to taking the Bronco apart and never getting it back together I have decided to get my axle swap done this winter. I am swapping to full widths from a '76 F-150 and have a couple questions. Is anyone running a Yukon Zip Locker? I was initially looking at ARB's and the Yukons where mentioned to me. I have seen the ARB video where they destroyed the Yukon locker but this is 4-5 years old and I was told they have a new design for the 9" that was stronger. Anyone have any knowledge on these? Also thought I was set on gears but now I am not sure, thinking 4.56 or 4.88. My rig currently has a 302/C4/D20 and 37's, future plans call for a 351W/ZF5/Atlas and keeping the 37's. Any input would be appreciated.

Go lower than you think you'll need. I'm on 37s with 5.13s and it's about right if I had overdrive.

Agree on the gearing. Go 5.13's and don't worry about it. 4.88's would be a little better on the highway but it's still a little 302. need all the gearing you can get.

Another option for at least the d44 is the auburn ected. It's a limited slip/locker. I wish they would make one for the 9" already.

So how would the 5.13's be once I switch to 351W/ZF5/Atlas?

I'm running the same setup you described (351W / ZF5 / Atlas combo with 37" tires) using 4.56 gears.

Personally I wouldn't change anything. Mine chugs along at 2500rpm doing 75mph. If I wanted to be more aggressive, I would switch to 4.88s, but not 5.13s. The Atlas adds so much gearing that I rarely use 1st or 2nd gear on the trail. I'm usually running around in 3,4, and OD. In fact, the ZF5 is so low, that even with 4.56 gears, I was running trails in the San Juans in 2WD HIGH and only selectively using 4-HIGH or the rear locker.

From a strength perspective, 5.13s and up are really shrinking the pinion size compared to 4.88s and numerically lower. Of course I'm also considering reliability from a towing perspective as well. Just keep in mind that a 351W has a lot more low end grunt than a 302 and with a 302 you may have to jump one or two gear sizes to get similar performance.

Thanks for the feedback on gearing, I think I will most likely go with 4.88's. Back to lockers, I really want to go with selectable lockers and my gut is telling me go with the ARB's. On the flip side the Yukon Zip lockers where mentioned to me and I just thought I would check them out, see if anyone has used them.

pgilbeau wrote:After missing any wheeling this summer due to taking the Bronco apart and never getting it back together I have decided to get my axle swap done this winter. I am swapping to full widths from a '76 F-150 and have a couple questions. Is anyone running a Yukon Zip Locker? I was initially looking at ARB's and the Yukons where mentioned to me. I have seen the ARB video where they destroyed the Yukon locker but this is 4-5 years old and I was told they have a new design for the 9" that was stronger. Anyone have any knowledge on these? Also thought I was set on gears but now I am not sure, thinking 4.56 or 4.88. My rig currently has a 302/C4/D20 and 37's, future plans call for a 351W/ZF5/Atlas and keeping the 37's. Any input would be appreciated.

What gears were you running?

pgilbeau wrote:So how would the 5.13's be once I switch to 351W/ZF5/Atlas?

The best thing to do is play with a gearing/rpm calculator. Set your cruising speed & gear & trans and it will out an RPM. You want that RPM to be high enough to have power on demand, and not lug, but not too high for obvious reasons. 302s like to run 2500rpm-2700rpm. 351s have much more power at lower RPMs.

70MPH, 5.13s, 37s, C4=3261rpm
70MPH, 5.13, 37s, ZF=2478

The 'Crusing RPM' calculator is down the page a bit

https://www.novak-adapt.com/knowledge/gearing/

It's very hard to find a perfect gear for now, and after a major change like an OD trans, or a 351. But, if you do the 351 & ZF at the same time, the extra low end power might make the lower highway RPMs work. I'd keep the gears as high (numerically low) as possible if you plan on an Atlas. Your Atlas gears will give you more than enough crawl ratio with any rear gear.

Regarding the locker, does the Zip come in a 9". I think the only selectable locker for the 9" is the ARB.

They do have them for the 9": http://eastcoastgearsupply.com/c-115736 ... ord-9.html

I am really just trying to get an opinion on the ARB vs Yukon. From what I can tell the Yukon is cheaper but not really sure that it is worth it in the strength department.

[quote="Digger"]I'm running the same setup you described (351W / ZF5 / Atlas combo with 37" tires) using 4.56 gears.

Which Atlas are you running?

I should have addressed this in my first post. I'd go with the zip locker over the ARB in the 9". You're correct in your statement that they did change the design and strength of the zip in recent years. Primarily better material and machining. I like their air line better than the ARB too. As for the dana 44, ZOSO recommended an electric locker and so do I. I installed one in the front dana 44 of my uncle's full size Bronco on 37s and it's been flawless and perfect. No issues with decently hard wheeling and a much heavier vehicle. I've heard of and personally seen far fewer issues with electric lockers over their air operated counterparts.

cravenbronco wrote:

pgilbeau wrote:After missing any wheeling this summer due to taking the Bronco apart and never getting it back together I have decided to get my axle swap done this winter. I am swapping to full widths from a '76 F-150 and have a couple questions. Is anyone running a Yukon Zip Locker? I was initially looking at ARB's and the Yukons where mentioned to me. I have seen the ARB video where they destroyed the Yukon locker but this is 4-5 years old and I was told they have a new design for the 9" that was stronger. Anyone have any knowledge on these? Also thought I was set on gears but now I am not sure, thinking 4.56 or 4.88. My rig currently has a 302/C4/D20 and 37's, future plans call for a 351W/ZF5/Atlas and keeping the 37's. Any input would be appreciated.

What gears were you running?

Currently running 4.10's with Detroits front and rear. Its all going to be for sale once the swap is done. As for not running that was my fault, took brakes and steering apart and never got it back together in time for the summer.

pgilbeau wrote:

Digger wrote:I'm running the same setup you described (351W / ZF5 / Atlas combo with 37" tires) using 4.56 gears.

Which Atlas are you running?

Older 2-speed, 6:1 32spline outputs f/r

5:1 is as deep as you can go now in a 2-speed.

pgilbeau wrote:

cravenbronco wrote:

pgilbeau wrote:After missing any wheeling this summer due to taking the Bronco apart and never getting it back together I have decided to get my axle swap done this winter. I am swapping to full widths from a '76 F-150 and have a couple questions. Is anyone running a Yukon Zip Locker? I was initially looking at ARB's and the Yukons where mentioned to me. I have seen the ARB video where they destroyed the Yukon locker but this is 4-5 years old and I was told they have a new design for the 9" that was stronger. Anyone have any knowledge on these? Also thought I was set on gears but now I am not sure, thinking 4.56 or 4.88. My rig currently has a 302/C4/D20 and 37's, future plans call for a 351W/ZF5/Atlas and keeping the 37's. Any input would be appreciated.

What gears were you running?

Currently running 4.10's with Detroits front and rear. Its all going to be for sale once the swap is done. As for not running that was my fault, took brakes and steering apart and never got it back together in time for the summer.

I'll take the front ring pinion and carrier if possible

I will be listing all the axles,wheels, tires etc. once I get further into the process and can ensure everything is what the PO claimed it to be. I will make a note about the front ring pinion and carrier for you cravenbronco.

pgilbeau wrote:I will be listing all the axles,wheels, tires etc. once I get further into the process and can ensure everything is what the PO claimed it to be. I will make a note about the front ring pinion and carrier for you cravenbronco.

Sweet thank you soo much

For gearing, I'd consider your plans with the bronco. Are you going to be cruising it mostly and trail riding occasionally, or will it be predominantly a trail rig? And what Atlas are you considering? I'd be inclined to setup your gears for ideal highway cruising (if you plan to do so) and then get your trail gears from the Atlas.

Lockers - Not a fan of air actuated ones. Electric seem to have a better reputation, but you still have a wire running into the pumpkin that is subject to snagging. However, the air lines seem more apt to breaking due to temp or age. Keep in mind that since you can unlock hubs, you may not have a need for a selectable up front. And with an Atlas, you can pop it into 2wd Low (I believe). I've been out of the game long enough not to know what is available for the 9", but I'd look at a full detroit up front and a good selectable in the rear.

Every rig I have had up to this point I never did the axles or anything, just ran whatever was there when I bought it. That being said picking gears and lockers is a totally new experience for me. At this point the axles are already being built so I will just have to see how I like it and go from there. I found it was kind of hard to figure things out because I plan to swap the engine/trans/t-case in the next 6-12 months after the axle swap. I ended up going with 4.88's and the new version of the Yukon Zip locker for the 9" in the rear and an ARB in the front. Its definitely a learning process. Now that the axles are getting built its going to be selecting tires, I am leaning toward the Cooper Discoverer STT Pro in 37 x 13.50R17.