Gear swap- Axle / locker life span?

[guidoverduci]

I will be upgrading the gears shortly and I had a question about axle and lockers. The PO had 31 spline axles with a Detroit locker installed I’m guessing 10ish years ago. He purchased the 3rd member from Wild Horses but the date is scribble out. I’ve got a hand written carbon copy receipt on pink paper from WH so it must’ve been awhile ago. The gears he had were 3.50s, and I will be upgrading to 4.56. I’m deciding between buying a complete 3rd member and swapping it in, having a shop do it, or do the whole thing myself.

I’m curious to what life span axles and lockers typically have? I know the rig was barely driven in the last 5 years. Do I need to replace the axles? If I buy a 3rd member, is a locker necessary? Can I reuse the Detroit one that’s in there? Not too much off road anticipated, except for some light trails. I leaning towards buying a complete third member- just not sure if I need to add the lockers in.

 

[Digger556]

I will be upgrading the gears shortly and I had a question about axle and lockers. The PO had 31 spline axles with a Detroit locker installed I’m guessing 10ish years ago. He purchased the 3rd member from Wild Horses but the date is scribble out. I’ve got a hand written carbon copy receipt on pink paper from WH so it must’ve been awhile ago. The gears he had were 3.50s, and I will be upgrading to 4.56. I’m deciding between buying a complete 3rd member and swapping it in, having a shop do it, or do the whole thing myself.

I’m curious to what life span axles and lockers typically have? I know the rig was barely driven in the last 5 years. Do I need to replace the axles? If I buy a 3rd member, is a locker necessary? Can I reuse the Detroit one that’s in there? Not too much off road anticipated, except for some light trails. I leaning towards buying a complete third member- just not sure if I need to add the lockers in.

Axles and lockers, treated kindly to mildly, will last the life of the vehicle. I'm talking 100s of thousands of miles.

You can reuse the Detroit, but unless you plan to do some serious wheeling, I would go to a limited slip diff. If money is no object, get a selectable locker like an ARB. I've been running them for years. I've own 6 ARBs in various axles and trucks with somewhere around 500,000 total miles between them. I sold a EB44 with 120,000 miles on it and my current rear axle has some where around 150,000 miles on its ARB with no failures.


My axle shafts have all been OEM hardware. I would guess the axle shafts in my current rear axle have between 250,000-300,000 miles and are in great shape, even with nearly 20 years of wheeling on them.

 

[sykanr0ng]

You can use that locker with the new rear gears, it may not be the best choice for your uses though.

Axles do not have an expiration date, they last until worn out or abused to death.


Your front end will need a new carrier, 4.56 is on the other side of the carrier break from 3.50

 

[spap]

I think a
Or depends on the power and how it’s driven.
9 inch rear end with stock power 150/200 hp and stock tires I think would last almost forever if the oil was changes once in a while. It s pretty stout add bigger tires and more power and they still hold up just not like it would in stock form

 

[Broncobowsher]

Even with good power it should last 100k without even changing the oil.
About the only thing that really hurts those parts is contamination or severe impact loads. And those have nothing to do with time or mileage.

 

[blubuckaroo]

If I buy a 3rd member, is a locker necessary? Can I reuse the Detroit one that’s in there? Not too much off road anticipated, except for some light trails. I leaning towards buying a complete third member- just not sure if I need to add the lockers in.

You're asking about your need for lockers?
That's a good question, because thre's no "works well all the time" answer, unless you opt for a selectable locker.
Trails can be difficult without some sort of locker or limited slip, any of these will cause some driving problems on icy/snowy or even just damp asphault.
I happily ran an open rear on trails for years. Then, while in there for a gear swap, I put in a nice Yukon limited slip unit. It's great on trails, but now that darned thing will swap ends really easily when the road gets wet.
It all depends on your application. Lockers are often installed to brag about.

 

[guidoverduci]

You're asking about your need for lockers?
That's a good question, because thre's no "works well all the time" answer, unless you opt for a selectable locker.
Trails can be difficult without some sort of locker or limited slip, any of these will cause some driving problems on icy/snowy or even just damp asphault.
I happily ran an open rear on trails for years. Then, while in there for a gear swap, I put in a nice Yukon limited slip unit. It's great on trails, but now that darned thing will swap ends really easily when the road gets wet.
It all depends on your application. Lockers are often installed to brag about.

I hear ya. This is a summer time, daylight, dry trails rig. I feel like lockers aren’t worth the cost for the rare time I’d need them.

 

[nvrstuk]

Really depends on what you call a "trail"... lol Seriously tho, a LS would be very inexpensive and might come in handy a couple times on light trails...remember this, you'd be surprised the number of times one tire on each axle is barely touching the ground...especially with stock supspension...you will be spinning a wheel on each axles and looking embarassed w/o a ls on one axle...

I love my selectable ARB's. Been running one in the front D44 since Feb of '87 and the rear since about '96 when their 1st gen came out for 31 spline axles. Hundred thousand plus miles...easy... Couldn't wait to throw my Detroit in the garbage...I live in snow and ice for 4+ months a year...it's nice to go straight with a selectable.

 

[Broncobowsher]

Remember, he already has a Detroit locker. Just doesn't have a good ratio.
I really think that replacing the whole 3rd member is a very expensive and un-needed plan. Pull the 3rd, have it regeared, put it back in. Lots of how to videos on setting up a 9". It would be what I would call a good choice for a first diff to setup.

 

[DirtDonk]

It's a tough choice in your case, because you could do better than a Detroit on the street, but you already own it too. So keeping it is surely a cost advantage.
A new heavy duty nodular-iron 3rd member with larger bearings and the gear ratio and limited slip of your choice is probably coming up on $1500 easily. Probably closer to $1000 with an open diff. Which in spite of what shows up on everybody's wish lists, is still a legitimate way to go.
But either way you have a perfectly good fully assembled 3rd member with Detroit Locker for sale to help offset the cost.
The 3.50's make it less desirable of course, but someone that does their own gear setups wouldn't mind a decent deal on a good condition locker and chunk. Not sure what the market is at this point, but a few hundred dollars at least surely. ????

Doing it yourself saves a bunch of money if you don't mind taking the time. Depends entirely on your individual circumstances.
I hated to do it, but I just bought a fully assembled Detroit Truetrac 4.11 nodular setup because I don't have the time to put one together right now. But if you're going to learn, the 9" is the perfect unit to start with!

And that's when you decide whether to stick with what you have and only buy gears and bearings, or keep adding to the list of what you want.
I'm not sure how much a shop would charge you to change the gears in your area. Varies by shop still I would imagine.
But here again, you can save money by doing some of the work yourself. Take the chunk out and down to the shop, hand him the parts and come back a day or two later. Assuming you have someone local that will let you supply parts, away you go for less than just about anything else except doing the work yourself.

Then there is good used. Luck of the draw if you find one in your gear, and luck of the buyer-beware syndrome if you get a good one. But people do it all the time.

Different ways of doing it, with each one making sense under some conditions.
Good luck with that!

Oh, and for the axles, the only way to know if they need replacing is to visually inspect them. If the splines are twisted or have worn shoulders beyond a certain spec, replace them. If they're good, they're good enough to use and you don't need new ones.
Check the bearings too. If you know they only have 10 years and 10k miles on them, they're likely perfectly fine to use.
But if they're older, have more mileage, or you just don't know... When in doubt, swap them out.

Paul

 

[guidoverduci]

Thanks Paul. So far what I’m seeing... assuming I’m looking at the right stuff on quick performance...

Complete 3rd member with limited slip is around $1K. W/O is $500-600.
Here’s the one I was thinking... .I’m not sure what to choose for yoke, or whether I need to add any of those other things.

A local shop quoted me around $1200 for a drive in / out gear replacement for the rear. I didn’t think to ask what it would be if I just brought them the parts and 3rd member.

And good point on trying to recoup some of the costs for the one I have on there. Right now, I’m leaning towards just buying the 3rd member. I’m short on time, and it’s been down long enough. Time drive and enjoy it!

 

[needabronco]

My very first set of gears I set up took me 45 minutes on a 9", second time less than 30 minutes. You need about $50 in specialty tools to set up gears. They are literally the easiest axle to set gears up on, especially if your are learning how.

I've run and beaten on a Detroit for over a decade and wouldn't hesitate to daily drive with one, and I do a fair amount of running around on the pavement in my Bronco. There's nothing to be afraid of, just swap gears for less than $200 and run it. If you don't like it you can always swap out carriers another time.

 

[DirtDonk]

I run a Detroit around in my '68 and don't particularly like it. It's not bad enough to stop driving, but it's not a good match for my rig. Just bad enough that I am trying a limited-slip instead this time.
I really wanted an open diff, but could not pass up the chance to finally drive a Truetrac. After all these years of recommending them to others!

I like the locker and it's going to go into my off-road rig (if I ever get back off road!) with the lower gearing. In my case it was more an opportunity to change ratios (like in this case too) than to just get rid of a locker.
Should be interesting to see how much difference there might be in road manners between the two though.

But mostly I'm interested to see how the taller gears work on the road with the smaller tires and really strong running engine.

Paul

 

[jamesroney]

I'm pretty sure that I have an extra 4.57 ratio 9 inch.

I can do your gear swap for a lot less than what others are quoting. Where are you located? I'm in Fremont.

Send me a PM, or e-mail jamesroney@yahoo.com

 

[snipes243]

Another idea is to switch out the spring in the Detroit locker to a softer spring which allows it to release easier in a turn, which would street driving better. A lot of the drag cars and road course cars do this mod.

I believe they come with a #78 spring but there is springs from #25 to #125

 

[okie4570]

I've run a Detroit in the rear for years and have had no issues, consider it a high dollar item that you already own. Just regear and keep the Detroit. It looks and sounds daunting but you can do it. The 9" is a good one to learn on and it will allow you to appreciate it when you start on the Dana 44, which really isn't that bad either, just not as setup friendly as the 9". Where are you located?