Limited slip differential installation.

[H20rider]

How difficult is it to replace an open diff. with a limited slip?
Can it be accomplished on the truck?
Is using a prebuilt assembly of casing, LSD and gears the easier and better way to go?
For light use, is the helical version worth the extra cost over the clutch style?

Extra things to take care of while the rear is open?


Obviously some of these are broad questions and I am not looking for precise, definitive answers…but more a sense of what I may be getting myself into.

Thanks, in advance

 

[73azbronco]

My sense is, I'm a 60 year old mechanic, certified, I have never opened a rear end because it's part magic, witchcraft and art. Recommend you drop the dough and have a shop do it.

 

[gnpenning]

A Ford 9 is one of the easiest to do. Plenty of information and videos on line.

The helical would be a better choice.

You can buy them all ready to go and just need to drop it in .

Watch some videos and then decide what works best for you.

 

[okie4570]

Like said above the 9" is easy and it's a great one to learn on. I will say I've regeared and rebuilt lots of axles over the years and I've put every one of them up on a lift to do the work. I most likely wouldn't have done very many without the lift lol. 9" is the only one I would entertain doing without a lift lol.

 

[Yeller]

Wish I could say that, I’ve never done one on a lift

As stated above. 9” is almost the easiest, second only to a 14 bolt. Watch some videos and decide. You do need a magnetic base, dial indicator, and a way to press the bearings on the new differential, the rest is just basic hand tools.

 

[Torkman66]

Yes 9” is easy compared to most others mainly because the pumpkin can be built on your bench. But…. getting gears set up with the right pattern, shims, preload, etc. is not easy to do right. Done wrong with just a few degrees off and your gears wil whine on Acc or deceleration.
My suggestion is to purchase a complete 9” pumpkin already geared with LS. All you do is pull the axels, pull the old pumpkin, put in new pumpkin, seat axels. That is all very easy.
A fully built third member with posi will run anywhere from $800 on eBay to 3 k from Curry. Why d you want limited slip anyway?

 

[jeffncs]

I built a 9” for my 65 mustang as well rebuilt the D44 in my bronco. While there’s a certain amount of magic going on in there, it can be done!

The 9” center is a chunk that pulls out the front of the housing. I used a wish-bone style mount that attached to my engine stand. Backlash and tooth pattern were challenging but it’s very doable.

 

[H20rider]

I was wondering because all of the videos I have found have the whole Rearend pulled.
As far as the question about “why posi”; I sometimes loose traction and I don’t want to get out and lock the from hubs.
I can usually overcome the traction loss with gentle throttling, but it is an annoyance.
And, no, the tires are not bald…haha

 

[bmc69]

I was wondering because all of the videos I have found have the whole Rearend pulled.

For 9" axles??

 

[DirtDonk]

Part of what the OP’s question is asking, what if they buy an assembly can it be done in the vehicle. Answer to that, as the others were saying, is absolutely yes.
If you buy a preassembled differential “chunk” (3rd member, hogshead, center section, etc) with everything already set up, then you just pull the axles, pull the old chunk out, put the new one in, re-insert axles.
Done…

However, that leads to the axles themselves. Most limited slips are still available in 28 spline variety. Most lockers are not. Some limited slips, (perhaps the Detroit Truetrac is one of them?) are no longer available in 28 spline.
So that would necessitate upgrading to 31 spline axles. Which is overall a good thing, and relatively easy to accomplish as a worthwhile upgrade.

 

[H20rider]

Yes 9” is easy compared to most others mainly because the pumpkin can be built on your bench. But…. getting gears set up with the right pattern, shims, preload, etc. is not easy to do right. Done wrong with just a few degrees off and your gears wil whine on Acc or deceleration.
My suggestion is to purchase a complete 9” pumpkin already geared with LS. All you do is pull the axels, pull the old pumpkin, put in new pumpkin, seat axels. That is all very easy.
A fully built third member with posi will run anywhere from $800 on eBay to 3 k from Curry. Why d you want limited slip anyway?

I was hoping that that was the case with a whole pumpkin. Does this mean all the bearings and shims are also in place. Forgive my ignorance.

 

[dmoses42]

I found this a while back, the videos look thorough to me but I've not tackled my rear diff yet...
https://hotrodregal.com/eaton-detroit-truetrac-install-9-ford-pem-racing/
They rebuild a Ford 9" third member to put in a Buick Regal. Just scroll down a little and there's 3 YouTube videos on the process. I've got this saved to my favorites for when I'm ready. Maybe this will help? Some of the more seasoned members on here will hopefully chime in if this is grossly inaccurate. Torque values might be different if the carrier isn't a Truetrac, I'm not sure. Good luck...

 

[DirtDonk]

I was hoping that that was the case with a whole pumpkin. Does this mean all the bearings and shims are also in place. Forgive my ignorance.

Yes. The differential assembly is completely within, or attached to, the third member.
When you buy a preassembled third member, you get a chunk (also referred to as a “housing” I believe), the new differential itself (the “carrier”whether open, limited slip, locker, or spool), the carrier bearings, the ring and pinion gears in the ratio of your choice and already set up properly.
You only need to add the gasket (or sealer), throw it on the main housing and probably never touch it again.

If you ignore the wheels and brake lines and vent tube, the entire “rearend” is comprised of four sub-assemblies.
The main outer housing, the axle shafts, brakes, and the 3rd member.
Those are the only things you will need to mess with usually. Other than maybe replacing old wheel bearings, if you’re not buying new axle shafts.
The drum brake backing plates can be left on the housing and just remove the axle shafts to free up the differential chunk to be removed from the housing, then replaced with the new one.

 

[Yeller]

In reality these are very hard to beat. I can’t buy the parts, let alone assemble for this price. It is 100% bolt in ready. I guessed at your gear ratio, they have 28 spline available as well, I find the 31 spline axles a worthy upgrade. Quick Performance complete 3rd member I’ve bought several from this company, very happy with them. This is with 100% all new parts, with even modest use I’ve found the factory 9” carrier housing to be disappointingly fragile. Nothing like seeing pinion spit out and laying on the ground 50 miles from pavement.

 

[Master Chief]

Depending on how you use or intend to use your rig, if you're going to install a prebuilt unit and have the money, it is also a good time to upgrade the axles.

I upgraded to a 31 spline third member with one prebuilt by WH and installed their extreme duty axles which come fully assembled with tapered roller bearings (meaning no separate seal).

 

[76YETI]

In reality these are very hard to beat. I can’t buy the parts, let alone assemble for this price. It is 100% bolt in ready. I guessed at your gear ratio, they have 28 spline available as well, I find the 31 spline axles a worthy upgrade. Quick Performance complete 3rd member I’ve bought several from this company, very happy with them. This is with 100% all new parts, with even modest use I’ve found the factory 9” carrier housing to be disappointingly fragile. Nothing like seeing pinion spit out and laying on the ground 50 miles from pavement.

Are the factory yokes 1310 or 1330? I'm not very smart, but I can lift heavy things!

 

[Yeller]

Are the factory yokes 1310 or 1330? I'm not very smart, but I can lift heavy things!

Most Broncos are 1310 however Ford or parts swapping in the past was notorious for slipping in a 1330.

Warning:
Nerdy technical overload data dump ensuing

There is basically no ultimate torque strength between 1310 and 1330, they use the same cup as bearing. However due to the cross being wider on the 1330 it does have a slightly higher continuous torque load over a 1310. In my opinion it is not worth making the switch as an up grade, if you have 1330 parts use them, if you have 1310 use those. If an upgrade is desired go to 1350.

 

[ntsqd]

In reality these are very hard to beat. I can’t buy the parts, let alone assemble for this price. It is 100% bolt in ready. I guessed at your gear ratio, they have 28 spline available as well, I find the 31 spline axles a worthy upgrade. Quick Performance complete 3rd member I’ve bought several from this company, very happy with them. This is with 100% all new parts, with even modest use I’ve found the factory 9” carrier housing to be disappointingly fragile. Nothing like seeing pinion spit out and laying on the ground 50 miles from pavement.

Interesting that they offer REM finishing of both the R&P and the bearings. For the $100 add-on cost I'd be all over having the R&P done as that should marked ly reduce friction (thereby lowering the diff lube's temperature) and improve wear life. I'm not so sure that it's worth doing the bearings.

 

[DirtDonk]

Something else to think about, if spending a little extra money isn’t a big problem, and falls in line with what you ultimately want to end up with, you can jump down the rabbit hole and grab a new housing as well.
For those that are upgrading their brakes anyway, you then have your complete original rear differential assembly that you can sell as a unit to someone.
Recoup some of your money.

Not really a viable rabbit hole, though, if really all you wanna do is change the gear ratio or add a limited slip. You can do that simply and effectively with all that’s been talked about already.
Just mentioning that all of the other options are out there, and not always completely out of line.

Says the guy that also sells really nice housings and brakes! haha!

 

[76YETI]

Paul you are a giver!