What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Rear End Upgrade

JeffWithers

JeffWithers

Old Fart
 Premium
Joined
Aug 15, 2021
Posts
13
Reaction score
4
Location
Texas
Building a 90 K5, and installing a new 383 Stroker, with Holley Super Sniper, realizing about 500HP. My existing rear end is a 10 bolt, 3:42, with stock axles. It has 300K miles on it and needs rebuilt, but I'm concerned its not heavy duty enough to handle new power and 35" tires. Looking for suggestions
 
If you can't find a 9.5" with 6 lugs and aren't going 8 lug, I would consider looking into an axle from the '00 on up trucks. They seem to be a little more durable than the old 10B and there looks to be a 9.5 option in the '10 and newer trucks. I haven't verified specs, just going off of the size of the center section I have seen in a few trucks.
There is a SF14 tech thread on here which has some information that can be helpful.

The question that I should have thrown out 1st is, are you ok with moving spring and shock mounts? If you have to hire that done, it can change your preference.
 
Another option that's not talked about alot and I don't know if I have personally seen done in a k5 is a ford 8.8.

They came in everything ford made after they discontinued the ford 9"
They are DIRT cheap in the junkyards because they are so plentiful and parts are cheap and available. I got one out of a yard with all the brackets and disc brakes for 75 bucks. It's a complete rear end with the factory ford trac lock and 3.73s. It was out of a exploder.
Not k5 width, but it for a car project I'm doing. its a great cheap budget rear end.

Obviously if money isn't an issue then a the ford 9" needs no introduction.

If I was going to run your combo of a hot small block and 35s I'd run axles in this order:
8 lug full floater 14 bolt.
6 lug semi floater 9.5 ring gear 14 bolt
Ford 9 inch
Ford 8.8

The downfall of the 14bolt if really only the pumpkin size.
They are huge and a 14 bolt on 35s is basically a 10 bolt on 33s for clearance
If you go 8 lug, get a 14 bolt out of a newer truck. (Post 2001) you can get them with factory discounts brakes. A good upgrade.

Not taking anything away from a later model 10 bolt as mentioned above, I just don't much about those axles.
 
The newer axles are nice for the built-in disc brakes and parking brakes, especially if you get a late model 9.5". You'd probably have to live with the metric wheel studs, but there may be an equivalent one that could go in the front.

If going to 8-lug, I keep recommending the H2 rear end. Disc brakes, parking brake, 4:10 gears, 9.5" ring and an E-locker. Converting that to 6 lug is probably possible, but I can't tell you what rotor or backing plates to use.

At the bottom of my list would be buying chromoly shafts and all the strongest stuff you can buy for the 10-bolt and crossing your fingers.
 
Blue85 said:
At the bottom of my list would be buying chromoly shafts and all the strongest stuff you can buy for the 10-bolt and crossing your fingers.
Click to expand...

If the use case is a street vehicle this would work just fine I think.
 
Blue85 said:
The newer axles are nice for the built-in disc brakes and parking brakes, especially if you get a late model 9.5". You'd probably have to live with the metric wheel studs, but there may be an equivalent one that could go in the front.

If going to 8-lug, I keep recommending the H2 rear end. Disc brakes, parking brake, 4:10 gears, 9.5" ring and an E-locker. Converting that to 6 lug is probably possible, but I can't tell you what rotor or backing plates to use.

At the bottom of my list would be buying chromoly shafts and all the strongest stuff you can buy for the 10-bolt and crossing your fingers.
Click to expand...
Seems like a great rear end to grab.

But you will still need alot of fab work to cut off the rear suspension and add leaf spring pads and shocks.
It basic fab work but the OP didn't state what he did or didn't want to do as far as fab work goes.

Some of my options would require the same fab work.

I also think a fully built 10 bolt 8.5 would be strong enough. 35s aren't that big and 500hp seemingly isn't that much anymore.

Everything is a trade off of, axle strength, intended truck use, time, money, level of skill and talent for install, tools available and level of commitment for the project.
 
Last edited:
It’s also possible to use GMT400 6 lug axle shafts in a square body 9.5 sf housing. You’ll need about 1.5 or 2 inch spacers behind the backing plates on each side to get the brakes centered up properly. Someone on here or Pirate has a thread on it. Kinda makes the 6 lug 9.5 a bolt in.

9” ford or 8.8 ford rear ends from a 1973-1996 F-150 should be about the right width, if you go that route it’s easiest to use ford front hubs and rotors and go 5x5.5 for wheels all around. Otherwise you’re looking at custom shafts or redrilling bolt patterns.
 
nitro_rat said:
It’s also possible to use GMT400 6 lug axle shafts in a square body 9.5 sf housing. You’ll need about 1.5 or 2 inch spacers behind the backing plates on each side to get the brakes centered up properly. Someone on here or Pirate has a thread on it. Kinda makes the 6 lug 9.5 a bolt in.

9” ford or 8.8 ford rear ends from a 1973-1996 F-150 should be about the right width, if you go that route it’s easiest to use ford front hubs and rotors and go 5x5.5 for wheels all around. Otherwise you’re looking at custom shafts or redrilling bolt patterns.
Click to expand...
Do ford d44 hubs work on a 10b front? Would be surprised if they did. Maybe on an earlier chevy d44?
 
muddybuddy said:
Do ford d44 hubs work on a 10b front? Would be surprised if they did. Maybe on an earlier chevy d44?
Click to expand...
Direct bolt on. Just swap the Chevy 6 lug rotor and hub for the Ford 5 lug rotor and hub. Keep the Chevy caliper and bracket.

The entire Ford knuckle will fit also, it uses a 5 bolt spindle and most have the stupid rubber wedge calipers. Not sure if the hose fitting is the same.

Just for reference any open knuckle/internal lockout 8 lug dana 44 outers (Chevy, Ford, Dodge or Jeep) will swap over to your axle also. You can keep your outer axle shafts with any of them. You can keep your knuckles with any but ford as again, the Ford spindles are 5 bolt (Chevy, Dodge, and Jeep all used 6 bolt spindles). If you use Chevy 3/4 ton stuff you can keep your calipers although 1/2 ton calipers have a smaller piston than the 3/4 ton units.

Chevy D44 and 10 bolt are identical from the knuckles out. Housing and inner axles are the only difference.
 
I knew d44 parts interchanged, thought there may have been some differences with 10b’s. Good to know
 
I installed a 14 bolt six lug out of a pickup, forgot they year. Bought the bracket kit from Off Road Design and had a race car fabrication/driveline guy do the install. Bought a Yukon Duragrip and all new axles and bearings. 3.73 gears with 33" tires. It works great and is a touch narrower than stock.
 
Tiger5 said:
I installed a 14 bolt six lug out of a pickup, forgot they year. Bought the bracket kit from Off Road Design and had a race car fabrication/driveline guy do the install. Bought a Yukon Duragrip and all new axles and bearings. 3.73 gears with 33" tires. It works great and is a touch narrower than stock.
Click to expand...
GMT400 2wd axles are a little narrower than square body axles. The GMT400 4x4 rear axle is about 3” wider than the squarebody and pushes the rear wheel track closer to even with the front on squarebody.

Lots of extended cab Z71’s have the 9.5 14 bolt.
 
You must log in or register to reply here.

Latest Posts

Top Bottom