New guy here, broke my 10 bolt rear in first 6 days of ownership... recommendations?

[Bent77]

Huh?

That is EXACTLY what people should do.... tire size will dictate the gearing, lift height, and amount of HP/TQ to move it effectively.

If the OP doesn't actually want to run 35s, I could see stepping down in size to make the whole setup closer to "stock" configuration.

I'm a big fan of keeping things stock anyway.


-G

Dude. You suck at trolling

Just sayin

 

[Greg72]

Dude. You suck at trolling

Just sayin

You are a poopypants.

-G

 

[Bent77]

You are a poopypants.

-G

Your thread needs a moderator

Poopy head

 

[Blue85]

Huh?

That is EXACTLY what people should do.... tire size will dictate the gearing, lift height, and amount of HP/TQ to move it effectively.

Yes.

Swapping lifts is fairly simple also, he could be done in a weekend and by the time he sold the tires he has now be out a lot less money and headache in the long run.

No. Your "lift" determines axle pinion angles, driveshaft lengths, and a host of other factors that are not quickly changed. The lift might drive you to a C/V rear drive shaft, long-slip front drive shaft, 3/4 or 1-ton axles, slip yoke eliminator, crossover steering, shock mount location and even axle location. A lot of these parts will be custom if you do it right. That's why picking a final solution at the start saves money in the long run. Just re-gearing for a different tire size costs over $1k at a shop.

I agree that if you want simple and cheap, do like a 2.5" lift with stock driveshafts and steering and just plan for a regear (and lockers!) or axle swap. Even at stock height and 31" tires a lot of these trucks need lower gears.

 

[Big Ray]

All 1981-1986 K20's are 8 lug. He would need a GMT400 to get a 6 lug 14bsf.

Martin

Yeah, I meant the housing for our trucks bolt up fine, and use the 6 lug axle shafts from the GMT 400 trucks.

I think that came out right....I have done lots of reading on this...there is such a thing as information overload....

 

[Bent77]

There's a 1/2" difference per side from the 6 lugs to the 8.

Get the axle assembly, not just the shafts

 

[6.2Blazer]

Quickest and cheapest solution is to buy a used 10-bolt and slap it under the truck. Verify what gear ratio you have and go from there. I would recommend finding an open diff 10-bolt for now. Another option for a slightly stronger rear axle is a 12-bolt, but they are starting to get more rare since they have been out of production since the late-70s to early-80's. But also as mentioned I would caution about spending a lot of money on a 10-bolt....slapping in a $100 used axle is one thing but I would not spend a bunch of money on new gears, differential, and the labor on the 10-bolt.

Lower gears are better on the trans with 35's but not like the trans will magically go poof if you drive it the way it is. I can tell you from experience that axle gears are rarely changed on street driven 4wd trucks when they get jacked up and larger tires. A lot of the guys I have talked to, and this includes the newest fad in daily driven Jeep JK's with 35-37" tires, have not clue about axle gears and their relation to tire size. The biggest thing with the 700r4 is to keep it out of overdrive unless cruising down the highway at 60+ mph. It is the constant shifting between 3rd and OD, and locking and unlocking the torque converter, that causes issues.

 

[Blue85]

12-bolt is no stronger than 10-bolt.

 

[6.2Blazer]

12-bolt is no stronger than 10-bolt.

Sure it is. It is not a huge increase in strength but it is stronger. The comment about a 12-bolt not being any stronger has been going on for years on this site and likely stems from the typical internet legends. We have a saying here at work that is "the enemy of better, is best". What this means that people will disregard something that is slightly "better" because it is not the "best". In this case the 14FF is the "best" and therefore most people think anything less is a pile of crap.

I have personally known several people that have blown up 10-bolts and replaced it with a 12-bolt and then run for years with no problems. Is a 12-bolt the ultimate upgrade....heck no! If you are building a hardcore wheeler with big tires should you swap in a 12-bolt...again, heck no! But if you need a slightly stronger rear axle that is a direct bolt in then go for it. In most cases I recommend a 14FF swap but this is not really a direct bolt-in deal and costs more money......convert the front axle to 8-lug, new 8-lug wheels and possibly tires to fit, modify rear driveshaft for correct u-joint, new spring plates and u-bolts, and probably have to regear the front axle to match.

 

[82355]

A 12 bolt is no stronger than a 10 bolt. The ring gear is a freckle bigger, and the pinion is smaller. The comment about a 12-bolt being stronger has been going on for years and likely stems from the typical baseless legends.

I have personally known several people that have blown up 10-bolts and replaced it with a 12-bolt and then blew them up just as easily.

Martin

 

[Blue85]

On paper, the axleshafts will be stronger than the old 10-bolts, equivalent to the later 30-spline ones. I have seen some beat on quite a bit.

 

[rampage]

This is like arguing with someone who owns a Turd if his truck is better than a Chevy.

 

[dremu]

It has more bolts. It must be better.

-- A

 

[cyclic]

I just fitted in a 2004 Silverado 10 bolt with factory disk brakes. Stronger than the earlier axles, 4 inches wider than them also. Functioning parking brakes and no u joint changes needed. Spring mounts and shock mounts and you are done. Add in a small adaptor and bracket to get the parking brakes connected.

 

[Blue85]

It has more bolts. It must be better.

-- A

A rear 12-bolt is nothing special, but the front 12-bolt rules.

I just fitted in a 2004 Silverado 10 bolt with factory disk brakes.

Don't you know that the 2000+ axles are reverse rotation?








Just seeing if you'll believe it for a second....

 

[rampage]

Don't you know that the 2000+ axles are reverse rotation?

Just seeing if you'll believe it for a second....

If that was true just flip it upside down.

 

[sweetk30]

If that was true just flip it upside down.

and put a loop in the axle vent hose to keep the oil in.

 

[rampage]

and put a loop in the axle vent hose to keep the oil in.

Oil is overrated.

 

[dremu]

and put a loop in the axle vent hose to keep the oil in.

With a pump. You don't need to do this for factory mid-pinion axles though.

-- A

 

[cyclic]

And just as a reference, my burb is running 265/70r17 (32 inch) tires on a 2.5 spring front lift and rear flip. Dropped pitman arm, steering brace, 3.73 stock gearing, 1988 TBI w/ 700r4, sway bar links and some new shocks. Not too different from what your blazer was stock. I did go "over board" on my brakes, but not cost wise. The disk brake 04 axle compliments my Hummer H3 4 piston front brake conversion, which you can find on this site with a tiny bit of searching. Also giving me larger 14x1.5mm lugs all around. Not a huge truck, but definitely bigger than stock. Goes down the road VERY nicely.

And lastly, with her new rims and tires......................