14 bolt sf questions

[894x4burban]

hello all! im new to this site and i just want to say that im very glad to have stumbled across it, VERY knowledgeable people here...... My question today is i have an 89 half ton 4x4 burban and it came factory with 3.42 gears and it is currently at the shop getting regeared to 4.10's and im having them install a 14bolt 6 lug sf rear to upgrade from the 10 bolt..i call the shop today to check on the progress and he tells me that it is almost complete but the sf axle is 1.5 inches shorter on each side than my factory 10 bolt is but claims that it will work and that i lucked out because it has a posi unit and its in like new condition and he is looking for wheel spacers. i told him that i did not want to deal with wheel spacers nor did i want my suburban to look funny going down the road with a really narrow rear axle. my questions is .. what are my options? look for a mid 80's sf 8 lug axle and have the center section swapped out of the unit thats being installed and get 6 lug axle shafts or what?? any help would be appreciated

 

[Mav2u]

Is the burb like the blazers and the back is already narrow for tracking purposes? Or is that a blazer only thing?

 

[894x4burban]

good question..i dont know!! i am almost 100% that blazers trucks and suburbans and the same

 

[RollinKaos]

What do you have for wheels? You can get a different off set wheel, this will eliminate the need for spacers. I did not realize that the 14bsf with 6 lugs from the heavy halfs was narrower.

 

[Mav2u]

If I remember correctly the blazers rearends are 1/2 inch narrower for tracking through mud better, or so that was the design. I believe it was a 1/2 inch though. Which would make it a complete 1 inch shorter overall.

I can't seem to remember where I saw the info on here. But I know it is on CK5 some where.

 

[894x4burban]

im running factory rallys and thats what i want to continue to run

 

[894x4burban]

the 2 wheel drive heavy halves are narrower than their 4x4 counterparts,dont know why but they are and im thinking i got the 2 wheel drive version

 

[894x4burban]

anyone else have any ideas?

 

[Chevy305]

anyone else have any ideas?

Take a look at it for yourself and then decide. He may just mean that it doesn't track exacly like the front which is factory. The 4x4 14bsf 6lug is wider than the factory 10bolt from your burb. The 2wd is about 2" shorter than the 4x4 version. So it should be about an 1" narrower than your current 10bolt.

 

[6.2Blazer]

I guess it depends on whether he is saying the rear axle is narrower than the old rear axle or the exisitng front axle.

Pretty much all GM trucks had a narrower rear axle from the factory. 1/2 ton 10-bolts were around 1.5" narrower per side (3" total) than the front axle. If he is comparing the front to the rear axle then the 1.5" per side is normal and the same as stock.

If he is comparing the old rear axle to the new axle then you likely have the 2wd version of the 14SF which is about that much narrower.

 

[894x4burban]

he told me that from drum to drum that the new sf axle was over all 3 inches narrower 1.5 on each side than the factory 10 bolt rear he just pulled out and drum to drum was around 7 inches narrower but he said it has huge brakes...either way if it is 3 inches narrower than my old rear can i just get an 80's model 8 lug 14 bolt sf rear and change guts out of this new rear the shop is installing and buy some new 6 lug axle shafts to put into the 8 lug rear? will that work??

 

[894x4burban]

anyone?....

 

[Chevy305]

he told me that from drum to drum that the new sf axle was over all 3 inches narrower 1.5 on each side than the factory 10 bolt rear he just pulled out and drum to drum was around 7 inches narrower but he said it has huge brakes...either way if it is 3 inches narrower than my old rear can i just get an 80's model 8 lug 14 bolt sf rear and change guts out of this new rear the shop is installing and buy some new 6 lug axle shafts to put into the 8 lug rear? will that work??

Everything will interchange except the axel shafts since the 2wd is narrower the axel shafts will be too short.

run a search on the 6 lug conversion, its not too hard I did it myself:
http://coloradok5.com/forums/showthread.php?t=181502&page=36

 

[K65]

GM Rear Axle Widths

Here is some data for the width of rear axles
GM Truck (wheelbase, outside flange to flange, inside backing plate to backing plate)

• 106.5, 64.5, 63.0 -- 73-87 Chevy Blazer 2WD
• 106.5, 65.75, 62.75--73-87 Chevy Blazer 4WD
• 131.5, 65.8, 62.7 -- 73-87 Chevy C-10, K-10
• 131.5, 65.8, 62.7 -- 73-87 Chevy C-20, K-20, C30
• 164.5, 65.8, 62.7 -- 73-87 Chevy C-30 Crew Cab
• 129.5, 65.8, 62.7 -- 73-87 Chevy Suburban

I took out the 14 bolt 9.5" Semifloater out of my K20 and replaced it with the 10.5" ring gear 14 Bolt Full Floating axle which I upgraded to 4:10 Yukon gears and a Detroit Locker.

The 10.5" 14 bolt is about an inch narrower then its 9.5" ring gear cousin, but the truck handles just fine, on road and off road.
High quality wheel spacers are fine to use on the rear axle if you really care about the width or how it looks.
Just remember to put loctite on the axle studs when you install the spacers.

 

[894x4burban]

thankyou guys you the input...well i got it out of the shop today FINALLY!!! i took him 3 weeks to do this conversion,i think i could have done it faster myself lol it looks really good and he put some wheel spacers on it and you never could tell that its narrower i just hope that this suburban isnt too heavy for wheel spacers,ive always heard that spacers put more strain on your axle bearings and being that 'burbans are so much heavier than other 4x4's i dont wanna get into trouble down the road should i decide to go on a road trip with my bumper pull TT

 

[Chevy305]

thankyou guys you the input...well i got it out of the shop today FINALLY!!! i took him 3 weeks to do this conversion,i think i could have done it faster myself lol it looks really good and he put some wheel spacers on it and you never could tell that its narrower i just hope that this suburban isnt too heavy for wheel spacers,ive always heard that spacers put more strain on your axle bearings and being that 'burbans are so much heavier than other 4x4's i dont wanna get into trouble down the road should i decide to go on a road trip with my bumper pull TT

I think you'll be just fine. I mean worst case you replace the wheel bearings right?

 

[andyblack]

I think you'll be better off with the 14 bolt and spacers than you would have been with the 10 bolt. I think spacers have a bad rap from the 80s and 90s when guys would put 3" spacers on their Honda Civics and wear out the wheel bearings and CV shafts and stuff. As long as you use a quality aluminum spacer and put it on with Loctite, you should have no problems.

If you don't mind me asking, how much did the 14 bolt SF cost you?

 

[PavementPounder]

It isn't going to look funny without spacers.

 

[894x4burban]

$400 for a really low mileage rear with a factory locker out of a '97 Z71...i guess thats fair but i recently heard that if the factory carrier came with a locker that you cant put an aftermarket one in...is this true? hey pavementpunder thats a really sharp lookin burban!!! what kindof set up you got if you dont mind me asking?

 

[PavementPounder]

It isn't really anything special and has gotten a lot rustier since those pics were taken. Fortunately, everything that has rusted is replaceable. It already had the 4" lift on it when I bought it, but it had a 6-lug 10b/14bSF with 3.73's and retard-width Mickey Thompsons that made it go all over the road.

I had a 4.56'd D60/14bFF in it for a while with F-350 dual-piston outers and 35-spline stubs/lockouts, but I suffered a spindle nut retainer failure on the rear and it damaged the spindle. Pulled that set to perform the housing swap and ended up selling them off while they were out.

Now it has an 8-lug 10b/14bSF set with 4.10's. The motor is very tired, but it still does okay with the 4.10's and 315/70r17's. It can tow around town, but nothing big on the highway anymore until I do something about the motor. But, that's what the TBI 454 is for that is sitting in the garage. I plan to eventually get it back on a D60/14bFF combo with 4.56's again and run full 35's.