8 lug swap questions

[mwood1985]

ok im a little overwhelmed here. ive got a of 38s for 16s cheap so its time to pull the trigger on a 14bolt swap.http://coloradok5.com/axleswap.shtml this writeup makes it seem like its a bolt in swap in the rear with no modifications other than driveshaft ujoint differences id like to use a full float 10.5 14 bolt for the rear and swap my front 10 bolt 6 lug hubs for 3/4 ton 8 lugs. I got the front parts figured out. what I need is info on what truck carried a ff 14 bolt that bolts up spring perches and shock mounts wise to a K5. my two best friends have a 76 K20 and a 85 both owned since new. the 76 has a full float an the 85 has a 9.5 semi float 14. from what ive read the 3/4 ton pickups and suburbans may have had both types over the years. i search for on car-part.com to find junkyards near me so im not wasting my time hunting for something not there. what years should i look for to get a bolt in swap 14 bolt full float? i cant put my k5 down for longer than a day to have someone weld on shock mounts ect because its the daily driver at the moment

 

[rebelgregory]

3/4 ton sqaure body with full floater is a bolt-in. 1ton is not - perches and shock mounts need relocating. The 14sf I'm not an expert on but I believe they are wider (not necessarily bad) and may not be a bolt in deal.

 

[4X4HIGH]

You need a 14ff from a 3/4 ton truck or burb. Not sure when the e-brake cable changed but if you find a year with the same e-brake cable it is a plug an play other than the u-joint. You may need to shorten the driveshaft though if the rig isn't lifted and you will need to adjust for pinion angle with shims.

 

[K85 Octane]

Not sure it's going to be so cut and dry. Only 3/4 ton trucks will have the right perches. Only 1 ton trucks FOR SURE got a 14BFF, but that doesn't help you.

It really comes down to this.
Search junkyards with vehicles that might have it
Or deal with CList and find something already pulled.

I can't give you a for sure answer. I don't know what year the 14SF started. If we narrow a list down by what vehicles we've seen them on......that REALLY cuts down your search results, missing out on possible deals I would also hate to mention that mine came from a '78 K20, but have you scope one out and find it different. Which happens with old vehicles anyway. Or weird things like a K20 suburban might have a 14SF but a K20 Suburban with 454 got a 14FF. That's how my cousin got his Or was that a C20 Burb. LOL, relying on memory

 

[lamberthkp]

It's been a long time but I did the same swap several years ago, changed 10bolt front from 6 lug to 8 pretty simple and picked up a 14sf at a junk yard no idea what it came out of but it bolted right up and I think I shortened the drive shaft. A few years later found a 1ton cucv with d60/14ff $100, on this one I did have to cut and move perches on the 14ff.

 

[82355]

The full floater is used in early K20's. 1973-1980 for sure in either 1981 or 1982 they switched to semi floaters.

No 4x4 Suburbans from 1973-1991 got a big block.

Martin

 

[mwood1985]

its a ways off from me trusting it to wheel on 38s with my current engine. too much torque for 10 bolts. im trying to do everything in as much sense monetary as possible. its currently the daily driver so I wanna swap axles fast on a day off til my sister gives me my duramax back. how hard is it to set up gears ect in a 14 bolt. I did my 10s but other than the adjusting sleeve thing on the 14 bolt is the pinion setup ect similar? im probably gonna have to regear whatever axle I find

 

[82355]

Find one with 4.56's.

The swap itself can be done in a few hours if you have everything.

If you have a ten bolt rear currently, you need a Precision #447 conversion U-joint.

Martin

 

[paratrooper307]

4.56 gears will likely be difficult to find in 3/4 ton, they were most common in military CUCV 1 ton trucks.

The 14SF is common in 3/4 tons built in the 80's and bolts right in. You'll want one from a 4x4 K20 or Suburban. The brakes are often easier to deal with too, although you will need to retain the brake cables, as some of them have significantly larger brakes (Mine had the 13" rear drums). 3.73 and 4.10 ratios were the most common.

You'll need the conversion joint, although you shouldn't have to mess with driveshaft lengths.

The front axle is going to be the same for gear setup as a 1/2 ton, and the 14SF is similar to a ten bolt. 14FF is different (extra pinion bearing, full-floating shafts, pinion assembly bolts in, etc) but not difficult. I'd go with the full-floater because of greater strength, parts availability, and full-floating axles. Plus with 38s, the lack of ground clearance won't be an issue.

 

[82355]

4.56's are much more rare than 4.10's or 3.73's, but they are out there. I've had a couple trucks with them that were not CUCV's.

Martin

 

[mwood1985]

im thinking do the 8 lug swap on my 10 bolt up front and just throw cromoly shafts in there. its already got 4.56s now. im not a hard core wheeler just dirt roads farm fields hunting property and mud but not much more than a foot or so. my goal is just make it reliable as far as strength with the 38s the 4.56s do well for me and I don't have plans to go any bigger with the K5. I went out to a friends junkyard today and all he had was 1 ton axles. mine measure about 45 inches outside spring pad to the other and the 1 tons seemed to be right at about 50 if that sounds right. is there a difference in width WMS from a 1 ton dually to a 3/4 ton srw? or is it the same just different spring mounts? and how about brake differences? if I can get all these questions figured out im gonna do a writeup ect on if for a tech article. make it easier on the guys later down the road

 

[82355]

There are two different widths of dually axles.

Spring perches are narrower on a 1 ton than they are on a 1/2 or 3/4 ton (which are the same).

If the guy has a bunch if 1 ton axles, you be better off spending money in a Dana 60.

Martin