Axle Swap

[Ebrown]

I have 1986 K-5 blazer with a 6.2 and 700r4. I found a set of axles for cheap.
My question: (8 lug GM 10 bolt front w/ 4.10 gears 8 lug full floater 14 bolt w/ 4.10 gears

1) Will they bolt up to my blazer with out changing my spring pads on the axles?
2) I plan on running 31X10.50X16 tire in the winter and 33X12.50X16 in the summer will the 4:10 work the trans more and engine harder?

any input would be help

[wodan]

1: I don't know, but I think it will bolt up.
2: What kind of ratio do you have now?

[snoman87]

If they are from a 3/4T pickup then they will fit ... the 14bolt will not fit if it's from a 1T pickup/crewcab or 3/4T crewcab

4.10 gears with 33's will most likely be a similar final rear ration to the stock ration ... go for it :)

[Ebrown]

The ratio in my blazer is 3:42. why I'm asking is because my rear axle has some slop in it!

[snoman87]

The ratio in my blazer is 3:42. why I'm asking is because my rear axle has some slop in it!

The 14bolts are a very stout diff ... it's going to be much better than a 10bolt rear. As for the front a 10 bolt is a 10 bolt ... depending of your driving habits while 4x4'ing your probably going to snap the axle shafts with 33's. If your careful you will get buy without snapping ... avoid sharp turn with power.

What is your intended us, off road or DD with highway travel. It makes a big difference of gearing and tire size recommendations.

What size tires are you running now with the 3.42 gears?


Here is an example fo you to give you an example of engine RPM's ... I am running 3.73 gears with 33's behind a 6.2TD/SM465 combo. When traveling at 110km/h in 3rd (1:1 ratio) my RPM's are around 3K. Obviously OD would drop that down a bit, say 2300-2500 but your talking same sized tire and lower gears so with OD I think you still in the high 2's.

If it's a DD 4.10's are probably a little low, if it's a x4'ing machine then 4.10 are good enough for 33's

[AndyL]

I have a 14bff with 3.73s laying in the garage if you want buy it!

[Ebrown]

My blazer will be used for a dd and weekend off roading. As for now my blazer has 32 under it! The front axle has aftermarket shafts , u-joints and stub shafts in it. So I should look to see if that 14 bolt is the large or the small one?

[Ebrown]

AndyL,
Thankyou for the offer, But you are kindof far to travel for a axle!

[NH2112]

For a weekend wheeler I say a 10-bolt or Dana 44 will handle 33s, especially with 4.10s since you won't have to give it as much pedal to get moving. For hardcore wheeling you'd be pushing it, IMO. The 14-bolt will easily handle 36s in hardcore situations, and in a DD role 44s. The front pinion support bearing is a real nice feature in a 14-bolt FF and gives it a lot of strength.

[john8662]

If they are from a 3/4T pickup then they will fit ... the 14bolt will not fit if it's from a 1T pickup/crewcab or 3/4T crewcab


Why only 3/4 ton?

I would think that as long as it's a single rear wheel configuration that there wouldn't be a problem with the pads, etc. The main difference also could come the length of springs used, the 1 tons obviously had tougher springs, probably longer too.

Dually configurations would be different for sure...

Just curious!

Ebrown,

It might be cheaper/less hassle to rebuild the 10 bolt rear with the slop. IIRC the slop is mainly going to the in the spider gears (which are cheap) in the carrier... Fixin' to be doing the same thing in another purpose vehicle...

[DmaxMaverick]

I ditched the 10 bolt on my '85 years ago. Got tired of pickin' up pieces blown through the cover every 2 years or so. That was with 3.73 and 33X12.50/15's. I replaced it with a '78 12 bolt and changed the ratio to 4.10. Best thing I've ever done to it. 1/2 the miles on the Blazer have been with the "new" setup and 33" tires, and not so much as a hicup from it. My acceleration, mileage, and general manners really improved with the change, not to mention towing ability. Gearing was too tall, even for just highway, with 3.73 and 33's. Mileage went from 19-20 to 25-28. It's just happier there.

[Ebrown]

I had a chance on buying a built dana 44 with a electric locker and a corp 12 with a detroit. found them here in Michigan and mailed a a deposit check to the guy. He call that afternoon and told me that he had sold them. so I put a stop on the check ( Deposit ). So now I have a chance at a Corp 10 bolt 8 lug w corp 14. I don't want to mess this one up! To have axles rebuilt here in my town can cost alot of money and I don't want to put it into rebuilding 10 bolts.

[john8662]

fair enough. I can't agree more about 10 bolts lack towing ability. In something light they work fine.

[Ebrown]

I talked to the person that is selling the axles last night! He told me that the rear is a ff14 bolt. so the question is will I have to change the spring perches to work under my blazer? Some people say yes and some say no.

[Ebrown]

I talked to the person that is selling the axles last night! He told me that the rear is a ff14 bolt. so the question is will I have to change the spring perches to work under my blazer? Some people say yes and some say no.

[84 Convert]

I know that the perch width on the 3/4 ton is different than the 1-t. That should be a 3/4T set-up with the 44 front. As far as I know it should work for you. You might try calling and asking what the measurement is and check your own. try outside to outside of the perches. Oh yeah, the shock mounts are in a different place 3/4-1T 1-T is inboard the springs 3/4T is out board.

Hope this helps.
Gregg