Quick question:

Does anyone know off the top of their head what the distance between
the spring perches should be on the rear axle of an '86 K5 Blazer /
pickup / Suburban? This would be for a 1/2 ton truck...

I found a cheap 14-bolt locally, and I'm trying to figure out whether
it'd be a bolt-in or whether I'd need to have new perches welded on.
This 14 Bolt came out of a 1998 truck.

My Blazer unfortunately is in a different state, so I can't measure it
:-(

Thanks in advance...

~jp

On 19 Jan 2007 09:15:26 -0800, "Jon R. Pickens" <jonrpick@gmail.com>

Will not bolt in. 88 on P/U's have different spring perch spacings.
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Well...that's OK. So what, the perches need to be relocated...no
biggie. What about the two shock mounts? Will those need to be
relocated as well?

~jp

On 19 Jan 2007 15:11:17 -0800, "Jon R. Pickens" <jonrpick@gmail.com>

I agree that the perches can be moved, it just is not a bolt in as it
sits. I cannot say for sure on the shocks. I have a 89 burb that is
like the one you want to swap axle into and a 2000 K3500 that is not a
silverado (1 tons that year were still old body style) so if need be I
can look at them both in the driveway and tell you more if need be in
regards to shocks.
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TheSnoMan.com

Well, no biggie... if I get this axle cheap, it'd be worth it to
relocate everything at once.

As far as springs go, should I swap in 3/4 ton springs too? What's
this going to do to the ride / handling characteristics of the K5?

~jp

On 19 Jan 2007 16:15:17 -0800, "Jon R. Pickens" <jonrpick@gmail.com>


It depends on what spring pack is on them now. Some 2500's came with 6
leafs and a boosterand new one today have 4 leafs and a booster to
make them ride nicer. If this a going to be a big lift with big tires
you want at least 5 leafs and a booster. It will make ride a bit stiff
but it will better control axle wrap up in springs from trying to turn
big diameter tires aggressively.
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TheSnoMan.com

Well, I'm looking for a decent compromise here... I'll need it to flex
some when off road, but be stiff enough to where it's not rocking back
and forth down the road.

I have thought of adding a "helper" and going with maybe a softer
spring. This is what I had in mind for a helper:
http://www.drivetrain.com/activesuspension.html

If it works, I could run a spring that's not too stiff but the Active
Suspension System would assist in managing body roll.

FWIW, I do plan on running some lift. I'm going to lose ground
clearance in the rear when I swap in a 14-bolt, so I'll probably add a
few inches of tire to compensate, and enough lift to allow it. I'm not
going to add too much lift. I don't need my axles to have a great deal
of articulation. I'm more into trails than I am rock-crawling.

I'll probably go from the 31" tires to 35" tires.

~jp

On 20 Jan 2007 07:31:54 -0800, "Jon R. Pickens" <jonrpick@gmail.com>


Problem with this setup is that it will increase axle wrapup under
high torque loads (the spring on it will increase spring wrap up)
wh9ich also causes changes in pinion ujoint angles and can lead to
shorter joint life too as well as wheel hop at times.


BTW, I looked under my 89 burb and 2000 K3500 old style truck and the
shocks are a bit different. They are staggered the same from side to
side but the shock tops are further away for axle centerline and they
are mounted inside of frame rail rather than out side like 87 on back
truck and 88 thru 91 burbs and full sized blazers. There is also a
different bracket on axle (which can be again fixed with a torch and a
welder) My gut still tells me to go with a 9.5 axle here because it
weigh about 75 pounds less, has better clerance, 6 lug hubs and it is
more than a match for 35 inch tires and it basically solid up to 38's
or a bit bigger. It also has more after market locker options too. I
am not knocking the 10.5 14 bolt as it is a strong rear end but it is
a bit over kill here and its stradle mounted pinion design (pinion
ride in 3 sets of bearings in a removable cage) limits size and design
or diff housing moreso that a convertional rear axle with 2 bear
pinion design and hence the reason for less locker option for the 10.5.


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TheSnoMan.com

Well, they say the Active Suspension setup is supposed to reduce axle
wrap and wheel hop...

I was just discussing the 14B on another forum, and someone started
recommending the Dana 70. Apparently better ground clearance with
equal strength. I know either is overkill for my tire size, but I'd
rather err on the side of strength. Besides, it's one less thing to
replace if I ever decide to go bigger, which is entirely possible.

The D70 does seem to have a good selection of gears and lockers. Not
quite as easy to find as the 14B, but they're out there, and not in
anywhere near the demand that D60's are.

My bigger concern is the 10 bolt front end. True, I won't be in 4x4
most of the time, but still, I don't trust it any more than I trust a
10B rear. Seems like there's no intermediate step between D44/10B
strength and a D60 front end. I just wish I had a trailer to carry
stuff in, as I missed an opportunity to get a free rebuildable D60
front and 14B rear from a scrapped CUCV...

~jp

On 20 Jan 2007 12:47:13 -0800, "Jon R. Pickens" <jonrpick@gmail.com>


If you look at the physics of the design, the more it is loaded with
weight, the more it trnd to cause pinion to pitch up before torque
input is even applied

A D 70 is over kill for your needs. dsome mid 70's to mid 80's GM 1
ton P/Us with single rear wheel came with a D70 and all dualies then
did too. A GM 10.5 14 bilt is petween a 60 and 70 in strength. and a
9.5 about the equal of a 60 (a bit less but not much)

Your concerns are well founded. THere is two thing to consider with a
axle be it front or rear and that is the axle shaft and "pig" strength
and the strength of the housing. Most worry about axle shaft and not
housings though which is a bit of a mistake. A 10 bolt front axle is
good for about 3600 lbs of load (give or take) as designed. Yes you
can exceed it but shorter life results When you used bigger tires and
ofst wheel you effectively reduce the capacity of axle because you
change the load center in relation to spring pads and axle pivot which
exerts more leverage on axle so that the same stress is seen at a
lighter axle load they with stock tires and wheels. YOu might want to
consider a D50 because it is basically a D44 in a D60 housing and with
stronger axle shafts to anf has about 90% of the torque capacity of a
D60 in a front axle. Ford has used this axle for manys years in some
models of trucks and they are not that hard to come by and offen over
looked. Something to think about anyway.
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