spring perches

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
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wrote:

Will not bolt in. 88 on P/U's have different spring perch spacings. ----------------- TheSnoMan.com
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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
SnoMan wrote:

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wrote:

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. ----------------- TheSnoMan.com
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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
SnoMan wrote:

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wrote:

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. ----------------- TheSnoMan.com
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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
SnoMan wrote:

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wrote:

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.

----------------- TheSnoMan.com
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SnoMan wrote:

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
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wrote:

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. ----------------- TheSnoMan.com
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SnoMan wrote:

Well, really, it'll come down to whichever is easier to get. Right now I've got a guy emailing me locally with a 14B from a 1990 Sub. I don't know if it's from a 3/4 ton or a 1 ton. Was there a difference between the two as far as the axle goes?
I don't mind overkill. It's better than underkill. And like I said, who knows what the future will hold? I may one day decide to slap on more lift and some 44's :-)

I've seen the D50 before. I know externally it's the same size as a D60. To me, it's sort of a waste. That thicker housing is stronger, sure...but I'm sure the thicker D50 weighs more. So that's one more vote for a 60 right there. There does seem to be a shortage of parts for the 50's. You don't see much, if anything advertised for them in the way of aftermarket parts.
As far as aftermarket options for a GM 14B-FF, the axle ratios I need are available, and so are air lockers. Yes, I know a Detroit is strong and cheaper, but I like being able to selectively lock, and I cringe every time I read or hear about the clunking sounds a Detroit makes while in use. Just wish I could get an E-locker. Wires are easier to replace in a pinch, and no compressor would be needed.
~jp
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