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FAQ - Chevy/GMC Solid Axle Swap
12-09-2005, 01:42 AM
Post: #1
 
Can an admin make this sticky please?

A lot of people are interested in converting their 88+ year chevys from Independent Front Suspension (IFS) to a Solid Front Axle. This is called a Solid Axle Swap (SAS). Some of the advantages of doing a SAS are better flex, strengh, and reliability, which means fewer broken parts with larger tires, and it is easier to get larger lifts. You an convert to either a coil sprung or leaf sprung suspension. The leaf sprung conversion is easier.

I have done a leaf sprung SAS on an 88-98 truck, usually called Old Body Style (OBS), so I will discuss that.

You will obviously need a solid axle for the front. The best axle to get is a dana 60 from a 78-79 Ford F350 or F250 with Snowplow package. This is a strong 1-ton axle with a drivers side pumpkin, so you can keep your factory transfer case unless it is autotrac. This axle also has kingpins which are stronger than balljoints. You can also use a dana 60 out of and 86+ ford F350, but the spring perches are wider and this may cause your tires to rub the leaf springs. You can get a dana 60 out of a Chevy 73-91 Chevy 1-ton truck, although it is passenger side pumpkin and you will have to change your transfer case. Other axles that will work are Ford 78-79 Dana 44's, which you can get from an F250 or CrewCab F150 or Chevy dana 44/10 bolt from 73-91 1/2 ton or 3/4 ton truck, although they are all more prone to breakage.

One of the hardest things about a leaf sprung SAS is finding something to use for brackets to hold the leaf springs. You can fabricate those out of parts from an older Solid Axle Chevy, or you can buy a bolt on kit that a company sells. I used the kit from Offroadumlited (ORU), http://www.offroadunlimited.com. They sell 4 different kits. When ordering, keep in mind that Ford 78-79 and all Chevy axles are 32.5 spring pad width, and Ford 86+ is 36.5 spring pad width, so you must order the kit that matches your truck and the front axle you plan to run. ORU sells kits for 88-98 2wds and 4wds, and 01+ 2500's. Another company that sells bolt on kits is Fabritech, http://www.setstr8.com. I don't have experience with their kits, although I have heard good things. They do sell kits for New Body Style (NBS) GM 1500's, I believe for 2000+.

The ORU kits include front and rear brackets and shackles to hold the leaf springs, ubolt plates and weld on shock tabs for the axles, bump stops and longer brake lines. You will need 47" long leaf springs that fit the front of an 88-91 blazer or suburban. Leafs that fit a 73-87 Chevy will work, but you will have to buy bushings for an 88-91 since they are designed for a larger bolt on the shackle side. You can buy these springs in lift heights from 2"-12" and you could have larger ones custom made. The ORU brackets add 3" of lift by themselves so you could have up to 15"+ of suspension lift if you wanted.

Beside the axle, brackets or ORU/Fabritech kit, and leaf springs, you will need new shocks, possibly a sway bar, and crossover steering. You may also need a new front drive shaft and transfer case.

The crossover steering that is in the TOTM in the forum is basically the same as what you will use in SAS. When doing a SAS though, you can use your factory steering box. Your stock pitman arm gets replaced by a saginaw pitman arm with a hole in the end instead of a balljoint. I got my pitman arm from Offroaddesign (ORD), http://www.offroaddesign.com. You will also need a steering arm for the passenger side of your axle, and a custom length drag link to connect the 2. ORD sells all this, as well as ORU. I got my drag link and steering arm from Sky Manufacturing, http://www.sky-manufacturing.com.

Most likely you will need new wheels and tires after you do your SAS. One of the reasons for doing it is normally for strength, which in turn lets you run bigger meats. Most of the axles mentioned above are also 8-lug so you will need wheels to match.

As far as costs, they can vary greatly depending on whether you use a dana44 or a dana 60, what kind of steering you use, if you buy brand new wheels and tires or used ones, if you regear and get lockers, and if you use a kit or make your own brackets. I have about 2500 not including tools and wheels and tires in mine. Tools and other little parts can add on quite a bit, so budget accordingly. I have seen some solid axle swaps cost as mush as 10k.

I know this doesn't cover everything, but hopefully its the basics. Anyone please feel free to add any info you have to this.

Here are two excellent SAS threads by Choga and Big Will:

http://www.pavementsucks.com/forums/view...opic=50418 Choga's SAS

http://www.pavementsucks.com/forums/view...opic=39296 Big Will's SAS
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09-30-2006, 08:04 AM
Post: #2
 
Thought I would update this with more info. I decided to go bigger with my SAS and I ran into some more problems. I am now running 16" suspension lift (3" bracket, 12" springs, and 1" zero rate). I had some pretty good bump steer with 10" lift so I new it would just be worse. As leaf springs get more arched it is possible for the bushings to give more and therefore your axle can move sideways. Since your steering works sideways as well your truck can actually steer itself as you hit bumps, and this is called bump steer. You may end up constantly steering left and right to correct it. I trac bar works against this by holding your axle from moving sideways. I purchased ORU's trac bar for around $300. Its not the ideal tracbar but works decent enough for me and is completely bolt on. You may wish to fabricate your own or have a shop do one.

I also ran into a problem getting driveshafts to fit. In my experience a stock front driveshaft on an 88-98 model Chevy will start to bind at ride height with 8" lift. You can grind some areas and get it to work higher, but it still might bind with suspension droop. I am running a front driveshaft with a dual cardan/cv joint on the transfer case end. Even with that I had to do some grinding to make it work. The angle on the axle end will start to become a problem at this much lift as well. You may wish to have your axle tubes cut and the pinion turned up, or you can also get a front driveshaft with dual cardan joints on both ends to help this problem but be prepared to spend $800-$1000. You may also wish to have a dual cardan joint put on your rear driveshaft to help eliminate vibrations.

I had original done my SAS with a dana 44 front, but I have a dana 60 now, and I pretty much completely rebuild all of it. Unless your truck is a trail only rig and you just want to be as cheap as possible on your SAS I would recommend you replace bearings, seals, balljoints/kingpins, u joints, rotors, pads, and calipers in you have a junkyard axle. I can't stress enough how important new parts are on an axle that will see any time on the road. I don't know for sure how much my SAS costs are now but I would guess 8-10k for everything including axles, rebuilding them, springs, regearing, brake lines, driveshaft upgrades, and tires, and much more.
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12-01-2006, 09:36 PM
Post: #3
 
I have designed a trackbar that seems to be working well on my SAS 94 Suburban.I will try to get pictures when i get ahold of the camera.Mine has 8" of lift so its not as exstreme as yours but i dont have any bumpsteer.
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12-01-2006, 10:28 PM
Post: #4
 
ive done a couple sas setups , id like to see your design

post pictures Thumbs Up!




~ken~
aka. out
get your bouncing truck here, http://www.bouncingtrucks.com
my 88 sas "mudwasp" here http://www.pavementsucks.com/board/threa...otor-build
88 chevy k2500, started as reg cab lb, now reg cab shortbox, sas 17'' of lift, 52'' front springs large bbc , 79 dana hp 60 chevy outers, 14bolt ff spooled 5:13 gear ,divorced 205 and 44" tsl front 21.5x16.1 ag tires rear
1998 k3500 gmc crew cab dually L65 6.5TD 4l80e with a couple of mods
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12-03-2006, 08:03 PM
Post: #5
 
Here is the pictures of my trackbar
[img][/img][Image: SSA52544.jpg]
[img][/i[Image: SSA52545.jpg]mg]
The tube im using 1 1/4" .250 DOM , 1" threaded end and rubicon exspress flex joints
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12-03-2006, 08:05 PM
Post: #6
 
[img][/img][Image: SSA52545.jpg]
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12-03-2006, 09:43 PM
Post: #7
 
where do you get those joints?




~ken~
aka. out
get your bouncing truck here, http://www.bouncingtrucks.com
my 88 sas "mudwasp" here http://www.pavementsucks.com/board/threa...otor-build
88 chevy k2500, started as reg cab lb, now reg cab shortbox, sas 17'' of lift, 52'' front springs large bbc , 79 dana hp 60 chevy outers, 14bolt ff spooled 5:13 gear ,divorced 205 and 44" tsl front 21.5x16.1 ag tires rear
1998 k3500 gmc crew cab dually L65 6.5TD 4l80e with a couple of mods
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12-03-2006, 11:04 PM
Post: #8
 
rubiconexpress.com probable!!!!!


Loser




~WILL~
My S.A.S THREAD..... http://www.pavementsucks.com/board/threa...-07-UPDATE
-1990 GMC Z71: S.A.S'ed - Ford HP D60 / 14-Bolt FF, TH-350
-2007 GMC CrewCab 2500HD: 285's, stock for now...
-2004.5 GMC X-Cab 2500HD: DD w/ EFILive and 4" MBRP Exhaust
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12-09-2006, 11:10 AM
Post: #9
 
Quote:On 2006-12-03 19:03, gengland wrote:
Here is the pictures of my trackbar
http://i53.photobucket.com/albums/g53/lo...A52544.jpg
[/i[IMG]http://i53.photobucket.com/albums/g53/lostlake825/SSA52545.jpgmg]
The tube im using 1 1/4" .250 DOM , 1" threaded end and rubicon exspress flex joints

Most people that do a tracbar do a similar design, going from the frame to the right side spring plate. Even if you don't notice you actually get some bumpsteer from that design because it is shorter than the drag link.
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01-14-2007, 11:50 AM
Post: #10
 
I was thinking on doing a sas and starting with the rear for now and doing the frount later with a d60.What rears would match the frount as far as wheels???? 14ff? dana60?ford9"????
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