Swapping a 14b FF into 1st Gen questions

[k2-k5]

bought a 3/4 ton 14b FF to go in my 1st gen Blazer.

I know i need to move the spring mounts and at least one shock mount. My questions are:

1. What is the spring mounting center to mounting center distance for a 1st gen.? What is the tolerance from center center 1/8"-1/4"
2. How much tolerance do you guys think I could get away with side to side. anotherwords if I missed it by a 1/2" would everything still function ok. The tires would noticeably sit to one side. I should be able to get it dead nuts but just in case just wondering what I could get away with.
3. I'm doing a 4" shackle flip and about 3" blocks should I worry about rotating the housing slightly before welding on new mounting pads to improve driveline angles. Any Idea how much to rotate it?

Thanky very much.

 

[Beast388]

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bought a 3/4 ton 14b FF to go in my 1st gen Blazer.

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Same here.....except I have a '71 Burb.

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I know i need to move the spring mounts and at least one shock mount.

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You will need to move both spring perches and both shock tabs. The shock spacing is wider on the 14BFF.

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1. What is the spring mounting center to mounting center distance for a 1st gen.? What is the tolerance from center center 1/8"-1/4"

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The center to center distance of the spring perches is 40". I would recommend measuring many times.....and then measure some more. Then measure one more time to be sure. /forums/images/graemlins/histerical.gif

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2. How much tolerance do you guys think I could get away with side to side. anotherwords if I missed it by a 1/2" would everything still function ok. The tires would noticeably sit to one side. I should be able to get it dead nuts but just in case just wondering what I could get away with.

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You would end up with truck that "dog tracks". Once again, if you measure carefully, you should get it really close. Don't use the pumpkin as a reference when measuring, it is offset to one side. I used the square pads that the brake drums mount to. You know that those are centered. /forums/images/graemlins/waytogo.gif

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3. I'm doing a 4" shackle flip and about 3" blocks should I worry about rotating the housing slightly before welding on new mounting pads to improve driveline angles. Any Idea how much to rotate it?

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I would recommend mocking it all up and then use an angle finder to get it perfect.....or really close. With the shackle flip and blocks, there is no way to guess and get it right. /forums/images/graemlins/waytogo.gif

One of the shock mounts will end up straddling the seam where the drivers side axle tube meets the cast housing. There are a couple of things you can do. I notched the shock tab and did some fancy welding, but some guys here on CK5 just fudged the mount over a bit so it is entirely on the axle tube.


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[ZZ4x4]

One thing a few of us do is to actually bolt the axle on (lightly) with the spring perches installed but not welded. Then you can adjust pinion angle and even side to side spacing until you get everything perfect. Then just tack weld the perches and shock mounts in place and remove the axle for the final welding and painting. /forums/images/graemlins/thumb.gif

 

[k2-k5]

I thought the pumpkin looked offset to one side.

I thought about installing everything loose then adjusting pinion angles tack welding pads then remove to fully weld pad. More work then I wanted to do but that would ensure everything is right.

 

[Triaged]

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One thing a few of us do is to actually bolt the axle on (lightly) with the spring perches installed but not welded. Then you can adjust pinion angle and even side to side spacing until you get everything perfect. Then just tack weld the perches and shock mounts in place and remove the axle for the final welding and painting. /forums/images/graemlins/thumb.gif

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That is exactly how I did mine. I also found that one of the shock mounts wants to be welded half on the center section /forums/images/graemlins/eek.gif I moved it a bit so it would only be welded on the axle tube.

 

[k2-k5]

right on /forums/images/graemlins/thumb.gif

 

[chulisohombre]

i didnt have to move the spring pads on my 14ff.i did the howlin off road shock mounts so i didnt use the stock shock mounts.i also did disk brakes.still dont have a ebrake though so i cant get my blazer inspected.just like every one said measure everything like 4 or five times and then do a mock up before you do the finish welds. /forums/images/graemlins/thumb.gif