Page 1 of 5 12345 LastLast
Results 1 to 10 of 44

Thread: m1028 cucv axle swap questions

  1. #1

    Default m1028 cucv axle swap questions

    I picked up a set of cucv axles last week to put under my truck. I've been searching on here for the best/safest way to acheive this. Which way would help keep the spring perchs at the right angle: Move the springs under the frame to match the perchs or move the perchs to match the stock 715 spring width? Can the stock cucv perchs be left on as a guide to get the angle correct while welding on the new perchs? The big cheese has the look i'm after with the 42's. Does anyone know if 42"x15"x16.5" tires on 12"x16.5" rims with 3.5" backspacing will fit ok with these axles? I'm going with the spring over,shackle flip and rear disc conversion. I guess this is enough rambling for tonight.
    Thanks Andy

  2. #2

    Default

    You want to set the spring perch angle to get the correct pinion/ driveshaft angle. For the front you also need to be sure that your caster angle isn't out of spec. Caster over rides pinion angle. Shouldn't be too much of a problem with the long front shaft though. Usually what I do is put the new perches on the tube and bolt it in loosely, set the angle, tack the perches in place and then take it out and weld them up.





    http://www.4xshaft.com/driveline101.html

  3. #3
    Join Date
    Oct 2009
    Location
    Methuen, MA
    Posts
    323

    Default

    It's up to if you want to move spring/shackle hangers or perches, I found moving perches easier. You're moving 2 points of reference vs 4. If that's what you choose, yes you can use the old perches to set your angle. Here's what mine looked like:

    Obviously the drivers side was set with the width and angle after welding this perch.

  4. #4

    Default

    Quote Originally Posted by 97XJSP View Post
    You want to set the spring perch angle to get the correct pinion/ driveshaft angle. For the front you also need to be sure that your caster angle isn't out of spec. Caster over rides pinion angle. Shouldn't be too much of a problem with the long front shaft though. Usually what I do is put the new perches on the tube and bolt it in loosely, set the angle, tack the perches in place and then take it out and weld them up.





    http://www.4xshaft.com/driveline101.html
    Hmmmm. I do not know the correct answer, but do recall learning (wrongly perhaps) that a C.V. joints name implies all U-joints have the same angle (and resulting constant velocity). The upper illustration adheres to the theory. The lower illustration appears to show varying geometry so the two DS mounted U joints look straight, and the initial (furthest forward) has an induced angle.

    Undesirable harmonics might develop since there are assymetrical centrifical forces which cannot negate each other.

    Yes the axle should be angled upwards, but only to the degree that it again matches either of the two CV angles, so that all 3 angles become essentially the same regardless of the extent to which the suspension is compressed.
    Last edited by cleefurd; April 21st, 2011 at 02:04 PM.

  5. #5

    Default

    Believe I was mistaken. A quick search seems to corroborate the drawing.
    D'oh!

  6. #6
    Join Date
    Jun 2009
    Location
    Litchfield Illinois
    Posts
    596

    Default

    I moved the axle perches on the rear and used the stock springs. You will have some clearance issues on the rear axle with brake calipers. You will need to rotate them down and under the spring (not a big deal). You should be fine with 3.5 inches of back spacing on the rear. My wheels have 4.5 and the tires clear the leaf spring by about 3/4 inch (a little closer than I like)

    As for the front, I moved the springs under the frame, but I wanted to soften the ride and use Chevy 3/4 to springs (like Ryanroo). It is correct it takes more fabrication since you must make custom hangers. I chose to reverse the spring shackles and put them in the rear. It might be a bit easier if you did shackle forward because I think you could get by with more off the shelf parts such as from Ruff Stuff.

    If you are going to do a spring over/shackle flip, I would simply move the perches on the axles for ease of the project. Simply pick up the new perches and weld them on.

    One last thing. For your front end to not have death wobble, you need to keep it between positive 6 - 8 degrees. Once you have that set, then you can decide what type of front shaft you need to run.

    Good luck and send some pictures.

  7. #7

    Default

    Thanks for the answers guys! I've been looking at the photos of the swaps to get an idea (which pictures really help). I think since i can leave the stock perchs on i can match the angle so im going to concentrate on that route. Hudlow Axles in Chattanooga,TN told me to fab it up,tac the perchs on and bring it to him to set the pinion angles. The Death wobble is what concerns me the most.
    I really like all the knowledge on this site and try to find what i'm looking for before i ask any questions. Monday i'm going to order a disc brake conversion and dual non power master cylinder. Hopefully i ( or better yet my wife) can figure out how to post some pictures of my truck. Its #19179 restored 12 years
    ago. Andy

  8. #8

    Default IM not sure with your axles but with the stock ones

    Im not sure with your axles but with the stock axles on the truck i went with
    40in x 16.5 x 16 rim and with marshall rims 12x 16 and i went with 5 1/2 backspacing and slid the front axle 1/2 inch forward so the tires will not rubb when turning . and this setup is without a axle flipp the springs stay under and not over .
    agian im not sure if this helps but maybe it does alittle .

  9. #9
    Join Date
    Oct 2009
    Location
    Methuen, MA
    Posts
    323

    Default

    I didn't think you could fit a 40" tires with the front spring under, if so I'd think about doing that. The cucv axles aren't as wide as stock so I have concerns the front will rub. A spring over and shackle flip makes these things big, pictures don't do them justice. Also the rear is more than just a shackle flip, you really need to flip the posts as well. This is for 2 reasons, centering the axle and raising the rear enough to equal the front spring over. Wanapinz has some pictures of the spring under cucv axles with hummer rims.

    Sent from my SPH-D700 using Tapatalk

  10. #10

    Default

    Well today i decided to drop my axles off at Hudlows. One of my yokes had a missing tab on it so its being replaced. He is also changing the other yoke to a 1350. When i get it back monday i'm going to try to figure out what disc brake conversion kit to buy.
    Any info on complete tire size,rim size,backspacing and spring postion is useful. Alot of searchs i've done, i find most of the info i'm looking for but always some important part ( to me anyway) isn't mentioned. Especially when you find a truck you really like the stance of.
    I'm going to flip the shackle and the post. I do want to keep the front and rear as close to level as possible. Putting new perchs on probably concerns me the most.
    Does anyone know where i can buy some cucv factory spring perchs?
    Andy

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Site Upgrade, Design Modifications & Administrative Support by:
Palm River Enterprises LLC, IT Solutions
President: Tom King, User ID=teking
This site is owned and operated by:
M715 Zone, LLC
President: Jon Schmidt, User ID=brute4c


If you have any suggestions, comments, problems or questions, contact:  brute4c@m715zone.com
Use of this site means you understand and agree to our TERMS OF USE

Copyright Notice:
This web site is subject to the protection of the copyright laws of the United States and other countries. Except for Personal Use Only, you may not modify, copy, distribute, transmit, display, perform, reproduce, publish, license, create derivative works from, transfer, or sell any information obtained from any part of the M715 Zone website without the prior written permission of M715 Zone, LLC. Written permission can only be obtained by contacting brute4c@m715zone.com

Copyright 1998-2024