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Technical Driveshaft: Modify '40 driveshaft & torque tube for '32

Discussion in 'The Hokey Ass Message Board' started by HHRdave, Dec 1, 2007.

  1. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    We started on this project a couple of weeks ago and about half way through I realized I could make a tech article out of it. This article is about taking a '40 Ford rear end and modifying it to fit a stock '32 frame with a Model A rear sping/crossmember and a Halibrand QC. I know this has been done several ways before, but this is how we did this one.

    First we mocked up the frame with the '39 trans and '40 rear bells and axles to the Halibrand QC and Model A rear spring. We got everything real tight and then attached the U-joint to the trans and the driveshaft with the stock coupler on to the QC center section and took a measurement. We came up with 50" for this driveshaft. *NOTE-always check your measurements, don't use this as a rule.

    Next we cut the torque tube at the rear portion of the tube about 2" in. We then chucked this small section in the lathe and trued it up square. Then we attached that portion of the t-tube to the QC center and the other long portion of the t-tube to the front coupler and took a measurement. We came up with about 52". *Check your measurements-don't use this as a rule

    Next we cut the drive shaft at the rear section, this leaves the bearing surface in tact so it can ride on the bearing (I have heard some people eliminate the bearing because the shaft is now shorter and doesn't really need one). We beveled the ends to be welded together.

    Next we had to fabricate a coupler. We took a peice of round stock about 3" dia. about 5" length and bored out the center to the driveshaft diameter. The we bored 2 sets of holes about 3/4" through the coupler piece in opposite ends. These holes will serve two purposes.

    Next we took the fabricated coupler and slid it ove the driveshaft ends to be joined. We used the 3/4" holes to line up the ends and to tack the ends in two places, rotating the coupler to used the hole on the other side. Next we rotated the coupler (keeps the driveshaft lined up while welding) and TIG welded the butted beveled ends. *Clean all metal parts real good before welding.

    Next we centered the coupler and then TIG welded the coupler through the holes to the shaft in four places (4 holes) for strength. Then we TIG welded up the ends of the coupler.

    [​IMG]

    Here is a shot from rear end of the driveshaft:

    [​IMG]

    Next we cut the torque tube and squared up the end and the placed it in 4" angle iron, clamped it and tacked it up in 4 places.

    [​IMG]
    [​IMG]

    Then we proced to TIG weld the torque tube, making sure the weld area is clean it all times. *Oil and grrease build-up in the tube will get hot and melt and contaminate the beveled groove and it will need to be cleaned before proceeding.

    Here are the parts now shortened:

    [​IMG]

    You can barely see how the bearing surface lines up with the zirk fitting fort the bearing in the torque tube.

    Here is the driveshaft and torque tube installed in the chassis:

    [​IMG]

    Weld cleaned up on the torque tube:

    [​IMG]

    You can see the U-joint in there lines up good and there is room for the speedo gear and clip.

    [​IMG]

    Next we needed to shortend the rear trailing arms or radius rods depending on what you may call them.

    [​IMG]
    First we cut off the ends and clean them up and bevel them. Then we bolt them to the bracket on the torque tube. Next we bolted the trailing arm to the axle bell end and then slowly bent the arm (while heating the rear end of the rod lightly with the torch) to get it close to the bolted end. We then take a mark and cut it. Unbolt it, bevel it then get it lined up. This is what I had to do to line it up to tack it. :
    [​IMG]

    Here it is all TIG welded up and cleaned up:

    [​IMG]

    Once you do the trailing arms and tighten everything up, you now have a '40 rear end with juice brakes set up for your '32 with Halibrand QC.
     
  2. mazdaslam
    Joined: Sep 9, 2004
    Posts: 2,526

    mazdaslam
    Member

    Nice!!! Great tech!
     
  3. Rusty
    Joined: Mar 4, 2004
    Posts: 9,179

    Rusty
    Member

    Awesome post the only thing that I dont see is did you cut the torque tube in two places front and rear? You mention bolting the cutted rear section up to the rear. When did you cut the access of the two long tube?

    Rusty
     
  4. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    Everything was cut in 2 places and a section removed. The section was about 10" and was removed from the rear portion of both parts. - If this helps clear things up. I only wish I had taken more pictures from the start.
     
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  5. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    ***There has been some concern or question about possible harmonic or imballance vibration. We looked into the possiblities extensivly and this is why the coupler we designed is used toward the rear, where the actual FORD splined coupler will be used (next to it) and it is the most solid part of the driveshaft.

    Also, by incorporating this design, we have retained the bearing surface in its original position wchich may not be necessary (to use a bearing) it is added insurance in high speed use. I noticed a lot of typing errors and I have corrected those. Thank you for those who have appreciated this Tech article.
     
  6. alchemy
    Joined: Sep 27, 2002
    Posts: 7,880

    alchemy
    Member

    Possible other method instead of using a sleeve on the driveshaft, then a coupler: Could you just cut the shaft off, bore out the splines on the front end of the coupler, slide the shaft in and weld the coupler on? It won't be removable from the driveshaft anymore, but that's OK. One less joint.
     
  7. revkev6
    Joined: Jun 13, 2006
    Posts: 2,858

    revkev6
    Member
    from ma


    that's the way I did it on both of my rears. it is still removable though as the coupler comes off the rear after you take out the pin (grade 8 bolt)

    also, I don't shorten my radius arms. I cut the mounting ear off the torque tube and weld it back on after the torque tube is shortened.
     
  8. bushwacker 57
    Joined: Oct 3, 2007
    Posts: 384

    bushwacker 57
    Member

    Nice job . also could the front be rotated so speedo drive faces the right side like like the stock 32 . I found the speedo cable fits a lot better.
     
  9. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    The shaft tapers off after the ends of the splined area. You would be boring out a hole with some spline still left and have air gaps. This method would work, but it is a weak joint, weaker than Henry Ford originally built it.

    I see and understand your point. But now you have eliminated the strength of the FORD coupler by losing the splines and you only have one weld ring around it, or as one guy put it, a grade 8 bolt. This is OK for mild street use, but why risk it?? We made our own coupler so we would have 7 weld points/areas with full penetration, and we still get to use the strength of the stock Ford coupler.
     
  10. alchemy
    Joined: Sep 27, 2002
    Posts: 7,880

    alchemy
    Member

    I was just hypothesizing on my suggestion, but you make a valid point. Maybe the fellas above who have done it for real had a different year shaft that doesn't neck down? Anybody know any different shapes for the different years?

    On my project, we used a '32 driveshaft and it is a tube that can be cut. Then just stick the turned-down coupler in and weld it up. We used '40 gears in our '32 rear so we needed a different spline count than stock '32. It basically looks just like the kit that Spadaro now sells.
     
  11. revkev6
    Joined: Jun 13, 2006
    Posts: 2,858

    revkev6
    Member
    from ma

    actually, I figure the way I did it was stronger. you only bore one side of the sleeve, and the grade 8 bolt is only to replace the pin that holds the driveshaft onto the splines of the pinion shaft. (just makes it easier to remove later)

    Your way, when you put your sleeve over both pieces of the axle you only have two weld joints that can fail/warp during assembly.
     
  12. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    Like I said earlier, we welded the shaft in 7 different places: We butt welded (with beveled ends) the cut shaft ends--you don't see this in the first 2 pics, but its inside. We rosette welded through 4 holes 3/4" dia. then we welded the ends. All this was done with a TIG with 20 years of aerospace govt. inspected welding. How many guys on the HAMB can produce TIG welds like the first 2 pics? Nothing is going to fail or warp.

    When you eliminate the splines and shove a grade 8 bolt through, you have lost the strength of the splines (you bored them out) and you are relying on a bolt only. Bolts can shear under torque stress.

    To each his own I guess.
     
  13. tinmann
    Joined: Nov 11, 2005
    Posts: 1,556

    tinmann
    Member

    Did mine the same way except we machined to coupler to be 2 thou smaller I.D. than the driveshaft O.D. then heat shrunk them together. No welding needed. Good tech. I love B&W photography.
     
  14. revkev6
    Joined: Jun 13, 2006
    Posts: 2,858

    revkev6
    Member
    from ma

    not saying your driveshaft isn't up to the task. It's a great tech article and PLENTY strong. The weld on the driveshaft is much stronger than the weakest links in these rears.

    judging from the bold, I'm not sure I made myself clear on how I did mine. I took the original ford coupler that is internally splined and had HALF of it bored out at work to a press fit on the drive shaft. (also an aerospace machine shop BTW) The other side of the coupler still retains the original splines to mesh with the pinion shaft on the rear end. after you weld the coupler to the cut down drive shaft you line up the holes in the coupler and the pinion shaft where the original retaining pin went through. In place of that swedged retaining pin I put a grade 8 bolt. The bolt has no load put on it and is only to keep the driveshaft attached to the pinion shaft.
     
  15. 392_hemi
    Joined: Jun 16, 2004
    Posts: 1,739

    392_hemi
    Member

    I like your approach. How did you do the butt groove weld on the two driveshaft pieces through the 3/4" holes and then move the sleeve? I would think there'd be some weld buildup to prevent this. Also, how did you get the torch and filler in such a small, and somewhat deep considering the diameter of the sleeve, hole?
     
  16. HHRdave
    Joined: Jul 31, 2006
    Posts: 1,068

    HHRdave
    BANNED
    from So Cal

    Welded through the holes first, to the butt joint, rotate coupler, weld some more, rotate, weld. Used smalled ceramic cup on torch, holes keep the gas in for good penetration.

    When you can weld a bead with a TIG on top of a razor blade inside a valley that is 1 inch deep and 1/4 inch wide with no side arching of the torch...then welding inside 3/4 inch holes to a but weld is easy.
     

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