Model A Forums

General Discussion
See more
See less

Rear End

  • Filter
  • Time
  • Show
Clear All
new posts

  • Rear End

    If you jack up the rear end with car out of gear and rotate a tire back and forth how much free play is acceptable? I tried a search but came away confused.

  • #2
    There is really no spec on that and yes it will be sloppy. What are you trying to check or diagnose?
    3 ~ Tudor's
    Henry Ford said
    "It's all nuts and bolts"

    Mitch's Auto Service ctr


    • carolinamudwalker
      carolinamudwalker commented
      Editing a comment
      tire rotational play, I have about 1 inch free play. Club members are replacing ring & pinon gears but I suspect there are some self interest at play and some scare tactics by local mechanic. Color me suspicious.

    • Mitch
      Mitch commented
      Editing a comment
      You have to check the backlash on the ring gear directly. Rotating the wheel wont tell you squat. Something does sound fishy

    • BRENT in 10-uh-C
      BRENT in 10-uh-C commented
      Editing a comment
      Guys, the backlash that you are mentioning is probably not the ring gear, -but is more likely the differential (Spyder) gears.

    • Mitch
      Mitch commented
      Editing a comment
      Brent I think we are all on the same page with that.

  • #3
    Not sure which free play you mean?

    Up and down with the wheel to check axle bearings, then you shouldn't have more than a couple thousandths, but back and forth (rotational), you will feel a lot of play from the spider gears.


    • Mitch
      Mitch commented
      Editing a comment
      Good point Tom, I was thinking of rotational play and not axial from his description but you never know.

  • #4
    You can’t judge it by holding one wheel and then the other .
    You can really only judge the hub/bearing wear and outer axle condition and threads outside of disassembly . I’ve done in excess of 150- axle rebuilds and you really can’t judge full wear until it’s apart . Just that simple.
    larry shepard
    guy from Brent’s seminar
    Last edited by Larrys40; 07-11-2018, 05:15 PM.


    • #5
      There is a lot of self interest going on out there! And a lot of mis information! Just to illustrate, I was talking to someone today about grinding the head of my backhoe's Cummins 4 BT engine and this citizen was trying to tell me that it had some hardened inserts and had to be cut on a milling machine. This goes against everything I ever did as a toolmaker. We ground the hard stuff and machined the "soft" stuff. Got the head to the machine shop, and mentioned it to the owner. He laughed and said no, he had done plenty of them and ground them all. That was crazy! The point is, that maybe the guy just didn't know when he told you about the wheels. He was going by what someone had told him. Having just rebuilt a rear end, it's a long, complicated process, Lot$a Hour$! I was using a new, not broken in, gear set and the ring and pinion were positioned to have about .006 - .010 of backlash. And since this is near impossible to measure, you just have to go by feel. What is the radius of a ring gear? 8" say? I believe a Mod.A wheel is about 30-31" in diameter or about a 15" radius. The backlash is going to grow significantly with the 15" over 4". Myself, I wouldn't worry about it.


      • #6
        I think what he is saying and what I have noticed, with the rear jacked you grab the wheels and turn it back and forth and you feel that slight inbetween of gears meshing. At least that's how I take it.


        • #7
          As Tom mentioned, he is feeling the slop in the spiders.
          Almost any era car will have this, it is normal


          • #8
            Thanks everybody, that's the answer that I was hoping for.(leave it alone) Damn, I did not intend for this to go to the top of the page. SORRY
            Last edited by carolinamudwalker; 07-12-2018, 08:18 AM.


            • #9
              Concur with the guys ... you are going to have gear and spyder slop, that is normal .
              Unless you are hearing noises, doing a restoration, axles look ok on thread ends, and/or installing an overdrive which you already have I believe I wouldn’t worry about it till something arises . Agree with Tbird , Beauford, tom and the gang.


              • BNCHIEF
                BNCHIEF commented
                Editing a comment
                I agree with what Larry agrees with but then I am a agreeable guy.

              • Larrys40
                Larrys40 commented
                Editing a comment
                I agree with Steve because he is always right and has such an awesome knowledge . I called him last week while working on a zipper distributor unit on a house call and he had all the answers. Steve, thanks for all you do for us here in the VFF! Your the best !

            • #10
              If you put a Q-TIP in each ear & rotate one, will the other one rotate, also?


              • BNCHIEF
                BNCHIEF commented
                Editing a comment
                Probably in my case yes.

            • #11
              I need to clear up a bad post. The local mechanic that I referred to is not our club mechanic. That was a poorly worded post and I apologize for the confusion.


              Related Topics


              • Tom Wesenberg
                Transmission Ratios Out of Sync
                by Tom Wesenberg
                I've seen transmission ratios posted where the 1st and 2nd gear ratios include the rear end, but then 3rd does not, and lists it as 1:1. This can be confusing when they don't use the rear end with all...
                04-07-2018, 01:50 AM
              • DaWizard
                Rear end stress...
                by DaWizard
                I am sitting here bloated and sleepy from another wonderful belt busting holiday dinner wondering just how I can lift the rear end without stressing the banjo bolts and tighten them up. If I lift it from...
                11-23-2017, 07:45 PM
              • Terry, NJ
                Tight (very) Rear end!
                by Terry, NJ
                Bought a rear end for my coupe ! It was tight and the drums were on it. It had been laying out side and while it had some rust, it wasn't any more than a rear in a car. It was so tight I had to use...
                01-11-2018, 01:12 PM
              • Manager
                Early 28 rear end
                by Manager
                I bought complete front and rear ends not needed by a hot rodder. It's all in good condition and I have pulled the front end apart, got the bits I needed and went to start on the rear end. My shackle...
                10-17-2017, 09:51 PM
              • pAAt
                7 Tooth
                by pAAt
                Original Thread

                My new (used) 7 tooth looks great ! Thanks Tom for working hard to get it for me !!! Very tight with really no wear on gears. I will use a lighter grease than they used for...
                04-27-2018, 03:58 PM
              • old31
                How much play in the generator armature is ok?
                by old31
                Is it ok to have play in the armature?

                When I pick up on the bearing, I can lift up the back end about 3/4 of an inch. It spins freely, but I can wiggle the armature easily up and down....
                09-20-2018, 02:09 PM
              • dmdeaton
                Rear Axle Bearings
                by dmdeaton
                Quick question, when doing brake or axle work, do you guys pre pack the axle bearings in grease while reassembling? Or soak them in some rear end oil of choice? they are greased from the banjo oil?
                04-27-2018, 04:37 PM
              • Tom Wesenberg
                Generator End Play
                by Tom Wesenberg
                I just had a question about end play on the common long generator. It's the front bearing that controls the end play, so if you can move the armature in and out more than a couple thousandths of an inch,...
                06-02-2018, 06:33 AM
              • carolinamudwalker
                Front end play
                by carolinamudwalker
                With the car on the ground I can grab the top of a wheel (front) and rock it in and out and feel a slight maybe 8th inch play. Just replaced king pins and bushings but no change. I have changed front...
                07-24-2018, 09:02 AM
              • Terry, NJ
                Differential, Rear end stuff
                by Terry, NJ
                Today I bit the bullet and ordered a new 3.54 gear set from Brattons, only $465. Throw in new 4 (Timken a4221n) new bearings for $160 and the cups/races for$100, gaskets, etc, shipping and the bill is...
                01-22-2018, 03:26 PM