Author Topic: JL8/J56 or HD Service rear end setup question  (Read 457 times)

369

  • Newbie
  • *
  • Posts: 17
    • View Profile
JL8/J56 or HD Service rear end setup question
« on: September 24, 2017, 02:29:58 PM »
Hello all......I'm putting together a disc brake rear end with the "fixed mount" J56 corvette style calipers. I'm shooting for .005" axle end play......I know this will require custom c-clip thickness which will change as the posi clutches wear..I'm trying to get an idea of how often this will need to be adjusted or reset on a road car. I figured if anyone would know it would be someone here. Any guesses?

-So from what I've read, Penske would change his rear end every race so no issue here...

-the lesser funded guys...How often was this checked/changed? Was the pad knock back tolerable enough to make it thru a season?

-what about the JL8 owners.....I can't see this being a "dealer service" adjustment every other oil change or anything right?

Ok thanks guys.....Tyler

Jon Mello

  • CRG Member
  • *****
  • Posts: 3923
    • View Profile
Re: JL8/J56 or HD Service rear end setup question
« Reply #1 on: September 27, 2017, 01:09:08 AM »
No idea, really. Probably not a lot of miles put on the car and not a lot of heavy abuse so you probably could go a couple of years with no problem. Just a guess.
Jon Mello
CRG

69Z28-RS

  • Hero Member
  • *****
  • Posts: 4428
  • owner since 4-Apr-1976
    • View Profile
Re: JL8/J56 or HD Service rear end setup question
« Reply #2 on: September 27, 2017, 01:55:40 AM »
I've a good friend who ran a service rear in his '69 Z28 in SCCA and later IMSA races.   He's told me that he had the rear end gears changed very often, before essentially every race, depending on the track and the speeds anticipated.  I don't recall him saying anything about having to adjust for brake wear...  I'd think there would be sufficient pad thickness to not be anything close to 0.005" tolerance... The pressure on the sides of the rotor should be essentially equal even if one pad was wearing faster than the other.
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

firstgenaddict

  • Hero Member
  • *****
  • Posts: 1796
    • View Profile
    • Groome Family Automobiles
Re: JL8/J56 or HD Service rear end setup question
« Reply #3 on: October 13, 2017, 07:02:02 PM »
With the fixed mount calipers yes there is plenty of tolerance for axle end play, if you are worried about thickness of the C clip then set up every thing with rotor and caliper sans pads, insert different thickness C clips and check where the rotor and caliper are in relation to one another... I think you are going to have .375+ inboard and outboard of the rotor.
James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://plus.google.com/photos/112392262205377424364/albums?banner=pwa

369

  • Newbie
  • *
  • Posts: 17
    • View Profile
Re: JL8/J56 or HD Service rear end setup question
« Reply #4 on: October 21, 2017, 03:25:29 PM »
10-4.....thanks for the input. Im starting the assembly here this weekend so we'll see how it goes!

69Z28-RS

  • Hero Member
  • *****
  • Posts: 4428
  • owner since 4-Apr-1976
    • View Profile
Re: JL8/J56 or HD Service rear end setup question
« Reply #5 on: October 22, 2017, 02:18:38 AM »
take some photos, 368...  help to educate us... :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

369

  • Newbie
  • *
  • Posts: 17
    • View Profile
Re: JL8/J56 or HD Service rear end setup question
« Reply #6 on: October 25, 2017, 04:41:03 PM »
Yea-I'll shoot some this weekend.

So....interesting tidbit here...I downloaded and printed the "chassis preparation manual" that jon mello posted up here (thanks jon btw)......they list the axle end play spec as ZERO to .015".......ZERO!....playin' with fire there once that whole deal heats up to racing temp.

I know..I know........way over analyzing  but I just thought that was kinda cool