Register now to get rid of these ads!

??Disc brakes on rear axle only??

Discussion in 'The Antiquated' started by LWEL9226, Mar 11, 2020.

  1. LWEL9226
    Joined: Jul 7, 2012
    Posts: 306

    LWEL9226
    Member
    from So. Oregon

    What problems will there be with disc brakes on the rear and drum brakes on the front???

    Lynn W
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,126

    gimpyshotrods
    ALLIANCE MEMBER

    Instantaneous direction change on hard braking, without warning, and quickly enough that you will not have time to react.

    Or:

    Nothing at all.

    The problem is, the odds reset, every time you regain forward momentum.

    Can you afford that gamble?
     
    Truck64, mad mikey, LOU WELLS and 3 others like this.
  3. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 7,660

    Bandit Billy
    ALLIANCE MEMBER

    Ever pull the console mounted e-brake handle on a rent-a-stang at 60? Sure you have, we all have.
     
  4. 270dodge
    Joined: Feb 11, 2012
    Posts: 742

    270dodge
    Member
    from Ohio

    Did you ever see a factory produced auto with that setup? I think that I'd follow those engineers lead if at all possible. Is there a compelling reason to consider using rear only discs ?
     
    LOU WELLS and loudbang like this.

  5. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,379

    el Scotto
    Member
    from Tracy, CA

    Go for it!! I think you’re far enough away from me and all my relatives have moved out of Oregon :D
     
    alanp561, Truck64, mad mikey and 4 others like this.
  6. Disc in the front drums in the back is the factory style. This is because they like having a greater bias in the front than the rear. Generally there is a greater stopping capability with discs. Then again the fronts are usually larger than the rears so it factors out well. If you choose to do as you suggest, i would install an adjustable proportioning valve, just to get the bias right, and adjust it so the fronts come on first, or before the rears. You will most likely need a different master cyl set for your application as well.
     
    alanp561 likes this.
  7. G-son
    Joined: Dec 19, 2012
    Posts: 775

    G-son
    Member
    from Sweden

    If you can get the braking force divided properly between front/rear it could work just fine. If you get too much braking force at the rear, as you are likely to get, the rear wheels will become the front wheels any time you brake hard while turning, i.e. the rear wheels lock up long before the front wheels and from there you're probably just along for the ride until the car has stopped somewhere.
     
    alanp561 likes this.
  8. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,422

    OLDSMAN
    BANNED

    Don’t do it, There’s a reason from the factory the discs are on the front. They want most of the braking power in the front and not the rear
     
    loudbang likes this.
  9. In other words... the OP found a deal on a disc brake rear for his build...
     
  10. What’s the rear out of?

    was there an option in the vehicle for rear drums ?
    Drums can be easily adapted to an axle.

    or convert your fronts to disc as well.

    a drum front/ disc rear sounds silly and dangerous
     
    loudbang and Penetrator like this.
  11. KJSR
    Joined: Mar 7, 2008
    Posts: 2,409

    KJSR
    ALLIANCE MEMBER
    from Utah
    1. Utah HAMBers

    The hardest part will be driving backwards everywhere.
     
    alanp561, loudbang and badvolvo like this.
  12. DOCTOR SATAN
    Joined: Mar 21, 2014
    Posts: 711

    DOCTOR SATAN
    Member
    from okc

    You building a funny car....?
     
    loudbang and Penetrator like this.
  13. Kevin Ardinger
    Joined: Aug 31, 2019
    Posts: 318

    Kevin Ardinger

    I had a straight front axle drag car back in the day that only had 12x3 drum brakes on the rear. No front brakes at all. Stopped just fine at 100 mph
     
  14. jnaki
    Joined: Jan 1, 2015
    Posts: 5,790

    jnaki

    Hello,
    The topic of disc brakes is not HAMB friendly, but if you have the choice, get discs for all around, with larger ones on the front. The stopping power is at least 70-75% for the front. Look at some of the custom builds, the bigger discs and pads are in the front. The rears can be large, too, but the stopping power comes from the front.

    My brother had a 1000cc Kawasaki road bike and his front brakes made the rear ones look tiny. He said the stopping power for bikes is about the same, maybe more, since the rider is also leaning forward, too. It is standard in the industry. (cars and bikes...)

    Jnaki
    When disc brake applications came out for custom motorcycles and hot rods, there were standards sizes and people tried all combinations. (Airhearts) Then the designers and engineers took over and the math told them the stopping power is in the front and larger discs were necessary.

    Don't get fooled again... Stay with discs for pure stopping power, but traditionally, drums in the front and rear are HAMB appropriate. (or at least don't show your disc brakes in photos.)
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 48,703

    squirrel
    Member

    Lots of really wild misinformation in this thread. Assuming the rear disks under consideration are on a rear end that is from a vehicle that's similar in size/weight to the vehicle that's being built, and the front drums are also appropriate size, then the main effect is probably that the rear brakes are less likely to "go away" under conditions that might cause fade on the front brakes.

    Rear disc brakes are not the same as front disc brakes, guys. They have smaller pistons, etc. The braking proportion thing still applies with 4 wheel disk brakes.

    But it's all speculation, because we don't have enough information.
     
  16. I think it'll work just fine but you may have to turn your master cylinder
    180 degrees and rig up some sort of linkage;
    let me know how it turns out...
     
  17. LWEL9226
    Joined: Jul 7, 2012
    Posts: 306

    LWEL9226
    Member
    from So. Oregon

    Thank everyone that answered my question... Most of the answers are about what I expected, I just wanted confirmation....

    A friend wants me to help him put a newer rear end from an F-350 under his 1950 F-5....
    I will recommend him to return the disc brake rear and trade it for one with drums....

    Thanx.... Lynn W
     
    loudbang likes this.
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 48,703

    squirrel
    Member

    Oh...it's a big truck. That makes a difference.
     
  19. 41rodderz
    Joined: Sep 27, 2010
    Posts: 5,402

    41rodderz
    Member
    from Oregon

    It is always the rest of the story ......:D
     
    Hnstray, X38 and Blue One like this.
  20. What is he planning on doing with the big F-5??? Towing a trailer much? PACCAR (Peterbuilt / Kenworth) built many a tractor with rear brakes only, and nothing on the front axle. The concern with big trucks, especially ones that pull a trailer most of the time is if too much brake bias is to the front, it unloads the rear suspension under braking, locks/skids the rear tires and quickly leads to a jack-knife condition.
     
  21. jaracer
    Joined: Oct 4, 2008
    Posts: 1,004

    jaracer
    Member

    And many truck drivers had the front brakes removed from their rigs. The concern wasn't as much with the rears sliding as it was with not being able to steer if you locked the front brakes. Bottom line is that they were all wrong. A heavy truck will stop the best with brakes on all the wheel ends as long as they are proportioned correctly. It's more of a moot point since the advent of anti-lock braking.
     
    loudbang likes this.
  22. Agreed. Getting the bias is critical. My point was with the OP asking about putting a disc rear on an old F-5 sized truck, especially if it pulls a trailer or is loaded most of the time, it probably won't be a problem, but attention needs to be paid to the brake bias and front suspension geometry to minimize nose dive.
     
  23. bill gruendeman
    Joined: Jun 18, 2019
    Posts: 515

    bill gruendeman
    Member

    Jim, that is old school I don’t think that’s been done in more than 30 plus years and not legal any how
     
    loudbang likes this.
  24. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,126

    gimpyshotrods
    ALLIANCE MEMBER

    Yup. Totally illegal now.

    Plus, an ever increasing number of semi trucks have discs, in all positions.

    Haven't seen one with drums at our loading dock, in about a year.
     
    loudbang likes this.
  25. bill gruendeman
    Joined: Jun 18, 2019
    Posts: 515

    bill gruendeman
    Member

    I think the problem with disc on rear is they always self adjust and drums only self if they working properly
     
  26. DDDenny
    Joined: Feb 6, 2015
    Posts: 14,849

    DDDenny
    Member
    from oregon

    I see ADJUSTABLE proportioning valves and check valves in your future!
     
  27. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,126

    gimpyshotrods
    ALLIANCE MEMBER

    Just buy the front axle from whatever donated the rear axle. Get the rest of the brake system, too.
     
    squirrel and X-cpe like this.
  28. LWEL9226
    Joined: Jul 7, 2012
    Posts: 306

    LWEL9226
    Member
    from So. Oregon

    The truck will probably not ever be used very hard.... Big trailer not very likely....
    It was originally a flat-head 6 cyl….. Plan is to put in a small block Ford (302)….

    Already looking for a drum brake rear end….

    Thanx to everyone....
    Lynn W
     
  29. Nova Thug
    Joined: Jun 9, 2012
    Posts: 180

    Nova Thug
    Member
    from SG Vizzle

    One ton drum brakes are a pain in the A$$ to work on. I’d keep the disc brake rear end and up grade the fronts.. A couple years ago we did a front disc brake swap on my uncles 3/4 ton Chevy and it stops with confidence now.. It was vacuum boosted power drums before.. It was basically a spindle swap from an 80 C20 chassis on to his 69 C20.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.