Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 08-03-2020, 12:59 PM   #1
modelacarman
Junior Member
 
Join Date: Dec 2012
Location: oberlin ohio
Posts: 27
Default Rear brakes

Rear brakes. I’ve had my rear brakes turned twice and they are still out of round. I’ve had them turned by two different shops same results. Is it the shop that’s turning them not doing them right or am I missing something,can anyone help don’t know what to do!Any help would be appreciated, thank you.
modelacarman is offline   Reply With Quote
Old 08-03-2020, 01:02 PM   #2
Mike Peters
Senior Member
 
Mike Peters's Avatar
 
Join Date: Aug 2012
Location: South East Wisconsin
Posts: 1,279
Default Re: Rear brakes

Do you mean you had the brake drums turned?
Mike Peters is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 08-03-2020, 01:07 PM   #3
modelacarman
Junior Member
 
Join Date: Dec 2012
Location: oberlin ohio
Posts: 27
Default Re: Rear brakes

Ground or machined don’t know what else to call it
modelacarman is offline   Reply With Quote
Old 08-03-2020, 01:36 PM   #4
Jacksonlll
Senior Member
 
Jacksonlll's Avatar
 
Join Date: Jul 2012
Location: Michigan-- Member of Oakleaf of MARC
Posts: 1,686
Send a message via ICQ to Jacksonlll
Default Re: Rear brakes

They are hard to get right. It takes a very good shop to make them true. The shop should know if they are round or not.
Jacksonlll is offline   Reply With Quote
Old 08-03-2020, 02:09 PM   #5
1931 flamingo
Senior Member
 
1931 flamingo's Avatar
 
Join Date: May 2010
Location: new britain,ct 06052
Posts: 9,389
Default Re: Rear brakes

Bite the bullit and get NEW ones !
The originals were not meant to be turned. JMO
Paul in CT
1931 flamingo is offline   Reply With Quote
Old 08-03-2020, 02:52 PM   #6
The Master Cylinder
Senior Member
 
The Master Cylinder's Avatar
 
Join Date: Aug 2012
Posts: 875
Default Re: Rear brakes

Sponsored Links (Register now to hide all advertisements)
Quote:
Originally Posted by 1931 flamingo View Post
Bite the bullit and get NEW ones !
The originals were not meant to be turned. JMO
Paul in CT
It is mentioned in the Service Bulletins not to turn the original brake drums.
__________________
The Master Cylinder

Enjoying life at the beach in SoCal...
The Master Cylinder is offline   Reply With Quote
Old 08-03-2020, 03:22 PM   #7
modelacarman
Junior Member
 
Join Date: Dec 2012
Location: oberlin ohio
Posts: 27
Default Re: Rear brakes

Did not mention in my post that these drums were cast-iron replacements from snyder’s
modelacarman is offline   Reply With Quote
Old 08-03-2020, 04:51 PM   #8
Patrick L.
Senior Member
 
Patrick L.'s Avatar
 
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
Default Re: Rear brakes

What type of shop is doing this work ? Brake shop or machine shop ?

I'm wondering why 2 different shops are not turning them correctly.

What makes you think the work isn't correct ? If its because when you manually turn the drums when installed they catch/stick/contact at certain spots and turn free at other spots, thats normal.
Patrick L. is offline   Reply With Quote
Old 08-03-2020, 06:48 PM   #9
modelacarman
Junior Member
 
Join Date: Dec 2012
Location: oberlin ohio
Posts: 27
Default Re: Rear brakes

Automotive machine shop done the work two different ones and when you press the brakes to stop you get a pulsation in the break pedal. And the shops may have done it right but what am I missing is there something else wrong?
modelacarman is offline   Reply With Quote
Old 08-03-2020, 07:52 PM   #10
bobbader
Senior Member
 
Join Date: May 2010
Location: Huntington, NY
Posts: 268
Default Re: Rear brakes

I agree with Patrick L on this one. Brake drums on any car will "seem" to have high/low spots or be out of round when you spin them by hand. That doesn't mean they have been "turned" out of round. There are many variables. For example, when wheels are mounted, tightening of lug nuts will effect this situation as the tightening pulls on the studs and, therefore, pulls on the drums. Spinning the drums (or drums with wheels mounted) by hand cannot begin to approximate what happens with the weight of the car on the ground nor can it approximate what happens when the car is going down the road when brakes are applied at speed. Perhaps you need someone else's eyes or feel to determine if you actually have a problem. In any event, determine if there IS a problem before going further. Continuing to have the new drums "turned" is defeating the purpose of having new drums.

Good luck, Bob Bader
bobbader is offline   Reply With Quote
Old 08-04-2020, 06:04 AM   #11
Patrick L.
Senior Member
 
Patrick L.'s Avatar
 
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
Default Re: Rear brakes

Well, if the brake pedal pulsates then thats a classic sign of warped drums. So I'm assuming you're sure its coming from the rear and not the front. I'm not sure what to tell you now.
Patrick L. is offline   Reply With Quote
Old 08-04-2020, 06:29 AM   #12
Jacksonlll
Senior Member
 
Jacksonlll's Avatar
 
Join Date: Jul 2012
Location: Michigan-- Member of Oakleaf of MARC
Posts: 1,686
Send a message via ICQ to Jacksonlll
Default Re: Rear brakes

If your wheel is not setting flat against the drum, it can pull the drum out of round. I had that happen when a small bit of weld was proud to the surface and it was fine until I tightened the lug nuts. It was an old welded wheel.
Jacksonlll is offline   Reply With Quote
Old 08-04-2020, 07:28 AM   #13
deuce5wndw
Senior Member
 
deuce5wndw's Avatar
 
Join Date: May 2010
Location: Liberty, KY
Posts: 896
Default Re: Rear brakes

Maybe a bent axle.
deuce5wndw is offline   Reply With Quote
Old 08-04-2020, 07:32 AM   #14
BRENT in 10-uh-C
Senior Member
 
BRENT in 10-uh-C's Avatar
 
Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,484
Default Re: Rear brakes

OK, let's back-up a bit on this. Many shops do not have the equipment to do this task correctly, -and there in itself can be things that will exacerbate the problem just as you are describing. When you describing pulsating, I am willing to bet the problem originated in the hub(s).

To begin with, before the new drums were ever installed, the hub itself needed to be checked. Often times, the hub is not (re)usable due to the hub race inside the drum being worn. I have a machined slug that we use to slip into the race area. You can visually see if the hub race is out of round. Our test is to put our finger over the small end of the hub and remove the slug. It it pops due to the vacuum, it is a good hub. If it won't pop, then the cost to restore exceeds the cost of a new hub.

Now even if the plug pops, this only checks concentricity of the race surface however the hub bearing race also needs to be parallel with the centerline of the hub. If this is not repaired, the drum will not be riveted on exactly perpendicular to the centerline axis of the hub. This will cause pulsation.

Next, if the shop used a cone on the mandrel to center the small end, they could have missed it there as often times the ends are damaged from the axle shaft nut. I use the centerline of the hub to reference off of, and when I machined my mandrel, I have a live center pilot hole on the small end of the mandrel. I mount the hub on my mandrel which centerlines off of the machined taper where I can true the flange so that it is parallel to the centerline. Then, when the drum is riveted to the flange, I know the shoe surface of the drum is parallel with the centerline. The machining of that shoe surface then is only needed to ensure concentricity of the centerline.

.
__________________
.

BRENT in 10-uh-C
.
www.model-a-ford.com
...(...Finally Updated!! )

.
BRENT in 10-uh-C is offline   Reply With Quote
Old 08-04-2020, 08:09 AM   #15
modelacarman
Junior Member
 
Join Date: Dec 2012
Location: oberlin ohio
Posts: 27
Default Re: Rear brakes

Thanks Brent I’ll bet you’re right!
modelacarman is offline   Reply With Quote
Old 08-04-2020, 08:16 AM   #16
Jack Shaft
BANNED
 
Join Date: Dec 2019
Posts: 1,196
Default Re: Rear brakes

Pretty easy to see a drum not true on the lathe...did you check the front drums?Im with Deuce,jack up the car and spin the wheel see if it runs true
Jack Shaft is offline   Reply With Quote
Old 08-04-2020, 08:51 AM   #17
edzaha
Senior Member
 
Join Date: May 2010
Location: New Jersey
Posts: 206
Default Re: Rear brakes

How would a bent axle cause brake pulsation?
edzaha is offline   Reply With Quote
Old 08-04-2020, 11:37 AM   #18
Patrick L.
Senior Member
 
Patrick L.'s Avatar
 
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
Default Re: Rear brakes

Quote:
Originally Posted by edzaha View Post
How would a bent axle cause brake pulsation?
A rear could.
Patrick L. is offline   Reply With Quote
Old 08-05-2020, 09:18 AM   #19
Standing Elk
Senior Member
 
Join Date: Aug 2017
Location: St. Maries, Idaho
Posts: 162
Default Re: Rear brakes

I had my hubs installed into my new drums and then the drums trued by a shop. When I checked them after I got them back I found that they were no true. One was actually pretty bad. The way I fixed the problem was to insert the old bearing races in the hubs and then mount the whole brake drum / hub assembly in the lathe between centers using the old bearing races as the reference surface. In my case this, this allowed me to turn the drums concentric to the center line of the bearings.
Standing Elk is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:09 AM.