• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

Rear brake backing plate differences: Bugeye vs. later model MG Midget

DanLewis

Jedi Trainee
Offline
When I converted the front drum brakes to disc brakes, I dutifully changed the master cylinder and rear brakes to the later style from an MG Midget as recommended (see here). After reassembling the rear brakes, I found that the hubs were rubbing on the backing plates. At the time I temporarily solved the problem by adding a washer acting as a spacer between the axle and the hub, thus spacing the hubs outward a fraction of an inch.

Today I disassembled the rear brakes and took some measurements. It turns out that the original Bugeye backing plates are different from those fitted on later model MG Midgets. First, the outside diameter of the Midget's plates is greater, but that doesn't create any problems. The problem is the thickness of the flange on the backing plate that is used to mount it to the axle housing. I've attached a drawing to illustrate the problem. If anyone has changed their rear brake backing plates to the later model MG Midgets and made it work, please let me know what you did.

For example, does anyone know if the rear hubs on the later model Midget is different?

Thanks!
Dan
Backing Plate Differences.jpg
 
Country flag
Offline
My solution was to spend a few minutes with an angle grinder on each brake drum.
 

Rut

Obi Wan
Country flag
Offline
Dan,
Trevor X2. I reversed my drums on the hubs and spun them while using an angle grinder...doesn't take much.
Rut
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Hi Trevor and Rut,

'Sorry. I should have been more clear. Clearance between the drum and the backing plate are not the problem I was trying to describe. I too had to have some material removed from the edge of the drums. My drums are no longer rubbing against the backing plates.

The problem is that the hub (not the drum) rubs against the mounting flange of the backing plate because the flange lip extends further out from the surface of the backing plate.

Since apparently neither of you experienced this problem, I suspect there may be differences among backing plates from different years of the later model Midgets. I checked the online catalog of Moss Europe, and found the following listings for rear backing plates:

BTA566 (RH), BTA567 (LH): From chassis No HAN6 20792, GAN1 13555
BTA566 (RH), BTA567 (LH): G-AN4, G-AN5, H-AN9, H-AN10, A-AN10

I think the above two (same part number) are for the Bugeye, and the next two are for later model Midgets.

37H8804 (RH), 37H8805 (LH): G-AN6

ATA7076 (RH), ATA7077 (LH): GAN1 13554

Can someone translate this into model years?

Thanks!

Dan
 

Rut

Obi Wan
Country flag
Offline
Dan,
Some hubs are machined a little deeper and they make contact with the brake cylinder, but I've not had one contact the backing plate except when the hole in the backing plate was not round. A die grinder or rat tail file should give you the clearance you need.
Rut
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Thanks, Rut!
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Hi Rut,

Some hubs are machined a little deeper and they make contact with the brake cylinder, but I've not had one contact the backing plate except when the hole in the backing plate was not round. A die grinder or rat tail file should give you the clearance you need.
Rut

I was thinking about your suggestion of grinding the excess material off the hub, but then I remembered that it's in (I think) a difficult place to grind. It's the surface pointed to in the figure below by the yellow arrow that rubs against the flange on the backing plate. How difficult would it be for a machine shop to do that?

Dan

Rear Hub.jpg​
 

nomad

Yoda
Offline
I changed to the later brake backing plate as well and don't remember exactly what I did. Do remember having interference at that point and I believe I releaved the backing plate rather than the hub. Also had a bit turned off the brake drum.

Kurt
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Hi Kurt,

I changed to the later brake backing plate as well and don't remember exactly what I did. Do remember having interference at that point and I believe I releaved the backing plate rather than the hub. Also had a bit turned off the brake drum.

My experience exactly. I ground off some of the material from the mounting flange on the backing plate (as well as the drums), but I finally put a washer between the axle housing and the hub to space the hub a little bit more away from the flange. Not an ideal solution to be sure, and I'd like to go back and do it all over. I didn't like the mess I made of the backing plates and have never been comfortable with how the hub are spaced out by the washers since the axle nut no longer engages as many threads as before. If it's possible to solve all of this by having a machine shop relieve some of the material on the hubs, I'll get some new backing plates and do it right.

Dan
 

Rut

Obi Wan
Country flag
Offline
Dan,
I ground the inside of the backing plate, not the hub. If you continue to have issues you may have a 'large' hub and a 'small' backing plate hole as far as specs go. Let me know if you need an extra set if hubs, I think I have a few around.
Rut
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Rut,

Dan,
I ground the inside of the backing plate, not the hub. If you continue to have issues you may have a 'large' hub and a 'small' backing plate hole as far as specs go. Let me know if you need an extra set if hubs, I think I have a few around.
Rut

Is there an easy way to tell which I have?

Dan
 

Rut

Obi Wan
Country flag
Offline
Dan,
They are all considered 'normal' size, just match up with a little rub. Clamp the plate in a vise and make sure the hole is round and adjust it to fit the hub. I've used everything from a tack hammer to a file to relieve that area.
Rut
 
OP
DanLewis

DanLewis

Jedi Trainee
Offline
Hi Rut,

They are all considered 'normal' size, just match up with a little rub. Clamp the plate in a vise and make sure the hole is round and adjust it to fit the hub. I've used everything from a tack hammer to a file to relieve that area.

'Sorry, 'thought you meant that there were two different size hubs. :shame: So, it sounds like what people have done is only to relieve the backing plate, not the hub. That's what I did, but perhaps my mistake was to try to reduce the extent to which it protrudes rather than to make the round opening larger.

Guess I need to consider what I want to do next before jumping in again.

Thanks!

Dan
 
Similar threads
Thread starter Title Forum Replies Date
histerical Wanted WTB Set of Later Spridget Rear Brake Backing Plates Spridgets Classified 0
B Rear Backing Plates for Disk Brake Conversion Spridgets 6
J TR4/4A TR4A Solid Axle Rear Brake Backing Plates Triumph 17
vping Rear Brake Backing plates Spridgets 6
scottkilpatrick TR4/4A TR4 Rear Brake Drum Removal - Basic Question Triumph 16
B Rear Brake Cylinders Austin Healey 4
KVH General TR Rear Brake Shoe Orientation Triumph 12
BN6_L1232 Rear Disc Brake Installation Instructions Austin Healey 3
J TR2/3/3A TR3A Girling 9" Rear Brake Initial Adjustment Triumph 9
R TR6 Rear brake wheel cylinder fitment Triumph 5
D Rear Brake Drum Nuts Austin Healey 15
fpstude TR4/4A Replacing Rear Flexible Brake Hoses on TR4A w/ IRS Triumph 11
G Rear Brake Adjustment Austin Healey 30
Kurtis TR4/4A Rear wheel brake cylinder replacement Triumph 1
J TR6 1973 TR6 Rear Brake Operation Questions Triumph 4
R TR2/3/3A Lockeed rear brake banjo fittings. Triumph 7
K MG Midget Early and Later model rear brake shoes.... Spridgets 2
A AH 3000 rear disc brake conversion Austin Healey 28
K TR2/3/3A Rear brake wheel cylinder attachment again Triumph 1
J For Sale Triumph TR3 rear differential and rear brake assembly - Northern Illinois Triumph Classifieds 1
Gliderman8 TR6 Removing Left Rear brake line... help! Triumph 9
Got_All_4 General TR Is there a special tool needed for rear brake cylinders Triumph 14
BN6_2197 Question on rear brake drums BN6 wire wheel Austin Healey 15
warwick-steve Rear Brake cylinder connection Austin Healey 12
Michael Oritt Moss Motors rear brake "set" Austin Healey 11
J Spitfire Spitfire Rear Brake Bleeding Triumph 9
vette Tire Size and Improving Rear Brake Drums Austin Healey 17
regularman Gear leaking from axle housing into rear brake drum Spridgets 3
nevets BN6 rear brake pipes Austin Healey 15
nevets stuck rear brake drum Austin Healey 18
Jim_Gruber Reinstalling Brake Hubs and Wheel Hubs in Rear. Spridgets 5
Jim_Gruber Brake Lines for Bugsy - What do I need for a Flaring Tool / Rear Discs for Bugsy Spridgets 39
C Help diagnosing rear brake issues... Austin Healey 20
W BN1 vs. BN2 rear brake lines / pipes Austin Healey 4
A rear brake drum too tight after rebuild Austin Healey 3
SASSAMON TR2/3/3A Rear Brake Cylinder Recommendations Triumph 2
Jim_Gruber BE Rear Brake Spring Orientation Spridgets 13
A TR2/3/3A Newbie Question regarding Girling rear brake cylinder Triumph 5
M suggestions on vendor Rear brake rebuild Spridgets 15
Dave Richards Rear Brake Cylinders not Fitting Hand Brake Lever Austin Healey 2
L RE: Requesting help with identifying suspected rear brake adjuster piece? Austin Healey 4
K TR2/3/3A Rear brake drum won't go on? Triumph 12
RJS TR4/4A Rear Brake Hose Replacement Triumph 7
R Can't remove rear flexible brake hose Spridgets 5
J TR2/3/3A Add brake light to Rear turn signals Triumph 12
Dave Richards BJ8 Rear Brake Kit British Parts Northwest Austin Healey 4
C AH3000 MKIII - Rear Brake Problem Austin Healey 1
P Bugeye rear brake springs??????? Spridgets 5
CJD TR2/3/3A Early Rear Brake Cylinders Triumph 2
J TR2/3/3A Installation of rear brake cylinders for 9" brakes on TR 3A. Triumph 3

Similar threads

Top