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Handbraaake!


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Hi Marco,

this will give a deflection on the shoes because the springs are operating in another plane. The rod should best be close or in neutral (center of shoes).

Waldi

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Pete and Waldi,

yes you are right, and +1 for you Waldi, I guess I should work on that.

Until yesterday I had a problem with the upper spring on the same position as the rod.

I solved that with another drill in a higher position (already on the photo) for the spring, what worked very well.

This give me the possibility to get the rod (in the next step) direkt on the shoe.

Ciao, Marco

 

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Regarding debate on double vs single piston brake cylinders. I have a MK4 Ford Fiesta with self adjusting rear brakes with a double piston. When the brake pedal is pressed, pressure is applied to the system and one piston moves before the other. They never move together. Over time the one that moves second seizes up. Had many happy hours freeing up the second piston on the rear brakes of this car.

The TR single piston achilles heel is that it must slide on the backplate. It is vital that this is checked regularly and copper grease/oil is smeared onto the sliding face.

I have done Rogers suggested mod of moving the pivot point on the handbrake of my 4A. I moved it 11mm and the difference is incredible. No more white knuckle moments on steep hills. 

Keith

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9 hours ago, Waldi said:

Hi Marco,

this will give a deflection on the shoes because the springs are operating in another plane. The rod should best be close or in neutral (center of shoes).

Waldi

 

8 hours ago, Z320 said:

. and +1 for you Waldi, I guess I should work on that.

I also considered such deflection / twist would incur ..but then thought what does it matter ?  The brake-shoe movement is only about 1mm anyway,  and then ..even though the brake shoe is not being pushed evenly, it will soon be held square against the drum (because the boss you fitted is nowhere near the very edge of the shoe). 

If the wheel / brake drum was turning - then such uneven pressure would indeed wear the shoes unevenly, but because the handbrake is predominantly (excepting handbrake-turns, etc) used when the wheels are stopped - any uneven wear would be negligible in regard to the life of those brake shoes.   

Pete.

 

Edited by Bfg
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Hi Waldi, hi Pete,

perhaps it doesn't matter, but to bring the push rod closer to the center of the brake shoe is no mistake.

With the two nipples left on the photo it is as close to the brake shoe as the long leaver on the other brake shoe.

P1150581-b.JPG.13bf6a89d2edaf165b241c13dcd28797.JPG

Ready to drill the new brake shoes for fixing the leavers and to get the upper springs in a higher position.

Ciao, Marco

Edited by Z320
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Hi Marco,
That’s better (to me).

Hi Pete,
I think being out of plane of the 2 forces on the shoe can make the shoe wiggle (tilt) every time it moves. That would result in one side contacting and thus wearing more than the other. To what extend this matters, I do not know.

Waldi

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Hi,

I drilled the brake shoes, made some bushes, the push rods and bolt all together, nearly ready for the car.

P1150615-b.JPG.3c6e6c20347576b43857fc0b631455bc.JPG

The long leaver on the LH back plate in position, left you see the pushrod with its hex bush, right will come the bowden cable in

P1150618-b.JPG.763b3640769d80b55e2c719ad63d31f9.JPG

To get the brake shoes on the car up to this point is standard, nothing special,

next I slide the pushrod in and bolt it with its bush on the long leaver, the bush holds it "slack" with little play.

Ready, not difficult.

P1150619-b.JPG.70c104643bc2190901f9d2e1e7c56e56.JPG

Next you see the force from the bowden cable Fb.

The force on the front brake shoe Ff is 4.26 x the force from the bowden cable (115/27)

The force on the rear brake shoe Fr is 5.26 x the force from the bowden cable (142/27)

Please compare this with the Girling construction.

P1150620-b.JPG.8de5514ff811b90eb853514e93c84121.JPG

To bolt the pushrod as easy as possible in the long leaver I soldered a nut on there from behind

P1150621-b.JPG.c36203ffefaf76d2b0b07e0087082439.JPG

looks like this from behind

P1150623-b.JPG.3aa6d92b840f5eee0ad0e3def4d0faff.JPG

This is a photo specially made for Waldi. This is it?

P1150624-b.JPG.67453b5e3ccf1676070ba0f48f63ed66.JPG

Ciao, Marco

Edited by Z320
LH
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Hi Marco,

normally I look at the forum from my Phone, not this time, I needed the lab top:)
It makes a good read. It took me some time to understand the forces front and rear, you're a good static engineer:)

If you have an old drum that you can cut a part or even the entire centre out (so just a thick ring is left), you can verify if some components have too much deflection, like the pivot points, and take it from there.
The big gain compared to the Original design is the loss in friction between cyclinder and back-plate: the force from the cable that pulls the cylinder against the backplate,  creates friction (Ffriction = Fnormal x Coëfficiënt of friction), which is a 1:1 loss of effective hand brake force applied through the cylinder. 

It looks like Triumph solved that with the system Peter (W) showed earlier in this post from the saloons.

Are you planning on doing "before and after" measurements of the system?
And off course: keep them coming,!

 

Cheers,

Waldi

 

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15 hours ago, Z320 said:

P1150624-b.JPG.67453b5e3ccf1676070ba0f48f63ed66.JPG

Marco, I am sure know ..but in case not.. a staggered / dog-legged strut (like below) would have the  cleared the hub but also taken away all the aforementioned tilt.

      P1150624-c.jpg.0206002697b3693a1470349836f16aa3.jpg

Pete

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I think Marco's simple dog leg link will work assuming the attachments are tight enough to allow movement but keep slop to the minimum.

This is for the handbrake after all, so should there be any tilt it will be removed the moment the shoes make contact and as such there is no rotational movement of the drum to cause wear to the shoes.

 

Roger

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49 minutes ago, Bfg said:

 

      P1150624-c.jpg.0206002697b3693a1470349836f16aa3.jpg

Pete

You are an artist Pete. What software did you use for this?

Cheers,
Waldi

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Hi all,

we have been out to the "Retro Classics" at Stuttgart, a classic vehicle fair.

Had a nice day, met some friends and found interesting cars. My favorites today: a Fiat Moretti and an Alfa Romeo Giulietta Spider.

There was also a 1936 MG TA Q-type "special" with a brake different from the others pre war MGs, perhaps part of the "special project"?

Sorry, for any reasons I cannot upload the photo, error is "!" and "-200"

There have been also 3 Stags, they all had the same brake with the handbrake leaver out of the brake drum.

 P1150658-b.JPG.e367cbe8e82279908f8482f0bdafcb03.JPG

I my opinion this is not different from our 4A - 6 TRs.

On my construction all the bushes are like distancer and washer in one part, bolt tight but with about 0.1 mm play to the leaver / push rod.

So on the photo at the right side they work like a hinge, on the left side like a knob.

P1150670-b.JPG.f33f4f36eb942cbb8eae78bf52db4b36.JPG

Pete, thank you to be with me,

for what you suggested the brake shoe and the rod have to be cut in about 10 - 15 mm deep to stick in each other.

There is not enough material on the TR brake shoes for that, so this was not safe enough for me, I stopped going that way

(but did not mention that).

P1150672-b.JPG.3b0f57ace74946c4955463031f7afa27.JPG 

To risky for me for the case this slides out of each other when I use the hydraulic brake.

Sorry me, don't think I always have reflected before what you suggest.

Ciao, Marco

Edited by Z320
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Hi Jochem,

well spotted, but this Stag was jacked, with mirrors and illumination underneath.

I have to look at the original photo to tell you if it has been jacked on the wheels or on the frame.

But indeed, on the not jacked Stags this detail looked not that much better.

Possibly this is not better or worse with the car jacked or not?

Ciao. Marco

Edited by Z320
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On 3/1/2020 at 12:12 PM, Bfg said:

Marco, I am sure know ..but in case not.. a staggered / dog-legged strut (like below) would have the  cleared the hub but also taken away all the aforementioned tilt.

      P1150624-c.jpg.0206002697b3693a1470349836f16aa3.jpg

Pete

You could always re drill the brake backplate 30 degrees further round so the flat of the hub bearing carrier allows additional clearance for the handbrake reaction rod between the shoes.

Cheers

Peter W

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I fitted the cable already some days ago and realized this:

P1150680-b.JPG.3f270a70987d2225a21369b7d5dc75df.JPG

No problem for my tube bender

P1150681-b.JPG.e025f3606d5d2ff6b8421ad4b008ad5e.JPG

First fit worked lovely

P1150683-b.JPG.e579650f41f2e1165a9267f96c689533.JPG

But I have a problem with the limited space behind the flange

P1150685-b.JPG.996dd5ec71438c2ee493d87a2d1d1583.JPG

The pivot point has to be out from behind the flange, that's only about 12 mm

P1150691-b.JPG.82516aff08f90819f96ee641aec1c22a.JPG

Okay, have to do it again....

 

 

Edited by Z320
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Hi Marco,

I have no open example here so it may be useless but would it be possible to install the lever at the back side of the shoe?

It would also require the cable pipe to be lowered (tilted more to the front to rear line).

Waldi

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Hi Waldi,

this does not fit because of the lower part of the hub (the part that is fixed with 6 studs / nuts on the trailing arm).

And you want me to brake my fingers when I have to fix the cable and the push rod from behind? ;)

But no problem:

I realized the flange of the Goodpart hubs on the car are is 13 mm smaller in diameter than the TR original hubs that I used as a master until now.

So I have to change nothing on the leaver and push rod, only had to order other bolts with allen heads. The hex head is to big.

Ciao, Marco

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