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rear drums rubbing/catching - rear brake change - Spitfire


badgerspitfire

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Apologies for another post but been doing a lot of work on the Spitfire this week.   I've changed the rear shoes and about to fit new drums, but they won't spin freely (catching).  The parts are from Rimmers.   I've checked the following:

-  Adjusters wound right in

- Shoes correct way round, cylinder assembly free to slide against backplate

- handbrake cable slackened off (with the nuts attached to the cable - I guessed that was how to do it?).

- Cylinder pistons pushed in (same as other side not yet worked on).  Bleed screw opened to assist pushing pistons in be sure.

Do I need to machine a bit off the ends of the shoes (the metal parts) to allow them to fit better?  They don't appear a great fit / contact to the pistons.  Or sand a little off the pad material (looks very 'rough' - the suface looks like 80 grit sandpaper with 'ripples').

Any advice appreciated!

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Just a query. You say adjuster wound right in. Do you mean the 1/4in square adjuster on the rear of the back plate? This should be unscrewed out (anti-clockwise) with 1/4in spanner to allow shoes to close up at bottom. Shoes should not look like grit! Just a thought. Good luck!

 

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That lining surface is fairly normal for new shoes. The thickness looks OK, too - possibly a tad on the generous side but not by much.

When you say the drums are "catching", is that a general all-round reluctance to turn or a local drag spot at one particular angle? If the latter then it suggests the drums are out of true, although it could also be a bent hub or shaft, or some muck not letting the drum seat properly.

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I think you've hit the nail on the head! . The handbrake mechanism is holding the forward shoe off the cylinder piston slightly.  how do I completely back off the handbrake?  I've been playing with the nuts in the pic but doesn't seem to be doing much.

P1020294.JPG

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As a starter disconnect the handbrake completely by popping out the split pin from the clevis pin.  That takes it 100% out of the equasion.

After that it's hard to say from the pic but I'm not sure that IS the correct nut.  There should be a long "U" (ish) shaped fork at the end of the hand brake cable that has holes through it.  This goes over the rear drum operating leave and you drop a clevis pin through the holes in it/the operating leaver.  This "U" piece is then attached to the end of the hand brake cable via a square nut inside the U and a plain nut on the cable side, and it's that connection you want to be adjusting - losten the plain nut and you can spin the square nut/U fork up and down the threaded section on the end of the cable, effectivly making the cable longer or shorter.

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take the clevis pin out , adjust the shoes up hard, then adjust the cable to just take the pin without tension or slack,  then de adjust the square adjuster 4 click should be free

there is a setting angle for the primery cable compensator that may need resetting if previous have constantly adjusted the cable to the handbrake lever 

theres a nice picture in the manual but i cant scan just now 

the rasp marks are normal crown grinding the linings to a contour. 

Pete

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If it's a 1500 Spitfire you adjust the handbrake in 2 ways - the "gross" adjustment is at the hand brake leaver, the balance/finer adjust is at the drums

image.png.c0b367dbabc4aad37dd8b210fa3049ed.png

I think the bit you've unfastened is where the return spring attaches?

You need to take the clevis pin out and rotate the U shaped metal bit to run it up/down the threaded part in the picture.


If everything is ok with the cables disconnected then it's just the faff or adjustment that you need to endure!

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Result!  Thanks so much guys!  Removed the clevis pin and the drum now turns (I didn't spot it was holding the shoe slightly away from the cylinder piston).  Although it sticks/catches at part of the rotation - that issue is for another day! 

Now to tackle the other side....  And will need to adjust handbrake later.

19 minutes ago, Pete Lewis said:

take the clevis pin out , adjust the shoes up hard, then adjust the cable to just take the pin without tension or slack,  then de adjust the square adjuster 4 click should be free

Pete.  Is it case of using the adjuster (square 1/4" nut) to put the shoes hard against the drum, then adjust the cable using the nuts shown in the pic above?  I think I may need a gross adjustment at the lever too since I am way off getting the clevis pins back in (poss 5 - 10mm away)..

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Yep, had to let off a lot of cable at handbrake end 🤨.  The rear cables seem to have a lot of natural bend in them so need quite a bit of gentle tension to take out the slack.  I may have to take up the handbrake a little since it does virtually nothing till at least half-way now, but at least I understand how it works at last.  The 'thing' under the middle of the car looks about at the right angle too. 

There was so much thick solidified black grease on the handbrake mechanisms I couldn't even see any clevis pins or fasteners until I washed it all off!

What would probably take an expert a hour has taken me all day, but it is very rewarding to have it back together again looking shiny, and lots learnt.  Thanks again everyone for your advice, would have really struggled without it.    

IMG_20200528_180932_resized_20200528_100815870.jpg

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