Mik Posted August 24, 2014 Share Posted August 24, 2014 So I've now spent most of the last two days trying to assemble the rear brakes on my race car. I finally got all the shoes, springs, thingumies and whatchamacallits back in the right order after a battle with the shoe hold-down springs but now the drums won't fit over the shoes.The adjusters are fully unwound (and I've not got them balanced on the "peaks" of the square either!). The cylinder piston isn't stuck and it is pushed fully in (and the same for the adjuster pistons). The cylinder is free to slide on the backplate. The handbrake cable isn't connected yet.The brakes are the standard manual adjustment ones for a rotoflex GT6 (8 inch drums). All the parts are brand new apart from the drums themselves and the backplates. The drums (and the backplates for that matter) have been cleaned so there's no paint or corrosion on the friction surfaces. The two drums are slightly different (one's an original Stanpart and the other some later replacement version) but neither will fit. The problem is the same both sides of the car and the amount by which it's out of alignment appears to be the same on both sides.I've even tried fitting the trailing shoe upside down which made no difference whatsoever.I can move the shoes about to centralise them on the back plate but whatever I do the drums won't go over the shoes. I've experimentally tried modifying (i.e. grinding a bit off!) one of the adjuster pistons and also the contact heel on the back of one of the shoes in case the issue was just the thickness of paint/plating etc. This didn't seem to make much difference. I don't want to do to much damage though without knowing what the actual problem is.Anyone got any suggestions? Did I miss something? Picture below which probably won't help... and I know one of the shoes is upside down, I was clutching at straws! Quote Link to comment Share on other sites More sharing options...
JohnD Posted August 24, 2014 Share Posted August 24, 2014 Hi Mik!Have you tried offering up the shoe to the inside of the drum, both loose, in your hand? Is the radius of the shoe bigger than the drum's ID?What have you done (if anything) to the brakes? New parts? Are the shoes new or part-worn? Just trying to think of where the problem might lie. Picture doesn't come through. Try agian?JOhn Quote Link to comment Share on other sites More sharing options...
Mik Posted August 24, 2014 Author Share Posted August 24, 2014 All new parts apart from the drums. No modifications, just standard GT6 brakes (albeit fitted to a spitfire with CV driveshafts). Not sure what happened to the picture, I'll try againThe shoes looked to be the same radius i.e. when I offer up the drums they fail to fit by the same amount all round. I'll do a comparison on the bench though next time I'm in the garage. Quote Link to comment Share on other sites More sharing options...
Mik Posted August 24, 2014 Author Share Posted August 24, 2014 Update: Drum/shoe radius is perfect... Quote Link to comment Share on other sites More sharing options...
vitesse203 Posted August 24, 2014 Share Posted August 24, 2014 Piston looks to far out on the cylinder - the RH brake shoe is wrong way round ( I think), is the hand brake connected and bottom spring is wrong, Have the bottom manual adjusters have been correctly fitted as the shoes look further out on the bottom?Paul Quote Link to comment Share on other sites More sharing options...
GT6 M Posted August 25, 2014 Share Posted August 25, 2014 the HB seems to be on, as lever is ont ..pull side.. oft shoethe suspension aint free hanging is it, cos the roto set up pulls the HB on when jacked upand the right shoe is on upside doonM Quote Link to comment Share on other sites More sharing options...
cook1e Posted August 26, 2014 Share Posted August 26, 2014 Agree with the above comments. Piston is not pushed back in the slave fully, RH shoe is fitted upside down and handbarke is not fully released.I'd disconnect the handbrake clevis pin totally until you have the dums fitted and the brakes bled. Last job after adjusting and bleeding the barkes is to adjust and assemble the handbrake cable to the lever with the clevis pin. Quote Link to comment Share on other sites More sharing options...
cook1e Posted August 26, 2014 Share Posted August 26, 2014 Also the lower release spring should be behind the shoes not in front.... Quote Link to comment Share on other sites More sharing options...
Velocita Rosso Posted August 26, 2014 Share Posted August 26, 2014 Michael, those shoes do not look right to me . Generally most of the metal of the shoe is behind the hub flangeThe brake material( the whole o/d) seems to be nearly the same diameter as the back plateThe fault to me looks in the shoe itselfOur GT does not look like that....the Spit certainly doesnt The recess diameter on the drum should fit inside the backplate Quote Link to comment Share on other sites More sharing options...
drofgum Posted August 26, 2014 Share Posted August 26, 2014 Mik,Measure the old and new wheel cylinders. ISTR there are some new ones that are too long. Cheers, Paul Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted August 26, 2014 Share Posted August 26, 2014 Agree that the lower spring should be behind the shoes. However, the shoes are on the wrong sides. The right hand one is NOT upside down but it should be on the piston side. There is a wider slot on this shoe to accommodate the handbrake lever. This is why the piston is not fully returned and you can't get the drum on. Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted August 26, 2014 Share Posted August 26, 2014 Picture bottom right.http://mygt6.com/GT6-mysusp.html Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted August 26, 2014 Share Posted August 26, 2014 No I take that back, not right. :B There should be no brake material at the top of the shoe on the piston side and I thought there was but having blown the pic up my eyes have deceived me. So the one on the right is upside down except, the slot on this one does look wider, try it on the other side if it is wider. Quote Link to comment Share on other sites More sharing options...
vitesse203 Posted August 26, 2014 Share Posted August 26, 2014 And you should also remove all the grease from the adjuster and use sparingly copper slip, otherwise the grease will melt and coat your shoes.Paul Quote Link to comment Share on other sites More sharing options...
Mik Posted August 26, 2014 Author Share Posted August 26, 2014 Thanks for all the comments so far.It's not the handbrake cable causing this as it's not connected. Neither is the hydraulic plumbing for that matter so no pressure coming from either of those sources.As I said earlier, I know the trailing shoe is upside down in that picture. I tried both ways just to see what would happen (nothing changed, all four shoes are identical anyway).That bottom spring should be behind the shoes, I agree. It rubs on the hub where it is now. That's not causing the bigger problem though I think.I've just been and had another look. I've removed both shoes and all the springs again now. The cylinder is definitely fully retracted. I can easily move the piston out and back in and it comes to a definite stop at that point. The one on the other side is identical. At its shortest, the cylinder measures 1[sup]3[/sup]/[sub]4[/sub] inches between the outer faces of the piston and the opposite bearing surface for the other shoe. (Perspective on the photo below makes the reading look a little more more than it really is).Measuring the same way across the adjuster gives 1[sup]1[/sup]/[sub]8[/sub] inch (into the bottom of the recess in each adjuster piston).Anyone got any of these lying around that they could measure for comparison? Next time I'm in the garage I'll take some measurements from the shoes themselves. Quote Link to comment Share on other sites More sharing options...
Richard B Posted August 27, 2014 Share Posted August 27, 2014 Do you still have the original shoes?If so try fitting them and see if they fit ok. Then compare to the new shoes. Quote Link to comment Share on other sites More sharing options...
Mik Posted September 12, 2014 Author Share Posted September 12, 2014 Just thought I'd update this thread. I didn't have any old parts to compare with as I've converted from spitfire to GT6 brakes and lost the spitfire parts somewhere along the way. Found someone who had parts though and could take some measurements for me.The cylinders were identical but my adjusters were several mm too wide. I tidied the rather rough casting of the body with a file and then took an angle grinder to the back of the wedge shaped adjuster pistons and shortened them until they fitted properly.After refitting, the drums will go on now. Then I discovered the square adjuster head is 6mm instead of quarter inch. Not a large amount out but it's the difference between a well fitting spanner and one that just wants to slip and round off the corners!In short, a case of badly made reproduction parts it would appear. All fitted now though. Just need to finish the brake lines and flexi-hoses and I can try the brakes properly.Thanks everyone for all the suggestions. Quote Link to comment Share on other sites More sharing options...
herald948 Posted September 12, 2014 Share Posted September 12, 2014 mik wrote:Just thought I'd update this thread....my adjusters were several mm too wide. I tidied the rather rough casting of the body with a file and then took an angle grinder to the back of the wedge shaped adjuster pistons and shortened them until they fitted properly.After refitting, the drums will go on now. Then I discovered the square adjuster head is 6mm instead of quarter inch. Not a large amount out but it's the difference between a well fitting spanner and one that just wants to slip and round off the corners!In short, a case of badly made reproduction parts it would appear....I've heard so many bad things about the repro adjusters, but this is a new one, and it's even scarier than the other things I'd heard about them! ??) I will NEVER fit anything but an original Girling adjuster. It occasionally takes a bit of effort, but I've never yet failed to be able to free up a stuck adjuster and get it functioning again as new. It's more than worth the approximately 10 minutes it takes to do this: two minutes with a propane torch to free up the most stubbornly stuck ones; maybe five minutes to thoroughly clean the pieces; and about three minutes to carefully and sparingly lubricate and reassemble them! :) Quote Link to comment Share on other sites More sharing options...
yorkshire_spam Posted September 12, 2014 Share Posted September 12, 2014 Glad to hear you sussed it out Mik. Quote Link to comment Share on other sites More sharing options...
marktheherald Posted September 13, 2014 Share Posted September 13, 2014 Makes me glad that I've got a tub full of old brake parts, including half a dozen adjusters.. ;D Quote Link to comment Share on other sites More sharing options...
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