Brere Posted October 20, 2018 Report Share Posted October 20, 2018 A hard brake pedal on my spitfire 1500 led me to find my rear brakes were binding. Decided to service brakes and change hoses. When stripped down I could see wear on the backplate where the handbrake lever has worn at the pivot. Is this normal? I have looked at a few used backplate a on line and they have similar but not so visible wear. Would this effect the wheel cylinder sliding? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 20, 2018 Report Share Posted October 20, 2018 I'd say that's normal enough. I can't tell how worn yours is in comparison to others I've seen but it would take a tremendous amount of friction - and a lot of handbrake use - before it would wear anyway significantly. The cylinder won't slide that far in any case, no matter how worn the lever seat is. You do appear to have a couple of semi-circular notches along the lower edge; these may have more effect on the cylinders free movement. Flatten them back as much as possible to give a smooth surface, and grease well with copper grease. Link to comment Share on other sites More sharing options...
Brere Posted October 20, 2018 Author Report Share Posted October 20, 2018 Thanks didn't fancy trying to source a new backplate. Will do as advised. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 20, 2018 Report Share Posted October 20, 2018 Have you thought about fill with weld and grind back to a flush finish I would think the groove you have is going to restrict cylinder movement as to slide the hand brake lever pins have to ride out the grooving Reckon While its in bits some remedial work is worthwhile Pete Link to comment Share on other sites More sharing options...
daverclasper Posted October 21, 2018 Report Share Posted October 21, 2018 One of my brake plates is like that. I think it sometimes sticks if the car not moved for a bit and there is a thump when I first brake as the cylinder suddenly moves. Dave Link to comment Share on other sites More sharing options...
Nick Jones Posted October 21, 2018 Report Share Posted October 21, 2018 23 hours ago, Pete Lewis said: Have you thought about fill with weld and grind back to a flush finish I would think the groove you have is going to restrict cylinder movement as to slide the hand brake lever pins have to ride out the grooving Every backplate I've ever seen (a good number) has those dimples for the handbrake lever pivot are you really saying it's wear and not a design feature......? Nick Link to comment Share on other sites More sharing options...
Brere Posted October 21, 2018 Author Report Share Posted October 21, 2018 I've looked for images of new backplates but can't find any. I have checked the parts catalogues and service manual but the diagrams don't help. I decided to take both backplates off as my hub puller had sat on the shelf for 10 years unused. Both backplates are similarly affected. One worse than the other. Before taking them off I did experiment by moving the cylinder and they did catch in the depression. I am tempted now they are off to fill with weld and flatten but that could potentially leave them without a design feature. No one stocks NOS backplates only used so have nothing to compare them with. Bit of a dilemma! Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 22, 2018 Report Share Posted October 22, 2018 long time since i played with any on the vit6 but by design features if the handbrake lever needs a depression to locate the pivots then the wheel cylinder must have clearance to float over the top of the assembled pivot , there cant be any sticking in grooves or whatever or the cylinder will not float as intended if it sticks then one shoe is not being energised fully as the ride over the dimples absorbs or blocks the cylinder shifting when the piston is expanded just my thoughts Pete Link to comment Share on other sites More sharing options...
Ian Faulds Posted October 22, 2018 Report Share Posted October 22, 2018 heres a pic of a late gt6 brake back plate, you can see theres no wear or groove, I suggest as clive says you put a spot of weld on and dress it back Link to comment Share on other sites More sharing options...
dougbgt6 Posted October 22, 2018 Report Share Posted October 22, 2018 I thought Pete said weld and cut back? Unless Clive and Pete are the same person. I knew it! They're all Pete! Non Member, Colin, Dave, Clive, Marcus, all Pete! db Link to comment Share on other sites More sharing options...
Ian Faulds Posted October 22, 2018 Report Share Posted October 22, 2018 sorry pete , clive answered my distributor query and was in my mind. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 22, 2018 Report Share Posted October 22, 2018 Ian that pic answers my thoughts , a groove is not a good thing to have , unless its on a record peteanyname Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 22, 2018 Report Share Posted October 22, 2018 Groove is in the heart!! I had to go check my stock of old Herald components and the two I could find both have that groove, which to be honest I assumed was there originally, never having had a new backplate (deprivation...the squalor!) I'll check the early GT6 one if it's ever returned to me by the reconditioner... Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 22, 2018 Report Share Posted October 22, 2018 does the wheel cylinder have clearance for the cyl to slide over the HB pins ?? Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 22, 2018 Report Share Posted October 22, 2018 There's a corresponding slot in the rear brake cylinder for the lever. This points to the lever moving along with the cylinder, and is therefore not static; in which case the backplate should be flat and smooth with no groove. This means those two backplates of mine are now scrap, or in need of reprofiling... Link to comment Share on other sites More sharing options...
Brere Posted October 22, 2018 Author Report Share Posted October 22, 2018 Thanks for all the helpful advice. I’m going to fill with weld and hopefully grind smooth. Will post finished version when done. Link to comment Share on other sites More sharing options...
Brere Posted October 23, 2018 Author Report Share Posted October 23, 2018 Obtained one used backplate from Rimmer Bros today. In excellent condition and no sign of groove so confirms , as concluded, its wear not an original feature. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 24, 2018 Report Share Posted October 24, 2018 good that's another confirm my years were not playing tricks , Ha !i yesturday i took 25 memebers to have a day at the rolls royce heritage collection in derby now theres some engines to dream about ..how did they evolve that some amazing examples of .............necessity is mother of invention .......... through the years not just aviation , think I 'll stick with cars and trucks pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 24, 2018 Report Share Posted October 24, 2018 1 hour ago, Pete Lewis said: good that's another confirm my years were not playing tricks , Ha !i It's one of those things that you work with a lot but never really look at until someone asks. Now I've to check all of mine, even the fitted ones, to make sure they're not so worn as to foul the brakes. Link to comment Share on other sites More sharing options...
daverclasper Posted October 24, 2018 Report Share Posted October 24, 2018 Do you think Araldite/JB Weld may be ok for a more temp fix. (I tend to use handbrake lightly, and leave in gear most of the time). I'm attending a City/Guilds level 1 MIG course at the moment using top welders, though when I practice at home on my gasless Liddle cheap welder it just ain't that great. Cheers, Dave Link to comment Share on other sites More sharing options...
Ian Faulds Posted October 24, 2018 Report Share Posted October 24, 2018 sorry dave, I think youll need to weld it, the glue wont have the strength and its fairly shallow too. if your not sure ask your instructor to fire a bit of mig in for you. its only a two minute job. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 24, 2018 Report Share Posted October 24, 2018 Ive never done enough mig to make anything other than bird sh1t or blow holes or stuck the wire on a strike . Practise makes perfecf....lots of practise Pete Link to comment Share on other sites More sharing options...
Ian Faulds Posted October 24, 2018 Report Share Posted October 24, 2018 There's loads of stuff on you tube to aid you. The better the machine of course the easier it is and I find gas mig is far easier than gasless. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 24, 2018 Report Share Posted October 24, 2018 They always say you're listening for a sound like frying bacon. Every time I hear frying bacon, I leave the welding and go off for a bacon sandwich. Consequently, I can't weld. Link to comment Share on other sites More sharing options...
Morgana Posted September 10, 2023 Report Share Posted September 10, 2023 I'm tagging onto the end of this thread to help with search results. I have similar grooves in my backplate. Without the special hub puller, has anyone had success welding and grinding it in situ? A couple of passes with a 2.5mm rod ought to do it, and a small rotary tool could get it flat. Otherwise, I guess the whole hub has to come off to get at the plate... Wouldn't this issue be solved if the handbrake lever pivots didn't project beyond the grooves in the cylinder housing? I'm sure the photographs I've seen have them sitting proud in the casting. Link to comment Share on other sites More sharing options...
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