spitNL Posted February 1, 2012 Share Posted February 1, 2012 James, working on the drum spreadsheet. What do you think about a seperate spreadsheet for the drum brakes? I could incorporate it in the same spreadsheet, but I think a seperate will be easier to understand. Link to comment Share on other sites More sharing options...
spitNL Posted February 1, 2012 Share Posted February 1, 2012 James, it's still quite basic, but it works OK. As in the other spreadsheet; yellow is input, gray is output. drum brake1.xls Link to comment Share on other sites More sharing options...
James Posted February 1, 2012 Author Share Posted February 1, 2012 Fred— I can do the rest of the calcs by hand easily enough— Also— may be able to measure CG— awaiting a friend to reply to me Link to comment Share on other sites More sharing options...
James Posted February 4, 2012 Author Share Posted February 4, 2012 Thanks for the spreadsheet Fred. Excuse me if I don't rush outside to go measure my drums and shoes etc — it's ruddy freezing I'm working out some rear disc calculations — using 285 discs on the front and 270 (Saab 90) discs on the back gives a pretty damned good balance based on the rough CG that I am estimating. In fact with that setup you use the same size pistons front and back but with just 2 on the back. Link to comment Share on other sites More sharing options...
spitNL Posted February 6, 2012 Share Posted February 6, 2012 Excuse me if I don't rush outside to go measure my drums and shoes etc — it's ruddy freezing Sissy I changed front discs and pads outside this weekend. My hands were a bit cold afterwards. Sounds like you're on the right track. I would still err on the side of caution, i.e. "under-braked" rear. Why do you want to go to rear discs? Link to comment Share on other sites More sharing options...
James Posted February 6, 2012 Author Share Posted February 6, 2012 I might not It depends what your spreadsheet says If I can play with drums (work out Stag bits — will need to find someone to measure those for me) then I will probably stick with them. Just like the idea of being able to play with the rear a bit more and discs seems to give more options Link to comment Share on other sites More sharing options...
James Posted February 8, 2012 Author Share Posted February 8, 2012 HiSpec Motorsport Billet 4 w/ 38.6mm pistons in red Brembo 285mm x 21mm vented discs Mintex 1144 pads All bought! Bank account is aching. Link to comment Share on other sites More sharing options...
James Posted February 8, 2012 Author Share Posted February 8, 2012 Additionally — I also have the 265 discs that have already been modified to fit. I have a plan to make the brackets for the 265 discs and then make a 20mm spacer for the 285 discs. I have two options then — one that gives 7% and one that gives 15% increase over the standard setup. Link to comment Share on other sites More sharing options...
spitNL Posted February 8, 2012 Share Posted February 8, 2012 Any idea what you're going to do with the rear yet? Link to comment Share on other sites More sharing options...
RealWorld Posted February 8, 2012 Share Posted February 8, 2012 HiSpec Motorsport Billet 4 w/ 38.6mm pistons in red I replaced the standard M16 calipers on the race car with HiSpec lightweights - and would do it again, great retardation and very even/predictable/feel. Nice bits of kit. Running 1155 on the race car, but then you know it'll take a couple of corners to warm them up, and have the track to do it. R Link to comment Share on other sites More sharing options...
James Posted February 9, 2012 Author Share Posted February 9, 2012 Any idea what you're going to do with the rear yet? Need to feed that spreadsheet you've done for me Link to comment Share on other sites More sharing options...
James Posted February 10, 2012 Author Share Posted February 10, 2012 New discs and pads arrived — calipers are a two week wait as built to order. Pads fit the discs perfectly. Need to order some metric bolts — am guessing a coarse thread would be better in to aluminium. Link to comment Share on other sites More sharing options...
DaveNotSoSideways Posted February 10, 2012 Share Posted February 10, 2012 Thread pitch goes up with size usually on Metric. 1.5mm or 1.75mm. Course indeed. Link to comment Share on other sites More sharing options...
James Posted February 10, 2012 Author Share Posted February 10, 2012 Requires M10 so 1.5 pitch Have been thinking about the rears and how easy it will be to make a caliper bracket — am wondering how thick the part that sandwiches between the hub trailing arm needs to be. With the 2000 I have an advantage that I could use the later longer shafts to compensate for the thickness— the later shafts are an extra 31mm in length though I don't need quite that much and wonder how much the shorter shafts will stretch. Link to comment Share on other sites More sharing options...
Nick Jones Posted February 11, 2012 Share Posted February 11, 2012 James, when considering sandwiching stuff between the bearing housing and trailing arm, bear in mind that the snug fit of the shoulder of the bearing housing in the bore inside the arm is what takes most of the cars weight and cornering load - not the feeble studs therefore you need to leave as much of this engaged as possible. I guess you gain no more than 3mm removing the backplate, and I'd reckon on an absolute maximum of 3mm "spare" on top of that - so there is your limiting factor. I think the driveshafts would handle that! Nick Link to comment Share on other sites More sharing options...
James Posted February 11, 2012 Author Share Posted February 11, 2012 Thanks Nick— an important point that I didn't realise— I was thinking last night that those studs are pretty lightweight. A 6mm bracket doesn't seem all that strong though it's quite a large area with all those nuts. Probably needs to be out of steel rather than aluminium? The Herald drum adapter plates I had when I planned to put Princess type brakes on the front of my Spit's GT6 suspension were pretty thin! And of course because this is for the rear it's nowhere near as loaded as the front. I guess the other way is to put it on the outside of the bearing housing though that would probably need an offset bracket for clearance. I need to do some measuring Link to comment Share on other sites More sharing options...
James Posted February 11, 2012 Author Share Posted February 11, 2012 I _think_ this is Andy's setup— can't see how thick it is at the mounting point but it mounts on the outside. Link to comment Share on other sites More sharing options...
Nick Jones Posted February 11, 2012 Share Posted February 11, 2012 Guessing, but I'd estimate 8mm basic thickness of the plate reduced to 4 - 5mm at the flange - which should acceptable. The strength in "torque" to resist wheel rotation is not in doubt due to the size of the plate (as you point out) - the potential issue would be lateral flexibility -which is addressed in the above design by the "wrap-around" design. I'd be quite happy with that. Plate wants to have a decent radius where the thickness is reduced - looks like the one in the picture has this. Nick Link to comment Share on other sites More sharing options...
James Posted February 11, 2012 Author Share Posted February 11, 2012 Thinking laterally — something that is a similar shape to that adapter — a brake disc… http://www.ebay.co.uk/itm/CITROEN-BX-PEUGEOT-305-405-SOLID-FRONT-BRAKE-DISCS-/380405228396?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5891eb236c#ht_968wt_1185 Cheap as a starter to get the right shape — might be quite heavy though Link to comment Share on other sites More sharing options...
James Posted February 13, 2012 Author Share Posted February 13, 2012 You know how you should always measure twice I cocked up my calculations by somehow changing the pad friction at some point. I think I'll go back to using the 265 discs — bit of a pain as I just spent £60 on the 285 discs. 23% extra torque on the front seems a bit scary to me! If I do something with the backs I could use the 285s on the front of course. Final values all using 0.42 pad coef Triumph 2000 727 Triumph Stag (w/ 0.875 MC) 659 Triumph Stag 896 265, small pistons 651 265, large pistons 813 285, small pistons 704 285, large pistons 880 Link to comment Share on other sites More sharing options...
spitNL Posted February 14, 2012 Share Posted February 14, 2012 Have you got the large or the small pistons? Link to comment Share on other sites More sharing options...
James Posted February 14, 2012 Author Share Posted February 14, 2012 I went for large I actually think 265 is probably the way to go — lighter and will still easily cope with the heat. 285 was more of a show off disc size thing Link to comment Share on other sites More sharing options...
spitNL Posted February 14, 2012 Share Posted February 14, 2012 You're right 23% more torque does sound like a lot, specially without rear mods. Can you use the same caliper mounting holes for the 285 disc? Or do you have to relocate the calipers? If not it would be interesting to carefully try it out on some private road..... Link to comment Share on other sites More sharing options...
James Posted February 14, 2012 Author Share Posted February 14, 2012 The discs are identical apart from diameter so all I have to do is make a 20mm spacer for the caliper mount— so yeah I can try it out. Link to comment Share on other sites More sharing options...
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