RogerH Posted June 9, 2018 Report Share Posted June 9, 2018 Hi Folks, last week I fitted new rear brake drums to the 4A and noticed when adjusting the nearside drum that there was a high spot - drum binding at one point. On my tour of the Yorkshire dales I noticed that when the brakes were applied there was a pulsing from the nearside rear. This calmed down a little during the week. Yesterday I took it apart and found one of the small CS screws that hold the drum in place had its head almost sheared off !! On the lathe - using the large centre hole to hold it in the chuck - I found that the brake surface was a good 0.016" out of round/offset. The old Alfins I took off were a lot better at apprx 0.004" off. Should I expect the drum centre hole to be concentric with the brake surface? Roger Quote Link to post Share on other sites
Lebro Posted June 9, 2018 Report Share Posted June 9, 2018 I guess it's more important that the drum is concentric with the center of the array of the 4 stud holes (& the csk holes of course). Can you check that on your lathe, maybe using a 4 jaw chuck & 4 close fitting bolts ? Bob Quote Link to post Share on other sites
John Bracher Posted June 9, 2018 Report Share Posted June 9, 2018 Roger Could you mount the drum 'inside out' on an (old) rear hub?? I skimmed some old 'worn tapered' and eccentric drums down back in the day using this method. John Quote Link to post Share on other sites
DaveN Posted June 9, 2018 Report Share Posted June 9, 2018 More sh1t ‘quality’ parts Roger? Should I expect the drum centre hole to be concentric with the brake surface? Roger Um.......yep! What are you going to do, skim the brake surface or return for a new set? Quote Link to post Share on other sites
RogerH Posted June 9, 2018 Author Report Share Posted June 9, 2018 Hi Dave, picked up a replacement this morning and it is significantly rounder. I will get the other one reground by a local shop. Roger Quote Link to post Share on other sites
Willie Posted June 9, 2018 Report Share Posted June 9, 2018 As far as the retaining screws in the drums are concerned, I fitted countersunk hexagonal headed [allen screw] stainless units to mine in 2014. No more splayed screws! Size required is 1/4 UNF x 3/8". I cut down 1" units to fit. I installed new drums in my TR4 last November. Only about £30 each inc postage. Is that comparable to engineered costs? Whilst on drum subject, note TR4 studs are screw-in with protruding shoulder, so stud holes in the standard one-size-fits-all drums need opening to 15mm to abut properly against the drum. Best wishes Wiillie. Quote Link to post Share on other sites
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