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RogerH

Brakes Drums

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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

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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

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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

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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?

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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

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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.

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