Measure internal diameter 201mm

Wig

How would you measure an internal diameter of 201 - 205 mm ?

Vernier calipers of no use as there is a lip at the top of the drum (brake drum)

Telescopic Gauge seems good (I know of them as my dad has some) but the ones I can see in google shop are only upto 150mm.

or there is this type of calliper and it is big enough
http://www.workshopping.co.uk/product/spring-calliper-300mm-internal/AK9782/

I bought some drums from Euro Car Parts about £40 each but just found out they have no integrale bearing fitted, the bearings are an extra £29 each So they will be going back!
Vauxhall sell them £64 with the bearing already fitted.

I will probably just use the old drums but would like to measure them first before refitting them..

forgotmyname

Yep, that shows upto 300mm so no issued measuring 200mm

Depends how accurate you need the measurement, Exact for a press fit bearing?

Find the data on the bearing and see if you can source them cheaper.

Bearings have the inner/outer sizes stamped on them.

facade

Wig wrote: »

How would you measure an internal diameter of 201 - 205 mm ?

Vernier calipers of no use as there is a lip at the top of the drum (brake drum)

Correct answer internal micrometer (bore micrometer)

Cheap answers-
grind the lip off the drum (it makes it difficult to remove anyway)
Grind a notch into your callipers to clear the lip.
Measure the height of the lip- you can assume the unworn part is the correct diameter.

I assume you want to see if the drum is worn beyond limits?

Easier to fit the replacements and not worry, like I said if by some miracle the auto adjusters actually adjust, you can never get the drum off again. (There is supposed to be a little window that you can insert a screwdriver and de-adjust the adjuster, but I've never managed it, just use a puller to get the drum off and it pings the shoe retainers off, then you need new ones.)

londonTiger

tape measure

https://www.youtube.com/watch?v=TkoCWUJt10w
skip to 2:58

edit nvm, probably not accurate enough for your use.

torbrex

Easy solution is to measure the internal diameter using the Vernier calipers and add 8mm dowel pins at the measuring points.

EdGasket

Grind the lip off the drum. You should do that anyway so you can get the drum off next time!

s_b

its alright advising grind the lip off but its quite dangerous as its easy for the grinder to grab and jump and take a thumb with it
just saying.......

londonTiger

s_b wrote: »

its alright advising grind the lip off but its quite dangerous as its easy for the grinder to grab and jump and take a thumb with it
just saying.......

good advice, its one thing grinding a straight piece or a curve away from the grinder. But grinding the inside and you're asking for a lot of trouble, if it bites it will run up the inside of the drum, go out of control and cause serious injuries.

Wig

Max internal is 201mm (new 200mm)

So I had the idea I will cut something to be exactly 201mm

If it does not fit they are OK, if it fits with room to spare they are too worn.

EdGasket

s_b wrote: »

its alright advising grind the lip off but its quite dangerous as its easy for the grinder to grab and jump and take a thumb with it
just saying.......

Use a small grinding wheel in a variable speed electric drill; I would rate it is 0.1% on a scale of the most dangerous things I have done; no more scary than taking a wheel off.

s_b

EdGasket wrote: »

Use a small grinding wheel in a variable speed electric drill; I would rate it is 0.1% on a scale of the most dangerous things I have done; no more scary than taking a wheel off.

maybe so but doing it your way probably takes 25 minutes a drum,most people like me want proper tools that do it in under a minute hence my warning
i dont even possess a variable speed drill like most people wont ,anyway unless you count my £20 battery one i bought from lidl to fit my kitchen with

anyway at least one person agreed it is dangerous because it is
ho hum