ATE 17mm Master Cylinder Seals

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Rob H
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ATE 17mm Master Cylinder Seals

Postby Rob H » Tue Mar 12, 2019 1:12 am

Taking the advantage to overhaul the master cylinder, all is in good condition apart from the two seals.

Unfortunately the overhaul kits include a lot of parts I don't really need.

Does anyone know where I can get a pair of seals from either original type or something compatible?

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Re: ATE 17mm Master Cylinder Seals

Postby Roy Gavin » Fri Mar 15, 2019 3:21 am

Usually by the time the seals need replaced the bores are worn too , so seals are only a short term fix.
12 mm replacement M/Cs are easy to find, so you can almost double the force being applied to your pads too, compared to your 17 mm M/C
My local guy sleeves them with a 11 mm SS sleeve and has no trouble finding a 11 kit , ends up cheaper than a replacement and even coming from a 13 mm M/C there is a welcome improvement.
Forget the old wives tales of increased lever movement- 90% of your lever movement takes place before the bleed hole is closed so if there is any change you wont notice the difference the second time you use them.
Mine actually has less movement, so the 11 mm kit might have a longer piston than the 13 or 17 mm

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Re: ATE 17mm Master Cylinder Seals

Postby windmill john » Fri Mar 15, 2019 11:36 am

I filed down my lever where it meets the cylinder piston. This reduced the span to reach the lever and made applying the brake much easier and more comfortable.
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Re: ATE 17mm Master Cylinder Seals

Postby Rob H » Sun Mar 17, 2019 8:20 pm

Usually by the time the seals need replaced the bores are worn too , so seals are only a short term fix.
12 mm replacement M/Cs are easy to find, so you can almost double the force being applied to your pads too, compared to your 17 mm M/C
My local guy sleeves them with a 11 mm SS sleeve and has no trouble finding a 11 kit , ends up cheaper than a replacement and even coming from a 13 mm M/C there is a welcome improvement.
Forget the old wives tales of increased lever movement- 90% of your lever movement takes place before the bleed hole is closed so if there is any change you wont notice the difference the second time you use them.
Mine actually has less movement, so the 11 mm kit might have a longer piston than the 13 or 17 mm
Does anybody know of anyone in the UK doing this type of modification?

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Re: ATE 17mm Master Cylinder Seals

Postby Rob Frankhamr » Mon Mar 18, 2019 1:43 pm

Usually by the time the seals need replaced the bores are worn too , so seals are only a short term fix.
12 mm replacement M/Cs are easy to find, so you can almost double the force being applied to your pads too, compared to your 17 mm M/C
My local guy sleeves them with a 11 mm SS sleeve and has no trouble finding a 11 kit , ends up cheaper than a replacement and even coming from a 13 mm M/C there is a welcome improvement.
Forget the old wives tales of increased lever movement- 90% of your lever movement takes place before the bleed hole is closed so if there is any change you wont notice the difference the second time you use them.
Mine actually has less movement, so the 11 mm kit might have a longer piston than the 13 or 17 mm
Does anybody know of anyone in the UK doing this type of modification?


From your initial email, I take it that you don't have a problem and are just renewing the seals by way of preventive maintenance. If this is the case, I'd simply examine the bores and, if they are OK, replace the seals. If the brake has been looked after and the fluid kept clean and replaced there is no real reason why there should be excessive wear. A master cylinder should be good for at least 3 or 4 sets of seals without any problems. Of course, if the cylinder shows as scored or worn, that's a very different matter.

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Rob H
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Re: ATE 17mm Master Cylinder Seals

Postby Rob H » Tue Mar 19, 2019 1:28 pm

Yes there is slight wear on the bore.


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