Author Topic: This piston must need replaced?  (Read 1007 times)

Offline Eldrick

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This piston must need replaced?
« on: January 22, 2024, 02:37:51 PM »
Just checking that I am right to think I should replace this 400f front brake piston.

1975 Honda CB400f - Red

Offline K2-K6

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Re: This piston must need replaced?
« Reply #1 on: January 22, 2024, 02:39:49 PM »
Definitely.....it'll not seal well and damage a good seal if used.

Online Johnwebley

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Re: This piston must need replaced?
« Reply #2 on: January 22, 2024, 02:40:05 PM »
Yes,

I think Wemoto can supply stainless ones, and seals



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lifelong motorcycle rider,and fan

Offline Eldrick

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Re: This piston must need replaced?
« Reply #3 on: January 22, 2024, 02:49:35 PM »
Yes,

I think Wemoto can supply stainless ones, and seals



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I am seeing a few suppliers, prices from £20 tru £85
1975 Honda CB400f - Red



Offline Bryanj

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Re: This piston must need replaced?
« Reply #6 on: January 22, 2024, 03:55:06 PM »
Some people disagree but i have always had good service from him, buy the kit with the seal and clean the seal groove out meticulously

Offline Mikep328

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Re: This piston must need replaced?
« Reply #7 on: January 22, 2024, 04:34:17 PM »
Yes, replace the piston.

FWIW, I overhauled the front brake on my 400 last year.  It had been worked on by the shop that sold it to me, which included a new SS piston/aftermarket seal.  The brake was ABYSMAL and that's generous; the rear brake generated more stopping power!

I went through the brake, removed the (new) SS piston they had installed and replaced it with a (way more expensive) Honda piston, replaced the (new) aftermarket seals with Honda (way more expensive) seals, and replaced the brake lines.  With a new set of pads and some serious attention to breaking them in properly, the front brake was transformed into a very good brake!





Offline Matt_Harrington

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Matt
___________________________________
CB400F 1976 -  Almost finished
CB400F 1977 - On the road!
Moto Guzzi T4 - 1981 - My tourer (plus a loft full of spares)
Moto Guzzi Le Mans 2 - 1981
Triumph 3T - 1947 (somewhat dismantled!)
CD175 - To be restored

Offline Oddjob

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Re: This piston must need replaced?
« Reply #9 on: January 22, 2024, 06:42:24 PM »
Yes, replace the piston.

FWIW, I overhauled the front brake on my 400 last year.  It had been worked on by the shop that sold it to me, which included a new SS piston/aftermarket seal.  The brake was ABYSMAL and that's generous; the rear brake generated more stopping power!

I went through the brake, removed the (new) SS piston they had installed and replaced it with a (way more expensive) Honda piston, replaced the (new) aftermarket seals with Honda (way more expensive) seals, and replaced the brake lines.  With a new set of pads and some serious attention to breaking them in properly, the front brake was transformed into a very good brake!

Not being funny here Mike but the fact you did so much work on it all at the same time sort of confuses what was causing the poor brake performance, doing one change at a time is far more informative as it highlights what was the problem, it could have been such a simple thing as air in the lines and you changing the lines fixed that problem.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Bryanj

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Re: This piston must need replaced?
« Reply #10 on: January 22, 2024, 08:03:04 PM »
I have fitted quite a few of the stainless piston kits and never had a problem getting a good brake

Offline McCabe-Thiele (Ted)

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Re: This piston must need replaced?
« Reply #11 on: January 22, 2024, 08:59:38 PM »
Some people disagree but i have always had good service from him, buy the kit with the seal and clean the seal groove out meticulously

I too have had parts from "Honda Classics" without problems & delivered quickly - I think it's the  restoration side of the business where they fall well short of any sort of perfection. It might be they were good at restoration in the past but Peter's (teenybop1) recent experience illustrates how far that side of the business has slipped.

Like my Dad used to say a workshops reputation is only as good as its worst mechanic.
That is probably why good bike restorers tend to be one man bands who guard their repuaution that takes years for them to build & why they often become  expensive.
« Last Edit: January 22, 2024, 09:04:03 PM by McCabe-Thiele (Ted) »
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline K2-K6

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Re: This piston must need replaced?
« Reply #12 on: January 22, 2024, 09:32:10 PM »
Yes, replace the piston.

FWIW, I overhauled the front brake on my 400 last year.  It had been worked on by the shop that sold it to me, which included a new SS piston/aftermarket seal.  The brake was ABYSMAL and that's generous; the rear brake generated more stopping power!

I went through the brake, removed the (new) SS piston they had installed and replaced it with a (way more expensive) Honda piston, replaced the (new) aftermarket seals with Honda (way more expensive) seals, and replaced the brake lines.  With a new set of pads and some serious attention to breaking them in properly, the front brake was transformed into a very good brake!

Not being funny here Mike but the fact you did so much work on it all at the same time sort of confuses what was causing the poor brake performance, doing one change at a time is far more informative as it highlights what was the problem, it could have been such a simple thing as air in the lines and you changing the lines fixed that problem.

While it may not give us step by step analysis of the brake in question, it does serve to show that performance in a properly operating std system is much better than general statements that pervade the great wide Internet will have us believe....that what do you expect, they are just old brakes....that's often trotted out.

The performance isn't that bad, they were easily under 30ft stopping distance from 30 mph when new and we should be able to get them perfectly up to matching their performance capabilities now.

Offline Mikep328

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Re: This piston must need replaced?
« Reply #13 on: January 22, 2024, 11:17:10 PM »

The 1977 Cycle World test showed the CB400 stopped from 60MPH in 135 feet.  Interestingly, it is the same stopping distance that Cycle World reported for a 2022 Honda CB1000R. 

IMO the "common knowledge" that the brakes on a CB400 "were never very good" is not supported by actual road tests.  If returned to "like new" condition, they work as well as modern brakes...or at least as good as the brakes on a 2022 Honda CB1000R!   ;)


Offline teenybop1

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Re: This piston must need replaced?
« Reply #14 on: January 23, 2024, 07:59:09 AM »
Some people disagree but i have always had good service from him, buy the kit with the seal and clean the seal groove out meticulously

I too have had parts from "Honda Classics" without problems & delivered quickly - I think it's the  restoration side of the business where they fall well short of any sort of perfection. It might be they were good at restoration in the past but Peter's (teenybop1) recent experience illustrates how far that side of the business has slipped.

Like my Dad used to say a workshops reputation is only as good as its worst mechanic.
That is probably why good bike restorers tend to be one man bands who guard their repuaution that takes years for them to build & why they often become  expensive.
100% correct Ted, clearly whoever done the restoration side has left the business, leaving a parts man/marketing guy to attempt to provide a service. And failing miserably.its a handy shop to pick up parts, before a new owner steps into the driving seat, ps, shop isn't failing, owner just wishes to retire  :P
If anyone has ever had them do any restoration work within the past 3years or so, it would be interesting to hear about their experiences. They do claim to be a restoration specialist after all. A full report on the condition of my bike on return, was provided by the skilled engineer who sorted it out properly, and is available to view. I believe honda classics no longer accept restoration work, due to the impending sale. I wish any new owner the best of luck.
« Last Edit: January 23, 2024, 08:37:40 PM by teenybop1 »

 

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