Author Topic: Front Brake Caliper & Piston Question  (Read 1079 times)

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Offline DennyK

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Front Brake Caliper & Piston Question
« on: April 18, 2014, 03:50:55 PM »
I have a question regarding front brake calipers.  I have two CB750 bikes, one is a '71 the other is a '74.  The older bike has a seized engine and we are using it for a parts bike.  I suspect the bike has lived in Colorado all of its life, so a lot of the parts are in pretty good shape.  The '74 runs and this is the bike my son and I are rebuilding.  The '74 came from San Diego and it has more surface rust, also the PO let the bike sit for 8 years in his garage and the front brake was seized on the disk.  I have finally been able to get both calipers apart and remove the brake pads and piston.  (I did successfully use the grease gun method for both calipers.)

The caliper on the '71 is a bit cleaner and the piston has very little pitting on it whereas the piston on the '74 is not as nice.  I noticed that the caliper on the 71 has a 2 on the body where as the 74 has an eight; and the piston on the '74 is machined differently.  There is a recessed area on the '74 while the '71 is smooth.  The picture shows that.

Given this difference I am wary of using the '71 piston in the '74 caliper.  Honda no doubt improved the  front braking system from '71 to '74.   While there is some pitting on the '74 piston is it safe to use or should we just buy a new piston?     

Offline SOHC4 Cafe Racer Fan

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Re: Front Brake Caliper & Piston Question
« Reply #1 on: April 18, 2014, 04:16:25 PM »
The pistons are interchangeable between the different 750K Tokico-made calipers. You could opt for one of Godffrey's phenolic pistons. Much lighter and the will NEVER corrode.
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Offline Old Scrambler

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Re: Front Brake Caliper & Piston Question
« Reply #2 on: April 18, 2014, 04:40:17 PM »
+1 regarding fit...............use the best parts and then get the best pads...........and if the cam-tower and cam in the K1 are in good shape you may want to install them in the K4..........along with some 115 or 120 main-jets. 
Dennis in Wisconsin
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Offline DennyK

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Re: Front Brake Caliper & Piston Question
« Reply #3 on: April 19, 2014, 09:15:49 PM »
Thanks for the advice.  This is our first effort so we are eating this one bite at a time.  We are learning a lot and having some fun.  The phenolic piston looks like the way to go and I will look into those jets.  We are close to 5000 feet here in Western Colorado and altitude was an issue with my old Enfield.