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Discussion Starter · #1 ·
hi all,i am a new owner/member of the CX650T had the bike about two weeks now and went get it state inspected (only ridden once on the test ride).

and the brakes were stuck on, front and rear.(bike has sat for at least two years)

i am assuming i am going to have to strip the calipers down and regrease the pins and change out some seals.

is there a good source for a brake caliper rebuild kit.?

or is it back to honda and see what is available.

thanks mark
 

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Mark,



You need to rebuild the master cylinders and all brake calipers. The pistons have a built up laquer on them and need to be cleaned and reassembled in the calipers with new seals.



I would also recommend SS lines and DOT 5 fluid (Don't mix DOT 5 with any other fluid and make sure all componenets in the brake system are clean and dry) since you'll have the system all apart. After a full clean and rebuild the brakes will perform as in 83.



You can still buy master cylinder rebuild kits, and caliper seals from Honda.



PK
 

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Also, I have this info. on file about the front brake caliper parts interchange, please correct me if I'm wrong.





"The 83 CX650C used a new dual-piston caliper on the left side, shared with the CX650T, 84-86 CB700SC, 83 CX650C, 83GL1100, 83-86 VF1100C. The caliper bracket and brake disc interchanges with the 83-86 VT500C, 84-85 VF500C, 82-83 FT500.



The 83 CX650T used the same left caliper as the 650C, and the right caliper was the same design, shared with 84-86 CB700SC, 83GL1100, 83-86 VF1100C. It used the same brake discs as the 83 GL1100, different side to side. It used the same caliper brackets as the CX500T."
 

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I just went through this and CXTURBOBOOST is correct . Mine were frozen solid ,got the kit from Honda (o-rings) ,cleaned out the old crud carefully -gently with a dental pick. Surprised old brake fluid can get rock hard.

You may ,as i did, have to pop the caliper pistons out and clean um up. Mine had what felt like little pits on them that were getting hung up on the o-rings. Had to blow pistons out with air pressure .Rode all last year ,no problems.

Bofud
 

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Both of your master cylinder may just need the equalising port cleaned out - it is about a 0.3mm diameter drilling just in front of where the piston seal lip sits in the cylinder when the brake lever is in the release position.

It is sometimes the only thing stopping the brakes from releasing.

Tap the calipers with a rubber mallet - towards the disc - and see if you can then spin the wheel If so, then apply the brakes again , and see whether they lock on again. If so, it's a fair bet you only need to clean out that little hole.
 

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Both of your master cylinder may just need the equalising port cleaned out - it is about a 0.3mm diameter drilling just in front of where the piston seal lip sits in the cylinder when the brake lever is in the release position.

It is sometimes the only thing stopping the brakes from releasing.

Tap the calipers with a rubber mallet - towards the disc - and see if you can then spin the wheel If so, then apply the brakes again , and see whether they lock on again. If so, it's a fair bet you only need to clean out that little hole.


The relief hole in the master cylinders doesn't help the varnish build up on the pistons. It causes them to stick and not function properly. Originally they are a stainless finish...If you look at yours I bet they are yellowish..



I've rebuilt more CXT brake systems than I care to admit and all have been this way.



PK
 

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The relief hole in the master cylinders doesn't help the varnish build up on the pistons. It causes them to stick and not function properly. Originally they are a stainless finish...If you look at yours I bet they are yellowish..



I've rebuilt more CXT brake systems than I care to admit and all have been this way.



PK


Varnish on the pistons?

They`re supposed to be yellow - they`re electroplated steel (yellow passivate finish i think) to help prevent corrosion to the exposed pistons - a result of Honda fitting no protective boots.

I hope you haven`t been scrubbing it all off!!

The real cause of binding calipers is oxidation in the seal lands or sticky sliding pins/dried out grease (assuming the master cylinder is not blocked).
 

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Discussion Starter · #8 ·
are the cx500t master cylinder and calipers the same as the 650 and would a stainless brake line kit for the 500 fit the 650 also.

thanks mark
 

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Varnish on the pistons?

They`re supposed to be yellow - they`re electroplated steel (yellow passivate finish i think) to help prevent corrosion to the exposed pistons - a result of Honda fitting no protective boots.

I hope you haven`t been scrubbing it all off!!

The real cause of binding calipers is oxidation in the seal lands or sticky sliding pins/dried out grease (assuming the master cylinder is not blocked).


The pistons are stainless... The brake fluid dries and creates a yellowish gunk residue on them. This creates friction. They need to be cleaned and polished properly to perform as they did new. Otherwise they will drag and catch.



PK
 

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The 500 and 650T run different front master cylinders and calipers. The rear are the same. The handlebars are different on the US spec so you need different brake hose that's longer for the master cylinder to the "T"



PK
 

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The 500 and 650T run different front master cylinders and calipers. The rear are the same. The handlebars are different on the US spec so you need different brake hose that's longer for the master cylinder to the "T"



PK


If you want to confirm how stuck the pisons are just remove the calipers and try to supply a small PSI of air to move the pistons... It won't happen. Once cleaned properly and reassembled it takes very little air pressure to move the pistons in their bore. Then they function more efficiently and release as they did in 82/83



PK
 

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Discussion Starter · #12 ·
Thanks again,

i have got some of the parts and some are on order.


the hoses seem ok for now i think i will just do the calipers and masters for the time being.

cheers mark.
 

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Just to add, there has been lots of mention of using dot 5.1 rather than the others. May be a bit hard to find, but I think it was mentioned that most bike shops will carry it. Marshall has made many posts regarding that. I can't imagine that would be any different for a turbo.



Joel in the Couve
 

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Using compressed air to move stuck caliper pistons is DANGEROUS in the extreme. The stored up energy in the compressed air can propel a caliper piston out of its bore with lightning speed, if not restrained.

Why not use what was originally designed to move the caliper - hydraulic fluid under pressure from a master cylinder?

You can get far MORE pressure from that mode, to move even the most recalcitrant caliper piston - if that's not possible, then your caliper is very close to a write-off.

Using the master cylinder system, you have "vernier" control over where you want the caliper piston, and there is NO compression energy to be watched out for, other than how much pressure your hand is putting on the brake lever.



Eurovee, I'll second your remarks about build-up of corrosion in the grooves that the dust-seal and oil-seal are located.

I've done more than my fair share of twin-piston caliper clean outs, and 90% of those have been mainly due to the dust seal being damaged when guys push the pistons back into the caliper to allow the replacement of worn-out pads with new ones - without cleaning the outside of the piston that was protruding when the pads were worn down. Only 10% of the oil seals had been damaged - mainly due to the corrosion build-up behind the seal (in the groove).
 

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Just pulled my cx500tc front calipers apart as they were stuck (long storage time with little fluid in system as front line was removed for fairing removal by others)



The pistons were tarnished with gum, made of stainless and polished up as new. The seals were lovingly cleaned and (you guessed it) reinstalled. No corrosion on any of the slides.



Great quality bike.



There was crap in the seal grooves, which made the seal tighter than normal on the piston.



The trouble with fluid piston removal technique, is your stuck at the bike (on the floor) - -and there is four pistons to control, else you loose pressure.



I used vice to hold the caliper, bolt in the line in to seal it, and air into the (removed) bleed nipple hole. I used a g clamp to restrain the pistons from shooting out too far.

I found this comfortable, safe and not so messy.

Grease gun would have been my next approach.
 

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Using compressed air to move stuck caliper pistons is DANGEROUS in the extreme. The stored up energy in the compressed air can propel a caliper piston out of its bore with lightning speed, if not restrained.

Why not use what was originally designed to move the caliper - hydraulic fluid under pressure from a master cylinder?

You can get far MORE pressure from that mode, to move even the most recalcitrant caliper piston - if that's not possible, then your caliper is very close to a write-off.

Using the master cylinder system, you have "vernier" control over where you want the caliper piston, and there is NO compression energy to be watched out for, other than how much pressure your hand is putting on the brake lever.



Eurovee, I'll second your remarks about build-up of corrosion in the grooves that the dust-seal and oil-seal are located.

I've done more than my fair share of twin-piston caliper clean outs, and 90% of those have been mainly due to the dust seal being damaged when guys push the pistons back into the caliper to allow the replacement of worn-out pads with new ones - without cleaning the outside of the piston that was protruding when the pads were worn down. Only 10% of the oil seals had been damaged - mainly due to the corrosion build-up behind the seal (in the groove).


It's so dangerous that the service manual says to do it.... You may want to look at a factory Honda CX500 Turbo service manual...



I've done more of these than I can remember and I don't know how it could be dangerous unless they are extrememly stuck in which case I would NOT use brake fluid because it gets all over the caliper and ruins the paint. I use grease at this point to save the caliper paint. I'm picky and like things original if possible. The thing to remember is that you need to have the caliper removed and away from the gold anodized wheel. Do I really need to explain this? Common sense. So, once its off its no longer connected to the master cylinder. Keep the calipers away from the bike. That fluid is old and will ruin paint quickly. Again.... Grease works good, but you must wash and clean very well after having grease in the system. I've never not been able to rebuild a caliper using grease to remove the pistons...It should NEVER be a "write-off".



I've also done many on very low mileage bikes with the original pads so the pistons will have never been pushed back into the caliper and they are all stuck.. It has nothing to do with that. It is all about the residue built up on the piston. Salty is right. You must clean the pistons or they will start sticking again.. This is common caliper rebuid technique done by all major manufacturers...Nothing out of the ordinary... Common guys...



PK
 

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Pete, I beg to differ on your use of grease - unless it is non-mineral-oil based.

If you use any mineral-oil-based grease, you then have a big problem getting all of its traces out of the caliper, as those traces DO cause swelling of the seals, hoses and pistons in a normally Glycol-based hydraulic-fluid system, as our CXes always started out.

It just shows how Honda don't always get it right in their manuals. Ask any OH&S expert, and they will tell you quite quickly - that compressed air is NOT the way to do it.

Neither do you take the dents/dings out of fuel tanks using compressed air - you use water pressure.
 

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Pete, I beg to differ on your use of grease - unless it is non-mineral-oil based.

If you use any mineral-oil-based grease, you then have a big problem getting all of its traces out of the caliper, as those traces DO cause swelling of the seals, hoses and pistons in a normally Glycol-based hydraulic-fluid system, as our CXes always started out.

It just shows how Honda don't always get it right in their manuals. Ask any OH&S expert, and they will tell you quite quickly - that compressed air is NOT the way to do it.

Neither do you take the dents/dings out of fuel tanks using compressed air - you use water pressure.


Don,



I'm assuming that anyone reading this would also know you must clean all grease out of the caliper using warm water/soap and brake cleaner followed with compressed air. It's always worked just fine for me..... I've used this method for many years... My brake systems work as new in 82/83. It doesn't matter how you get the pistons out, just as long as they are out so that you can thorogly clean everything and install new seals for assembly. Clean sealing areas, pistons and calipers are a must for long lasting CXT brake systems. You are right about making sure the relief hole is clean on assembly of the master cylinder also...



I don't take dents out of tanks, so I have no idea why you've referenced the water pressure option????
 

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Discussion Starter · #20 ·
Replace the hoses with SS lines when converting to DOT 5.. those hoses are 28 years old.....


yes i am going to give in and i ordered SS hoses to do the whole system in a one time deal as opposed to dribs anf drabs.

thanks for the advise

cheers mark
 
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