reverse brake bleed

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1chris1
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Rides:: BMW R 1150 GS HONDA innova 2008 honda nss 300 forza

reverse brake bleed

Post by 1chris1 » Sat Aug 25, 2018 10:02 pm

has anyone done a reverse brake bleed on a innova? recently bought one and the brakes are not very good. pads look ok so i think i need to change the brake fluid.
i been looking at reverse brake bleed kits on ebay, only about £6. consists of two syringes and a 4mm clear plastic pipe. add a bottle of dot 4 and good to go.
how much brake fluid does the innova take?

cheers
chris

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gtd65
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Re: reverse brake bleed

Post by gtd65 » Sun Aug 26, 2018 12:11 pm

Just make up a vacuum pump with an old spray or pump bottle and a bit of hose if you have the parts available.

I had to do my GSX-R750 that way...check out the video:

https://youtu.be/PdIp3MsKSyY

Just forward to 4:20 if you just want to see my home made vacuum pump. :mrgreen:

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AE86
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Re: reverse brake bleed

Post by AE86 » Sun Aug 26, 2018 1:29 pm

It's very little, like on the order of maybe 50 - 75 ml

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Diesel Dave
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Re: reverse brake bleed

Post by Diesel Dave » Sun Aug 26, 2018 4:25 pm

If the system is already full and your just changing the fluid there is no reason to reverse bleed.

Different if it was empty to start with.

remmington
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Re: reverse brake bleed

Post by remmington » Sun Aug 26, 2018 6:47 pm

Reverse brake and clutch bleeding works well...

It is how they do it, in the factory - where they make cars and motorbikes.

Some eccentric clutch slave cylinders on cars and vans can't be bled any other way.

In my car repair workshop - we have a bottle we have made up with a small Mityvac type hand pump to make a positive pressure in the bottle above the fluid.

More goes on than you think - less pressure is required than you think - due to the true meaning of PSI - pounds per square inch. When you pressure a larger surface area and then put the pressurised fluid thru a smaller pipe you are creating a hydraulic action-pump. So you have to be mindful to how much pressure you use (very little is required). You need to use a gauge and measure the surface area of your bottle then use some maths.

Another key point with reverse bleeding is - never actuate the lever while filling - or the clutch pedal on a car. You want the master cylinder piston in its fill point of the stroke - to allow free passage of the air to go into the reservoir. You don't want to move the piston to its pressure position - then pressure the seals - O rings in reverse.

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Atodini
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Rides:: 1974 CB500/4; 1971 C90
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Re: reverse brake bleed

Post by Atodini » Sun Aug 26, 2018 9:21 pm

An anecdote - not Innova-related but might be of interest.

A month or two before its last MOT, I decided to sort out the very wooden and not very effective front brake on my CB 500/4. Even when new, these brakes (the swinging caliper type) could be problematic and mine was no exception!

I'd been meaning to do this for a while, and had sourced all the parts needed to replace the complete system, all bar the pipe from master cylinder to caliper, being genuine Honda spares, mostly from CMSNL.

So bright and early one Saturday morning, I drained the fluid out and removed all the hydraulic bits. I renewed the swing plate and its pivots, although mine were actually not seized - unusual - having copiously greased the pins beforehand. Then fitted the new pads and caliper, the new pipe from the master cylinder (an Aeroquip stainless braided one) and a new master cylinder complete. All sealing rings and such also replaced.

Now to bleed it - this is what I did. First off I carefully filled the system with dot 4, with the bleed nipple just cracked, allowing the fluid to drain through by gravity from the top. I'd done exactly this before with a previous CB 500/4 in the mid 1970's and it had worked first time. This time it didn't!

A break for lunch, then on return, bled it conventionally, slowly pumping the master cylinder until no bubbles could be seen in the jar - again no joy....

I do have a reverse bleed pump, bought years ago for one of the wife's cars, forget which one, that had to have its clutch reverse bled (think it was a Renault)… This didn't work either so out with the "big guns", a compressor driven suction bleed kit that I had never used - a present from my prodigal a few Christmases before. This was a doddle to set up and use, but, again the brake still wouldn't work, so shower and bed - try again in the morning...

I'm told I have the patience of a saint and it was certainly being tried this day - a whole day for what, at most should have been around an hour's work.....

Anyway, next morning, out to the garage and before starting I grabbed the lever - it felt perfect!! Checked the fluid level followed by a road test - the brake was the best its ever been (and has remained so since).

Somehow it must have sorted itself out overnight...

My usual MOT place having closed down, I took it to another dealer in Bletchley, where it passed, but the tester commented on the lack of a front brake light switch, which its never had since I got it. The 3 previous CB500/4's I've had, the first one (a 1971 K0) never had one, it's replacements (1973 & 75 both K1's) both did. This one was first registered in 1975 but the frame number dates it to 1972 and as a K0. It's always been a UK bike...

I investigated fitting one, but luckily before ordering any parts, I did check the wiring loom, finding that the wiring needed (one black and one green with a yellow trace), is not actually included in this loom, also the bottom yoke doesn't have the fittings for the switch. It'll have to do without methinks!

John

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gtd65
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Re: reverse brake bleed

Post by gtd65 » Tue Aug 28, 2018 8:13 am

Bikes didn't require a front brake switch until sometime in the 80's I think?

A bit of a silly omission when you're supposed to be using the front brake in must situations, over the rear.

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AE86
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Re: reverse brake bleed

Post by AE86 » Wed Aug 29, 2018 3:41 am

^^Is that a UK specific thing? Because I've had several 70's Hondas that all came with front brake switches, but that was Japanese market.

Front brake switches arrived with the ZZ models.

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gtd65
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Re: reverse brake bleed

Post by gtd65 » Wed Aug 29, 2018 9:37 am

AE86 wrote:
Wed Aug 29, 2018 3:41 am
^^Is that a UK specific thing? Because I've had several 70's Hondas that all came with front brake switches, but that was Japanese market.

Front brake switches arrived with the ZZ models.

I think it just wasn't required as part of the MoT, so in many cases wasn't fitted. I think the front brake light switch came in around 1986?
Any bike over 50cc built after 1985 should have a separate front and rear brake light system.

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Atodini
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Rides:: 1974 CB500/4; 1971 C90
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Re: reverse brake bleed

Post by Atodini » Wed Aug 29, 2018 11:57 am

I'd be much happier with a front brake light switch but on the CB500/4's, the set up was a pipe from the master cylinder to a three-way splitter bolted to the bottom yoke, then another to the caliper, the third port on the splitter having the switch in it. As I've nowhere to bolt the splitter, plus my wiring loom does not contain the necessary wiring, I've decided that its better to leave it as it is for the time being.

I am on the lookout for a later bottom yoke though as I already have a splitter, switch and the necessary pipework. The wires should be simple to add.

That said it's a very handy feature to be able to moderate your speed without notice if you spot a patrol car in your mirror - but having had a clean licence for over 50 years now, you might guess that speeding is not one of my vices!

John

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