Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: PatM on August 18, 2010, 08:24:35 PM
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Hi All!
I went for the MOT today after my rebuild and failed on front brake binding and the throttle cable snagging on full-lock. One is an easy fix- but the brake is a b'strd.
I fitted new pads and yep, it does bind- but as they are running in , I left it. the non moving pad has only just got a kiss on it and the moving- I cant tell (as Ive only done about 10 illegal miles, fettling- without an MOT..)
I have had problems with 400/4 brakes in the past- trying to get a good brake on a 400 is a black-art Ive never mastered- but the only way I can reduce the bind on this is to either loosen the capiper (err, a non, no) or fit the moving old pad.
The brake is still crap, but it might just do...as the rear locks a treat!
any comments/help or jibes, feel free!
Rgds
PatM
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When you fitted the new pads, did you pump out the piston and clean out the groove in which the seal is fitted? Corrosion tends to "grow" behind the caliper seal and squeeze it onto the piston, preventing it from returning properly. Often not helped if the piston is just pushed back into the caliper after fitting the pads as any dirt on the piston is forced towards the seal.
Other problem area can be if the tiny bleed hole inside the master cyclinder is blocked, not allowing brake fluid an easy retrun to the master cyclinder after squeezing the lever - use a pin to clear it.
These things are pretty old now - only solution with them is to strip, thouroughly clean out the caliper (especially the seal groove) and re-build with new fluid, etc. I use rubber brake grease behind the piston seal, and DOT 5 silicon brake fluid (doesn't burn the paintwork if it spills / leaks). Old pads have often glazed, and have been known to detach from the backing plate, so would certainly fit new ones if in doubt (which of course you have). Corroded pistons, perished brake pipes should be replaced too.
Obviously new pistons, seals, pipes ets are desirable, but even with the original parts (subject to condition of course) these brakes can be made to be pretty good even if they OF COURSE are never going to compete with the latest generation 6 pot twin disc set ups!
Have fun! - Chris R.
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Good response from Chris, covers just about everything you should be doing.
To add a bit to this about the seal and how it works: I believe the seals of this type deform in cross section as the piston drags out past them it is dragged further out at the piston contact point, when you release the brake pressure the seal elasticity? pulls the seal back to it's original shape and has the effect of taking the piston with it back into the caliper so giving a small pad to disc clearance and hence no binding.
It's vital to clean the seal area as chris says to restore the tolerances that enable this to happen. Only a small amount of muck/corrosion on the pad side of the caliper seal effectively blocks the space for the seal to operate as designed so it's critical. also I have always been able to return bike caliper pistons into the bore with two thumb pressure, it's a good measure of the piston not binding.
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Main problem used to be the pivot pin siezing
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And of course, as Bryan suggests, make sure the caliper arm pivots freely - loosen the caliper bolts, the arm should pivot freely with the spring capable of moving it. Fitted a grease nipple to my winter hack 400/4 caliper arm so the pivot can be greased - no more seizures.
Chris
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A friend had a similar problem with his CB500K. Somebody had rebuilt the front end incorrectly & bolted the front mudguard stay between the upper caliper mount that locates the top of the pivot pin, thus misaligning the caliper mounting bracket. Once the upper mount had been placed between the fork leg & the mudguard stay the caliper bracket was realigned perfectly & the fixed pad had full contact with the disc.
Just a thought...
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All
Thanks for the replies and advice-
You are correct in that I have replaced the pads- as the ones fitted were glazed (and the brake was crap..)
Before writing the 'Help'- I put the old 'moving' pad back in and that seemed to solve the problem-ie, the brake didnt drag- so I think a strip and re-build this w/end is in order.
The final advice regarding the mudguard- yes, Ive replaced the mudguard when I refurbished and painted the forks- Ill have a look if I can understand what you are sayong to see if Ive put something back on wrong. The pivot is obviously free- as I said, Ive stripped and re-built.
Ive had 2 400/4s and ive never had good brakes on them!
My 2001 R1 is a bit spongy know , but by golly-stops on a sixpence and my daily hack- a GS1200 Bmw has excellent stopping power- it needs to, as I do 30k a year on it!
Thanks a lot all!
PatM
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I also had a spongey front brake on my 2k R1, so I replaced the standard master cylinder with a radial Brembo one, Ferodo Supersport pads, pistons from a '01/'02 R1 front calipers & Aeroquip hoses. Now, if i'm not careful, I could be thrown over the handlebars if I were to sneeze while braking.
The R1 master cylinder went onto the Exup1000 after a clean & rebuild.
(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/20100514_6.jpg)
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Thats my bike! except mines original, apart from the mirrors! Ive dinged my exhaust twice now and still managed to get a replacement- once when it was someone elses fault and the other when I dropped it- BNIB
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I have a noisey pipe but I prefer the OEM item. I heard that plod were down at the Oakdene & they did anybody with a noisey pipe, dark visor or small number plate. My R1 is very standard as I don't need the aggro.
See also www.yamahar1.co.uk (http://www.yamahar1.co.uk)
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I have to agree with honda-san, that build up of not only muck but corrosion behind the seal. Also as the seal ages it becomes hard it's less likely to pull the piston back. Also if you have changed the fixed pad you might need to reset the clearance to the disk to 0.15mm. Just slacken off the adjuster for the fixed pad and slip in a feeler gage and then tighten up the adjuster until it starts to grip the feeler gage then back it off a little.
Best of luck.
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Right chaps- I stripped and cleaned the caliper- it was clean(ish)- Ive had worse! I removed the seal and cleaned groove out with cotton-bud- washer the whole lot in hot water and fairy- blew it all dry with compressor- Now it is all back together you can see the caliper moving and no drag. But- I fited the old pads- as I think the problem is pitting on the piston causing stiction. I will re-set one the inner pad (which is new) beds in properly- as its only doing about 20% of its work judging by the marking on it. Theres just no way I can think of to bed thse pads in so they give 100% contact of the disc. So, off the the MOT place agin this week. The jobs a whole lot easier when you can legally run the bike on the road and do these tweeks!
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MOT Passed!
Now I can enjoy!
s*it....its raining out there...maybe not..
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Hi Folks,
Interesting reading on the recon of a 400/4 front brake. I did mine, followed both of the manuals, advice from sites like this, used all the right components mostly new or cleaned like a new pin, Used the right grease in the right places................. Brake works a treat, BUT........ it squeels like a good en when applied, something it never did before......... any ideas please ???
COLIN.
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I found using genuine Honda brake pads resolved the squeal problem. Twice the price of pattern ones of course but the front brake seems a whole lot better now. The brake hoses are the standard ones and I'm using silicone fluid. I know there is some questions as to the suitability of using silicone fluid in these old bikes in that in can have an adverse effect on the seals. I've been using it for at least five years now with no probems.
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Hi Kent400,
Many Thanks for your Ideas / Tips.
COLIN
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Well done, it's always nice when you get a pass and can get out on it legally.
As above Colin if you changed the pads then you could try the old ones if still serviceable to see if that's the origin.
Just a small point and probably not related to the noise, I've always set the static pad by rotating the wheel and adjusting the screw until you can just hear the pad touching the disc, not enough to slow the wheel but to wipe the surface. A common complaint with this era is poor response when wet, but if you get a slight rubbing they are more progressive in rain (should not generate heat when dry though when running and not used).
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Hi K2-K6,
Many Thanks for your points. :D
COLIN.
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Thanks for all your comments and support on this one and all points noted and compared.
I have actually stripped and re-built the caliper as suggested and to my amazement- it was fairly clean inside and upon removing the seal- no growth or material build-up that may have been causing stiction.
On assembly and bleeding- I used standard DOT 5- there was little difference with the new pads
I then changed back to the old driven pad and left the new fixed- and the wheel rotated with minimum interference and rubbing- the adjusted being backed off a good deal- I suppose I got some satisfaction that I could know see the assembly moving, upon application of the brake-leaver.
And it was in that state that it passed the MOT.
My younger bro has a mint 400/4 and he's had 5 to my knowledge- loves them since they came out.
In his experience this is all very familiar. He said that EBC pads seem to be slightly more generous in thickness and in his recollection it took a good few hundred miles before the EBC pads worked properly!
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I have always found EBC pads last forever but have no feel and do not slow the bike down noticeably. I recently bought whatever are the pads that Dave Silver stocks, Vesrah I think, and they are excellent. I did not realise pads could make so much difference, they have made it feel like a different bike.
It is worth noting that it is worthwhile to strip and clean the caliper fairly regularly and, of course, replace the seal. The winter is very harsh on the caliper. Lets face it, the brakes on these bikes are terrible at the best of times.
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Your'e right there Florence, they do need a regular clean to keep them operating as well as possible.
I don't think the caliper is that bad as an engineering solution, more that you can't get enough leverage with standard master cylinder. I call this effect the first real anti-lock disc brake system as you'd have to have hands like king Kong to lock the wheel in the dry!!
Ran a K2 750 with twin standard discs and std master in the 80's and they were suprisingly effective as the effort you have to put in was reduced for any friction that was generated.
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You are right, but I was very surprised how much difference the pads make. I had put up with the brakes for years and accepted that they were just a bad design. I stripped and cleaned the caliper, used a new piston and seal and the Vesrah pads from David Silver and adjusted carefully. The brakes are now the best they have been in 15 years
One day, as an experiment (with the old EBC pads in), I found a quiet long straight stretch of country road. I placed a stick in the verge, went back down the road and approached my marker at 60mph making sure there were no cars following. When I reached the stick I did an emergency stop to see how far I would travel. I was surprised to see that the braking distance was not in any way as far as I had imagined it would be. Evidently, the brakes have no 'feel' but are actually not as bad as one perceives them to be.
The best brakes I have experienced were the ones on my CX500, twin disc with twin piston calipers. They were amazing, I could stop on a sixpence with those in the dry, from any speed. If it could be done, without loosing the wire spoked wheels, I would love that set-up on my CB500.
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(http://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Earlydays034.jpg)
When I did the twin disc conversion on my commuter 550 it used a set of Ferodo sport pads on one disc & Vesrah in the other. As the Ferodo were good in the wet but the others were rubbish it was auto-select disc system. The standard master cylinder was utilised with careful bleeding of the system...& the front wheel was easy to lock up if I got heavy handed with it...like when I was speed zapped one morning on the way into work. 42 in a 30, but that was once he had a lock on me, so I was probably going faster.
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As you say Yoshi, if you blead them well they are fine with a standard master cylinder and I guess that later ones with taller reservoir was to give more fluid "stock" between services. If you check the level regularly there is ample safety margin.
I'm making the assumption that operating two calipers with the same master then you would halve the hand effort to get the same amount of squeeze at the wheel?
I like brakes with a softer start point anyway as if they are too grabby at first they are harder to control over a range of grip levels, you just need them to keep on getting more power as pressure is applied in a linear fashion.
Yes Florence the pads have a major effect so worth evaluating if you are not happy with what you've got, and sticking to a good type when you find it.
Your point about the CX500 are interesting. Years ago rode a superdream 400 (same brakes I think) track bike and they'd used a girling master on std brakes which they found too sharp so had then fitted a device to add some squishyness? into the system to make them easier to control, they were still very potent though.
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I had all sorts of brake issues with my CX500 but I have to admit most of it was due to corrosion and riding it in all weathers- but what a bike! Most people that took the piss out of it were either loaded or had never ridden one. They were all-season bikes, for sure. I miss CUC 500V!
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Yes PatM you are right about the CX they were a all season bike i rode it all year round .
The ones that took the piss had not ridden one, i found it the most comfortable bike i have had.
I dispatched on mine, did well over 130k on it before i was taken out on the west way and put it into the back of a petrol tanker it never hit the deck just well and truly stuck in the back of the tanker took 4 coppers to get it out ;D, me went to the Hammersmith Hospital it to a breakers :( .
I would have one again if i could afford one after my 2 rebuilds.
Paul
My CX over the years
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Paul
Ouch!- the joys of all-year round biking- I can recount some of those also- the best being when I dived under a Rover SD1 jumping a set of lights on my hack-of-a-A100 Suzi- only for the whole lot to burst into flames! Yep, recovery is slow process- skin-grafts take ages- and with a slimmer degree of certainty than restoring bikes.
I was waiting for my MOT last week and a couple of well-healed kids were debating what bike to get- R1, R6, etc- their education or parenting had done them proud- they certainly had some money by the sound of it. I engaged conversation, as the waiting for an MOT at Maidstone
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Sorry this is highjacking the thread but the George at Shoreham used to be a haunt of mine back in the late '70s. There used to be a crowd of guys who had CB400/4s who called themselves the 'Bromley Racing Team' & would offer out anybody to race them up through the lanes to Badgers Mount roundabout & back again. But the pub had too many complaints about the hordes of bikes & had to ban bikers. I went back there a few years later, ordered a load of drinks, then put my leather jacket on. When they said we're not allowed to serve bikers we walked out ...& left the drinks on the bar unpaid.
The George used to be a good place to go to after the Mayday Run. We were too tired to cause any noise as the day was quite intense.
Them were the days.............
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Hooray for CXs. Lots of people say rude things about them but anyone who has ridden one will know how great they were. Although quite heavy, mine would go round corners incredibly well leaning right over until everything was scratching and sparking, it took some nerve but once I realised what amazing traction it had there was no stopping me. It devoured miles and was very comfortable. I had koni shocks to stiffen the rear and I had upside-down honda k4 handlebars. When the exhausts fell apart I used a pair of old BSA A10 silencers on home-made flexible exhaust (from a tractor) down tube; sounded fantastic. I discovered that sliding the forks an inch up in the yolks speeded up the steering and made it feel less heavy at the front. I also cut down the saddle to improve the riding position. One needs to sit 'in' a bike like that, not perch on top. As the headlight unit was so ugly I replaced it with two CB125S units bolted together which made the bike look rather like a frog.
There were two downsides however, it did not have a kickstart so winter starting was always a pain and not an easy bike to bump start (always park on a hill I say). The second problem was the water pump, which always leaked.
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Knock...knock!
Who's there?
CX500!
An old joke, but one that I remember well. Several friends had CXs & they had numerous problems...big ends being the main one. Then generators. Then cam chain tensioners. And as said, water pump leaks.
Glad that I bought a CB550/4.
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Hi again
just picking up on the George front- yes, the same pub and yes, part of the same lot- it was essentially the Eltham and District Bike Club I believe you are referring to- a crew who still get together now and then- but sadly few of them ever turn up on bikes- (I do!) I suppose age and getting married can ruin a happy relationship! I was a late vocation to bikes- my next brother down was there before me. He worked with 2 guys at the co-op in Woolwich who had 400/4s- and that started it. You will know one of them; I
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Sorry about diversifying from the main subject again, but there's more on 'The George' saga in Shoreham.
My missus of 28 years remembers that the Bromley Racing Team bought their CB400/4s from Normand Mobikes in Burnt Ash Lane Bromley (now a Toyota dealer) & there were about 6 or 8 of them. She used to go to school with one of them, his name was Paul Salmon, & his brother wasJohn (maybe...). Anyway, both of them were gingers apparently. The Team often did Brands on a Wednesday, which was when ACU licence holders could do a test session for about
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Have to respond to that- positively!
I saw John Salmon about 18 months ago and his brother- I think hes Paul- at an Eltham and District do in Farnborough. I was a bit late and married (still am, to same missus- 33 yrs) so thefore skint in those day to engage in that malachy! But Dave M was one of them, and duly blew his h/g. As I said in my last post- hes still got it! I see JS, DM, Pat Haverty, and Paul (the treasurer of EDBC) during a few get-to-gethers when I can make it! I'm the old one that turns up on a bike- sadly- The R1 caused some discussions last meet in Shorne.
anyway, I'm also sorry for digressing and If I'm banned form the Form, Ill know why- less chat, more bikes! I'm comming to the Gamecock tonight with my Bro on our 400/4s- so might see ya!
PatM