I'm working on daughters new (to her, 21 year old) Honda motorbike. She would normally do it (under my supervision) but Covid etc etc.
I've done the chain and sprockets (un-seizing the rear brake in the process) and today replaced the fork seals and dust covers and in the process, found the front brake caliper to be pretty stiff (single sided floating caliper with dual pistons) so currently have it on the bench with some Plus Gas round the pistons.
Now in the past I have forced the pistons out with compressed air (restricting their travel with suitable blocks of wood / rag / clamps etc) but feel it would be better to do hydraulically because it would be more predictable and possibly safer.
So I might hook it back up to the bikes front brake system this time but I was wondering about rigging up a general purpose hydraulic hand pump for when I need to do such things.
It seems they do them fairly cheap on eBay and I'm assuming I could use basic hydraulic fluid (less likely to take the paint off?) but I'd need to make up some fairly high pressure adaptor hoses (25 bar)?
Is this something one can do diy and if so, do you need any special tools for the joints etc?
I think the pumps come with a 1/2" male (looks tapered) outlet and so I'd need a mating female to whatever I was working on, in the case of most motorbikes, a 'banjo' connection of some sort.
Given that you already have a hydraulic pump with all the right fittings and fluid to hand this seems like a lot of work.
If you are going to make a general purpose system you have a choice between using mineral oil and "brake fluid". (When you say "hydraulic fluid" earlier it is not quite clear what you mean). I would generally use mineral oil (absorbs less water, gives better lubrication for a stuck or rusted system, and less likely to strip paint). But, you might then worry about compatibility with seals specified for brake fluid. No problem if you are going to replace them once you get the thing apart. In fact in general people worry more than is necessary about compatibility of mineral oil with rubbers other than nitrile and viton. Provided the exposure is short and it is cleaned off well with suitable solvents there should not be a problem. Although mineral oil will cause natural and many other rubbers to swell and become soft the effect is generally reversible.
I still use reusable fittings for repairs, they're good up to 200bar
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The ferrule has a bastard thread which you wind on the hose, there are different types depending on whether you skive off the outer rubber first or not or how many steal braid layers the hose has, you then wind the coupling in and the taper grips the hose to the ferrule.
They are deprecated by the hydraulics engineers whose code of practice does not allow them to repair hoses but only supply a new hose with new swaged fittings.
Well true, it's just that I'll have to do that with the caliper dangling on the bike and with risk of spraying brake fluid everywhere rather than on the bench in the workshop. ;-)
Jack oil? I saw a litre of something like that when looking for fork oil yesterday but will have a closer look at it today.
Yup, they seem to be the properties I'm looking for.
Good point and true.
As would be the case (brake cleaner).
OK, thanks.
I appreciate Tribology is your thing <g> but do you have any experience of any diy-able fittings that can takes the sorts of pressure you might find in such a system?
So no need for an outer crimp / ferrule or is there still one?
Understood. This would only be for the odd thing like this where I have always wanted something more powerful (than ear) and more controlled (than air) and for £12 for the hand pump and reservoir (plus some adaptors), I thought it was worth the cost / effort setting something up (even this late in my life). ;-)
We currently have 7 motorcycles in various states of readiness and several cars so there is a 'good chance' I will be able to make use of something like this in the future (as might mates etc).
I'll have to have a measure up and see if the motorcyles tend to use the same size banjo connector and if so, I might just need one 'tail' (1/2" female to banjo) adaptor (and it doesn't matter if it isn't a perfect fit, as long as I can seal it for the job).
Could be handy if I do car related stuff (and I might) so thanks.
For the moment I'm interested to consider how I might 'best' convert whatever the fitting is that comes on the hose supplied with this pump kit and whatever I might be trying to test.
Like, do I leave the 1/2" mal thread on there or cut it off and fit a hydraulic quick connector of some sort (that might be more logical / flexible. If that makes it all too expensive, the idea of screwing a temporary fitting to the cut end of the flexi hose might be sufficient (assuming I can get what I want in the right size in that format etc).
I've never DIY'd hydraulics apart from flaring brake pipe (easy enough with the right tools) or buying and fitting ready made commercial hoses. In another life a colleague of mine used to recharge Citroen suspension spheres (I'm not sure what pressure they ran at). Another poster gave a link for DIY hose terminations that looked quite interesting. Since I replaced my tractor with an ATV I don't have any hydraulic kit except on the cars and vans (and I only touch those in emergencies).
Yeah, I will follow those up, when I get the pressure testing gadget thing.
Understood. ;-)
Cheers, T i m
p.s. Whatabout what difference it might make if I put 5W oil in a motorcycle fork as opposed to the recommended 10W?
I ask because one of the issues that most people suffer on motorbikes is 'dive' under braking and unless your bike is fitted with any 'anti dive' solutions (one of mine is), I don't think going between most of the std weight oils used in such roles would impact that much (given how much the suspension has to move 'normally' to give a reasonably smooth ride)?
The one anti-dive system I had that really worked was on an MZ 250 with a leading link fork. The torque reaction on the shoe carrier plate (can't remember the proper name for it) made a huge difference. Contrast that with the Aerial Leader / Arrow with their trailing link suspension, I'm convinced that even with the tiny 6 inch drums the braking effect was deliberately weakened to reduce dive.
I don't know about modern anti dive systems, is there some cleverness? The only passive effect I can see with a telescopic fork is that the torque reaction will increases the loads on the plain bearings. (On the MZ you could actually feel the front lift when you braked hard).
Putting in a thinner oil will just reduce the damping a bit. But 10 to 5 is not a very big change. I know all the design theory about EHL film thicknesses, but (within limits) gearboxes are not actually all that sensitive to oil viscosity because a thicker oil will run a bit warmer, and that will drop the viscosity significantly. The same is probably true of fork oil, especially on bumpy terrain.
I had a few step though mopeds and small motorcycles that were the same. ;-)
Backplate?
Like fitting narrower tyres to stop a car from rolling over. ;-)
All the active suspension and electronics.
On my GPZ550 it has hydraulic anti-dive. When you operate the front brake it actions a piston in a bypass valve on the fork legs that prevents the damper oil going past the damper itself and so stops the fork from diving. Also it has 'air assisted' front suspension (you pump it up).
It also has a complex rear suspension linkage (Uni-trak) that provides 'anti squat' (the back sinking down on acceleration) so it was quite technically advanced tool in it's day. ;-)
Yeah, like the bikes I mentioned above. ;-)
I guess as with most things it's a compromise. For me it would be right if it keep the front wheel running smoothly on the road (no patter or other anomalies) whilst providing the best ride for the rider?
Yeah.
Oh, for sure, Paris-Dakar suspension units spontaneously combusting is proof of that!
Whilst the UK roads are bad, they aren't quite that bad so I think some of it can be a bit suck it and see (within some constraints).
It's funny, when I thought I was going to put the 2L Pinto engine in the kitcar (instead of the 1300 Kent) I needed to replace a broken road spring to took the opportunity to upgrade the struts for stronger ones with heavier springs and damping. Then I changed my mind so had some std tension springs made (with +1" lift to offset the extra weight over the donor vehicle) but left the h/d dampers. So, if you sit on the front in now sags as would be right for a comfortable ride but you don't actually get one once moving because of the stiff dampers. ;-(
I kept the springs and may return to them if / when I convert it to electric. ;-)
I was forgetting that with these new fangled hydraulic brakes on bikes it's relatively easy to add a second actuator. Damned clever, these Japs.
(Cue Peter Sellers in Dr Strangelove, "The swine! Funny thing is they make such bloody good cameras")
Although of course that doesn't prevent the weight transfer to the back wheel
Agreed
Agreed. If it really made such a difference you would use a multi-grade, or change the grade from summer to winter. I guess since the quantities are small they probably have a high viscosity index, perhaps even Group V synthetics.
Well, I guess some might call the early 80's 'new fangled'. ;-)
They have certainly be good at getting stuff out there, knowing it made sense, even if isn't 'typical' of the time. As soon as they did the killed the British Bike industry as we failed to do that looking ahead ... ;-(
;-)
Indeed, as anti dive doesn't to the front, it just feels 'flatter' for the rider. There was a marked difference in both when comparing my BMW R100RT (sorts tourer) and her Yamaha XV750 (custom cruiser). Because hers was much lower, you didn't seem to get anything like the dive / squat of the BMW.
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Good point.
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That's (or it's the latest variant of) what I used on daughters front forks, doesn't give you a list of ingredients, only that it's ISO22.
OOI, does that mean that I could use 'any' oil that complied to ISO22 (average viscosity 22 @ 40DegC etc) or is that just an umbrella term (because of the additives I believe you have mentioned previously)?
It's a highly refined mineral oil, so not likely to have a particularly good viscosity index (this is a measure of how rapidly viscosity changes with temperature).
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ISO 22 just tells you about its viscosity. Most hydraulic oils seem to use Group II base oils (refined mineral oils) with assorted additives including anti-wear, anti-oxidation, anti-sludge, foam inhibitors. I'd go for something that claims to be suitable for m/c forks since a trolley jack oil doesn't really need anti foam performance, for example.
Ok thanks ... I was only wondering if it was just marketing.
Talking to an old motorcycle mechanic the other day and he said he'd often used ATF in forks and it worked well?
When I drained the forks on daughters new bike the other day the leg the PO said he's changed the seal on (but was still leaking) had some cleanish fluid in it but the other side that had an unchanged seal in it wasn't leaking because there was only an eggcup of a grey sludge in there (grey from the ally of the from the inside of the fork leg). ;-(
In one way I'm glad it showed the signs of needing a 'good going over' as otherwise she might have been riding it like that.
Once I've got the front forks / wheel / mudguard / new disk and pads and rebuilt caliper back on, I'll change the oil and check the air filter and take it out for a test ride for her (assuming it's not still raining ... ). ;-(
I'll probably get mine back on the road as well as I like to have at least one bike available, just in case ... and it's nice to have a pootle round the B roads. You get some nice dry days, even in the winter and she's bound to want to go for a little ride out with her old Dad. ;-)
ATF is the same sort of stuff and probably very similar viscosity. There's perhaps not quite the same scope for foaming as in forks.
I don't often feel tempted to get another bike, I get my kicks (as it were) from horses these days. However having been dumped on a rock the other day leaving me with a very bruised glute I do sometimes wonder.
OK. I've not played with ATF much, only ever adding it to the auto box on our 1300 Mk1 Escort. ;-)
True, I'd imagine it would get pretty 'busy' in there, especially on more bumpy roads.
I try to look upon such things is that the manufacturers probably put a fair bit of effort of tweaking the characteristics of this hardware (even though it might be used across a range of different vehicles, albeit that they would probably all share similar roles, like 'commuter' or 'offroad' bikes) and therefore it would be sensible or respectful to follow their guidance. That said, these vehicles can be used by a range of people (weights, riding styles, goods carrying) and in a wide range of climates that might all need catering for, to maintain the original functionality.
A classic example of people generally making things worse is those who dump the factory exhaust (optimised for all sorts of things across the entire rev range) and replace it for something that is 'lighter' (when they could same loads more by going on a diet) or better because it's louder' (when it's actually worse, if not Dyno'd in etc). ;-(
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I think if you have ever had a bike, especially from a kid (first motorised transport etc, rarely the case these days probably) it's difficult to be without one.
I'm lucky as apart from commuting to college on my moped(s) and then BT on my Lambretta scooter for a bit (there was a railway crossing and being on a bike meant you could *always* get across on the first opening when it might take several goes in a car), I've only really used my bikes for the odd trip when it was likely to be faster (traffic) or in the early days, more economic (fuel costs) and recreation. Going somewhere on the / a bike for a change, like motorcycle touring / camping.
Yeah, there do seem to be some quite nasty injuries from people being thrown / falling from horses (helicopter rescue as there are rarely on the high street) but there are probably loads more associated from biking, even if equally not always the riders fault (someone pulling out without looking like a horse being spooked etc).
From a vegans POV, ignoring the general moral aspect of 'not exploiting animals for any reason', I would put the idea of a light person riding a large horse at a rate the horse enjoyed and over terrain the horse found easy / enjoyable and given all the pampering and care they might also enjoy, that would be well down the list ... and certainly well below horse racing and jumping etc.
I think any arguments against could be countered to some degree by the idea of increasing the animals enrichment, over what it might experience if it was doing it's own thing in the wild.
Daughters rescue terrier seems 'game' to climb / jump up / over anything ... and often climbing stuff taller than me. We first learned this when we took him to dog training and whilst being the worst behaved dog there (and certainly the noisiest) he seemed more than willing to try all the agility equipment on the breaks. 7' tall ramps, see-saw, tunnels ... you only had to point him at and he'd do them, not quite so good at the zig-zag thing. In contrast, the lurcher we are currently providing convalescence to has no interest in any of that sort of thing and just wants to run.
The good news is how many dogs you meet that are out walking are also 'rescues'. One, a lovely Great Dane came from turkey where they clip their ears ... ;-(
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I think it's to make them less vulnerable in a fight or when hunting? ;-(
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