ally tonks Posted February 13, 2009 Share Posted February 13, 2009 Hi all New to the forum... I have just purchased a '77 V75a (my mum rode one years ago - funny!) and would like some assistance regarding the automatic box on this thing 1 how does it work 2 it has a rattle from the clutch on idle that disappears as soon as you are underway, what would this be from? also the previous owner (not met as acquired through a 3rd party) removed the oil pump drive from the autolube, I found whilst trawling that ther was a modification for the oil feed as gravity could cause over oiling, any ideas? thanks in advance ally Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 13, 2009 Moderator Share Posted February 13, 2009 Hi Ally to the forum I think those clutches work by centrifugal force low revs disconnect and a Vee belt is gradually spun out of the pulley to give a higher gear. it may rattle a bit as the fulcrum bob weights move around in the clutch. that's all I can remember about auto gears from when I was a YOOF many moons ago drewps Link to comment Share on other sites More sharing options...
JimR Posted February 14, 2009 Share Posted February 14, 2009 Hi all New to the forum... I have just purchased a '77 V75a (my mum rode one years ago - funny!) and would like some assistance regarding the automatic box on this thing 1 how does it work 2 it has a rattle from the clutch on idle that disappears as soon as you are underway, what would this be from? also the previous owner (not met as acquired through a 3rd party) removed the oil pump drive from the autolube, I found whilst trawling that ther was a modification for the oil feed as gravity could cause over oiling, any ideas? thanks in advance Hi Ally, First off does the clutch noise disappear if you use the low ratio gearbox (moving the little lever towards the rear rather than forward)? If the noise occurs in both positions the noise will be worn clutch shoes and/or location pins. V75 clutch is run from the crankshaft via primay gear, as the crankshaft speed increases the clutch spins faster and some rollers in the clutch are moved outwards by centrifugal force. As the rollers move out they force the shoes against the outer housing of the clutch which in turn starts the g/box input shaft to spin (you now have drive). The rather jerky change into second gear takes more explaination, but I can explain this also if you want. The rest of the transmission to the rear wheel is via chain. I would find an original oil pump and refit it ... if adjusted correctly they were well reliable, but it did hinge on the pump being setup correctly. Regards Jim ally Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 14, 2009 Moderator Share Posted February 14, 2009 Link to comment Share on other sites More sharing options...
ally tonks Posted February 14, 2009 Author Share Posted February 14, 2009 thanks jim and drew, appreciate the input I'm awaiting delivery of the bike so will get back you on the high/low ratio issue Jim, I would like to know more about the transmission if you are willing to spare the time. My biggest question is how two clutches operate three gears. I have managed to find what I believe to be the second clutch (16620) and am searching for the first, the images I've seen shows a bearing in the centre held with a circlip, is this likely to be the trouble or wear on the pins as you have described? Unfortunately I haven't managed to find very good images for the auto clutch and transmission together, I have a rather half hearted attempt from a haynes manual (!!!!!) which I cannot fathom. The bike has only covered about 7k miles and has been stood for 20 odd years before being found again. The chap I purchased it from surmised that the owner may not of felt comfortable with the new fangled autolube in principle possibly relying on the tried and tested of premix instead. I've been a comfirmed yammy addict after riding a neighbours rd250lc around our block when I was fourteen - he must have been bloody mad - am just getting back on bikes after having to give up when I became a single parent (my daughter was really pissed!!). This came up by chance as is a purchase driven by nostalgia after seing my mother return from work with the front mudguard shattered and various bent appendages covering the bike and a squashed cauliflower in the saddle bags after my mum had been checking out a bit of totty up some scaffolding without his shirt and his arse hanging out of his jeans and promptly ran in the back of a 40 footer in Croydon - funny to this day Will be on the look out for an IT490, RD350YPVS and an '81 XT500 in the future. Thanks again for your help and time, it's appreciated. Ally Link to comment Share on other sites More sharing options...
ally tonks Posted February 14, 2009 Author Share Posted February 14, 2009 hey Jim the rattle is present whether in high or low range ta Link to comment Share on other sites More sharing options...
JimR Posted February 15, 2009 Share Posted February 15, 2009 hey Jim the rattle is present whether in high or low range ta Hi Ally, The V75 was a 2 speeder & not a 3 speeder the semi automatic V50/70/80/90 had the three gears. The V75 would have needed 3 clutches in order to have 3 gears, if you look at the picies you will see a big spring holding the clutch shoes in, as the engine speed increased the rollers ran out and the drive was taken up, in order for second gear to be engaged (clutch2 had a stronger spring) the centrifugal force had to overcome the spring strengh, when it did the second clutch engaged which in turn engaged second gear. With the rattle in both high & low range the fault lies with the pins between the clutch shoes, the noise is the shoes moving about. Does the bike take up drive smoothly or does it 'lurch' before taking up drive ? Does the bike take a long time to change from first to second ? you should have one of these problems which will indicate which clutch is at fault The motor needs to be stripped and the offending clutch replaced (part 5 or 8) and at the same time its worth putting a new spring around the rollers (part 13), and the noise will be gone. I did notice on ebay someone was selling a V75 oil pump quite cheap which will return the bike to standard. Regards Jim Link to comment Share on other sites More sharing options...
ally tonks Posted February 15, 2009 Author Share Posted February 15, 2009 Hey Jim That makes a lot more sense, good old Haynes, always half the information!! I'm not legal yet so haven't managed to drive more than a few yards, the take appears fine. Will let you know Cheers Link to comment Share on other sites More sharing options...
JimR Posted February 15, 2009 Share Posted February 15, 2009 Hey Jim That makes a lot more sense, good old Haynes, always half the information!! I'm not legal yet so haven't managed to drive more than a few yards, the take appears fine. Will let you know Cheers Hi Ally No problem ... just let me know if you need more help on this subject !! Regards Jim Link to comment Share on other sites More sharing options...
MarkyBDA Posted March 12, 2009 Share Posted March 12, 2009 I will send you an oilpump of you want 1! You get more rpm without it in the bike and its easier to have a throttle acble because if you have the doubble cable and cannot buy a new one, you end up converting anyhow.... Link to comment Share on other sites More sharing options...
ally tonks Posted March 12, 2009 Author Share Posted March 12, 2009 I will send you an oilpump of you want 1! You get more rpm without it in the bike and its easier to have a throttle acble because if you have the doubble cable and cannot buy a new one, you end up converting anyhow.... Hi Marky I've just had it apart today funnily enough. Pump is there but missing the gear, pin and clip which I have now ordered. The pump looks like new, was planning on spinning it up with a drill to see if it pumps ok but didn't get around to it yet. I see from your profile you have a number of these bikes, where are you from? Can't get the bike to go above 38mph (my old fizzy did 44 but I was slimmer then!) Getting the gear together to have it looked at by a forum member (thanks man....). I got chatting to a lad in the Bahamas who ported, bored, carb'd, expansions and electronic ignition mods (ended up buggering the swingarm!) Do you have any recommendations for improvement, any other parts? Will let you know how I get on with the pump, appreciate the offer. Ally Link to comment Share on other sites More sharing options...
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