Hi guys, I`ve just bought a Pantah 500SL, had a hankering for one for a long time...well, since 1981!!! When moving off in 1st gear all seems well then there`s a "jump" in the transmission, then all`s well through the gears. I have ruled out clutch problems as the clutch is fully engaged when this happens, and I can`t replicate it in any other gear. I have replaced the "control fork" mechanism inside the alternator cover with a nearly new one, there was quite a bit of wear on the old one. I noticed that the bolt holes are elongated for adjustment. I haven`t tried it yet to see if there`s any improvement, but I would like to know...how do you know where, (in what position) to tighten up these holding bolts, is this likely to improve things and anyone else had similar grief?? Thank you in advance. Colin.
Your 500SL probably has the original 6-dog gearbox. The dog engagement was not all that great, and the rather small dogs were not hardened very well. After a while the dogs are prone to get a bit rounded meaning that they may not engage securely or may slip out of engagement. This mainly affects first gear, since the dogs have a hard time when the rider engages first gear from rest. At some point during 1981 Ducati began to fit the later 3-dog gearbox to 600s and the later 500s. If yours was made in 1979, 1980 or early 1981 it might be 6-dog. You could just put up with it, and take it a bit steady in first gear. Or you could strip the bike, split the crankcases, and fit a later gearbox if you can find one.
If you are on Facebook. Seek out a John Wittman. He was Witty Ducati and he built all 3 of my racing Pantahs. 650/748 and 877cc. He may just have parts for the 6 dog gearbox or perhaps a whole 3 dog gearbox as I know that he still has hoardes of parts. Tell him Allan sent you.
Thanks for the replies PR and Pete. I have what looks like a hardly used 6 dog cluster which came with the bike, it looks like the previous owner was expecting trouble. I was hoping for a simpler solution before stripping it down. I`ll get started maybe this weekend and post my progress on here. Are there any problems I may encounter? This is not something I do every week, but I`m not afraid to get stuck in!!
If you spilt the cases you'll need a new centre gasket, the classic ducati place in thr Netherlands still has them in stock ;-)
I actually have a complete 6 dog box with the lower dogs ground off making a 3 dog, exactly as Mr R describes, in my garage. It works OK except that backlash in the drivetrain is increased. I was going to keep it until I might need it (or parts of it) for some bike with a problem gearbox at some future date. But I might be persuaded to part with it, if you really need it.
Thanks all. There seems to be plenty of options. I`m going to insert the cluster that I got with the bike when I bought it. I realise they are a weak point but the bike won`t be doing big mileages, so it makes sense to utilise it. Thanks for the pointer towards the Netherlands I`ll get some stuff ordered asap...well, as soon as I get it stripped to assess whats required...gaskets/seals/tab washers etc etc. I keep yuz posted!! BTW I was amazed at the way the bike handled when I rode it the other day. She`s sooooo light and nimble. Love it!!
Thanks all. I`ve just split the crankcases and after a closer inspection of it all and now a better understanding of it, I`m going to grind off the lower dogs as suggested by you knowledgeable guys. Do I grind ALL the lower dogs off or just those on 1st gear which is causing my problem? Also, I can`t understand what these lower dogs actually do. Is it to eliminate backlash? In my innocence I was thinking a "ramp" shape to stop the engagement on the lower dog leaving a vertical edge for backlash...but I`m no engineer. I got new gaskets off the guy in Netherlands...thanks for that! Fingers crossed.......! Colin
I suggest taking a close look (with a magnifying glass) at each dog on each gear, to see if they are rounded off, pitted, or flaking, etc. which some probably will be. Those gears which are in perfect condition (if any) could be left alone. 4th and 5th may well be OK. Those which are visibly worn or failing are the ones which require attention, especially if the case hardening on the steel has given up. If you are going to grind some off, it has to be all the lower three dogs on each of the affected dog-pairs. I suggest taking several photos of all the spacers, washers, circlips, etc as they come off - it will help a lot when you come to put it back together. Why it was thought to be worthwhile to have three full-height dogs and three half-height dogs on each gear I have no idea.
Thanks Pete. The dogs are now ground off. I just need to see my son-in-law on Tuesday to get a couple of helicoils done while its in bits then re-assemble. My fingers have never been so crossed!!
So given that a five-speed gearbox has in all 10 sets of six dogs, how many of them needed removing? All of them? And how good are remaining dogs looking? Just curious.
I only did first gear. The rest looked ok and there wasn`t a problem with any other gears so I left well alone. I got some threads repaired this morning and put most of the motor back together today. We are away now until the weekend, so will continue when I get back. Many thanks.
A very good day! I put it all together again and tested it up the road. BRILLIANT! I want to say thanks to you guys for your ideas and help. It changes gear nice and doesn`t jump out. She`s not taxed or insured yet, in fact she still has her german plate on so I daren`t give it a proper ride until I complete the legalities which should take a couple of weeks......no more than that I hope! Still, very happy and I can`t wait for a rideout. Cheers!!
Fair point Steve. But it was all a bit of a step in the dark for me. I was concerned about introducing loads of backlash into the transmission. After trying it on Sunday I couldn`t discern any at all in my brief road test, so if I was to advise anyone then yes do it! A slight downer is that it is going to take 4-6 weeks to get it registered! Don`t they realise, I CAN`T WAIT THAT LONG!!!!! I`ll get some pics up when I get a chance during this week. Cheers.
Pics as promised. All road legal now and going well.....but!...... Is 80lbs/Sq.in too much oil pressure? Seems a bit much to me.
The workshop manual says: "With the engine warm at 4,000 rpm (or more) the oil pressure should be 5.5 - 6.5 Kg/sq cm." You'll have to convert that into lbs/sq in yourself!
Thanks lads. It would appear I worry too much! Someone`s had fun in the past because there`s an oil pressure gauge fitted, and not a cheap affair, a nice liquid filled one with a nice braided pipe. So I was thinking the worst. It wouldn`t occur to me to fit one just for the hell of it to a road bike so that`s what got me concerned. (love this bike)!! Cheers fellas. Colin.
