Not got access to a machine any more but just one quick tip. Pack the slit in the yolk with washers and tighten the bolts before boaring, otherwise it will chatter and go out of round. Best bet is to hold the yolk in a four jaw lathe chuck, clocking it in to the existing hole before starting. I'd advise using an ISO boaring bar taking no more than 1mm at a time turning at 625 rpm Don't forget the radius of the hole will increase by 1.5mm so you need to ensure the pinch bolt passes more than 1.5mm away from the edge of the existing hole, or it won't work.
Now I'm worried... I just sent some parts to Aldermans Green Industrial Estate, Coventry but your post prompted me to check my receipt for a top yoke last October and it's Willow Park Industrial Estate, Stoke Golding . Hopefully still the same, just moved - I'll phone on Monday... Made me a lovely top yoke for 900SS -> 1098 fork swap Yokes by Lindsay fae Angus, on Flickr
there are a few on here Anth, I sadly have no access anymore. I think 'Android' might be able to help if he picks this up.
taking 1.5mm off the thickness of the tripple tree will weaken it and introduce flex which will offset the advantages of the thicker forks better to source the correct yoke and flick the old yokes on fleabay, by the time you add up machining costs this may also prove to be a cheaper option
I don't know which yoke he is using but the 748/9xx yoke uses the same casting for the 53mm and 56mm versions. So in Ducati's eyes there is enough material. I machined a set on my Myford lathe. Mounted the yoke on the vertical slide. Work holding was the main problem and I wouldn't try it again. Really needed a bigger machine than the Myford.
There is no real correct yoke for this (cheers Nog...I've turned the spell checker off :tongue other than the whole DP kit with the forks. The 1098s one is different in the stem attachment, length and steering stops. I'm more than happy to have the machining done on a set of road going yoke as they are by far way over engineered with lots of excess material. Dan Kyle does sell a conversion yoke to complete this conversion and I have the data sheet from them and even with the existing ones machined there is still over 1mm more material on them than the Kyle ones. It was a family member from the USA that suggested the milling route as it appears that most of the people he knows over there who have done it went that way and is the most common method. I'm just putting the feelers out here before I go to find a decent machine shop, I've already had the long conversations about material loss, weakening and flex ETC and I just want some bigger holes :wink:
I have a slotted table mounted on the cross slide. I was thinking of holding the yoke on that and using the boring bar in a 4 jaw chuck. But it would be a nightmare. You can see a similar lash up here; 066549680 01 by Lindsay fae Angus, on Flickr
Please consider the safety aspect of increasing the hole sizes, I know you are not intending removing much but 3mm is 3mm - I am unsure if this is standard practice in the ducati world to bore out the yoke but don't think I would do it. cheers Gaz.
Thanks Gaz, but If you read my earlier posts, you'd have the answer to your concern! This is not being done on a whim, I have done 'some' homework already, and as DM mentioned there is other yoke's that are from the same casts with differing size holes already. I'm simply asking if anyone here has the ability to do it, before I get home and go to an engineering shop to carry it out. I'm not really needing the science behind it, just a machinist with a horizontal mill. but thanks anyway
Sorry it was late and must admit I did scan read the thread, will read threads more carefully in future but thought better safe than sorry. Cheers Gaz.
