Despite only about 5000 miles, there is play in my swinging arm. I am looking to replace the bronze bushes that are in the rear of the engine cases (item 18 in RH case and similar in LH case). I have removed the swing arm pivot and the swing arm. I have tried tapping them out with a steel bar on the inside edge of the bush, though there is only about a 1mm lip to press against. They seem a tight interference fit. So far they haven't budged and I have slightly burred the edge of the bush. Has anyone been this way before? Next thought is to apply heat to the rear of the engine cases. Splitting the cases would allow me to press them out easily, but that seems a little extreme and a whole engine strip and rebuild.
With a hacksaw blade, carefully cut along the bush until you have gone all the way through. Then collapse the bush carefully with a screwdriver. Then tap out from the other side.
Might be worthy of a call to Phil at Italia, Ray Petty or Paul K at Ducati Services to get any hints. Otherwise FE’s right. There might just be a trick of the trade.
@final_edition Suggestion is a good one as i had to do this approach to a bush i had to remove some years back, a bit of patience(i do not have this in spades) and jobs a goodun.
Thanks guys. Sawed the LH side out first and slightly marked the bore they sit in (though not that it should cause a problem). When I realised they were split I sawed the RH bush near and along the slit and managed to remove without marking the bore. Interesting that the dots in the bushes are smaller where the bush was facing down, and more in the right hand bush. I'm supposing that smaller dots indicate greater wear. Intuitively I would have expected that at the upper part and maybe more in the left hand side due to the final drive chain being on that side. Just need to order new parts now and fit.
Life is never simple! I collected new bushes from JHP last week. New swing arm pivot in transit from Italy. I measured the bushes today and the inside diameter is 27.5mm, which is 0.5mm smaller than the swing arm pin, which is 28mm diameter. Clearly they won't fit, let alone pivot. Part numbers, and in all other respects they are correct to the parts manual and the ones I removed. The 750F1 workshop manual gives no information on replacement. My guess is that they are a fit and then ream to size item, but reaming a 28mm hole sounds like a challenge. Doing it accurately and square without splitting the cases and putting then on a pillar drill or mill even more so. Anyone been this way before?
Send the bushes and the pin here, http://www.ocservice.co.uk/. An old school engineering company. Andy
Thanks Andy, I hadn't thought of that approach. It gets around having to machine them in situ, my only concern is as they are an interference fit in the crankcases, how you allow for shrinkage of the diameter once they are pressed onto the crankcases? I don't have the kit to measure the crankcase bores accurately enough to allow for it in caclulations. Though I suppose I could source it.
I’d phone the guys but if you would be able to package the relevant bits, I’m positive they would assemble and ream the bushes in situ. Andy
There is something wrong with the parts you have. I wouldn't frigg about reaming bushes, as this can take the friction coating off, or increase wear rate. If you have a split bush, this can open out slightly, when you fit the shaft onto it. As it may be out of round.
Finally got a solution to this. As the service guy in the Ducati dealer was unsure which way to go, I had a chat with my local engineering shop that has helped me out in the past. He was surprised they were nearly 0.5mm undersized as in his opinion that was an awful lot of material to take out with a hand reamer. He was also not convinced about machining down to size prior to fitting due to the ucertainty of the interference fit changing the bore dimension, and getting them precisely concentric and aligned. His suggestion was to grind them to 0.1mm undersize (and square up the ends, which turned out not to be square with the bearing OD) then press them into the casing. He had an adjustable reamer with a mandrel fitted that he lent me. I turned down a nylon bush to accurately fit the bush and the mandrel so the reamer was aligned concentric with the bearings. I first made the bush 32 mm diameter to fit the casing and fitted one bearing and reamed it to size. I then turned it to 28mm diameter, pressed in the 2nd bearing and fitted it in the reamed bush. My engineering guy also ground my original pin down to .025 and .05mm undersize that I used as a gauge to check when I was getting close to size. Plenty of engine oil used to lubricate and frequent removal of the swarf was required, along with gradual opening up of the reamer diameter until the correct fit was obtained. New shaft is now a close sliding fit with no discernable wobble. Swinging arm fitted, and no dicernable sideways movement. Happy days! I'm just hoping these bushes last longer than 5000 miles, as I don't fancy repeating the exercise.
