SSD FSP cush drive problem

[gioto3]

Yes, I have the cush drive problem.
I was so foolish to hope to avoid this issue, but isn't the case.
But I am a bevel man, so madness is quite normal for me.
This is my sproket carrier


and this is a badly ovalized hole

And obviously the sprocket bearings are gone.
Before to undo the wheel I got spare bearings for the wheel axe, but not for the sprocket, so now I have plenty of time to think a good solution, since I don't think I'll be able to have the bearings before 10 days.
I have read the posts about this topic in the forum, but I'm quite unwilling to drill larger holes and put oversized bolts.
The holes are about 8.2 mm x 9 in the side of wear and obviously have got a conic shape. What about trying to use inserts similar to Helicoils? The hole is too large for put an M8 Helicoil, but maybe it's possible to find something that can be made fit.
The original cush drive rubber seems in quite good conditions and I have a new spare part for F1 and Pantah 0795.80.230 that should be compatible, do you know if I can mount it without problems or do you think it's better to use the original one?
One more problem, a bolt fixing the cush drive house to the rim is broken.

I'm thinking to drill and extract it . Do you know the length of the bolt? I'm not very keen of trying to remove another, that can broke as well, until I'll be able to extract this one, knowing a little more about it will facilitate my task.
Yes, this is working at an old bevel
Ciao
Giovanni

[rwhc80]

Gio,

I have one word for you ....... Heat !!!!

whenever you are suspect about a rusted or stuck bolt, capscrew or any threaded item, apply heat. I have seen so many broken bleed nipples in Brembo calipers, it's not funny.

Apply heat from a heat gun, or heat the part in an oven, and you will be much more successful. Aluminium will transfer heat much faster than steel, so the surrounding area expands and will allow the bolt to undo.
Likewise, when you fit new bearings, heat the part first, and the old bearing will easily be pushed out.

Dont be concerned about sleeving the sprocket carrier, it's a much better permanent fix. The problem you have is common to Ducati's when the mounting bolts are loose, or the wrong bolts are used. The movement will eventually stretch the holes, but won't happen with a steel insert. Having said that, I have seen much worse elongation of the bolt holes than yours.

So, Heat, Heat, Heat, the old broken screw before you try to remove it !!

Good luck
Rick

[Craig in France]

Hi Gio,

<snip>
The holes are about 8.2 mm x 9 in the side of wear and obviously have got a conic shape. What about trying to use inserts similar to Helicoils? The hole is too large for put an M8 Helicoil, but maybe it's possible to find something that can be made fit.

What might work is a solution called a Big-Sert. These are thread repair inserts specifically designed for use in holes that have become too large - often because a previous repair using a Helicoil has failed . (Which is what happened on the head of my Laverda Corsa, but that's another story ...)

I won't try to explain it, but have a look here and then come back if it's not clear. You can buy Big-Sert kits off Amazon US. They're a) hard to find; b) very expensive here in Europe. But they're much better than Helicoils.
http://www.timesert.com/html/bigsert.html

The original cush drive rubber seems in quite good conditions and I have a new spare part for F1 and Pantah 0795.80.230 that should be compatible, do you know if I can mount it without problems or do you think it's better to use the original one?

If the old one is hard, Gio, fit the new one. As to compatibility, my parts books for both the Darmah and the Pantah show the same part no. for the cush drive rubbers - which makes sense 'cos both bikes use the same FPS wheels. Just check your number, tho' - it should start 0797, not 0795.

One more problem, a bolt fixing the cush drive house to the rim is broken. Do you know the length of the bolt?

I'll have to go look. Or perhaps someone may reply in the meanwhile ...

Ciao

Craig

[gioto3]

Hi rwhc80 and Craig
thanks for your help.
The first lucky strike was to find an open shop with the needed bearings today, not easy in Italy on Sunday 13 August !!
So now the new bearings are in place.
I was able to drill the broken bolt for all its length, and it's quite long, about 29 mm. I wasn't able to extract it with a conic extractor, after warming the hole with a heat gun too, so I'll let it with penetrating oil for two days and I'll try again. I fear I'll have to drill it completely and to put an Helicoil in.
Thanks Craig for the suggestion of Big-Sert, I think it's really what I need, I will check.
I just realized that my spare cush drive rubber is exactly the same proposed by Steve
http://shop.bevelheaven.com/detail.aspx?ID=102 so now I'm sure it's OK.
Ciao
Giovanni

[Eldert]

Hi Gio

i bought a lot of time serts and big serts from E Bay seller toolskwik

Eldert

[gioto3]

Hi Eldert,
thanks, it seems a very good source of inserts.
I was thinking about to use in the sprocket carrier not threaded inserts, just to restore the original engineering shape, with tightening only provided by the nuts and inserts restoring the correct clearance between holes and bolts. What about this strategy?
Ciao
Giovanni

[gioto3]

I decided to have my sprocket carrier fixed by an engineering workshop and I had the holes drilled and repaired a steel insert to obtain the original clearance.
It seems a good work. Obviously I fitted new bearings too.

Can you suggest the correct tightening torque for the sprocket bolts?
I torqued them at 25 Nm but I'd like to have a confirmation of the value before fixing the safety tab washers.
I'd like a suggestion too for the torque of the rear axle bolts.
Thanks
Giovanni

[garryc]

In the search field type
torque and axle
and look at the results

[gioto3]

Thanks garryc
Found it.
So I'll go for a torque of 80 Nm for the axle bolts and 29 Nm for the sprocket carrier bolts.
My main question was about the sprocket carrier cause I know it's a weak point in our bikes.
If this sounds incorrect please advice.
Ciao
Giovanni