Checked Final Drive Splines ST1100 …

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Joined
Feb 28, 2025
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285
Location
Oslo, Norway
Bike
ST1100AX
I have finally checked the Final Drive Splines on my ST1100 which was purchased in May. Have disassembled and checked the Final Drive Splines on my ST1100 which are worn and need to be replaced, see pictures. Will buy new parts from Japan or Europe.

Have tried to take a picture of the condition of the splines in the differential which in my opinion can be used as is, sorry I haven't cleaned there yet but it will be done thoroughly before the parts are installed.

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Ouch...
Wheel appears usable, drive spline(spider) and ring gear are finished though... :(
Sorry for bringing the bad news there... but I'd seek a used, decent, low mileage final drive on eBay or directly at a parts breaker...

I don't think you're in the mood of rebuilding the f/drive yourself:
you'd need a jig to hold the case and some special tools/socket to open the input side, a mill to remove the needle bearing (held by a snap-ring), pinion and ring gear must be purchased as a set, and then you'd need all bearings and seals, plus the set of spacers/shims to properly adjust alignment and backlash...
The $$$ of such a task explains why we're so anal on spline maintenance...

It seems possible to swap the inboard cover (featuring the cast sensor bracket) of your ABS-II/CBS f/drive onto a (used) non-ABS f/drive casing, but I'm not 100% sure if such has any impact on mentioned backlash trimming...
From (years of) observations on this (and other) forums, is it a PITA to get that wheel sensor out the holder/bracket, many failed, even broke the aluminum cast off...

But as a quantum of consolation: this isn't the worst spline assy we've seen here... some manage to wear that down till it spins almost freely, hence no forward momentum of the bike...
 
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I agree with @ST1100Y about the final drive splines. But...I find it hard to believe that the wheel's were so thoroughly trashed with no damage to the fd's. Seeing wear through the grease and paste is impossible. I'd like to see those splines when clean. Final drives for 1300's were cheap on ebay when my fd went south (a very rare happening). No idea about the availability of 1100 fds now. It will be cheaper and easier to just replace the whole unit if need be than buy a part and rebuild it.
 
After washing are these the best pictures I can get, visible wear on the pressure side of each tooth. Is this abnormal after 105,000 kilometers and a lot of driving with a trailer... I'll buy a new flange with splines that sits on the rim and replace it, but I maybe want to keep driving with the differential ... From the pictures you see here is it really stupid? The only option now is to buy used online as my inquiries elsewhere didn't lead to anything.

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yep... those worn spots already peeked through the grime in your other photos...

The alloy of the ring gear is a lot harder then the one the drive spline is made off ("sacrificial" parts design...), so it will tear down a new drive spline assy in foreseeable time...
So finding a decent used f/drive, swapping the parts and getting a new drive spline as already discussed would be my favored procedure...
By doing so you'll have properly mating parts which, given correct lubrication, will last well beyond 100,000km again...
 
I think you made the right choice. The wear on your final drive splines will not mate properly with the new wheel splines and the uneven loading will wear the new splines more quickly. Changing both is the prescription for long life for these parts.
 
Right over the weekend, I'm going on a week-long vacation with my wife and I'm thinking of riding after the nice weather. Since we wanted to stay in Norway, we can only hope it won't be rain for a whole week :) When we get back home after the trip, hopefully all the parts I ordered for the ST1100 will be in place so I can continue there. I hope I can take one test ride before winter comes :thumb:

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Larry Fine said:
Where does one get the two splined parts these days?
Click to expand...

In the UK, Ebay is a good source for really good condition and reasonably priced final drives (I have fitted one to my outfit and have another two as spares, just in case), the same goes for the flange, but this can also still be bought new from quite a few places but the cheapest seems to be Webike in Japan

www.japan-webike.ie

HONDA OEM Motorcycle parts : Flange Set, Final Driven [42630MT8305]

Product Description: HONDA OEM Motorcycle parts Flange Set, Final Driven [42630MT8305] : Fits:HONDA ST1100P 03 A REAR WHEEL : HONDA ST1100 99 AC REAR WHEEL (1)... - Webike
www.japan-webike.ie
 
Flexit said:
In the UK, Ebay is a good source for really good condition and reasonably priced final drives (I have fitted one to my outfit and have another two as spares, just in case), the same goes for the flange, but this can also still be bought new from quite a few places but the cheapest seems to be Webike in Japan

www.japan-webike.ie

HONDA OEM Motorcycle parts : Flange Set, Final Driven [42630MT8305]

Product Description: HONDA OEM Motorcycle parts Flange Set, Final Driven [42630MT8305] : Fits:HONDA ST1100P 03 A REAR WHEEL : HONDA ST1100 99 AC REAR WHEEL (1)... - Webike
www.japan-webike.ie
Click to expand...
That appears to be only the wheel half. What about the hub half?

Added: 41310-MT3-305
 
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