Advice needed in Mongolia: Transalp output shaft/ sprocket/ retainer problem, Urgent

[chris]

Hi guys
I'm nearing the end of my 7 week trip through Central Asia, Altai-Russia and Mongolia.


I have a problem, I think, and would be really grateful for suggestions/ comments/ possible solutions. It is also urgent as I fly home to England next weekend (today Sat 25th Aug, flight Sat 1st September). I was hoping to leave the bike in Mongolia to continue my trip into eastern Siberia next summer, 2013 (preferred choice). If necessary, however, I can freight the bike back to the UK from Mongolia, but would need to set things in motion very quickly.


The bike: 1988 pd06 XL600v Honda Transalp, unknown mileage (I'm the 12th owner!), but anywhere above 50/80 thousand miles/kms. On this trip the bike has done 8500km/5000miles, about 50/50 pavement/gravelMudSand. The front sprocket is OEM Honda 15 tooth, rear steel aftermarket and chain expensive DID 525 118 link vx. All 3 are still in good condition, I believe. Please see images below.


I reached my destination Ulaan Baatar, the capial of Mongolia a week ahead of schedule, so decided to take a ride south to visit the Gobi desert. Yesterday morning (8300km/5000miles into this trip), just before setting off I noticed the damage to the sprocket cover (see image: I removed the plastic centre circle, it was still 2/3 attached to the cover). This damage would have happened very recently as I definitely would have noticed a gradual issue.


Before leaving for the Gobi, I replaced the sprocket retainer (number 1) with a new spare (number 2). It last precisely 200km/120miles! See image.


I rode as carefully as I could back to Ulaan Baatar today. Before setting off I also loosened the chain a bit more too. Retainer number 3 is already half worn after this further 200km/120 miles!


The front sprocket does “wobble” a little on the shaft.


How/why did this happen? I believe the chain tension wasn't too tight. The output shaft is IMHO in good condition (much better than the one on my 1995 Africa Twin...).


What's the solution?


1. Weld the sprocket onto the shaft? (not a problem, the bike is cosmetically very nasty and only really worth gbp600/us$1000/euro700, if that). This can be done locally, if I can find a competent Mongolian welder who understands English or German.


2. Replace the output shaft? The would require a full engine rebuild, for which I don't have the expertise. Finding a competent English/German speaking mechanic in Mongolia will be a challenge! Also the parts would have to be sourced and imported. I can ship the bike back to England where I know a very reliable mechanic, but I can't justify the cost (it would be 1500euro shipping for a 700euro bike and that is before paying parts and labour.)


3. Just put on a new front sprocket? I don't have one with me, but could easily bring one with me when I would return to Mongolia in 2013 for my Siberia trip. I'd also bring a job lot of new retainers with me.


4. Or? Over to you!


FWIW, I am sending this email using the wifi at the Oasis Guesthouse. Rene and Sybille, the owners, are currently out of town, but back on Wednesday. I'm hoping to be pro-active from Monday (27th August) morning onwards.


Several images are below that will hopefully help solve my problem.



Retainers from left to right
1 lasted 8000km
2 lasted 200km!!
3 is half worn after 200km!!
4 is new (for comparison)





Chain tension





Chain tension





Chain pulled off rear sprocket, still v good condition, IMHO





Retainer number 3 on sprocket, before setting off this morning.





Output shaft looks Ok to me, I've seen a lot worse on my Af Twin that has about 1/3 missing off each tooth





See above comment





When I pulled over for a pee, a quick glance revealed this shocking image (of the sprocket/retainer/shaft, not my manliness!)





See above comment





Sprocket looks fine, but does wobble a little on the shaft





See above comment





Sprocket cover after removing the worn central section


Any input is very gratefully received! Thanks in advance! If we meet, payment in s. If not, good Karma all round!


Ride safely,


Chris

[McCrankpin]

I'll offer some thoughts, having run loads of Hondas over loads of years.
Plus some questions.

There must be some force pushing the sprocket longitudinally along the gearbox shaft, away from the gearbox.
Normally in my experience there's very little sideways force, which is why the retaining washer isn't particulary substantial.
As you've no doubt experienced they last a long time, tens of 1000s of miles, and maybe become a little thinner on the internal lugs.
Also, I'd say the sideways force must have some 'hammer' effect to destroy your latest washer so quickly.

So what could be doing that? My first thoughts are: rear wheel bearings, or swing arm bearings.
Have you noticed any change in handling at all?
Maybe even a swingarm that's broken somewhere. (Sounds like you've done a lot of off-road. Particularly fast or heavy-going?)
With rear wheel off the ground, apply a strong arm to the tyre and see if you can make any side-to-side movement.

If handling is definitely OK, does the chain have any seized links? (Although not very likely to cause this). Check with rear wheel off the ground (see below).

Rear sprocket carrier bearing?
Don't know the cush-hub arrangement on the TA, if it has one, but is it OK?

Is there any longitudinal free play on the gearbox shaft? (In-and-out). There should be none (or maybe very little).

Put everything together, but leave off the retaining washer. Adjust the chain to the correct up-and-down play.
Set the rear wheel off the ground with bike vertical.
Start engine and select 1st gear. Watch what happens. With no drive force being transmitted through the chain (just enough to rotate the wheel) the sprocket should stay in place. At least for quite a while.

If not, the way it behaves may give a clue.
Does the chain bounce a lot forcing the sprocket off?
Does the gearbox shaft move in-and-out noticeably?
Watch the chain in motion. Is there a single link badly damaged and out of line? Or a pair or three links together?

As another test, try winding a length of mild-steel wire around the shaft in the groove, enough to fill the groove and leave a turn or so raised above the level of the splines. Wind it quite tightly and twist the ends together firmly.
That should be enough to hold the sprocket on for quite a few miles. In Turkey we did that to a fellow-traveller's Honda after he lost the two retaining bolts and the washer. It got him to Iran OK, quite a few hundred miles.
You could try solid copper wire if no steel, should be just as good.
So, if you go only a few miles before the whole lot comes off, there's definitely something wrong with the whole alignment of the two sprockets (a frame/swingarm/bearing thing), or the bearings of the gearbox shaft.

That's about all I can think of for now.
Hopefully others will have more to offer.

Best of luck!

[navalarchitect]

Interesting! Especially as I only ever change the retainers every third or fourth chain and sprockets (50,000 km plus and even after that I have never seen wear that bad)

The only way I can see the retainers wearing out out that quickly are impact loads due to the sprocket continually belting into it. After trying to think of all the possibilities I think the answer is in your statement that the sprocket "wobbles" a bit on the shaft. I suspect that wobble is enough to provide the necessary continual impact - especially when you think it is revolving something like 1500 times a kilometre. This would be worse if there was any form of misalignement - have you checked your rear wheel bearings? Also looking at the photo's the front sprocket looks reasonably worn with a lot of wear on the side flanks and this may be one of those occassions where wear has reached a critical point, as material wears of the side flanks of the teeth and the teeth deform the sprocket can move a bit more within the chain, the retainer sees more impact - seemingly suddenly you are at the point where retainers last no time.

So my guess is a new front sprocket and retainer will fix everything. I know its a pain when you can't prove it but I would be fairly confident. You also at the end of the day have the fall back option next year that if it does keep failing going to the welding solution - but I'd safe that until you've proven the other doesn't work.

Another possibility is you were unlucky and the spare retainers you bought were from a bad batch - it happens but frankly I think its extremely unlikely.

So in your situation I'd stick to your original plan leave bike and return next year with a complete new chain and sprocket set plus a good handful of retainers and then hope like hell you have enough of those good karma points for it all to work out.

Enjoy UB.

[roger2002]

The only thing I can add to everyone else's suggestions (which are excellent) would be to question the chain tension. I keep my V-Strom chain loose enough to be able to almost touch the bottom of the swing arm when fully loaded on the side stand. Your photo seems to show that yours is quite a bit tighter than that. I don't think the tension is causing the wear but I'd loosen it before checking the bearings etc. I believe chain tension usually takes out the seal and or bearing on the output shaft rather than the rear wheel bearing and your seal is obviously not leaking but maybe you got lucky?

Roger

[chris]

Sorry to not yet have responded to all the people who have replied: I need to go out for food. Mongolia is 7 or 8 hours ahead of Europe. I will tomorrow.

Possibly I put the rear spacers on the axle on the wrong way round on the last tyre change. Hence the sprockets are out of allignment.

Can somebody with a rear disk model pd06 Transalp (or even Africa Twin) nip out to their bike and tell me which side which spacer is? On my bike it's currently the bigger one on the left (sprocket) side and the smaller one on the right (brake disk) side.

I will do all the checks suggested tomorrow in the daylight. There's a dutch Toyota Landcruiser man here too who has a full workshop with him. I'll be raiding his stuff

Many thanks!

[Dazzerrtw]

Hi Chris. sorry I cant see all the photos, but should the front sprocket be the other way round ? it looks like the chain is catching the engine cases . I seem to remember the front sprocket as a flat side, which faces outwards and the side with the raised face, faces the engine cases. hope this helps.

Dazzer

[chris]

Hi Darren
Hope you and Leigh are having a fun time.

The front sprocket on my bike is bolted on as shown in the sketch in this thread at xrv.org.uk: T/A Front sprocket question, similar question, but different to others?

It doesn't have any nylon cushioning on it, like previous sprockets I've had from David Silver.

It's past 10pm here in UB. At least the here tastes great.

I need to do a full set of checks tomorrow.

cheers!

[tcevro]

I have a 94 TA since 95 and have known many with TA´s and AT´s during the years since then. Been on Transalp lists since way back, forums. Deti´s Transalp Pages, Transalp.de etc.

I cant remember ever having heard of this problem at all, something must have been changed, parts missing, wrong type or incorrectly installed is my first thought. This should not be an issue on a normal Transalp. CDI´s on pre 94 models are known to fail, rear wheel bearings wear out early on many, speedo drive gear often fail and on early models; I believe 87-88 starts to use oil at some point. Apart from that, bomb proof bike if normally looked after.

I looked at the pictures; your chain is way too tight if it is on it´s side stand. If you have ridden with a tight chain you should both feel and hear it easily and that will most likely cause premature wear on parts. it says 3,5-4,5 cm chain slack, 3,5 is actually too tight, stay at 4,5, its an off road bike. Better a bit loose than a bit tight.

You say it is an 88 model? Maybe the engine is but the rest of it is not. Can that explain anything irregular? It looks as if you have an early Transalp engine (black) installed in a 97-99 Chassis. Double front discs, swing arm with rear disc brake, fairing is 94 or newer. Silver coloured rims (96->) etc. Do you mean you have a 98 TA with an 88 engine?

Its a strange problem, maybe a mismatch between the Transalp parts you have there?

Anyway, good luck!

[chris]

Originally Posted by tcevro

I have a 94 TA since 95 and have known many with TA´s and AT´s during the years since then. Been on Transalp lists since way back, forums. Deti´s Transalp Pages, Transalp.de etc.

I cant remember ever having heard of this problem at all, something must have been changed, parts missing, wrong type or incorrectly installed is my first thought. This should not be an issue on a normal Transalp. CDI´s on pre 94 models are known to fail, rear wheel bearings wear out early on many, speedo drive gear often fail and on early models; I believe 87-88 starts to use oil at some point. Apart from that, bomb proof bike if normally looked after.

I looked at the pictures; your chain is way too tight if it is on it´s side stand. If you have ridden with a tight chain you should both feel and hear it easily and that will most likely cause premature wear on parts. it says 3,5-4,5 cm chain slack, 3,5 is actually too tight, stay at 4,5, its an off road bike. Better a bit loose than a bit tight.

You say it is an 88 model? Maybe the engine is but the rest of it is not. Can that explain anything irregular? It looks as if you have an early Transalp engine (black) installed in a 97-99 Chassis. Double front discs, swing arm with rear disc brake, fairing is 94 or newer. Silver coloured rims (96->) etc. Do you mean you have a 98 TA with an 88 engine?

Its a strange problem, maybe a mismatch between the Transalp parts you have there?

Anyway, good luck!

It's a 88 engine and chassis/electrics with everything else off a 98 bike, so your explanation of various colours of rims/engine/number of brake disks etc is all correct.

The swingarm was put into the chassis by a proper bike mechanic including new swingarm bearings.

As explained earlier, I believe the issues were caused by a too tight chain, fuct sprocket carrier bearing and dubious cushdrive rubbers, combined with a non-textbook refitting of the back wheel following a tyre change. Also, the bike was ridden very aggressively due to the condition of the terrain being covered. I believe only a fraction of Transalps get the abuse I've given mine.

As far as burning oil, all 3 of my Hondas do:
* a 87 TA (very high miles: maybe 100k miles?: up to a litre for 1000miles, but only if I ride with rpms over 5000. I just never do an oil change, just top it up),
* a 88 TA (the bike in question: probably high miles, this bike gets it all: oil top ups and oil/filter changes)
* a 95 AT (50k miles, top ups and changes...)

So I ride everywhere at 50mph/80kmh: best fuel consumption and least oil consumption (the TA is on 4500 rpm and AT 4000)

A mate in the trade gets me oil at cost price which is substantially less than retail.

I'm now back home in the UK and the bike is parked in Mongolia until summer 2013. I can't do any more diagnosis/checking in the interim. I'll take all the parts listed previously and hope for the best. If that fails I'll weld the new sprocket on. If it all goes tits up, then the bike only cost me gbp 500, so who cares.

It'll be fine, it's a Honda.

[Dave222]

Judging by the side wear on the front sprocket, the sprockets are out of line, check with a straight edge/string.
If you weld the sprocket on, you do not need to weld All the sprocket to the shaft, just put a couple of blobs on to stop the sprocket coming off, do it so it can be ground off later, try and weld on top of the splines, not in the valleys.It shouldn't take much of a weld to stop it coming off.