How Screwed am I? Stripped Gearcase oil plug?

Nah, I really like Time-Serts but they are pricey, thassall.

Pete

I just went through this on my Stelvio. The dealer over torqued and stripped my transmission drain bolt. I used a time sert and it worked beautifully. Took a total of maybe 10 minutes to install and is better than the original in the case.

The hard part for me was removing the center stand frame and exhaust to get at it. I've used helicoils in the past and time serts. IMO time serts are superior.

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After drilling and tapping the case, I hosed out the transmission through the filler plug with WD40 to rinse any swarf out. Also hit it with a shop vac. Very minimal material ends up inside.

All done...

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You do good work Doug.

Thanks, but a trained monkey could have done that repair. The hard part is taking a deep breath and not freak out as you're running a drill bit into your transmission. The first revolution of the drill is the hardest. Once it starts to bite, you're committed one way or another.

   

Well, based on the above discussion and recommendation of the local shop owner that's going to do the work, I opted for a Time-Sert M10 X 1.50 Metric Thread Repair Kit; it'll be here Friday. The kit and my bike will be going into the shop on Saturday for work on Monday. I think the repair kit will end up being more $$ than the repair itself.

Moto International said that they use Helicoils on this kind of repair all the time, but the Time-Sert just seemed to be the better, more permanent [and more expensive] solution.

Soooooo, hopefully I'll be back on my bike early next week!

OK - having had it back for a couple of days, I'm finding a very slight leak coming from the Time-Sert plug.  Perhaps 2 drips overnight; the drain plug has a slight sheen of 80w-90 on it.

Is this normal?  I'm thinking I should ask the shop to re-do their work, but only if this is a Bad Thing...

use a new washer? it should seal outside of the repair area

New washer installed. That's why I suspect that the oil is leaking afrom the pan-Time-Sert interface.

is it a rubber lined one or a crush type

Rubber-lined, new from the dealer.

try an after market pressure sealing washer from mc master carr I will try to get you the number in an hour or two it will be just the next english size larger than m10 , this has a larger rubber seal and will seal outside the repair area...my guess is the factory one is not centered well, it is also a smaller rubber element than the replacements from parker I use

Excellent - thanks for the assist!

try thesse
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sorry for delay I was on the road

Hey Northbaygriso
After reading all this hope all works out OK please let us know.
All who replied, man awesome.
What a site.

Status: short-term solution found, will evaluate possible longer-term solutions.

Basically, after consulting a couple of local non-GRiSO bike shops, I drained the transmission, applied some thread sealer to the drain plug, refilled.  No more drips, no more seeping.

I'll take it to work tomorrow [with proper warm-ups!] and see how things end up.

you can also go to a conventional aluminium crush washer, what is happening is the molded in o ring is not quite big enough to span the outside of the repaired thread area and obturbate on the flat surface , that is why i suggested going up just slightly .5mm on the sealing washer it has a larger diameter element which spans a larger diameter counter-bore type surface. Pm me with your address and I will mail you a few 7/16"sealing washers,

will be thursday though, before I am home...just hold it centered on the drain plug while you tighten (may not have to) and I think all will be fine...

I do not know if I forgot to mention or not senility being a bitch, but I usually coat my inserts with retaining compound locktite 620

Uzidzit wrote:

the real problem is there is a gear shaft right over the drain and drilling and tapping is gonna be a bitch as the tap cannot project into the transmission very far,  you may have to thread partially and the shorten the time cert tool and go a bit further, and repeat this process several times then set the time cert with a retaining compound to ensure no weeps...it is a bitch to destroy a time cert tool set to do this but it beats pulling the tranny.

Great info Uzidzit. So the tap can't project into the case enough.You mention the time sert tool may have to be shortened. Do you mean the tap may need shortening because it's tapered? Just ĺearning about this type of repair so I'm unsure about a couple of things.

Thanks!

QUOTE:  As mentioned the worst thing is getting a good run at the hole. Best bet with the GRiSO would be remove the footrest hanger plate and master cylinder assembly and then go in with first a taper tap and then, after you have it started, a bottoming tap.

Just how much clearance is there between the top of the drain plug hole inside the case and the shaft that uzidzit described?  My tapered tap has a taper of about 1/2 inch or slightly more than 1 cm, so for that tap itself to work sufficiently there would have to be that much clearance between the top of the drain hole and the shaft that uzidzit described.

Just found the drain plug on my replacement Sport 1200 gearbox is stripped.
Torque wrenches are cheap nowadays and castings are not - why on earth ......

Anyway....as i have the old gearbox with casing as a fall back for a proper engineering mend.

My first-aid fix is - that I am going to tap the hole out to take a m12 x 1.24mm magnetic drain plug (Suzuki SV650 item).
My plan is getting the Rt pork chop and brake lever out of the way then tipping the bike up at the rear so i can work upwards comfortably.

The clearance hole for an M12x1.25 tap is 10.8 mm
so once i strip out the remainder of the thread i will clean it out with a 10.8mm drill
Then i can start the taper-tap (packed with grease) in the existing hole & then run the (greasy) plug-tap in.
Finally wash out through filler with paraffin and then use a 12mm dowty washer
20Nm torque same as the SV650

If it F**ks up i will strip the old gearbox and get it done properly

Or "the easy option" is to utilize some JB weld after cleaning what's left of both bolt and hole and run a tap through hole gently. Clean and micro vac or flush for shavings as mentioned. Then just butter on the JB on bolt threads and a bit on face and threads of gearcase and tighten to it's new max. And it's a shady tree mechanics permafix. Now gear oil change is drop bike on her side and drain then stand to fill.....Not proud of it but it's working till it's time to do the clutch.

Worth noting the casting the gearbox drain screws into is only 8mm thick.
Recommended thread depth for good strength in aluminium is 1.5 to 2 x diameter so this thread should be 15mm to 20mm deep.

So no wonder it strips the gearbox if it is over torqued .

Also the thread is so shallow that when i tried to thread it as 12mm x 1.5mm it would only take 30Nm Imho this is too close to the factory figure of 20Nm so i am getting a insert fitted as the next owner may not use a torque wrench.

happened to me ~3 years ago -
i heli coiled it and ~15 k miles later zero issues

Yes i reckon a helicoil would have done it as according to various Youtube tests they seem to survive higher loadings than Timeserts.  Local engineer said that m10 Timesert was 14mm long so a bit of a gamble that it would spread and lock in place in 8mm alloy. He made and fitted a steel insert which appears to work.

He also moaned a lot about manufacturers making threads of less than 1.5 diameters in alloy. Said it was a designed-in failure. I tend to agree.

Amusingly
He also said that the casting is so thin that 20Nm is quite close to the limit of stripping;  
so the first thread that i cut at 12mm to take the Suzuki drain plug was probably fine and it was a bit dim of me to stress-test it to 30Nm



Well they say you live and learn....
I live but i don't always learn

You can't get the short Timeserts in a kit, you have to order them separately. I just went through this last year, I bought 9mm depth. Locked in perfect, if you use anything longer the oil won't all drain out.
Might not use them up at 70yrs old but got my job done. I might use them in a Tonti bike, if one comes around.