problem joining cases

[SliderNH]

Everything has gone smoothly till now. I'm trying to join the cases and I can't get the top half to come down properly. I can feel it binding on rubber. The back goes down just fine. Took a closer look and the crank bearing o-rings keep wanting to get pinched between the case halves. Its been kicking my ass. I just put the crank in the freezer to try and get that rubber to shrink up a little bit. I tried oiling them to make them slippery, please help!

Other question, do you guys use any gasket maker between the case halves? when I pulled it apart they were clean - aluminum to aluminum and no leaks. Thanks - Brad

[Barry S.]

You have to bond the cases with something like 3-bond, or something like it like Yamabond, they were not put together with nothing or it will leak. Some bikes has a peg in the lower case that goes into a hole in the main bearings, check yours.

[SliderNH]

Thanks for the reply..I'll give yamabond a try... on the t500 all the crank bearings( left, middle, right) have holes and there are corresponding dowel pins in the lower case. I have checked and rechecked to make sure they are clean and the pins go in all the way. All the gears and bearings for the transmission are the same, those are seated properly too. the problem seems to be strictly the o-rings.

[GT750Battleship]

Be aware that crankcases are a "matched set" from the factory so the two halves align perfectly,this is due to the boring process at the time of manufacture!!

Regards,
GT750battleship.

[SliderNH]

I got it done tonight. Used threebond. Took a few tries to get it right, but its done. This is my first motor rebuild so I had a lot to learn with this process. I did it well and I'm better for it. This past week has been a real good learning experience for me. I think I did everything wrong atleast once. Too much oil dripping from the crank when i put it in so when I flipped it over, oil came dripping out the front if the case, ruining my clean mating-surfaces...too much grease around the o-rings and bearings which squeezed itself between mating surfaces, too much threebond ended up with excess in the crank area and the trans...putting the crank in backwards...yeah. After working on this for 5 days, and several failed attempts I almost gave up. I came very close to bringing it to the local T500, guru have him do it for me, and alleviate the whole headache. I decided to give it one more try today, and glad I did!

So come to find out the cases go together nicely when you tighten the bolts in the specified order, and aren't scared of the 1/8th inch gap around the crank. I was terrified of pinching the o-rings. I was certain that if the cases weren't 100% together before bolting it together i'd ruin the rings. I tried a couple different methods that worked well to get the cases to lay together tightly but weren't the right way to do it. First I tried putting the crank in the freezer - ended up with condensation all over it - had to pull it all apart, douche it with wd-40 and oil waited a day and tried a different method. Put the cases in the oven at 170 for 30 mins, went together nicely but that was the attempt when I had too much oil in/on the crank, so that didn't work either. Final attempt with very moderate smear of oil in the crank and grease on the bearing-to-case surfaces worked well. Put all the bolts in finger tight with a light smear of grease on the threads, then came back through and torqued them down. I'm very confident it's good to go. Thanks for the tid-bits and advice.

[locobuilderbri]

Glad its all gone well for you eventually.
Its not a good idea to grease or otherwise lubricate threads it can lead to overtorquing
with the possiblity of stripping the threads.
The threads should be clean and dry if you must grease apply sparingly to the bolt shank
ensuring none gets under the bolt head for the same reason.
Lubricating makes the torque wrench click off later exceeding the indicated setting by
approximately 25%.
Regards Bri e

[SliderNH]

cool thanks for the info. I guess both make sense in a way... I'd rather be more cautious.. I'll think twice about greasing threads next time. I was told that greasing the threads sparingly allowed the wrench to tighten more accurately and consistently compared to dry threads. Its good to hear both sides of it. 25% tighter is a lot, definitely more than I would have expected. Fortunately it went well and I didn't strip any threads. Also, some very good advice here, as Bri said, if you do grease...grease threads sparingly. I learned this with my experience/multiple screw-ups. I used too much on one of my first attempts, and had some squeeze up between the cases and mix with the liquid gasket. Not good so beware of that too.