Jump to content
Sign in to follow this  

How to assemble crankshaft

Recommended Posts

Hi,

I got a new Hotrods crankshaft but have problems assemble it.

I dont want to damage or unbalance the crank therefore I need some hints of someone.

Please help me.

Thanks a lot!

KC

Share this post


Link to post
Share on other sites

you're obviously doing bearings too, so if you haven't installed them yet, do the following:

Place crank and bearings into freezer (keep in their bags)

Remove bearings from case halves using one of two methods:

1 - puller

2 - heat and pull (very easy)

Clean up your cases removing all traces of oil, place left case half (case1) on BBQ on low or in oven on 200F - when warm, drop cold bearing into place tap with backside of screwdriver all the way around to seat flush. Repeat on right case half (case2)

place case1 into oven/bbq again - heat.

Case1 needs to be set on a jig since the cold crank shaft drops right through - a box frame made of 2x4 stubs on end to cradle the case will work for elevating the case off the bench.

let cool naturally.

Place in freezer for at least an hour - have a beer - bbq some burgers....

after 1 hour Place case2 into oven/bbq and heat

Remove case1/crank assy. from freezer, drop in tranny assy. and shift forks/shift cam assy. (MAKE SURE YOU GO THROUGH ALL GEARS UP/DOWN ONCE TO TEST) place studs into holes, use yamabond or permatex motoseal to create your gasket bead - don't get all sloppy with this - it can be done in a clean fashion.

Next step requires accuracy and speed - keep rubber mallet within reach

take case2 from oven/BBQ - flip over, look straight down on your assembly and drop/guide into place it should drop right onto studs with some small wiggles to seat tranny shafts in their bearings maybe leaving 1/4 gap - with mallet work your way around case tapping lightly and it will drop right on, insert at least 5 bolts in star pattern and bring to within 2 ft/lbs of final torque while continuing to tap case2. Let it all cool and install all remaining case bolts.

The only other way requires a crank puller, but this method works for me every time - just plan it out well and know exactly what you are doing/have to do before doing something wrong.

Share this post


Link to post
Share on other sites

thanks for the very detailed info but the new crank bearings are already in the cases, also with bearing glue because there was a very bit freeplay between bearings and cases.

maybe putting the crank into a freezer and the case with bearing in the oven will help.

Share this post


Link to post
Share on other sites

Is this on your bike, or yet another customer's bike?

Sir, you are indeed the king of asking how to work on a bike you are getting paid to know how to repair. Congratulations.

Share this post


Link to post
Share on other sites
Is this on your bike, or yet another customer's bike?

Sir, you are indeed the king of asking how to work on a bike you are getting paid to know how to repair. Congratulations.

lol, you gotta be kidding me

Share this post


Link to post
Share on other sites
thanks for the very detailed info but the new crank bearings are already in the cases, also with bearing glue because there was a very bit freeplay between bearings and cases.

maybe putting the crank into a freezer and the case with bearing in the oven will help.

Bearing Glue *** is that? If you have freeplay between the bearings and cases that motor is going to gernade the first time it starts.:)

Share this post


Link to post
Share on other sites

hi_im_sean, I'm not kidding. He has several threads in the suspension forum for different makes and models. Just look at the threads he started.

Share this post


Link to post
Share on other sites

I wouldn't put the seal in the case and then into the oven. I bought a 12 ton H frame press from harbor freight for $135 and it had paid for itself 20 times over.

Share this post


Link to post
Share on other sites

That press isn't going to get your crank into the case/bearing though, you'll need to get a crank installation tool.

You can put seals into the oven no problem - at the specified 200 deg F they will be fine - have done it many times. Bottom end seals get very hot during normal engine operation - they are designed to withstand the heat.

Share this post


Link to post
Share on other sites

"a suitable tool" looks like a pipe or something to me

There is no "crank installation tool" on Kawasaki's beyond the jig tool to keep the halves aligned during assembly.

Share this post


Link to post
Share on other sites
There is no "crank installation tool"

...then again....maybe there is.....

tusk makes a universal crankshaft installation tool, a free spinning threaded rod is connected onto the threaded end of the crank after it is partially inserted through the bearing, you slip a tube that sits on the inner race of the bearing over the rod/crank - the other end of the tube has a hole for the rod to come through, you then put a nut onto the threaded tube and tighten it down onto the top of the tube, the more you tighten, the more the crankshaft pulls through the bearing until it is fully seated against the bearing on the inside. remove the tool and Voila!

This method puts absolutely NO stress on anything that might throw the crank balance out of whack or possibly cause damage to your bearing.

Yamaha actually makes a kit for their bikes because they think of that kind of stuff - Yamaha's kit can be used across the board with all jap bikes as long as it threads onto the crank.

It is actually the CORRECT way to install a crank - it just happens we're all too damn cheap to buy the right tools so we cheat with heat.

http://www.rockymountainatv.com/productDetail.do?&navType=type&webTypeId=140&navTitle=Tools%2FShop&webCatId=22&prodFamilyId=17166

https://support.yamaha-dealers.com/klsupply/motor/motor52.pdf

Share this post


Link to post
Share on other sites

I bought the tusk tool but it looks like it'll only work on the stator side of the crank because thats the only end that threaded :)

Share this post


Link to post
Share on other sites
I bought the tusk tool but it looks like it'll only work on the stator side of the crank because thats the only end that threaded :)

That is the side I always install first.

Share this post


Link to post
Share on other sites

geesh, I feel so outdated, I generally press the crank halves in a press, and remove the bearings with a puller, always press my bearings in my cases, rarely use heat on any treated metals, Align my cranks with a dial guage and a big bronze hammer, not sure how many cranks and engines I have built but There has been a bunch lol, never had one fail yet from any problems I did, although once long ago I had a wrist pin circlip failed but still not sure if it was me or it, never know now,

Share this post


Link to post
Share on other sites

I made it the bike is running!

put the crank overnight in the freezer and in the morning take it out and put the both cases in the oven for a few minutes, inclusive the crank seals.

than it worked the bike runns great now.

p.s. its my own bike

Share this post


Link to post
Share on other sites

if you look on youtube, rockymountainmc has a 3 part video on R&Ring a crank. It is very good and detailed. as soon as I saw it, I immediately went to order the tools from them. Of course they were on back order. Granted I haven't done a bottom end since 1987, but I fabbed up my own case spiltter, crank puller, etc. and it was just as easy now as it was then. nothing changed in 20+ years. But I will have all the tools soon.

Share this post


Link to post
Share on other sites

matt4x4, thanks for the link to the Yamaha page. I have that main tool and some of the adapters, actually. For me, Yamaha tools are a nightmare to find out about, compared to Kawasaki tools.

I'd be leary of using the Tusk tool. I would rather just use a press, I guess.

Share this post


Link to post
Share on other sites

This maybe a dumb question, but, what harm does it do to the crank if you use a rubber mallet to remove/install?

Share this post


Link to post
Share on other sites

If you use a rubber mallet to install, you are hammering right beside the crankshaft when trying to force the case/bearing onto the shaft which is balanced at the factory - and if you notice - the crankshaft is not continuous through it from end to end - what can happen is that you throw the crank out of balance - that's why there's a tool you can wedge into the crank halves to fill the gap opposite the pin for the lower con rod - the con rod and tool will stick out the cylinder hole and you can hammer away - without the tool - hammering is bad - you can tap (but no heavy hits) if using heat since everything will slip together easier (heat on outer part, while the inner is cold = bigger tolerances between the two).

A puller - as discussed above will pull the crank in and put absolutely no pressure on any other crank components, it also uses the inner bearing race to pull off of so the bearings do not incur stress either.

Normally, when pulling a case apart - you also use a puller to pull the case off the crank eliminating sending shock through the entire crank.

Sometimes the bearing sticks on teh crank and pulls out of the case instead - just depends where the most amount of friction is.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×