Changing The Infamous Starter Clutch On 750 Twin

I am planning to replace the starter clutch on my '79 750 twin. Of course, I have no tool to hold the flywheel while I crank loose the mega bolt that holds it to the crankshaft (FSM says 105 ft-lbs torque, so factory setting is probably twice that)....

Just curious: can I use engine compression as a "brake" and put a wrench on the nut and tap the end of the wrench with a hammer? That would be sort of like an impact driver effect.

The problem is the torque twisting the crankshaft would be applied to the piston rods so it could twist the crank.

Better ideas would be appreciated.

Bountyhunter: Two thoughts, 1st, In casual reading, I seem to recall someone searching for said rotor bolt, and having probs as it was NLA from ma Kaw, and that it was L/H threaded. rec. looking/research. (l/h thread bolts /nuts, usually have a indented line circling their flats.2nd air impact is usually the easiest opt for removing bits where special holders are un avail.( a 12 pack is usually sufficent "grease" for some one w/an adaquate gun & air. luck G

The bolt on the shaft is definitely reverse thread. I haven't actually had a go at cranking it yet, I will be tearing into it this week. I was actually wondering if anybody had an opinion about the "tap the wrench" method using the engine compression as resistance.

I don't have an impact wrench.

get a cheap strap wrench from any auto parts or tool supplier like harbour freight or up here prinncess auto that will hold the rotor just fine.

timebomb33 wrote:

get a cheap strap wrench from any auto parts or tool supplier like harbour freight or up here prinncess auto that will hold the rotor just fine.

I've been looking for one of those. I'll see if I can find one tomorrow.

A "hand and hammer" operated impact driver is also relatively inexpensive and commonly available.

Accomodates various size bits and also 3/8" sockets.

Here for reference is the impact driver listed by Z1E. Click > impact driver

Good Luck!

Bountyhunter, You might not need any additional tools. Using the balance holes on the outside of the rotor and flat blade "screwdriver" as a stop, you can break the bolt loose with a wrench and a hammer.

Also works when using the axle threads (RH thread) to remove the rotor and clutch assembly.

Also, don't forget this when reinstalling the rotor bolt.

If the bolt loosens, the rotor and clutch assembly will spin freely on the crank shaft taper instesd of turning the crank.
Hopefully you won't have to find this out in the parking lot of the DMV. And while in the parking lot, removing the side case to tighten said bolt without thread locker, also find out that much more oil poures out when the bike is on the side stand instesd of the center stand.

Good Luck.

Thanks for the idea, that does look like it might work...... I will be wearing eye protection when I do it.:laugh:

I was planning to use blue loctite on it for sure.

BountyHunter, post up some pics after your done. Would be most interested in how it goes for you and if you have any tips afterwards. I think mine is getting "tired" so sooner or later I'll have to do it too. TIA.

AtLarge wrote:

BountyHunter, post up some pics after your done. Would be most interested in how it goes for you and if you have any tips afterwards. I think mine is getting "tired" so sooner or later I'll have to do it too. TIA.

Didn't have a camera while I did it, but here's the blow by blow description so far:

The screwdriver flywheel holder as shown above in this thread worked perfectly. I used a long 17mm box end wrench on the shaft nut and tapped it with a hammer and it came loose easily.

Getting the flywheel off was nearly impossible, even using the rear axle as a puller. At first, I was using one long screwdriver to twist the axle supporting it under with my left hand. NEVER MOVED. Eventually, I got two screwdrivers and shoved one into each side of the axle nut's through hole and twisted with both hands (one on each screwdriver) and it finally let go.

AS AN ASIDE: My clutch didn't need changing, it is in very good condition. In fact, better condition than the used one I bought to cannibalize for parts should I have found anything broken in mine. Amazing, almost 80k miles on mine and it has very little wear at all. I just cleaned everything and polished the rollers and pins. The springs looked very good.

Oh, well. My starter did "squawk" a couple of times recently when I hit it so I thought it needed fixing, but maybe not. The engine may have just kicked back over against it.

Good to know. Thanx for the follow-up. Wow. 80k is spectacular. Hoping for that out of mine.