Pre Load End Float

[jonduc74]

End Float
I understand that you have to “pre load” a GT750 motor by some thou to bring it in to zero end float when assembled, not sure what is the best amount, could someone help out there.
Also does anyone know if it is possible to remove “end float” from the crank by shimming between the casing and the flywheel, without have to split the cases?
Many Thanks John

[wdietz186]

Jonduc, The idea behind preloading the crank is to eliminate any endfloat when the cases are at operating temp. The mainbearings are of the angular contact type to better absorb the flexing of the crank during operation. A slight [003" to .006" ish ] pinch should be sufficent for a normally ridden street bike. I've been using this approximate figure on my 900 racer and haven't had any bearing problems for the past twenty or so years. Due to the design of the bearings the only way to shim them is between the crank cheek and the inner race of the bearing. If you have noticeable end float on your crank you likely need mainbearings.On a 750 this can affect your timing bevels too, and not in a good way! Best of luck, Bill

[jonduc74]

Hi Bill thanks for that, someone told me once around 2 to 4 thou I think, 3 to 6 thou would be about the same and sounds good to me!
My last mechanic did pre-load the crank and I have not done more than 30,000 miles, which I heard is all these main bearings will handle. I will be taking a look soon at the timing side and just hope there is no end float. I know there should be no movement, how much is too much?
I have also just fitted a Pazon Smart Fire Ignition system as I have heard digital ignition can increase the life of these motors.
Cheers Jonduc

[wdietz186]

Jonduc, If the crank was set up correctly,30k should be no problem. I have a 75 750 GT with about 60k on it [speedo took a dump years ago] The 750 engines are way understressed and don't make enough power to hurt themselves unless you really abuse them. Check the end float with a dial indicator.Press the crank toward the left and zero the gauge then carefully pry the shaft towards you.You will probably find all your worry was for naught. Good luck,Bill

[Laurence]

Would 3-6 thou be the same preload I should go for on my crankshaft on my 79 900ss.
Turns out im up to the exact point on my engine also.

[DesmoDog]

Jonduc, If the crank was set up correctly,30k should be no problem.

I'd agree with that, I've had similar experience. When I rebuilt my 750 GT it showed 62,000 miles and the speedo was broken. I sent the crank to Syd's where they pulled it apart, examined everything, and put it back together with the same parts as it checked out fine. Malcolme told me it looked more like it had 6,000 miles on it rather than 60,000.