GT750 Bolt Torque Specifications

[water cooled]

I've taken a look at the Suzuki 2-Stroke Torque Specification Bulletin No. 3 as well as the 1974 Manual regarding bolt torque.

I have never been completely clear on the the torque spec for the (six) 8 x 1.25mm clutch bolts that secure the clutch pressure plate into the hub.

The Service Bulletin references the following:
Std bolt torque for 8mm is 6.5-10.1 ft-lbs
Extra strength 8mm bolts are 9.5-17 ft.lbs.

Both seem a little high to me... these are 8mm steel bolts going into aluminum threads in the clutch hub. Is there a specific torque called out anywhere for these six bolts?

Thanks

[Suzukidave]

Kevin , i have this on engine specs

[water cooled]

Thanks Dave....that's a great resource you posted. Nicely consolidated.

I still dont see the GT750 clutch-spring bolts called out though. My concern is that it appears those 6 bolts have the "S" requiring pretty high torque and the clutch hub is fairly soft aluminum. Seems like you need to be careful on these bolts. Considering their importance, it seems its the one set of bolts on the bike with no specific torque requirement.

I guess one way to go is to torque them to 9.5 ft-lbs and according to the chart, it should cover both requirements for standard and high strength bolts. Actually, since Im inside the clutch as often as I am, I'll go with a lower torque and keep checking between races.

BTW Dave, the ALTO Red Eagle friction plates arrived and are high quality. Slightly thinner than stock which allows for a 9-friction/8-steel clutch pack for a total stack height of 38.91 mm. Only issue might be how much of a dimple the thinner friction tabs leave on the clutch basket fingers as they are transmitting higher HP across a thinner surface area per tab.

http://www.altousa.com/am/high_performance

[tz375]

I'd use the 550 figure of 2.9 - 5.1. They do not need to be very tight at all.

[water cooled]

That's more along the lines I was thinking. There is no load except the spring force. Just want to be sure they dont back out. The real concern is damaging the hub by over-torquing those bolts. Im anxious to try the ALTO plates and see how they do. I also have a complete "NOS" clutch pack as backup and understand the Suzuki plates are actually very good. The Barnett plates were ok but a few of the steel plates warped causing some excess drag. With the clutch pulled in, and rpms rising at launch, it had a tendency to pull the bike forward through the beams. Went back to stock steels for now.

[tz375]

That warping would probably be even worse with the thinner plates that I like.


Have you set a target for 2011 - low tens or less? And how is the weight saving plan progressing? My street bike had better not turn out to be lighter than your racer...... Like that's going to happen any time soon.

[water cooled]

That's a good one! However, I would not be disappointed at all to finally see that street racer of yours. Lots of good tidbits on that bike that I think the rest of us would really like to see and appreciate!

Interestingly, it was the Barnett steel plates that warped and only a few...but that was enough to cause problems at the starting line. As the revs climb during staging, I had to put me feet out in front of me to stop the bike from rolling through the beams.

So, the logic is, stick with the NOS Suzuki steel plates and try the ALTO friction plates. The friction plates are slightly thinner but enough that you can add one of each to the stack. None of the Barnett friction plates warped...they just wore out and it was only a few of the steel plates that warped. Once the plates start dragging in there, it probably generated some pretty good heat when you hold the clutch in and the rpms up above 8000.

You know me.... my next milestone goal is to get under 10.30 sec and over 131.19 mph to eclipse Gary Biddel's record on his "modified" GT750 set at Dragway 42 in W. Salem OH. Dont know what year but it was back in the day! Thats the lowest ET I know of for a "modified" GT which basically means stock frame cradle, swingarm, and std location for foot pegs. Modified allows for a slick and wheelie bars. In all fairness, Gary Biddel was foot shifting his GT to record those numbers....pretty impressive even by todays standards!