Jetfire Clutches Q&A
I have a question I hope you can help me with. I just learned last night that the clutch in my ’62 Jetfire 4 speed restoration project is a 10 inch clutch, as compared to the clutch in my ’62 Cutlass, which is a 9 1/2 inch clutch. I would like to obtain a new clutch pressure plate and disk to put in this car, rather than hope the old, used components will work. Is this 10 inch clutch for the Jetfire the same as other GM vehicles of the era (e.g. Corvette, Impala) so as to make it easy to source a new/rebuilt one? Or, is it entirely unique to the Jetfire?
I do not know the answer to this question. All pre 1964 GM 4-speed transmission set ups were Borg-Warner T-10’s. I do recall that the only difference between a 1962 Corvette and Jetfire transmission was the drilled and taped bolt hole in the center of the output shaft, this is to hold the yoke to the transmission. (I think the Corvette also used an aluminum center housing where the Olds T-10 was cast a iron center housing.) I do believe the output shaft and spline pattern was the same. If this is so, then the clutch should be the same. I also believe the pressure plate or clutch cover was three spring fingers (can’t recall the name for this style….Borg & something? or sprung hub), not the more modern diaphragm style. The two 4-speed “Jetfire” cars that I have made, one my convertible and the other the red station wagon were set up with 9-1/2″ bolt pattern flywheels and 9-1/2″ clutch parts. The 10″ Jetfire manual transmission flywheels were too hard to find! I used three finger pressure plates with all three (or 9) spring places filled with heavy duty springs to assure optimum lock up. The original 9-1/2″ flywheel only used two springs (center spring hole open). (pic’s attached)
I do believe the Jetfire 10″ set up also used the three spring finger style pressure plate. A friend just rebuilt his ’63 Jetfire clutch assembly and I supplied the 10″ original NOS Jetfire clutch disk. He had his 10″ three finger pressure plate rebuilt by a fellow here in MN, put back together with a new release bearing and turned flywheel face.
I tried a diaphragm style pressure plate back in the ’80’s and was not happy with the performance. Too much slip when I ran it hard. Pulled it out and replaced with the three finger style and have not had that problem since.
Probably have not answered your question! I would think that a good parts supplier or clutch mfg co. could give you the correct answer on interchange. Just be sure it all fits and the matching release bearing works with your bearing yoke/spring fingers. Good luck……
Thanks for your reply. It was very helpful. My clutch pressure plate is the three fingered design, as is the 9 1/2 inch one in my Cutlass. A friend of mine who is a transmission and clutch expert gave me some info and it appears that this pressure plate is still in pretty good shape, based on what he said. I think I will just clean it up and use it. I suppose it could be rebuilt, if necessary. As for the disk, I think it is probably still in pretty good shape too, but I think finding a new one shouldn’t be that difficult as all of the GM versions back then worked with a T-10. As long as I find a 10 inch one that fits the splines, I should be okay. I’ll let you know how it goes.