Shrink Fit

[Richard Carlstedt]

Sure does Collin ! The shrink is used to have the proper Tension in the rods.

Those not familiar with Thermo shrinks like rings on disks or wheels--- should know that size for size
a Thermo Interference fit is twice as strong as a press fit ! ( and you don't need a Hydraulic Press to accomplish the same process)

Rich

 

[Iampappabear]

Another method of stretching press tie rods was using a hydraulic nut. The hydraulic nut stretched the tie rod then the regular nut was spun down. Takes one whole load of pressure to stretch a 4" diameter tie rod 1/8"!!!

 

[kuhncw]

Kpar,

I'm suspect you are making a flywheel. Rich Carlstedt and others have posted a lot of good information on shrink fits. You should have no problem with the process. Another option is an easy slip fit between the parts and Loctite. This works well for adding rims to a flywheel.

Regards,

Chuck

 

[Kpar]

Thanks Chuck, yes it is a flywheel and lucky I've got another weight for a remake.
I done the unthinkable today made the final cut on the cast wheel and you wouldn't believe it,
I had .012" to go and that is what I dialed in on the cross feed. I couldn't believe it.
O well, Nothing else to do tomorrow.
Kpar

 

[jack620]

ouch.

 

[jiminva]

Not real scientific, but I shrank a ring gear onto a Ford Model A flywheel years ago. I just started a charcoal fire at dusk, so I could see the colors. When the coals were hot, I put the ring gear on. When the ring gear was a nice red (NOT cherry, did not want to temper it), I slipped it over the flywheel, and tapped it down. The major concern was getting it seated so that it did not cool and shrink down misaligned.

 

[oldengineguy]

Austin Healy Sprite ring gear on the BBQ @ 500f for one hour Slid on Aluminum flywheel no problem. Been on a race engine over 30 years. Guess it worked. Colin

 

[goldstar31]

Austin Healy Sprite ring gear on the BBQ @ 500f for one hour Slid on Aluminum flywheel no problem. Been on a race engine over 30 years. Guess it worked. Colin

I think that ALL the BMC A And B Series had shrunk on eing gear. I seem to recall the 'LandCrab(1800) and the Mazis. So as the Reliant Robin ( beloved of Trotters Trading), the 4 wheel version of the plastic pig were sort of A series they were sumilat so the Japapanese 'copied' them. I know that the cylinder heads had the same 'intervals'. So back pre War. I guess that my old 1937 Early Perpendicular and the Austin 7's were all similar. So That would probably include the Marinised ones?
And the we come to the C Class,

I'm that old

 

[Kpar]

Well I made up a new cast wheel and decided to do a test first before removing from lathe.
Brass Ring
Cold = 140.53mm ID.
Hot = 141.23mm ID (temp 450 f)
Cast wheel 140.70mm OD
Hopefully if I'm correct about 0.021" shrink fit.
I was not expecting the that amount as I always assumed 001" per 1.00"
Are my calculations correct ?.
Kpar

 

[Richard Carlstedt]

140.7-140.53=.017mm= .017mm x .039=.00663" shrink which is perfect for your ~ 6 Inch Wheel

Rich

 

[Kpar]

Well quite pleased with myself, just a back yarder in lots of things but this worked out ok.
The Webber Q seems to put out enough heat for future heat shrink fittings.