Synchro Hub Installation- 911 gearbox

[Scott Clarke]

I took a stab at installing my first gear synchro hub last night. Wayne's book suggests that a soft mallet should do the trick, but I had no such luck. Should I heat the synchro hub in oil in order to get it to go?
-Scott

[john walker's workshop]

a vise with soft jaws will do it. heat helps, and maybe put the gear in the freezer too. be sure it's on all the way around. hold it up to the light and look for any gap between gear and teeth. then slip the bearing and race inside and be sure there is no binding. occasionally the gear's bore can be distorted in the thinner area where the hub is pressed on. it can actually seize in service and lock up the trans, worst case. a trip to the local machine shop for a few passes over the sunnen hone is the fix.

[Jim Sims]

Depends on the interference resulting from the parts tolerances and factory swaging (peening) but even taking advantage of the thermal expansion/contraction you are likely to require a large heavy vise or hydraulic shop press to assemble the parts. IMO and experience a soft mallet is not likely to work. I use a hot air gun to heat the dogteeth and a hydraulic shop press to push them onto the gear. Given the currrent cost of these parts it's worth locating a shop press for this operation. In fact, if you ruin the gear and dogteeth you could likely buy two or three shop presses from Harbor Freight for the cost of the ruined parts.

[Scott Clarke]

Thank you, gentlemen. I will proceed with caution.
-Scott

[2garden]

Scott, this is how I was told to do it, and it worked fine. First I tried pressing it on cold and I broke the hub. Bummer. Put the gear in the freezer, and the dog tooth hub in a toaster oven at 400F. Work fast and it should drop right on. Good luck.

[higztar]

a small propane torch and heat resistant gloves

[Scott Clarke]

Any reason not to heat the hub in hot oil (in conjunction with cooling the gear). I have the gear in the freezer now. The wife loves it!
-Scott

[2garden]

it's too easy to toast it.

[ChrisBennet]

I stone the burred/peened back metal on the gear splines and then press the the hub on with a hydraulic press. Heating the hub with a heat gun helps. I use some red Loctite to keep everything together.
-Chris

[Scott Clarke]

Well, I used the hot oil and gear in the freezer method. I did this because it had the least potential for pissing of my wife! I used a camp stove to heat the oil/hub. I tried once after the oil was thin, but it wasn't going to go. So, I put the hub back in the oil and turned up the heat to the point at which it was smoking a little. This time, after placing a wood block on top of the hub, some sturdy blows with my brass hammer drove the hub into position. All is right with the world.
Thanks to all for the help,
-Scott