The Stub Axle

[John Coffey]

FYI... this little adventure happened exactly a week before my recent

excursion into the PIR turn 2 tire wall.

Third autocross run (the money run) at the Cal Club autocross at Hollywood

Park in Inglewood, CA. I KNOW this will be the fast time of the day (FTD)

run! Funny how you get that feeling just before...

Second gear, right hand turn onto the only real straight in the course. I'm

pretty much foot-to-the-floor exiting the turn at 2500 rpm when I hear a

BANG and the engine instantly hits the rev limiter. The car gets a little

squirrley as I let off the gas and coast off the course.

As I roll into the paddock I'm revving the engine a bit and trying all the

gears in the transmission. They seem to engage fine but I get no forward

propulsion. I can also hear a grinding from the rear. As I come to a stop

and shutoff I'm thinking, "Blew up the $1,000 Quaife diff...

Son-of-a-bitch!" I crawl under the back of the car and look around. No

oil, no debris, nothing appears broken, but the car won't got forward under

power. Great...

Bryan Lampe drives up after finishing his third run (and kicking my arse).

He seems to be around whenever I break something. I need to look into this

some more, but first, let me see if I can kill him. I ask Bryan to look at

the halfshafts while I start the car and put it in gear. He says OK and

crawls under the back of the car.

I fired the car up, put it in first, and applied a little power. After a

few seconds Bryan's head pops up and says, "Stub axle's busted." I shut the

car off and get out. He points to the left rear brake drum and, sure enough,

the center is pushed out and cracked, looking all the world like a crater on

the Moon. FYI... Quaife's need some resistance on each wheel for them to

move the power around correctly, otherwise they send all the power to the

axle with no resistance - my broken stub axle.

So, we push my car onto the trailer and I'm feeling a lot better 'cuz a stub

axle is a LOT cheaper than a new diff. On the way home I call Hiten Patel

to see if I can use one of the stub axles he left at Erik's shop (EMI

Racing) as part of the struts I'm having built (a whole 'nuther story). He

says OK, so I stop by Erik's and grab both stub axles (never know which will

work). Luckily I have a set of spare drums at home.

On Monday I go to MSA and Sam sells me bearings and lock nuts. Monday night

I jack the car up and start stripping the left rear. Well... the stub axle

broke in a weird way. The flange separated from the axle so I had to figure

out a way to use the halfshaft mounting bolts to keep the stub axle from

turning while removing the lock nut (180 ft lbs of torque holding that thing

on). Normally, a broken stub axle can be pulled/pounded out from each end.

After bending two screwdrivers and breaking a Craftsman box wrench I had to

find something better.

Searching through my collection of old tools I found a thick open end wrench

that said, "Forged in USA." It fit perfectly over a halfshaft bolt and the

other end anchored to the lower control arm like it was made for the job.

This is now my "Stub Axle Anti-Torque Wrench" and resides in an important

place in my tool box.

So... now I've got the rear of the car on 6 jackstands and 2 floor jacks,

the crimped sections of the lock nut ground off, the SAATW wrench hooked up,

a breaker bar on the lock nut, 4' of pipe on the breaker bar, and all 200

lbs (my wife says 210) of me standing on the pipe. Nothing. I wiggle a

little bit while balancing on the pipe. Nothing. I jump up and land on the

pipe. CRACK! CLANG! THUD-OOOF! Me and the pipe hit garage floor.

My wife sticks her head in the garage, "Are you dead yet?" She's such a

loving woman (I'm worth a 1/4 million dollars dead and she gets it all).

Anyway, the CRACK was the lock nut breaking loose so I was in business! The

disassembly, reassembly went easy enough and the next night (after a trip to

the machine shop) the car was back together.

I did learn that there are different sized stub axles. The splined end that

goes to the halfshaft has a larger OD for 280Zs. There are basically

interchangeable as long and the halfshaft piece matches the stub axle you

are using and you use the correct spacer between the stub axle bearings

(almost always the "B" spacer for a 240Z).

FYI... I was VERY lucky that the wheel and drum stayed attached to my car

when the stub axle broke. Stub axle failure is not unusual for a 30 year

old 240Z that's raced/autocrossed. Next time you are working on the rear

brakes, clean and check the parts of the stub axle and flange that you can

get to. Look for hairline cracks. Also, pull the halfshaft and check the

locknut for proper torque.

------------------

----------

John Coffey

johncof@veriomail.com