C900 gearbox girdle

[squaab99t]

One step at a time.

[squaab99t]

Doing the final fitup on the complete gearbox instead of just the mockup case.
Flipping thing is heavy. Tilted it up lengthwise and strapped it to the leg of my work table.

Got the frames in place and tacked to the diff cover and rosette tacks to the inner driver flange.

Two steps forward and one back. Not enough clearance pass the ring gear to get the complete assembly off the gearbox.

Thanks to my awesome wife, who helped lift the gearbox off the floor and on to the rotation fixture. Much nicer being able to stand and work at chest height. It is also held solidly.

[squaab99t]

Reach around fixed. Detacked via die grinder/. Cut off wheel, and cold chisel. Removed the extraneous inner driver flange to create needed clearance to get pass the inner driver and clear the diff cover pass the ring gear and shifter shaft. Tacked with Gaff tape for a trial removal sweep.

[squaab99t]

Added the rosette and fillet welds. Final fitting to the strongback next.

[squaab99t]

Some changes since the last post. I capped off the frame dimples. I wanted to add some rigidity (I value) with the dimples, but I hosed myself as I took away the shear of the panel.

Added a diagonal from the inner driver flange to the strongback.

Also redid the back panel with a smaller dimple and better fit up.

Last few parts. Need access to the inner driver fasteners that will be behind a cap. One could use a crowfoot and be cussing the whole time, or go with socket Allen head bolts.

[squaab99t]

Final piece fitted, tacked, and welded. The top cap really stiffened up the arm.
Next steps: paint, weigh, deflection vs load testing.

[squaab99t]

Over 3 years and now I can call it done.

[99Super]

It looks great! How much does it weigh?

[squaab99t]

Thanks. I’m pretty happy how it came out. I did not do a deflection vs load test which planning, but cold setting it to true up square, she is frickin tough.
Just under double the weight of the cover I build. Approx 2.8 lbs increase. Scale is set to grams. 2568g = 5.65 lbs.

[Geoff]

What is the installation process with this?
I'm guessing: Set the backlash/shim the driver cups -> install/tighten girdle to driver cup -> tighten rear cover bolts?
Are the bolt holes for the rear cover large enough to allow for the rear cover to move side-side a little to allow for different driver shims?

[squaab99t]

Bit of an involved process.
By design I left a gap between the inner driver outer flange and the interface with the girdle’s side plate.

I added (2) .60mm shims prior to tacking insitu the reach around to the strongback.
Opening up holes on the diff cover would reduce the effectiveness as a shear plate only relying on friction to keep the open end of the box true.

Install process:
A) set backlash with shims as normally without the influence of the girdle
B) remove the inner driver fasteners, leaving the shim stack in place.
C) add a stack of shims to the outside of the inner driver flange
D) slip the diff cover, gasket and girdle in place.
E) bitch and moan why it is so Fin tight
F) locate the diff cover fasteners and seat the cover
G) use a feeler gauge to check the gap if any between the girdle and inner driver fastener lands.
H) decide if you need to add shims
J) take the whole F thing apart to add the shim delta.
K) start from C and this time add thread sealant to the fasteners common to the inner driver if you are happy with the fitup.

L) pour your favorite beverage...

This is definitely not made for rally service time on race day. But again if the gearbox goes South it is swap the whole thing or game over.

[squaab99t]

Update, 30 months after completion it is finally installed in the car. I was second guessing myself in thinking the steering rack and the gussets would crash. Only one way to find out. She is right up there, but I have clearance. Under 3/8 of an inch. I have a hockey puck front motor mount, so I think I should still clear on max torque pulls. Shifter shaft and coupler clear for normal operation. Inner driver sleeves look good and fit up with the boots and most importantly the CV tripods.
The upper oil cooler port is looking to be challenging to get the fitting on. Lucky it is an AN, so it should thread on easy and not needed to be uber torqued tight.

[squaab99t]

So far everything is fitting. I got the oil cooler lines fitted without too much hassle. Exhaust hanger and mid pipe went back in with good clearances. Filled with oil a few days ago and as expected no drips. Ironically I used 76 gear oil 75w-90 that was sent from Jorgen Eriksson from Sweden as a bonus with the purchase of primary kits. The oil was refined/made in the USA. Full circle.

[Crazyswede]

When you get it proven out please consider a price for purchase if a few of us might be interested.

[squaab99t]

When you get it proven out please consider a price for purchase if a few of us might be interested.

Will do, road trip to South Dakota this summer and later on some dyno testing/tuning with the new ECU and intake. We will see what kinda power the gearbox setup will take?
Thanks for the interests.