Billet diff housing in the making

[flatchat(Chris)]

We have a customer who is doing an "exact" replica of a 962 Porsche
Using a G50 / 01 gearbox the right way up, means flipping the crown wheel --(as its a mid engine job)-- so, decided to do a billet diff housing --

Firstly, we do some reverse engineering for critical dimensions to create a model for cad cam, this then provides machine tool language for the 4 axis machining centre which uses various cutters to remove all the unwanted metal .

Then we start with a chunck of 6061 ally 350mm (14") square that we whittle away at till we have about 50% swarf, leaving a roughed out housing.

Next, is stress relieving or aging -- this allows the metal to relax or creep giving stable dimensioning for the finish machining

and wait for the next installment as we go thru the stages till completion

 

[Randy V]

Wow - that chunk of aluminum must have been pretty darned heavy to start with. Sounds and looks like a very interesting project!

 

[Dave P]

Chris:

How long does it take to do that stage of machining?

 

[Terry Oxandale]

Very nice! I priced some pretty good sized pieces of aluminum block for some billet uprights I want to machine, and that came close to $1000, and a lot of weight. Can't imagine how much money ended up on the floor for your block.

 

[Erik]

Just wondering why you did not just reverse rotate your engine instead? This would be a bit easier and perhaps less expensive, but I do really like what you have there. How many hours did it take to get to that point on the mill?

Erik

 

[Randy V]

Reversing the rotation of the engine is relatively easy compared to all the work the gearbox would take I think...

 

[HILLY]

Reversing engines are no where near as much fun as making swarf !!
Nice project.

 

[Jac Mac]

IIRC, G50 has hypoid R&P, therefore reverse rotation would swap all the helical thrust areas & shift the R&P load directions, create a big can of worms for someone to fix.

I am just trying to draw a mental pic, the axle c/l will now be further away from input shaft? or am on the wrong mental channel..

 

[flatchat(Chris)]

Three 44 gallon drums of shavings from a ~120kg block @ ~$12 aud per kg which took about 12 hours machine time -- being a one off takes a bit longer.

The diff had been operating in this configuration for some time before the decision came to re house it -- so , guess the customer knows what he wants.

Engine and clutch bolts to a Magnesium suspension cross member, the diff / gearbox is bolted to this also, an extended input shaft is used

 

[Terry Oxandale]

Next, is stress relieving or aging -- this allows the metal to relax or creep giving stable dimensioning for the finish machining

Love the work. So...what all was involved in the above step?

 

[Eric A.]

stress relief by vibrating maybe? aging by heat cycling?

 

[flatchat(Chris)]

We licked the end faces for a reference dimension prior to the hogging out then checked that dim. after, it hadn't changed much --maybe .2mm (.008")
so we resorted to a bush method of stress releif --to be sure-- this involves carefully placing it on a small pallet outside the shop exposing all its glory to the elements of the natural weather ie:- local temps are between 35°C day and 12°C at night -- a couple of cycles at that should do the trick.

The vibrating idea sounds interesting Eric --maybe ultrasonically ?-- naah, too technical for us

 

[Eric A.]

The vibrating idea sounds interesting Eric --maybe ultrasonically ?-- naah, too technical for us

I worked for a company where we machined some housings that were about 20 inches in diameter. To help keep the ID consistant they were roughed and then mounted to a table that vibrated. After a few hours there we finish machined them and were able to hold the dimensions to a closer tolerance.

 

[Erik]

IIRC, G50 has hypoid R&P, therefore reverse rotation would swap all the helical thrust areas & shift the R&P load directions, create a big can of worms for someone to fix

Not to pick on this,but changing the side that the R&P is on does the exact same thing. This does not hurt the ring and pinion so long as the bellhousing is strong enough to counter any deflection, which it would have been with the addition of a billet side plate.

Just FYI.

Erik

 

[Jac Mac]

Not to pick on this,but changing the side that the R&P is on does the exact same thing. This does not hurt the ring and pinion so long as the bellhousing is strong enough to counter any deflection, which it would have been with the addition of a billet side plate.

Just FYI.

Erik

Only on stuff with spiral bevel & tooth profile as per drawing: eg 901-915-930 etc.. G50 with hypoid wont 'like' high loads in reverse rotation & cannot be 'flipped' as this would require that the axle shafts be repositioned [ if even possible ] or a dedicated reverse rotation/cut R&P set made, this probably why we never saw a ZFQ made that would have suited the original Pantera application.

 

[flatchat(Chris)]

Finish machined at last

 

[Randy V]

Looks like a big chunk of expensive jewelry!

Nicely done Chris!

 

[Jacob van Gelder]

Any more photo's of that piece? Id love to add that to my wallpaper collection