I finaly found my sample 2nd gear that we used for the proverbial quick shift to 2nd...
I removed the material by spark errotion method..Lightened the assy by about 30% only--And I removed a lot of material.
The strength and integrity of the gear was paramount in the amount of material removed.It had to be super reliable and this was done on some computor annalysis at Denel (Militery aircraft manufacturer) by a friend of mine.Any more material removal was deemed unreliable...
Barry
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French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
Thought I would make the pix background more interesting as well......
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French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
how much do you expect this work to cost? for example, if the box was out and the gears stripped for synchros, would this really be "prohibitively expensive" or merely an incremental expense?
for street or even track work, the stock gears are bigger (heavier) than you need right?
why this method of machining? would not high speed machining further work harden the steel?
edit: ah, never mind... i actually read your post !
CAD huh? so i guess this machine controlled the spark machine with the gear the electrolyte?
damn nice baz, i didn't know tinkering with the alfas got this advanced..
Barry, from past excercises by others, we learned that there are additional benefits to be had by doing all 5 forward gears, as well as reverse, because they are all always spinning...
Overall reduction of the rotating mass seems like the way to go. Any reason you only did 2nd (while you had them all in your hands?)
Andy Garcia in Houston is doing the machine work for Jes and I.
Someone asked the question of money; here in suck-dollar land plan on about 2K to 2200 USD by the time you replace all 5 syncros, install a mild race clutch, lighten the REAR flywheel as well and have that whole unit balanced, replace some of the syncro sleeves, and replace the LSD friction plates plus add two more plates for the 48-50% lock-up...
I stripped them down to gear bundles and then Andy back-cuts and drills. He sends them out to shot-peene. The actual gear work is less than 500 USD.
What advantages to spark-erosion process? Shot-peening required?
...to Alfa, or not to Alfa? That is the question...
junglejustice wrote:
I stripped them down to gear bundles and then Andy back-cuts and drills. He sends them out to shot-peene. The actual gear work is less than 500 USD.
What advantages to spark-erosion process? Shot-peening required?
500 US? brillant, thanks. Thats not too bad at all... and thats how i expected it to be done..
AFAIK (not much) The spark-erosion process substracts small amounts of metal in an electrolyte (using the conductive sample as the cathode), its accurate as you can tell by the CAD process and it doesn't affect the metal structure any.
I dont think you'll be work hardening it afterwards, because the gears themselves take the brunt of the abuse, rather than the hollowed out section... (wouldn't wanna make it brittle, heh) I'm sure Baz can provide the juicy details !
Joey,The method of lightening the gears was accuracy and My mate did them at no cost for me.Try cutting these things on a conventional lathe-sparks and grinding with very little progress.I must also admit that we tried on a donkey lathe with probably not too great cutting tools-Im sure it can be done correctly.
John,It makes sense as to what your saying about doing all 6 gears-never looked at it from this perspective before-When you say Andy is drilling them,explain please-Is he drilling right through or just plunging into the gear?
As for spark eroding,it was available at the time so I used the method.No ,we never shotpeened them as the finnish was good and the core of the gear is actually quite soft-These were obvously only case hardened .A good friend of mine at Sanvik reckons this is the only process that thoughens the gear as well as makes them hard wearing.Makes sense,huh?
Mats,thanks,you cannot believe how I thought about the spelling of erosion......Crazy.......
John,when are you back in S.A.?
Barry
French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
I'm on a stand-by flight tonight - call you from Dawie's...
Edit... could not get on - trying again manana...
By “drill”, I mean cross-drill... Some of the gears get pretty small and hard to work with on the bench, so some drilling, some back-cutting and some – both!
Yeah Joey - Maybe now I'll stop my bitching... This TA box work aught to do it for me now...
I love these freakin' cars - since I was a kid.... My first car was an Alfetta sedan! I have had a Ford Capri (the real one - in SA), I have had Golfs, 320, 323, 325, 728, 735- 5 Speed!!!, 300 ZX, Nitrous Q45, Audi S8 recently, I mean - all kinds of shit! Still I keep coming back! I love my Alfas...
Barry, can you setup a piss-up for Saturday night? Maybe invite some other Alfa guys over from the Pretoria/Jo'burg-areas...?
Anybody else from here free say Friday or Saturday night?
...to Alfa, or not to Alfa? That is the question...
When I have my gears lightened with traditional high speed machining and drilling, will I need to have any hardening work done afterward?
I thought that the outer gear surface was hardened and that the parts that would be subject to metal removal (inner area) were softer unhardened steel. Am I incorrect? What do I need to do other than have the gears lightened by the machinist?
zambon wrote:When I have my gears lightened with traditional high speed machining and drilling, will I need to have any hardening work done afterward?
I thought that the outer gear surface was hardened and that the parts that would be subject to metal removal (inner area) were softer unhardened steel. Am I incorrect? What do I need to do other than have the gears lightened by the machinist?
You are correct.
Shot peening is also form of light surface hardening only without applying heat.
Banned.. ? Daily donky.. ==> BMW 325d
E36M3 (3.0) Ringtool ==> definitely BANNED!
AR 75 TS Ringtool '90, AR Spider 2000 veloce '79
Its not surface hardening but "compacting" so that it is very difficult for cracks to start and propagate. When reference is made to shot peening, specs vary according to type of part, metal type and finish required. There are variables like shot gauge (size), speed, angle and duration.
Jim K.
I finaly found my sample 2nd gear that we used for the proverbial quick shift to 2nd...
Daily donky.. ==> BMW 325d 
==> definitely BANNED! 
wrong choise of words, should have said: cold deforming of the surface. The introduced compressive stress increases resistance to fatigue. 
