ALFAGTV6.COM

I decided to get all my gearboxes together and strip them to make two good spare ones for the new season. The more I checked clearences and tolreances the worse things looked. Firstly I have never done this before but I have all the factory books and family to help out at any time .
I have started with a new LS unit to go into an origional GTV6 box but the crown wheel(from standard GTV 6) will not go over the new LS unit as the dims are totally different. My worn LS unit which I have had for years matches up prefectly in all dims.
Can anyone tell me(if they have an open box) if there diferential units matches these sizes, even internal crown wheel diameter will help.I will post pics but last pic might be to large.

Spiggot on My GTV6 standard diff 109.95mm
Crown wheel internal diameter 110mm(which is perfect machining 0.05 tolerance)
My PCD on bolts is 130mm.

My new LS spiggot size is 114.11mm. and PCD is 130mm. Hence will not fit. Have I got the incorrect new unit OR are GTV 6 in South Africa different which I find hard to believe as all boxes were imported when the cars were assembled here.

Anyone, anyone ?

Not sure if this pic will open. Spiggot diameter.

Both the units in the last pic are unknown to me, are you sdaying they came out of an alfetta-style gearbox?

The middle one on the second pic looks like the LSD units I've been working with.

The middle one in the second pic has just come out the box that I stripped the pinion gear(intergranular oxidation in the root of pinion teeth- discuss in other thread). Its nearly identical to the one on the left thats just come out my GTV 6 box. Only difference is the bearing goes further down the shaft so i would need to shim only a 1m. But they are both very different to the new one I have just purchased.
Just looking for some confirmation dimensions at this stage.

Maybe from a Sei diff? these are bigger.

The bearing span is the thing that tells me it's not an Alfetta diff, all the cases I've seen have the same span and all the crown wheels I've seen have the same pilot (but different thickness).

I was looking through my stored manuals, because I need to rebuild a gearbox for my track day TS and never stripped a box before.
And I heave not made up my mind what box to use as a base: 1.8 (and LSD it) or rebuild a TS lsd box.

And look what I found: there are three different types used

i believe the 1600 diffs are different. i've read somewhere that if you want to make a LSD into a 1.6 gearbox you need to make a big shim to fit between the diff itself and the crownwheel.

that would also explain the three diffs Maurizio found... the LSD used in the TS, V6 and Tb/ the open diff as used in the 1.6 / the open diff as used in the other models without LSD.

I think you read it here, I have an unfinished thread where I start to explain how to convert to LS.

My 1.6 box was identical to the other non-LSD boxes though. The thing is that the unknown diff above looks like an LSD unit too...

Sorry Mats, i believe it was on the Dutch forum.. a guy over here build a 1.6 LSD box for his giulietta racecar.

I've seen more cars with LSD's that shouldn't heve had them .. in some cars it was a factory option apparently. maybe your diff is a factory option diff and as such different as the original LSD?

Ok, Here's the link to the discussion in case someone is interested.
Click Me

Realize now I never got around to "Part 2".

Ok, finally discovered that the LS unit I was sent was not from the 116 series but the 105 series. As i have lttle experience with the 105 series unit(2000gtv) I did not recognise it. A new LS is been made for me at ther moment but it will be to late for my first race this month. At least the problem has been sorted out proffessionally with out delay from manufacturers.

Maurizio. To choose which diff to use you should know the rpm limit you want to use. Tire size of course. And then the power you have to determine the speed. I'd say if you don't want to rev high a TS box should be fairly OK on the ring.

Micke, what box (ratio) would you use with 7000rpm limit, 290hp, 205/50/15 on short twisty circuit racing where max speed is 160km and min is 40km(only on one hairpin) . Also taking into consideration which boxes have the stronger pinions(thicker teeth). Also car is a bit sluggish off the cam below 4000rpm.

Kevin,
With that much power I would add more tire - maybe try 225. Short of making a close ratio box, I would use a "Platinum box" and LSD: 2.88 1.72 1.23 0.95 0.78 with 4.1 ring & pinion. I think this is the same as 75 TS gear ratios and ring & pinion.
Jes