ALFAGTV6.COM

I am in the process of building two ST Class Milanos to run in IRDC / ICSCC here in the Pacific Northwest.

Couple of questions. What ring & pinion ratios aside from the 4.10 and the 3.55 were used in the transaxles? Both cars have 4.10 LSD's, but some of the local BMW racers are going to 4.27 or a 4.56 and are showing a competitive advantage on shorter courses (Pacific Raceways 2.25mi).

I believe Autodelta had a 4.56 ratio, and was wondering what ratio was used in the Milano automatic (terrible idea)?

Next question. Gearsets in the transaxles. Did the early GTV-6 have different gearsets, and is there an optimal combination of gears to mix netting a close ratio set?

Looking forward to your feedback!

Chris

Alfa 75:
1.6 4.5:1
1.8 4.3:1
2.0TS 4.1:1
1.8Tb 3.9:1
3.0v6 3.55:1

The last 3 usually are equipped with a LSD from the factory.
1.6 is quite rare and requires some work to use wit a LSD ( a steel shim needs to be made to fit between the crownwheel and the diff itself).

The 4.3 would be a great upgrade, not too deep of a gear to run out of top end on the shorter circuits.

Did this ratio come with any LSD? Would this ratio swap into a V6 transaxle currently with a 4.10 LSD?

Obviously, here in the States, we only got V6 cars, and are limited to the 4.10 and the 3.55, not knowing what ring & pinion was put into the automatic cars.

Thanks!

Chris

The 4.3 was never used with an LSD. But that can be retrofitted to the box. Not to hard of a job. the stubaxles have the wrong size boltholes but these can be drilled and tapped to accept the v6 halfshafts. the 4.1 LSD should fit, as does the 3.5 one.

The gears themselfs are the same ratios as the v6 box.

Finding a 75 1.8IE box would not be to big a problem in Europe.

You might try Larry at APE.
http://www.apedirect.com/main.htm
(209) 365-1383

Leave a message and they will get back to you if they don't immediatly answer.


They (Larry Jr. really) told me there is some parts swapping that can be done to get the 2-3 gears a little closer together. I didn't go for that because it meant that I needed the newer style speedo bits and i didn't want to spend my money on that.

HTH,

Or try Alfar7@aol.com . Richard Jemison has done a lot of this work.

I wouldn't recommend a GTV6 transaxle. Their gear ratios were different than the Milanos.

GTV6 Transaxle Gearset
1st 3.5 So low to be useless, even with the 3.48 R&P. Good for pulling a plow.
2nd 1.96 Low as well. Lower than the Milanos
3rd 1.26 Third gear is fine, but note the big (BIG) gap between 2nd & 3rd.
4th 0.95 Slight overdrive
5th 0.78 Common GTV6/Milano overdrive.

Verde Transaxle Gearset
1st 2.88 Wow, a 1st gear that is useable, even with a Verde 3.55 R&P !
2nd 1.72 2nd is taller too. Not a problem with a tall R&P. A strong engine can pull this.
3rd 1.23 Ever so slightly taller. Note the significant closure of the gap between 2nd & 3rd.
4th 0.95 No change
5th 0.78 No change.

So the Milano transaxles are the better choise here.

And then there is the Alfetta transaxle....
1st 3.30
2nd 2.00
3rd 1.37 Interesting short 3rd ratio. Richard Jameson (and others) noticed this too.
4th 1.04 Not an overdrive, also shorter. Hmmmm. . . . .
5th 0.83 Shorter overdrive here too. What if . . . ?

Merril

I think Wes on the alfabb was trying something on the order of what you are thinking Merril. He's working on his Lemons car.

I haven't been following the alfagtv6 web site much lately so I don't know if Richard Jemison posts or not.
Sometime in the past I saw combinations he created by mixing in Alfetta and Milano gears.

A short track gearset:
1st 2.00 Alfetta 2nd gear in 1st gear location.
2nd 1.72 Milano 2nd gear
3rd 1.38 Alfetta 3rd gear
4th 1.04 Alfetta 4th gear
5th 0.83 Alfetta 5th gear
R&P 4.10
Looks like a need for plenta of Alfetta gear cogs. I like.

Richard has also produced this:
1st 2.00 Alfetta
2nd 1.72 Milano
3rd 1.23 Milano
4th 1.04 Alfetta
5th 0.95 Alfetta
R&P 3.55 Milano
A taller combination for tracks with higher average speeds ?

Merril

Hello MR2 Zig, would that be Wes Ingram ?

Here are a couple more Mr. Jemison combinations.
Sorry for the short posts, if I type past the initial window the display jumps around.

Richard's Long Track Gearset
1st 2.88 Milano 1st gear
2nd 1.72 Milano 2nd gear
3rd 1.23 Milano 3rd gear
4th 1.04 Alfetta 4th gear
5th 0.95 Alfetta overdrive 5th
R&P 3.42 GTV6 1982-83 R&P !
The top three gears are relatively close together.
Why not a 3.55 ? Maybe tires with a small outside diameter ? Interesting.

And a combination he had on his GT2 car,
1st 1.72 Milano 2nd gear
2nd 1.23 Milano 3rd gear (this is getting interesting)
3rd 0.95 Milano 4th gear
4th 0.83 Alfetta 5th gear
5th 0.78 Milano 5th gear
R&P 4.10
A 4:30 R&P would make this a very interesting close ratio gearset.

I'm seeing that tire OD is a very big factor here.

Sure gets one thinking about the possibilities.
Also dependent on state of tune, i.e. restricted mods or a high strung cammy engine.

Merril

Yes, I think that is Wes Ingram. He was trying for a better short track gearset without spending lots of money. Richard made a few comments, but I don't think the two were communicating well.

Pics from workshop manual - gear ratios

http://i14.tinypic.com/4q88vfa.gif
http://i10.tinypic.com/5zmp25c.gif
http://i16.tinypic.com/66szuko.gif
http://i11.tinypic.com/4ou9ptu.gif

but some of the local BMW racers are going to 4.27 or a 4.56 and are showing a competitive advantage on shorter courses (Pacific Raceways 2.25mi)

Take a note that bmw is using different gear ratio and that influences on final speed, basically to couple with bmw's 4.27 you'll need 4.55 diff from Alfa (approx).

I converted 4.3 open diff gearbox to 4.3 LSD for my v6 24v. All you need is 3mm spacer to align crown to right place (but be careful and check three times before assembling). Click this calculator to see change between 3.55 an 4.3. You can use it to figure out your ideal setup...

Hopefully this isn’t hijacking the thread, but I have a thought regarding gear ratios.

Are we trying to tackle the ratio problem from the wrong direction ? What I’m thinking about is the desire to be in the fat part of the power band when it’s needed most. Like exiting a corner or pulling a hill. It almost seems like one should analyze the tracks they’re driving, the approximate speed (or desired speed) at the point they’ll be exiting a critical corner or climbing a hill, then work backwards from there to come up with the right gear for that condition. Given a track with three or so critical sections, one could conceivably get a selection of gears to make substantial reductions in ones lap times.

I was talking with (need gtv6.org handle here) about leaving Turn 6 and Pacific Raceway outside of Seattle WA. The corner isn’t all that special, but is the beginning of an uphill pull for a substantial distance before the next corner. If one is nearly at the end of the engines rpm range, then a shift is required. Shifting here just when the car needs to be pulling it’s hardest would really slow it down. If one could choose a gear/R&P combination that puts the engine a bit below its peak torque while rounding the corner would set it up nicely for max pull up the hill. Maybe even a good opportunity to pass if the other car has to shift, is lugging in too tall a gear or all rev’d out with no more acceleration in a short gear after exiting the corner.

For example, If the car is rounding the corner at 50mph and the engines peak torque is at 4500rpm I’m thinking that if the engine is at 4000 rpm you’d be pulling the hill right through max torque on up through max horsepower before shifting. There’s probably something about area under the curve on the horsepower/torque chart translating to getting the most work out of one’s engine. But, it’s been 30 years since I took physics and I don’t remember that stuff very well So a 205/50-16 tire with an outside diameter of approximately 24.1” would be pulling something like 4100rpm given a 4.10R&P with Alfetta 1.38 third gear. Not bad for bench racing I’d say.

Follow that up with a close ratio 4th gear to finish the pull and one is doing pretty good with the power they have.

Merril

Woops, (need gtv6.org handle here) should be Fast-Alfa-75

MRG

One thing to keep in mind...

BMW's have often had a 1.00 ratio for 5th gear.

If you are racing E30's or E36, a 4.56 isn't nearly as extreme as it would be for you with a .78 or w/e Milanos come with for 5th gear.