Ring & Pinion for a Giulia Sprint GT

Euroalfa73 · #1 (**permalink**) 04-01-2007, 10:23 AM

If I am not mistaken the standard ring & pinion on a Giulia Sprint GT according to the Alfa books is a 41:9 on the non limited slip diff.
Re-Originals and other Alfa suppliers offer a Go Faster Immediately option with their Ring & Pinion, 5:12 ratio 8/41, NOS, 185mm OD, 104mm ID 8 bolt 130mm pattern, which they say is great for 1300,1600 &1750 non limited slip diff.

Will this option that they are offering make a differance in the acceleration in any way, is it worth looking at?????

genericwood · #2 (**permalink**) 04-01-2007, 11:45 AM

A 5.12 rear will definitely improve acceleration, but at a cost. At any given cruising speed, you will be running 12-13% more revs. And at the price of a new 5.12 ring/pinion, there are a lot cheaper ways to gain that same acceleration!

Erik

Alfajay · #3 (**permalink**) 04-01-2007, 01:35 PM

I concurr with genericwood - a 5.12 might be OK for tight tracks, but for street use that includes some highway driving, 5.12 is unworkable, even with an overdrive 5 speed.

I had the stock 5.12 in my 101 Giulia normale for awhile, and really hated it. You could shift from 1st to 2nd at about 2 mph. All other shifts were at equally low speeds, and on the freeway the poor engine was just howling. Even with a relatively stock 1600cc engine, my Giulia just didn't need the additional torque at the wheels - Alfas are so light that the benefits of these "tractor" ratios are unnecessary for all but short track/autocross work. I switched to a 4.56, and even a 4.10 would probably work pretty well.

Keep in mind too that swapping ring & pinions is a big, big job. The alignment of the two gears is set with shims, and has to be 100% correct for the parts to last very long. This generally takes a skilled person, with a good selection of shims a LOT of time (read "expensive time"), because the procedure requires a trial and error. So, figure on spending as much for the setup as the parts will cost. Unless you need to do something exotic, the simplest way to change the final drive ratio is to just install an entire used rear axle assembly that was setup at the factory.