Gearboxes - Oh Not again but.....Please add your experience!

[brdee]

Having trawled the forum for what is the most appropriate gearbox for the Ultima build, we seem to have many different opinions. What is more important I believe, is actual experience (ie you guys that have actually used them!).

It appears there are 4 main contenders:

1. G50/02 - 5 speed
2. G50/20 - 6 speed
3. G50/50 - 5 speed
4. G50/52 - 5 speed
5. The 6 speed Getrag with Cable change (don't know if there sre different versions?)

There has been several threads/converstaions and differing opinions regarding gearing in that:

1. The factory insist that the good old G50/02 5 speed is fine overall, is strong enough etc

2. The G50/20 is hard to find but I am told 6 speed is almost counterproductive as the engine is so long-legged.

2. Some have suggested (mainly our american bretheren) that the G50/50 or 52 is better (although hard to find) since it is taller geared and strongest and it seems that many of the performance gearbox specialists use this for their conversions.

3. The Getrag seems to be a bit of a misnomer in that although it is an attractive proposition (cable change) I am told they are nigh impossible to repair or work on, that they are not as well built, That 6 speed again is unnecessary.

For us still looking at what to get (I am looking to build an LS2 derivative of the Ultima around 500bhp free revving) it would be extremely helpful if we could get a concesus from those who really KNOW - cos it confuses the hell out of me!....and I would hate to get it wrong!

[peterpsg]

I have a G50/21 6 Speed.

1st gear is pretty well useless at the lights, though I use it frequently for car parking & the like.

I need to check my speedo calibration, but I was getting ~70mph at ~2500-2700rpm ish last night in 6th gear (There's a previous post with the ratios).

I'll be able to tell you what top speed I got to once I have it on the runway on Sunday, and as I have a shade over 500bhp, it will give you a good indication of what your car will do.

I had an LSD (Quaife) put in my box, which added an extra £1k to the price tag, but my early impression is that it is money very well spent.

[steve_d]

I have the G50/20 6 speed. 6 speed is not required because of the torque on tap. I tend to go up the box 2 at a time.

I believe from what I have read/heard that the G50/52 is best as it has a physically larger diff for extra strength. An LSD version would be the icing on the cake.

Steve

[luckyp]

I have G50/03 5 speed from Factory. Can't tell you what it's like yet.....but once the wheels fall off the stock market, I'm stockpiling G50s!!! He-he!

Lucky

[BigMack]

My vote is for a 5-speed G50/03 with 500hp which is my setup. The G50/50's hold up better with higher torque applications but are somewhat hard to find.
Cheers!
-Mack

[Dr Peter]

I have a G50/21 6 Speed.
After driving cars with out LSD it was a must for me, much more fun.
If 1st is no good, can you change the gearing?

[brdee]

Anyone with experiences with the Getrag versions (and which one they all can't be the same?)

Keith

[usagtrman]

I HAD a G50-03 5 speed LSD box. I HAVE a G50-20 6 speed LSD and like it much better. The ratio's are quite similar 1-5 but with the 50-20 you have the 6th cog for a lower cruise rpm and higher top end. I agree with what was said about 1st being too low but my 50-03 was the same. I do use 1st for maximum acceleration effect but most starts are 2nd gear affairs. Regarding the strength of these boxes, I believe GMAN has a 50-20 in his car and doubt many have had a rougher life than his and apparently no problems. All in all for my type of driving the 50-20 is perfect.

Brad Z

[andygtt]

Regarding the Getrags, there are two very different versions that I am aware of.

One uses a completely differnet stud pattern to the G50 and is the one that is reputed to be not repairable.
The other is basically a re-cased large diff 6 speed G50 that is cable shift and fitted to the GT's and twin turbo only... but very rare and pricy.

The major benefit of the Getrags is the cable shift gearchange which is sweet.

[G Man]

I run a G50-21 6 speed, with 685BHP 377 ci engine, what I would say is the gearbox is perfect for that engine, Steve_d is right, the chevy has so much torque and so little weight to push 4 gears would be enough, but what engine are you going to use, what is you rev range, a G50-21 will allow an Ultima to hit 204 mph if you rev to 7600 without regearing. So match your engine and gearbox, if you have a 350 or 377 ci rev engine, a 6 speed is for you, if you are going for a 383/427 torquey type then a 5 speed G50/02 is what you want in the ideal scenerio, although I don't think for 98% of the time it will matter