G50/50 -- changing 5th gear - what does it 'take'?

[Craig 930 RS]

Currently I hit redline at the track with the 5th I have in the G50/50. Nothing like a rev limiter cutout in mid-turn

What is involved in changing 5th gear in a G50/50 transmission?

Thanks in advance - !

[911teo]

U talked to Paul Guard? Geary on this board

1 530 878 4499

[don911]

What turn are you hitting the limiter in 5th gear? If we're ever at the track same day, remind me that I really don't want a ride in your car.

[Craig 930 RS]

Turn 1........ "the turn that kills" ;-)
Right around 150 I have to glance at the tach.
---------
Just spoke with Paul - it is a pretty easy job - have to take out the transmission, and 5th and reverse come out together. About $695 for the pari of gears.

[Bill Verburg]

Be careful, a change in one gear will lead to an avalanche of others to keep the splits in line.

[Craig 930 RS]

Luckily the 4th to 5th split is shorter than the rest and lends itself to a higher gear -

[Bill Verburg]

Here're your stock splits as a %
43% 29% 24% 22%

You want the % to decrease as you go up through the gears. If 5th is made much taller it increases the %

You have a ton of torque so can handle bigger splits than a n/a engine but there is still a limit.

a good n/a box might look like this
50% 21% 14% 11%

[Craig 930 RS]

Bill -

What should I use for a new 5th?
Looking for another 15-25 mph or so:

[Bill Verburg]

The trans has already been regeared according to that chart.
If it is correct your 5 is the stock 4. That would be the source of your problem.

what tire height and rev limit are you using?

[Terrh]

Perhaps changing the final drive ratio would be a better (easier) process?

[Bruce M.]

Yeah, hitting the rev limiter in a stock G50/50 shouldn't happen at 150. That's a tall gear, stock.

150 at turn 1 is smokin' pretty good, I'll give you that.

[Bill Verburg]

Here's the splits w/ that box

 g50.50			41	35	30	40	29

modified short		13	17	19	33	30

			3.15	2.06	1.58	1.21	0.97

		3.444	10.86	7.09	5.44	4.17	3.33

split %			35%	23%	23%	20%

speed @6800		47	73	95	124	155

the above is w/ a ~25.7" rear tire, taller gives you a couple of mph in each gear

[Craig 930 RS]

Does this help - a better view of the charts?

[Bill Verburg]

Does this help - a better view of the charts?

No, that is the information I used in my last post

here is what a stock G50/50 looks like

g50.50			41	34	33	29	31

			13	19	26	30	41

			3.154	1.789	1.269	0.967	0.756

		3.444	10.862	6.163	4.371	3.329	2.604

split %				43%	29%	24%	22%

speed @6800		47	84	118	155	199

[Craig 930 RS]

Right, giving a closer view in case it was hard to read.
So Bill, what would you use for 5th gear?

[Bill Verburg]

Craig, that's not going to be as easy as swapping out 5th

If you only change 5th to something like 24:29(0.89) 170mph top speed then the split to 5th becomes 27% w/ an rpm drop of ~1800. That's pretty ugly

So then you need to redo 4, w/ the same result etc. etc.

As I said a cascade of gears is needed.

I would probably want the factory w/ a little shorter 3,4,5

I started to fiddle w/ some gear charts but another out side project is needing my attention. I'll continue later.

[Craig 930 RS]

Currently, the RPM drop from 4th to 5th is 1,372 -- subjectively it could really stand about a 500 increase.

Thinking out loud:
So with the Turbo I'd shift at 6,300, dropping the rpm to 4,500 instead of 5,000 at the 5th gear change with the 24/29 set.

Appreciate the number work, Bill. I'm a neophyte with gearing.

[Craig 930 RS]

She's still pretty healthy at 4,500...added this for reference

[Bill Verburg]

Gears are almost the only thing I've been thinking about all winter

I've got gears coming out my ears

Ok, so if I run some #s, 6300 rpm shift point? either the height or revs/ mile(better) is also needed. I've been using 6800 and 25.7" tire

[Bill Verburg]

Oh and the max rpm drop you would be comfortable w/

from the dyno charts I would say 1000rpm