Ratios for IRS Gearboxes - T1 & T3

Grey 57 · 2005-06-08T21:28:15+00:00

Trying to understand what the ratios are for the IRS Gearboxes for T1 & T3 are. Do they all have the same final drive ratio? I have a IRS box with a yellow paint mark on it, Does this give some info about what ratios it has inside? What is the tallest final drive ratio available, that would fit inside this box? Thanx

Grey 57 Old Grey Cruiser

2,937 posts · joined Aug 2002 · 9 Jun 2005, 10:27 pm

#369920

So Steve do you think the 3.88 wouldnt survive attached to this motor?

Just read the post properly Steve. weak 4th gear, not R & P.

[Edited on 9-6-2005 by Grey 57]

Grey 57 Old Grey Cruiser

2,937 posts · joined Aug 2002 · 9 Jun 2005, 11:10 pm

#369947

Using the calculator that Steve posted a good combo for me might be

3.88 R & P
1st gear - 3.78
2nd gear - 2.06
3rd gear - 1.26
4th gear - 0.77 = 116kph at 3000 rpm
Albins 4th gear

Cheers Astro and Steve for your help

[Edited on 9-6-2005 by Grey 57]

[Edited on 9-6-2005 by Grey 57]

[Edited on 9-6-2005 by Grey 57]

Gracey Wolfsburg Wizard

511 posts · joined Feb 2003 · 10 Jun 2005, 9:45 am

#370064

Grey 57 wrote:Gracey, mine is a 2.4 MFI out of a 72 911T. The mild one. 157 SAE horses (or 140 DIN hp)

Cool, that should have plenty of torque to pull tall gearing.

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 · 10 Jun 2005, 9:55 am

#370072

Hi

It might be a good idea to look at the factory gearing for that motor, 5 speeds is pricey but if you could start off with a 1st the same and 4th the same as the Porsche 5th and fill in in the middle with 2nd & 3rd.

Steve