3speed to 4speed?? is it worth it?

[fc_special]

Hi everyone...driving to the city the other day i felt like the 138 needed a fourth gear..Will i lose alot of value to the car if i put a 4speed gearbox in??.The gearshift is already on the floor...i have been told a toyota 4 speed would suit best is this right??

[robbzfc58]

hi there   im no expert so my opinion may be worth nothing..but the ratio in top gear on 3 or 4 speed is the same..so nothing would be gained if you were looking  for taller gearing.   if you went to 5 speed toyota ,you'd have the ultimate but you would rarely use 5th gear because its an overdrive..the car would struggle on hills.     personally  i think the phillipino 4sp boxes from uc toranas & early commodores(4&6 cylinder cars had same box) are  nicer than the aussiebox& cheaper..my boys have thrashed em & never killed em!! but top gear ratio is still the same
 to fit a toyota 4 or 5 spd would be fairly costly          so  i suggest ya leave it as it is unless you need to replace it for mechanical reasons
          cheers trev

[nicko]

why not change to a taller diff ratio,that way you dont need any mods

[oldgmh]

The standard ratio is 3.89.  
You could try a 3.55 or a 3.36 from later models.  
They will fit into the existing diff housing okay but the standard grey might not have enough grunt - depends on your driving requirements.

[RET]

An otherwise stock grey runs great with a 3.55 diff.  I know blokes who have run a grey with a 3.36 but personally I think that's going a bit too far.

cheers
RET

[EJ_Dave]

I have run both 3.36 and 3.55s behing my stock grey and I'd agree with RET that the 3.55 is the best option. 3.36 is just a little bit too tall down low and at cruising speeds you don't really notice the difference.

David

[EJ_Dave]

Forgot to mention that I started with a 3.89.

Some useful numbers to consider. 3.55 is 10% taller than 3.89, 3.36 is 15%. This extra 5% is just pushing it over the edge- you always need to work to get the car up to speed. You don't feel this with 3.55 but you can hang on to 1st for longer. With the 3.89 I always felt that you'd  only just be rolling and you'd have to change up.

David

[Nick Athans]

thanks heaps guys..i was never interested in cars untill i bought my FC last month..now between the manual and work mates ive learnt heaps....much appreciated...Nick.A