Manual and diff gears NA6

[The Monty]

What is a good choice for diff gears for the manual AU 6's? I do a bit of both highway and town driving, but dont mind it revving a little high on the highway. My auto with 3.9's sat at 2150, and that was fine, so what does a manual with 4.11's sit at? Around the 2500 mark?

[XR6 Colin]

2300rpm

[bartsau]

My Wagon sits on around 2350 at 100km/hr with 3.9's. And just under 2500 at 110km/hr

[The Monty]

So around 2450 at 100 and 2600 at 110km/h. Ok thanks. and how does it drive with diff gears and manual?

[XR6 Colin]

Just do it Josh!

You know about the 3" now believe in the 4.10's !!

[bartsau]

Manual plus the diff gears are the best mods so far to the wagon. Gets things going real quickly

[AU Mont]

i wouldnt go higher than 3.73's behind the T5

[The Monty]

Ok, what have you got behind your Manual AU 6, and why would you not go higher than 3.7? The car is to be used for drags....

[AU Mont]

Originally Posted by The Monty

Ok, what have you got behind your Manual AU 6, and why would you not go higher than 3.7? The car is to be used for drags....

my older falcon had 3.73 behind an EA t5 and it was a pig to drive, and although felt "seat of the pants" quicker, it wasnt....... the ratios were too short

i beleive 3.9's would have similar overall gearing when used with the world class T5

therefore i would recomend 3.45 behind EA-EBI T5, and 3.73's behind EBII-AU

(not sure what ratio is in the BA's?)

[bartsau]

Nothing wrong with 3.9's behind an au with a t5. I have taken the wagon to the drags with this and before hand with a 3.45. I wouldn't go back and the times don't lie. In particular the 60ft time dipping below 2seconds with 16"street tyres. Yes first sometimes seems a touch short on the road but after 12months I still would never go back. I know I cross the line in 4th gear but not too sure on the revs.

[AU Mont]

Originally Posted by bartsau

Nothing wrong with 3.9's behind an au with a t5. I have taken the wagon to the drags with this and before hand with a 3.45. I wouldn't go back and the times don't lie.

i just read your build thread, love the manual wags, very nice!!

i had a look at the times you posted though and from what i gathered you went from 15.0 with factory LSD and 3.45's to a 14.85 with a full diff rebuild including 3.9's and tru-trac LSD

15 hundreths of a second is a slight improvement, but at the same time plenty of other things couldve been a factor such as track/ambient temp, driver skill etc

it doesnt matter though, because it looks like the o.p. had made his mind up when he started the thread anyway

[FreddyDUZ747]

You want the gear ratio that will see you at about 5600-5800 imo when crossing the line in 4th,what this ratio is will be to hard to guess without tire size,weight,cam selection etc.

[The Monty]

I had 3.9's in the auto, seemed to long still, need something like 4.3's. The cam I will be using will be allowing me to set the "redline" at around 6400rpm (maybe a little higher if it feels like it). The cam will need short gears to get going, as it is rather lacking down low.

[FreddyDUZ747]

Think you have answered your own question in last post.4.11's it is

[The Monty]

I may have a diff lined up already, I think it will suit my needs admiraly. But its LSD, and I dont have a great history with LSD's...

[Sox]

I had 3.7's in a 5spd XLS ute with a DEV5 cam, headers/exhaust, went like the clappers, but it was a multi purpose car.

For drags only 4.11 should be fine, but if used a lot on the highway could be a bit of a pain and maybe a little thirsty.

[The Monty]

The diff I may be getting is 3.9's. Im sure it will do admirably.

[The Monty]

Yeah, mind is made up. Its a bit of a dud thread, as you guys dont know the cam I am using, I have used it before in an auto, and trust me, it will need very short diff gears. 1st gear wont be too short when it gets spun to 6500rpm....