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M factory final drives, practicality?

Posted: Sat Mar 25, 2017 11:03 pm
by JEBB4
So I'm trying to get an idea of what either the 4.6 or 5.1 m factory final drives actually be like to live with..

Which ever one I buy will most likely be going in an M2A4 box as that is the most common lower ratio box here in Aus and I will also be putting an LSD in too..

i like the idea of the 5.1 but a lot of things I see on the net say even the 4.6 is hard work on a daily basis just for the cruising rpm in 5th..

I know a few people on here have had the 4.6 so what did you think? Would the 5.1 be too much for a daily?

Any input appreciated :)

Posted: Sat Mar 25, 2017 11:13 pm
by Dino
Ive had two 4.64FD boxes.

Although manageable on a day to day, it does push the boundaries of a Daily driveable car IMHO. Personally i wouldnt even consider a 5.1 unless it was a race car.

Posted: Sat Mar 25, 2017 11:28 pm
by RattyMcClelland
As above. Don't even think about a 5.1 on a daily drive.


I have a 4.64 fd and it's the single best mod I have ever done. Better than the supercharger.

However....i also own a 6 speed VW t6. It's my daily drive and I'm used to 6 gears.

On The Prelude I get through the gears quick and when in 5th I go to change to 6th at 50mph..... but wait it's not there. :evil:

At 70mph I'm at 3900rpm iirc. It's fine at those speeds. More annoying of course but as above the limit of a daily drive.


10% increase in wheel torque. Epic difference in acceleration.

Posted: Sun Mar 26, 2017 5:57 pm
by Therealjj91
Yeah I agree with the above, only annoying thing for me is the higher rpm in 5th.

Posted: Mon Mar 27, 2017 10:15 am
by JEBB4
Thanks guys, just as I thought really, 4.6 it is..
Diff wise I take it the m factory helical is the one to go for?

Posted: Mon Mar 27, 2017 10:19 am
by Merlin
Yeah the Torsen (helical) the best daily use diff.


Echoing the other two, the 4.64 is ok to live with but a pain on the motorway. The 4.64 in a M2F5 gives even higher cruising rpm, but stronger 5th gear acceleration. The 5.1 would be too much.

Posted: Mon Mar 27, 2017 10:25 am
by JEBB4
Cool, now I just need to source a box :)
Thinking of doing the gearbox build myself as well..

Anyone on here done it and are there any special tools I need?

Posted: Mon Mar 27, 2017 10:55 am
by Merlin
What box do you want to use?

Posted: Mon Mar 27, 2017 11:18 am
by JEBB4
Merlin wrote:What box do you want to use?
Guna be using an m2a4 (AUDM VTEC manual) I think as it's the most common VTEC h series box over here..

EDIT: Missinformation alert!!!

The native VTEC box here in Australia is actually M2F5 same as uk... M2A4 is JDM VTEC box..

Poop's :facepalm: :suicide: :zip: