Guys,

Just noticed this on the RPW 380 page:

RPW also has available for manuel models, a differential drive gear upgrade to reduce the rpm per km ratio by 500 rpm. Quite simply, in all gears, for the same speed, rpm levels would drop by 500 rpm to improve fuel economy. The engine is a very torquey engine and there is no reason to have it revving at 3000 rpm at 100km/hr like factory. This is a direct bolt in and only requires a speed drive gear change to recalibrate the speedo.

(Never mind that they can't spell 'manual' and 3000 rpm in 5th gear = 112 km/h, not 100 km/h).

That's probably the one gripe I have with my manual 380, the fact that it's doing a few too many revs for my liking at country road cruising speeds, and as a result the fuel consumption could be better. It's a function of the short final drive ratio and relatively short 5th gear ratio in manual 380s. Would also be nice if second & third gears wound out a little further, and this might just do the trick.

I searched the RPW site and couldn't find any more details about it.

Has anyone had this fitted?

Any idea on price?

Can any competent mechanic fit it?

KJ.

its RPW i wouldnt expect anything good about them being heard from amc

If my memory is correct they are talking about replacing the 380's 4.11 Diff ratio with the 3.7 magna 3.5L manual diff ratio

wouldnt that also put your speedo all out of whack?

wouldnt that also put your speedo all out of whack?

Thats why you also change the small speedo "drive gear" as well (use a magna one)

I would be very interested in this too!!

What warranty implications do you think there would be?

I mentioned this a while ago when I was trying to get a Quaife LSD for my auto.

If you're gonna go to all that trouble to break your gearbox open & play with the diff ratio you may as well get the LSD fitted at the same time. :woot:

I mentioned this a while ago when I was trying to get a Quaife LSD for my auto.

If you're gonna go to all that trouble to break your gearbox open & play with the diff ratio you may as well get the LSD fitted at the same time. :woot:

Totally agree with your statement. Do it once do it right ;)

Err wouldn't this be the opposite of a performance mod? I suppose with a supercharger it wouldn't matter a whole lot.

You kind of have to wonder why they made the ratios as they did though

Err wouldn't this be the opposite of a performance mod? I suppose with a supercharger it wouldn't matter a whole lot.

You kind of have to wonder why they made the ratios as they did though

I believe it was to make the illusion of the car actually going a lot harder than the auto so they could sell them easier.

I believe it was to make the illusion of the car actually going a lot harder than the auto so they could sell them easier.

Job well done then. :iough:

Emailed RPW with a query a couple of days ago and got this reply just now:

"This replaces the differential crownwheel which is what dictates your overall gear ratio. Easy to fit, this basically gives the vehicle "Longer legs" in each gear.
You would need to remove the gearbox, pull the differential and crownwheel out, and then fit the differential to the new crownwheel.

Pricing is around $750.00 for the kit"

Sounds like $500 minimum labour cost, so at least $1250 all up.

Bit exxy for my liking, might look around for a late model Magna manual trans crownwheel & speedo drive gear and ask my fave mechanic what he could do it for.

KJ.

Emailed RPW with a query a couple of days ago and got this reply just now:

"This replaces the differential crownwheel which is what dictates your overall gear ratio. Easy to fit, this basically gives the vehicle "Longer legs" in each gear.
You would need to remove the gearbox, pull the differential and crownwheel out, and then fit the differential to the new crownwheel.

Pricing is around $750.00 for the kit"

Sounds like $500 minimum labour cost, so at least $1250 all up.

Bit exxy for my liking, might look around for a late model Magna manual trans crownwheel & speedo drive gear and ask my fave mechanic what he could do it for.

KJ.

The kit probably includes the diff bearings & speedo drive gear. Why don't you see if they will do you a deal on the Quaife LSD, crown wheel, bearings & speedo gear fitted ready to drop in. It will improve your launch & drive out of corners especially if you're thinking of sticking a bit more power through the wheels.