I thought that my rear end was a 3.9 rear end, but I was wrong. According to mazdatrix it's a 4.1..... So I bought this 4.3 ring and pinion. Besides worse gas mileage, what is this gonna be like?

Thanks,

Albert

 

probly a not too much of a differnce in fuel milage becasue its only 2 tenths of a rotation differnce

and prolly a little noticable accelication gain to go with it.

 

Like gear grinder stated a little quicker acceleration and slightly lower gas mileage. If you want to maximize the potential of the 4.33 you could get a GTUs transmission. The gearing in that transmission is slightly different.

 

There is about a 200-300 rpm difference at 70mph between the 3.9 and the 4.3, so the difference should be about half that.

 

.2 / 4.3 ~= 5%. You'll have about 5% more torque in 1st gear, but you'll shift 5% sooner so after that point the gains are less. Assuming a 0-30 of about 2 seconds for a stock or mildly upgraded TII and assuming most of the gains are in that range you'd be shaving off 0.1 seconds from your 0-30 and 0-60 times.

Likewise I'd expect less than 1 mpg lost and only on the freeway.

 

GTUs has the same gearset as all S5 N/A engines with the exception of 5th gear, and believe it or not its actually lowerd gear, were you'd think it would be taller to keep mileage the same because the lower final drive, but its not, its lower so 5th gear on highway speeds RPM will be higher due to the lower 5th gear AND lower final drive. AGAIN, 1st through 4th are the same ratios as all S5 N/a's.

And yes, what everyone else has said, there would be noticable acceleration in the lower gears and slightly better pull at highway speeds at the cost of slight worse gas mileage due to high engine RPM's.

~Mike..............

 

hmm.
I got a 4.3 rear end, and a S5 turbo trans
at 3k rpm on 5th I am at 65mph o_O
i thought it would be around 70mph or so

I tested it with gps and the traffic mph signs and its definitly around 65mph.
I was so used to 3k rpm at around 75-80mph
I will quadruple check again this weekend.

 

he is right i do love the extra take off at lower rpm and how i can shift at 2 grand and still pull up hills. my set up is a s5 gtu transmission with a s5 gtu na diff with my s4 drive shaft and engine. oh and highways will kill my fuel mileageif i try to keep up with traffic or i get ran off the road for going too slow

 

The difference between my S4 GXL and my buddie's S5 GTUs is ******* amazing.

However, I also have more weight and he has the VDI... None the less, I think the gearing makes a big difference.

 

Just to add, the GTU-s has a fifth gear ratio .76. There is about 300 RPM difference at 60MPH.

 

That is quite possibly one of the dumbest thing I have ever read on this forum.