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-   -   4.08 Frontier gear swap (http://www.the370z.com/engine-drivetrain/18209-4-08-frontier-gear-swap.html)

kevin8086 12-25-2010 04:23 PM

Quote:

Originally Posted by Solus (Post 802740)
Do you know off hand what kind of RPM increase you saw at highway speeds? say 70-80 mph?

i would like to know this too. also would you say this is the most noticeable mod you have done to the car for the price.

Junior370z 12-25-2010 05:18 PM

Are you planning on getting some runs in on the dyno? Interested on the numbers the gear change makes. I guess if you didn't dyno before the change you'll have nothing to compare.

seungklee 12-28-2010 12:25 AM

I hear if you change the final gear it effects gas mileage, is this true? I think I got this from Z1 website. Correct me if I am wrong please.

CBRich 12-28-2010 12:31 AM

Definitely true. If your car is always running at higher RPM to make the same speed then you will use more gas.

esfourteen 12-28-2010 02:06 PM

Quote:

Originally Posted by Junior370z (Post 866378)
Are you planning on getting some runs in on the dyno? Interested on the numbers the gear change makes. I guess if you didn't dyno before the change you'll have nothing to compare.

The car wont make any more power on a dyno, changing the final drive changes how the car accelerates. A 3.69 (stock final drive ratio) the transmission output turns 3.69 times to turn the wheels 1 full revolution. By using a shorter gear in the final drive, like the 4.08, the transmission must now turn 4.08 times to turn the wheel one full revolution. Basically this allows the engine to accelerate quicker because it requires less effort to turn the wheels, but you won't be going as fast.

For example, if your stock gearing is at 40mph at the top of 1st gear, using a shorter gear would be at say 30mph, but it would get to 30 faster than the taller gear will hit 30mph. I just made those numbers up for the example, but I hope that makes sense.

The net result is quicker acceleration at the cost of some top speed and fuel economy. I believe someone with the 4.08 gears (jnaut maybe) said he was still able to hit 160mph, so the loss in top speed isn't noticeable without forced induction and a death wish.

Junior370z 12-29-2010 07:42 AM

Quote:

Originally Posted by esfourteen (Post 869087)
The car wont make any more power on a dyno, changing the final drive changes how the car accelerates. A 3.69 (stock final drive ratio) the transmission output turns 3.69 times to turn the wheels 1 full revolution. By using a shorter gear in the final drive, like the 4.08, the transmission must now turn 4.08 times to turn the wheel one full revolution. Basically this allows the engine to accelerate quicker because it requires less effort to turn the wheels, but you won't be going as fast.

For example, if your stock gearing is at 40mph at the top of 1st gear, using a shorter gear would be at say 30mph, but it would get to 30 faster than the taller gear will hit 30mph. I just made those numbers up for the example, but I hope that makes sense.

The net result is quicker acceleration at the cost of some top speed and fuel economy. I believe someone with the 4.08 gears (jnaut maybe) said he was still able to hit 160mph, so the loss in top speed isn't noticeable without forced induction and a death wish.

Cool! Thanks for clearing that up!:tup:

dasoupdude 01-20-2011 08:19 PM

Did you ever use one of those dial tools when installing the ring gear?

apologies for rasing the dead btw.

oh and jason i sent you a pm

jnaut 01-20-2011 08:52 PM

got it:tup:

Torgant 01-21-2011 07:45 AM

Quote:

Originally Posted by jnaut (Post 530082)
all done....tomorrrow ill post all part numbers of everything you will need to do this.as for the srm works perfectly except its off about 2 to 3 hundred rpm but it is very close. cruise control works perfect. no ssues at all. it is deff not to radical of a gear, sooo much better acceleration down low in the rpms where we have no tq.

Is SRM still working??

jnaut 01-22-2011 07:10 PM

Quote:

Originally Posted by Torgant (Post 905298)
Is SRM still working??

yes... just fine. the only issue at all is after random top end pulls( 130mph or faster) it does shut the srm down. this has only happen about 3 to 4 times. after i restart the cars all is fine then.

Red__Zed 01-23-2011 06:09 PM

If I didnt do so much highway driving this would be a ^no brainer

jnaut 01-23-2011 06:41 PM

Quote:

Originally Posted by Red__Zed (Post 908449)
If I didnt do so much highway driving this would be a ^no brainer

"normal" highway drive no issues at all.

Red__Zed 01-23-2011 06:59 PM

Quote:

Originally Posted by jnaut (Post 908478)
"normal" highway drive no issues at all.

Eh, I don't think it would be a huge problem, but it gets annoying on long trips.

I had the stock 4.10s in my s, and switched to a 4.44, and eventually down to a 3.90 final drive. I love the pull of an aggressiv fd, but when I am making long highway drives, it's just not worth it.

dasoupdude 01-24-2011 06:35 PM

Quote:

Originally Posted by Red__Zed (Post 908500)
I love the pull of an aggressiv fd, but when I am making long highway drives, it's just not worth it.

brace yourselves for epic gas prices again..:ughdance:

chuckd05 01-26-2011 12:09 AM

My z went down about an average of .7 on gas mileage from what I noticed... I can still get 25+ on the highway if I keep it around 70mph though...


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