4.08 Frontier gear swap

kevin8086 · 12-25-2010, 05:23 PM

Quote:

Originally Posted by Solus

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, 06:18 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, 01:25 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, 01:31 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, 03:06 PM

Quote:

Originally Posted by Junior370z

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, 08:42 AM

Quote:

Originally Posted by esfourteen

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!

dasoupdude · 01-20-2011, 09:19 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, 09:52 PM

got it

Torgant · 01-21-2011, 08:45 AM

Quote:

Originally Posted by jnaut

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, 08:10 PM

Quote:

Originally Posted by Torgant

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, 07:09 PM

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

jnaut · 01-23-2011, 07:41 PM

Quote:

Originally Posted by Red__Zed

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, 07:59 PM

Quote:

Originally Posted by jnaut

"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, 07:35 PM

Quote:

Originally Posted by Red__Zed

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..

chuckd05 · 01-26-2011, 01:09 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...

12-25-2010, 06:18 PM	#62 (permalink)
Junior370z A True Z Fanatic Join Date: Apr 2009 Location: Las Vegas Age: 50 Posts: 1,024 Drives: over the speed limit Rep Power: 293	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. __________________ DON'T DO IT! ( Click to show/hide ) Stillen CBECAI-U/D PulleyGround KitSwaysSetrab Oil CoolerIchiba Rear Camber KitAgility CoiloverBerk HFCTechnosquare TuneGT-R ButtonVenaci MeshSP Performance Cross Drilled/Slotted RotorsSPC Toe BoltsBomex LipMud flapsAero Jacket Type III WingSold

01-20-2011, 09:52 PM	#68 (permalink)
jnaut A True Z Fanatic Join Date: Dec 2009 Location: wpb, fl Posts: 1,146 Drives: 09 370z Rep Power: 17	got it __________________ Best 1/4 mile 12.24 Best mph 114.5_______

01-26-2011, 01:09 AM	#75 (permalink)
chuckd05 A True Z Fanatic Join Date: Oct 2009 Location: NY Posts: 2,391 Drives: No longer a Z Rep Power: 20	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... __________________ 09 370Z 6M PW - FBO Best 1/4 mile = 12.926 @ 109 SOLD -- 08 BMW 135i - FBO 12.1@120mph SOLD -- white 09 e92 335 Coupe Mtech - 11.9 @ 119 :-)

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12-28-2010, 01:25 AM	#63 (permalink)
seungklee Enthusiast Member Join Date: Oct 2009 Location: SoCal Posts: 291 Drives: you around! Rep Power: 16	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.

12-28-2010, 01:31 AM	#64 (permalink)
CBRich A True Z Fanatic Join Date: Apr 2009 Location: SC Posts: 2,464 Drives: 370Z Rep Power: 544	Definitely true. If your car is always running at higher RPM to make the same speed then you will use more gas.

01-20-2011, 09:19 PM	#67 (permalink)
dasoupdude Base Member Join Date: Jan 2010 Location: WPB Posts: 24 Drives: 05 z33 Rep Power: 15	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

01-23-2011, 07:09 PM	#71 (permalink)
Red__Zed A True Z Fanatic Join Date: Jul 2010 Location: window seat Posts: 28,940 Drives: Mostly on two wheels Rep Power: 120	If I didnt do so much highway driving this would be a ^no brainer