Hey Jadcock

aaronford · Apr 21st, 2003, 08:08 PM

Thought that would get your attention... Hey, you list the tranny ratios for your 95 4WD on your website. Does the 2WD use the same tranny? Ratios? BTW, Nice truck.. Aaron

jadcock · Apr 22nd, 2003, 07:36 AM

Hey man. Yeah, it did get my attention.

I don't think the 2wd tranny uses the same ratios. I have a '95 brochure at home...I'll check for ya.

Thanks!

aaronford · Apr 22nd, 2003, 09:27 AM

I calculated that if the ratios are the same, my valves float @ 6100 rpm. Not that its important, but I have no tach and I was curious of my engine speed during my 2-3 shift. If my 1st gear ratio is the same as well, I am shifting to 2nd at only 5000 rpm....
This is based on tire diam (in) X pi / 12 to get foot per revolution /5280 to get revolutions per mile. Then x mph /60 min to get tire speed at 58 mph. Then X 3.55 for axle ratio and 2.246 for 2nd gear ratio should get my engine speed. It figures out to
25.5 x 3.1459 / 12 + 6.67588 foot per revolution of the tire. Thats 790.90 revolutions per mile and 764 revolutions per minute at 58 mph. Mutiplying by axle ratio and gear ratio gives me 6095 rpm at 58mph in second gear.
I find it ironic that all my manual tranny cars have never had a tach, but all with automatics have.... Aaron

jadcock · Apr 22nd, 2003, 09:35 AM

You wait until your valves float to shift into 3rd? How do you know they're floating?

The first time my mother in law drove the truck, she turned off the radio so she could hear the engine and know when to shift. She said that cars never used to have a tach and she listens to the engine. Every car I've owned (both manual and auto) have had tachs, so it's all I've known. Even my '84 Cutlass had a factory tach. Same goes for the truck. I usually shift mine at about 3500 rpm if I'm just tooling around. If I get hot on it, I shift around 5000-5500. I've never hit the rev limiter, if there is one.

I'm a gauge watcher -- I'm one of those guys who's always looking down at the dash to check things out, including the tachometer. I'm used to V-8 cars, and they're happy cruising along at 1500 rpm (even the DOHC Northstar in my Cadillac). But in the Nisssan, I've gotta use 4th a lot on the Interstate around here, and I'm always goin' down the road at about 3500-4000. Just something to get used to I guess.

The engine sounds like it's idling at 2000.

aaronford · Apr 22nd, 2003, 10:51 AM

Normal shifts occur somewhere around 3500, I only take it to the max when I'm imposing my will on some one who deserves it, or hotlapping the access road at work. You will know when valve float occurs. It is normally associated with a decrease in acceleration and a change in engine tone. It is due to the valvesprings no longer being able to follow the camshafts profile and leaving the intake valves open during compression stroke of the pistons. It can be remedied by stiffer valvesprings, but this may also require balancing/lightening of the reciprocating assembly to handle the additional revs. How 'bout the 2WD ratios? Aaron

aaronford · Apr 22nd, 2003, 11:08 AM

I ran your combo using the info from your website and the diameter of your tires as listed by tirerack.com and came out with some figures. At 70 mph, you should be running 3477 rpm in 4th and 2890 in 5th. At 80 you should be at 3974 in 4th and 3302 in 5th. Yeah, I'm bored... I did not know that Nissan ran an overdrive trans... I assumed 5th was a 1:1 ratio. Learn something new every day. Aaron

jadcock · Apr 22nd, 2003, 01:18 PM

Quote:

Originally posted by aaronford
You will know when valve float occurs. It is normally associated with a decrease in acceleration and a change in engine tone. It is due to the valvesprings no longer being able to follow the camshafts profile and leaving the intake valves open during compression stroke of the pistons. It can be remedied by stiffer valvesprings, but this may also require balancing/lightening of the reciprocating assembly to handle the additional revs. How 'bout the 2WD ratios? Aaron

It can also be remedied by shifting sooner.

I'll get the ratios when I get home.

jadcock · Apr 22nd, 2003, 01:20 PM

Quote:

Originally posted by aaronford
I ran your combo using the info from your website and the diameter of your tires as listed by tirerack.com and came out with some figures. At 70 mph, you should be running 3477 rpm in 4th and 2890 in 5th. At 80 you should be at 3974 in 4th and 3302 in 5th. Yeah, I'm bored... I did not know that Nissan ran an overdrive trans... I assumed 5th was a 1:1 ratio. Learn something new every day. Aaron

Yep. On the Interstate, I'm between 5th and 4th. Mostly 5th. The truck is a dog in overdrive.

I think most every transmission these days has an overdrive gear. In the 80s (and before), it was common for 3-sp autos to have 3rd gear as 1:1 and 4-sp sticks to have 4th gear as 1:1. But recently, almost all 4-sp autos and 5-sp sticks have the highest gear as less than a 1:1 ratio.