Lets talk about rear axles and ratios for maximas

[ChrisQ]

I am kinda getting tired of the fuel prices going up! With this in mind i have noticed that our vehicles were built when the speed limit was 55 miles per hour.

I have tries a little larger tires in the back,and it works to a certain extent.
What i have come up with would be a complete gear or third member swap.

I have been told that there are 3 different series (R160, R180, R200)of 3rd members offered by nissan that fit in our cars. Apperently there is a light duty,medium duty,and heavy duty that came in the 300zx turbo,and possibly subarus, Yes subarus!

What i cant seem to find out is what ratios were available in there 3rd members

I have not had a chance to check the one in my 82 maxima with a automatic,but i know its to low for todays highway speeds

If you have any nissan axle data you would like to share,or have a link to post please do.
If there has been a simular discusion on this board that i missed please point me to it

Thanks i million in advance
ChrisQ

[davehoos]

subaru was owned by nissan[25%].now GM.
jatco transmissions are 100% owned by nissan-they supply alsorts.
nissan own 100% of the finance companies.
the car manufacture side only a small % is owned by nissan.

diff ratio.amercan/australian models normally have taller axle ratio than other markets this is due to the fact that the vehicles will be used on hyways and good suburban streets.exhauste emissions are measure over a set distance,so the tall ratio help.

a japanese LD20/LD28/RD28 car will use a 3.7:1 and 13/14 inch wheels.
american model is listed around 3.5:1.
a van will use 4.8:1/4.3:1 and a coach will be around 4.11:1.

my P76 conversion LD20 found that gearbox and diff ratio didnt change the performance much.it had a 3.89:1 diff.with the 3 speed auto it had trouble getting past 50MPH.this is due to the tourque convertor.the usa model had a lockup.once the car got to 60mph it would cruise up to 80mph.
the 5 speed allowed the car to go straight to 80mph.running in 5th gear on level ground used more fuel,but was quiet.at one stage i had a 4.2:1 first gear this was good for carpark crawl and towing a boat trailer.

you need to look at your use of the vehicle.if you fit a taller axle thinking that the engine is at a lower rpm you often use more fuel.a lower axle ratio you often find that the engine is at a higher rpm but the throttle is off and your coasting along.the diff ratio often has more to do with marketing and the type of buyer.

nissan R31 skyline and holden VL commodore have the same RB30E engine.the skyline is heavier.the auto model has the same transmission,but the holden has a 3.45:1 versus the nissan 3.89.the early model had a taller overdrive used in skylines in thirdworld counties.

the skyline has a quicker performance higher top speed and better fuel economy.when the 4.11:1 diff from the RB20E is fitted to the holden it goes much better than the skyline.the holden previously had a 202 CI version of the 250 chev 6 cyl and 5 speed was rare,new car buyer are concered that the nissan engine reved to much.the nissan engine was replaced with a buick 3.8 and 700r4 3.08 ratio axle.

R30/R31 skyline is the sporty version of the laurel C31/C32.the petrol skyline has mush lower axle ratio and smaller tyres.the diesel has the same ratios.

i prefer a wide ratio transmision,but when swaping cogs you dont want the engine to drop too low on the tourque band.i worked at landrover and engineers there tried to explain their method of choosing ratios.it didnt make sence to me.but a lot of thought goes into it.

[asavage]

What i cant seem to find out is what ratios were available in there 3rd members . . . If there has been a simular discusion on this board that i missed please point me to it

I put together a comprehensive list of Gen1 Maxima axle ratios. Some speedo gear info here.

[ChrisQ]

I believe that the factory engineered the maximas powertrain to get the best fuel economy at 55 mph seeing how that was the speed limit at the time.
Now that the speed limit is 70 it seems to be more than likely that those of us who do a lot of freeway driving could benefit from a gear change.

I do believe that if the speed limit had of been 70 back then, the engineers would have geared the car accordingly!

As you may have guessed i do a lot of freeway driving.

ChrisQ

[davehoos]

I do believe that if the speed limit had of been 70 back then, the engineers would have geared the car accordingly!

not the case.

hyway running speed would have not been an issue.at this time australia had unlimited speed limits and lower axle gearing.especially with japanese companies of this age.companies like GM-h sold models with different gearing options in different regions of australia-same deal in america.some cars are geared to run between stop lights or suburban crawl.camshafts manifolds and gearing are a marketing art.ive been involved with diff swaps for complaint customers often without telling them.

in the 70's overdrives are a non event,becoming the norm in the late 80's.
fitted mostly to reduce cabin noise.certian cars are marketed to certian buyers.a skyline/bluebird sold as a commercial vehicle in japan was fitted with 3 speed auto and small wheels.

[HowlerMonkey]

American maxima gassers got 3.54 for automatic without overdrive.

American gassers with overdrive got 3.7.

I think the original author of the thread wants to be able to cruise at todays speed limits without going fast enough to put the ecu into open loop (read bad gas mileage).

On the 280zx turbos with 3 speed, you get 3.54 and 70mph is the limit for closed loop operation with the engine being roughly at 3500rpms.

This is confirmed by my factory manuals for the turbo but I haven't checked for the normally aspirated ecus of the same vintage for that behavior.

[davehoos]

3.9:1 witt 14 inch wheels equal 20 mph/1000 rpm.
2.9:1 equals 25 mph/1000.

i though it was a diesel but the same rules apply to
closed loop gasoline.
14.6:1 A/F ratio.
economic running 15-16:1.
disconect the oxygen sencor and get the engine tuned properly.then reconect the sencor.water temp must be oK.air flow meter must be adjusted.

at high rpm 3500+ the AFM stops working[over simplificatiion], due to volumetric effeciency air mass reduces compared to RPM.
i found that when cruising the vane AFM max out at these type of speeds.
diferent story with hot wire type.

this rpm is considered going silly and to stop the cat over heating it goes rich,this is not the case with later ecu.an R31/Z31 ecu could be modified to run a L24E/L24ET.etc.but it much easier to modify a L20AE ecu but i dont know how to retune these.I had a R30 L24E-these are so basic with ignition only that the rich mixture can be fixed with air leaks or fuel pressure changes.

you need an over drive.-or big tyres.

nissan R31 skyline and holden VL commodore have the same RB30E engine.the skyline is heavier.the auto model has the same transmission,but the holden has a 3.45:1 versus the nissan 3.89.the early model had a taller overdrive used in skylines in thirdworld counties.
the skyline has a quicker performance higher top speed and better fuel economy.when the 4.11:1 diff from the RB20E is fitted to the holden it goes much better than the skyline.

[240ZD]

I have an r180 3.54 in my Z, and you can get the same ratio in an r200 diff (with better half-shafts than r180) from an automatic transmission, non-turbo 280zx. Also, the non-turbo five-speed from a 1981-83 280zx has taller gearing than earlier five-speeds.

These combined gear ratios easily push my G-ride over 110 mph~

-samee

[HowlerMonkey]

280zx turbo autos also have 3.54 R200s with cv joints.