# Junk Yard Tuning Questions (please Help)



## pm90sentra (Jul 10, 2009)

:newbie:
I recently purchased a 1990 sentra with a 4 speed manual transmission and a GA16i, i am looking to do some performance upgrades on a budget (the car cost 400). The pic a part near me is having a sale and i wanted to know if i could get some performance for cheap. The stipulation is that you need to be able to carry the parts out in your arms. So i was wondering what parts i could snag and install without to much customizing. There are some 91-94 sentras there and some 240s with ka24e's i was wondering if any of these heads would bolt up to a ga block (may be a stupid question but i have never had a nissan before) i was also wondering about any 5 speed transmissions, suspension pieces and brakes that would bolt up to the b12 platform. I think that Junk yard tuning is a valuable asset with today's economy so if you have any mods that you've done using junk yard parts from other makes and models lets get them listed on here too! Thanks in advance to everyone who pitches in.


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## sonicgundam (Aug 15, 2007)

to start with, ga16i b12's came with either 4 or 5spd manuals, grab a 5spd . 

front and rear sway bars from a Pulsar SE (with a CA16/18DE) are a major suspension upgrade

brakes from b13 sentras are direct bolt ons. also grab a booster from a 89-93 maxima for the most effective results.

anything else i've missed guys?


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## bob89sentra (Sep 15, 2005)

5 speed from a 89-90 pulsar with Ga16I is a great swap into the B12, it has the same final drive ratio as the 4 speed, but has an extra gear (the sentra's 5 speed just adds a higher gear above 4th, so the acceleration is the same)Brake booster from a 87-94 Maxima bolts right in, and if you do the 4 wheel disc brake conversion you can take the master cylinder and resivour too.
as said before brakes and swaybars from the NX-SE pulsars.
The GA16DE head on the 91-94 Sentra would bolt to the GA16i Block, but you would be better off taking the whole engine, and you still would need to get the computer to control it properly.
Rear disc brakes can me made to fit on a B12 from the 91-94 Sentra SE-R, but is a little more work because 2 pieces will need to be manufactured for each side to adapt them.
Headers off the 91-94 Ga16DE will hook up with a little modification.
There are many more things that can be swapped across, from most mid 80's to late 90's Sentra, Maxima, Stanza, Pulsar, Pathfinder, but with varying amounts of work to get them to fit right.


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## sonicgundam (Aug 15, 2007)

bob what are the gear ratios for the b12 and kn13 GA trannies?

i was gonna use an NX tranny but if pulsar ones are good too...


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## Spitrod (Sep 22, 2008)

> 5 speed from a 89-90 pulsar with Ga16I is a great swap into the B12, it has the same final drive ratio as the 4 speed, but has an extra gear (the sentra's 5 speed just adds a higher gear above 4th, so the acceleration is the same)


See? I didn't know about this. you learn something new every day.



> brakes from b13 sentras are direct bolt ons. also grab a booster from a 89-93 maxima for the most effective results.


If I'm throwing disks on the rear of my b12, what kind of serious mods (as far as welds and stuff goes) do I have to do after I ditch the drums? I'm so sick of the rear drums.

I'm ready to do some big time upgrades to the Sport Coupe as well as 
a possible swap now that I have a reliable back-up car. For a long time, 
my b12 was my trusty "get in and go" car so I didn't want to mess with
it.


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## bob89sentra (Sep 15, 2005)

1989-1990 Sentra B12 with GA16i-- 4 and 5 speed transmissions
These are the ratios for the RS5F31A five speed...
1st Gear 3.333:1, 
2nd Gear 1.955:1,
3rd Gear 1.286:1,
4th Gear 0.902:1,
5th Gear 0.733:1,
Reverse 3.417:1 
Final drive ratio 3.895:1
And here are the ratios for the RN4F31A four speed...
1st gear 3.333:1,
2nd gear 1.955:1,
3rd gear 1.286:1,
4th gear 0.902:1,
Reverse 3.417:1
** Final drive ratio 3.650:1 ____see note below
1989-1990 Pulsar N13 with GA16i RS5F31A 5 speed has
1st gear 3.063:1,
2nd gear 1.826:1,
3rd gear 1.207:1,
4th gear 0.902:1,
5th gear 0.756:1,
Reverse 3.417:1
Final drive ratio 4.167:1

The N13 Pulsar RS5F31A 5 speed has lower gears than the B12 Sentra's RS5F31A 5 speed, there are several other RS5F31A, RS5F31V, and RS5F31H 5 speed transmissions available with different gear ratios and final drive ratios, but none of them will bolt to the GA16i. The RN4F31A (4 Speed) has the same gear ratios as the RS5F31A’s first 4. 
The breakdown of the Part number is as Follows…
*RS*5F31A
RS=Reverse mounted shifter
RS*5*F31A
5=# of forward gears=5
RS5*F*31A
F=front wheel drive
RS5F*31*A
31=Series of gearbox
RS5F31*A*
A=non-LSD (non-limited slip differential) 
there is also a V, and H with LSD


** this does not seem right that the 4 speed would have a higher final drive ratio than the 5 speed, but I have not been able to find info to say otherwise. 
From driving with all 3 transmissions in my Sentra I have seen the 4 speed from the B12 has almost the exact same RPMS at the same speeds as the N13’s 5 speed (both in top gear), and the 5 speed from the Sentra has higher gears (lower RPM at same speeds) than both other transmissions. This is running all 3 transmissions in the same car with the same tires, ect.

Bob


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## bob89sentra (Sep 15, 2005)

Spitrod said:


> If I'm throwing disks on the rear of my b12, what kind of serious mods (as far as welds and stuff goes) do I have to do after I ditch the drums? I'm so sick of the rear drums.


No welding necessary, you can see the write-up in my sig on my cardomain. all you have to do is machine 2 adapter plates for each side (1 wheel spacer, and one caliper mount plate)
With the parts in hand it is quite an easy mod, and did not take long to do.


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## sonicgundam (Aug 15, 2007)

thanks for the ratios bob.

as for the 5spd being lower than the 4, its because that last .733 ratio drops the final ratio for the five gear gearbox.


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## bob89sentra (Sep 15, 2005)

I figured out my mistake the RN4F31A in the B12 has a 3.650:1 diffrential.
The B12's RS5F31A has a 3.895:1 diffrential.
Where they say it is the final frive ratio I was confused, they are talking about the diffrential's gearing, not the overall ratio between the input and output shaft.
So the B12 Sentra's 5 speed overall ratio would be:
5th gear (.733:1)X diff ratio (3.895:1)= 2.855:1

and the B12 Sentra's 4 speed overall ratio would be :
4th gear (.902:1)X diff ratio (3.650:1)= 3.292:1

and the N13 Pulsar's 5 speed overall ratio would be:
5th gear (.756:1)X diff ratio (4.167:1)= 3.150:1
That means for the transmissions that the N13 Pulsar's 5 speed is slightly higher geared than the 4 speed from the B12 Sentra

To compare 
3,000 RPM in Sentra 5 Speed= 73MPH
3,000 RPM in Sentra 4 Speed= 63MPH
3,000 RPM in Pulsar 5 Speed= 66MPH

2,000 RPM in Sentra 5 speed= 49MPH
2,000 RPM in Sentra 4 speed= 42MPH
2,000 RPM in Sentra 5 speed= 44MPH

with P185-65-R14's
Hope this info helps!
Bob


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## sonicgundam (Aug 15, 2007)

hmm i'd like to know what the 60 ft and 1/8 mile time differences could be with a pulsar ratio vs a b12 ratio.


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## blownb310 (Jun 10, 2002)

bob89sentra said:


> The breakdown of the Part number is as Follows…
> *RS*5F31A
> RS=Reverse mounted shifter
> RS*5*F31A
> ...


Bob,
This is great information. Any idea what the "N" stands for in the RN4F31A trans?

I'm trying to asertain whether the taller 3.65's from it can be swapped into the RS5F31A?

Mike


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## bob89sentra (Sep 15, 2005)

Mike, 
Looking through the databases for the diffrentials, it looks like both thransmssions use the same one... so I am thinking there was a different pinon gear used on the 4 speed from the 5 speed.

If you follow this link and scroll allmost to the bottom of the page it has the section for the Sentra and the diffrentials that were in each transmission. It has the same diff listed for both the 4 and 5 speeds, and the same bearing sizes for the pinon. Maybe if you just swapped over the pinon and shims it would work.

I don't know off hand what the "N" stands for, now I am curious...

Are you going for taller gears for higher speeds, or better economy, or just to lower the RPM's?
I do like the idea of keeping the RPM's lower on the Highway when crusing at 75.
Bob


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## blownb310 (Jun 10, 2002)

Thanks for that reference link Bob. It's encouraging that the diff bearing specs are the same. I'll bet the ring and pinions will swap betweeen the B13 four and five speeds. 

The swap would be for lower rpms on the highway for better mileage. I wish Nissan would have put a _much_ taller 5th gear in their transmissions, particularly the RS5F32A's in the B13 SE-R's.

Mike


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## blownb310 (Jun 10, 2002)

It's also very interesting that Nissan called the 4WD B12's five speed an RS5F31E. I never knew that. Wonder what the "E" stand for?


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