Trans Short Gears - How To Tell?

pgilliam1

pgilliam1

Experienced Member
Joined
16 October 2008
Messages
1,869
Location
St. Louis
I bought this 1991 and the owner said, "the owner before him had the transmission rebuilt with short gears at R M Racing" (he had no documentation). My question is how can I tell? Would someone with a stock tranny please tell me at what speed and RPM they shift as they go through their gears? That should tell me since if I do have the short gears I would be shifting at a slower top speed at the same RPM in the same gear. If my logic is wrong feel free to correct me - I'm wrong often.
Thanks,
 
simplest way to tell asuming you also have stock size tires is your 2nd gear should redline at about 78-80 mph if stock.have fun testing:biggrin:
 
I believe V-Tec is 6,100rpm.

Redline in 1st gear, upshift to 2nd:

Stock = ~4,400rpm
Short gears = ~ 5,800rpm



...that or redline in 2nd:

Stock = ~80mph
Short gears = ~70-72mph
 
Guys,
What would be easier is if someone would go and drive their car and note MPH readings at say 3,000 RPMs in 2nd, 3rd and 4th gears. This would be much easier for him to check. I would be glad to, but my car is up on jacks with my tranny on my work bench installing SHORT GEARS.
Brad
 
OLDMNSX said:
my tranny is on my work bench
Click to expand...

What a coincidence. So is mine!

Kristen_Billie-Davis.jpg
 
OLDMNSX said:
Guys,
What would be easier is if someone would go and drive their car and note MPH readings at say 3,000 RPMs in 2nd, 3rd and 4th gears. This would be much easier for him to check. I would be glad to, but my car is up on jacks with my tranny on my work bench installing SHORT GEARS.
Brad
Click to expand...

The link Nikey posted has everything you need, unless you think the info is suspect. At 8000 RPM, stock speeds are as follows:
2nd - 81mph
3rd - 114mph
4th - 144mph

If you want the speeds at 3000 RPM just multiply the above #s by (3/8).
 
OLDMNSX said:
Guys,
What would be easier is if someone would go and drive their car and note MPH readings at say 3,000 RPMs in 2nd, 3rd and 4th gears. This would be much easier for him to check. I would be glad to, but my car is up on jacks with my tranny on my work bench installing SHORT GEARS.
Brad
Click to expand...
Redline in 1st gear or 70-80mph on the freeway in 2nd doesn't seem too much to ask...

Here's your wish:

MPH @ Cruising RPM (3,200rpm):

US gears/US final drive (4.062) =
32mph in 2nd
47mph in 3rd
60mph in 4th

JDM (short) gears/US final drive (4.062) =
30mph in 2nd
41mph in 3rd
56mph in 4th
 
So much easier to do a simple 1-2 shift at redline and see how far the revs drop. It also takes the R&P out of the equation which is desirable since it is an unknown.
 
Hugh said:
So much easier to do a simple 1-2 shift at redline and see how far the revs drop. It also takes the R&P out of the equation which is desirable since it is an unknown.
Click to expand...
Ring and Pinion final drives do affect the mph at redline and will also affect what RPM/speed after a shift.
 
stuntman said:
Ring and Pinion final drives do affect the mph at redline and will also affect what RPM/speed after a shift.
Click to expand...

I'm well aware of that. That's why I made the suggestion to simply do a 1-2 redline shift. All we are looking for is how far the revs drop when 2nd gear engages. This will tell pgilliam if he has UDM or JDM gears. Once he knows the answer he can then compare the speed of the car to the revs and determine what R&P he has.
 
First, Thanks to all for the input/info! At redline in second gear I'm at 68MPH. There is a little drop in RPM's when shifting from 1st to 2nd but not much (My wheels are not stock as I have 18's on the rear and 17's up front).

Conclusion - I must have the shorties. :biggrin:

I hope to have the other mechanicals ready by spring so I can get her on the track. Man what a car this is! If I didn't drive it - I wouldn't have believed it.
 
I think you may also have a 4.55 R&P.
 
pgilliam1 said:
First, Thanks to all for the input/info! At redline in second gear I'm at 68MPH. There is a little drop in RPM's when shifting from 1st to 2nd but not much
Click to expand...

docjohn said:
I think you may also have a 4.55 R&P.
Click to expand...

This sounds like shorties and 4.23 to me. My similar set-up redlines at an indicated 70 mph with 16/17 wheels.
 
pgilliam1 said:
First, Thanks to all for the input/info! At redline in second gear I'm at 68MPH. There is a little drop in RPM's when shifting from 1st to 2nd but not much (My wheels are not stock as I have 18's on the rear and 17's up front).

Conclusion - I must have the shorties. :biggrin:

I hope to have the other mechanicals ready by spring so I can get her on the track. Man what a car this is! If I didn't drive it - I wouldn't have believed it.
Click to expand...

Congrats on confirming the information. Even though the wheels you have are not stock, the diameter of the tires you have mounted are probably very close to stock. You can get the exact difference and see the actual percentage difference by using this handy dandy tire size calculator and comparator.
 
For a 265/35-18 rear tire:

Redline in 2nd gear =

68mph for 4.55 and JDM (short) gears
69mph for 4.44 and JDM (short) gears
73mph for 4.235 and JDM (short) gears

Pending your tire size and speedometer accuracy, i'm pretty sure that you can say you have the JDM gears and either a 4.44 or 4.55 R&P.
 
Hugh said:
Congrats on confirming the information. Even though the wheels you have are not stock, the diameter of the tires you have mounted are probably very close to stock. You can get the exact difference and see the actual percentage difference by using this handy dandy tire size calculator and comparator.
Click to expand...


That's a neat calculator. By it's measure my speedo is 1.6 mph too slow with the 275/35/18's I'm running. So by that I guess I'm running a 4.44 R&P. And OH YEAH! this car is a blast to drive. My only complaint is the understeer - guess I'll have to slow it down a bit - OR NOT!

Thanks Again to All for the info!
 
pgilliam1 said:
That's a neat calculator. By it's measure my speedo is 1.6 mph too slow with the 275/35/18's I'm running. So by that I guess I'm running a 4.44 R&P. And OH YEAH! this car is a blast to drive. My only complaint is the understeer - guess I'll have to slow it down a bit - OR NOT!

Thanks Again to All for the info!
Click to expand...

For a 275/35-18 rear tire:

Redline in 2nd gear =

69mph for 4.55 and JDM (short) gears
70mph for 4.44 and JDM (short) gears


It's really tough to say, but their's a good possibility you have a 4.55


What suspension are you running (and spring rate), what is your front tire?
 
stuntman said:
For a 275/35-18 rear tire:

Redline in 2nd gear =

69mph for 4.55 and JDM (short) gears
70mph for 4.44 and JDM (short) gears


It's really tough to say, but their's a good possibility you have a 4.55


What suspension are you running (and spring rate), what is your front tire?
Click to expand...

My front tires are 215/40/17. I just replaced my suspension (which was OEM 1991 117,000 miles) with OEM from a 2000 with 15K miles. Made a big difference in ride and handling. Probably should have gone with a more agressive setup but most of my driving is through these Missouri hills and not on the track. This car is more than I had hoped for - a dream come true for this enthusiast!
 
Statisticly speaking I'm sure there are more old comptech 4.55 running around than OS Giken 4.44.
 

Similar threads

Fabunoz
Issue going into gears
Replies
7
Views
372
drew
drew
vra4anin
Automatic Transmission problem - won't change gears, CEL code ERROR 15
2
Replies
28
Views
591
vra4anin
vra4anin
Z
NSX Dirty Secret, No 91 thru 94 Owner Will Acknowledge
2
Replies
35
Views
1K
Zero2
Z
D
Short Gears Circa 2024 and other Hard find stuff.
Replies
11
Views
489
The Kid
The Kid
RYU
  • Locked
*** SOLD *** Freshly Built: JDM Type R 5spd Manual Transmission (Short Gears + 4.23 Short Final Drive)
Replies
8
Views
885
RYU
RYU
Back
Top