Gear ratio calculator, rear gears, and transmission ratios

[rficalora]

Can someone point me to the Microsoft Excel gear ratio calculator that was posted several years back?  It enabled you to input transmission gears, rear end gear, tire size, etc and calculated speed at RPM for each gear.

I want a better 1st gear ratio - or possibly different 1st and rear gears.

[mgb260]

Rob, What do you have for first and rear gears?

[MGBV8]

Gonna cost you big bucks either way since you can't just change out 1st gear.

[MGBV8]

Borg Warner T5 five speed from a 1994-95 (SN95) Ford Mustang. (Input shaft and bellhousing are 1" longer than typical 5.0L Mustangs. Gear ratios: 3.53:1, 1.93:1, 1.33:1, 1.00:1, 0.68:1, and 3.15:1 reverse. 1-1/16" 10-spline input shaft. 0.668" input shaft pilot diameter. 28-spline output shaft. 8-tooth speedometer drive gear. ATF fluid.) King Cobra clutch. 1994 Toyota 4Runner slave cylinder.

Rear End:    1996 Nissan Skyline viscous limited slip differential (same R200S case as Nissan 240SX). 3.54:1 gears. Uprated halfshafts from "The Driveshaft Shop" in Salisbury, North Carolina.

Yeah, I wouldn't be happy with that 1st gear, either.  I would like the 3:54 rear gears with my 2.95 1st gear.  You could go with a 3.08 since you have that 302 torque.

Dan Masters' gear ratio calculator (in Excel)   http://www.britishv8.org/Articles/chart.xls

[v8mgb]

Rob:  Google Search found this

http://www.glenn-ring.com/tech/tranny_calc.xls

http://www.tremec.com/calculadora.php

[rficalora]

Thanks.  Note there's a typo in the HIWD, current 1st is 3.35.

Tires are 225/45/15 so about 23" diameter.

Carl - yeah, pretty much requires changing clusrer.  There's a guy who'll build me what I'd need for about $1200 (with no core charge)  I think I could resell my current trans for $600-750 so makes it fairly doable.

[mgb260]

Rob, Ford Racing T5Z has the 2.95 first. Or like Carl mentioned the 3.08 rear gear. The V8 can pull a taller gear fine. The V6 guys like around 12 combined first and rear. Higher power V8 do better in the 10's. Unfortunately you would have to switch to the 8.8 for the 3.08. I think the Nissan 200R 3.54 is the highest ratio they have. Also the 2.95 only comes in the shorter pre 94 input length. I did find this aftermarket 94 and newer input shaft, you would use your bearing retainer:

https://www.ebay.com/itm/Ford-Mustang-94-95-Z-SPEC-2-95-ratio-V8-WORLD-CLASS-T5-input-shaft/262909337211?epid=705138037&hash=item3d369e1e7b:g:VBUAAOSwc-tY1dwB&vxp=mtr

[BlownMGB-V8]

Mine comes out to 11.5 with a 25.7" tire (3.54 x 3.27). Equivalent to 10.7 with a 24" tire or 10.3 with a 23" tire. Still a kinda short 1st gear but at least usable and good for launches. Much better that the T5 that's in the car right now which works out to about 12.7 with a 23" tire or 13.3 with a 24" tire. That one is still usable but almost pointless. Tire diameter increases are roughly equivalent to steps in axle ratio, so keep that in mind too.

I'm going to need to swap out that tranny soon. Maybe this weekend would be good, I think I have everything now.

Jim

[rficalora]

I'm seeing on the internet that Titans, Armada's, & XTerra's had a 2.95 rear so I did the following compares.  What would you do based on these?

[mgb260]

Rob, Those rears are much larger than your R200. I think about a 10" ring gear compared to your 8". I think the 2.95 first in the transmission would be your best bet. 2.95 x 3.54 = 10.44. Your lower profile tires, like Jim B mentioned above, also lower the rear ratio. I googled the R200 gear ratios and the ones you have are the highest available for that rear.

[mgb260]

Tire size to gear ratio calculator, Shows your effective rear ratio is now 3.68 :

https://tiresize.com/gear-ratio-calculator/

[mgb260]

Rob, 91-96 and 99-08 Infiniti G35 used 3.36 gears in the R200 with the automatic transmission. The older R200 longnose in the 280ZX turbo and 2+2 also used that ratio but has smaller holes in the ring gear and longer pinion so I don't think that would be viable. You may be able to find the Infinity G35 in a pick and pull. Gear tooth count is 37-11.

[rficalora]

Bummer on the 2.95 rear gear.  I googled R200 ratios & found it there; must not have looked close enough at the page .

So, sounds like the 2.95 1st gear transmission & find a 91-96 Infinity G35 will be my best answer.

[mgb260]

Rob, The Newer 99-08 G35 have that ratio too. That combo would be perfect for your car. Lots of the newer ones, some with Limited Slip on Ebay.

https://www.ebay.com/sch/i.html?_odkw=91-96+infiniti+g35+3.36+differential&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.X+infiniti+g35++differential.TRS0&_nkw=+infiniti+g35++differential&_sacat=0

[IaTR6]

I seem to be thinking along the same lines. I have the R200 w/3.54 and a T5 with 3.35 1st. and I would like more range in 1st gear.
In traffic, I am shifting too soon. I suppose it would be O.K. for a heavy vehicle, and it keeps me from stalling it, but the 302 torque
would seem to allow something taller. Now I have 3.35X3.45=11.86, and a change to 2.95 would be 2.95X3.54=10.44, which would be better.
Changing the input, cluster and the 1-2-3 gears on the mainsheet gets pricey, and leaves you with a .59 ratio 5th, which is very tall.
I have not found a combination of 5th gears that suit me, but the T5Z has a .63 5th, which would do. Of course, they are $1750!
I'll watch here for a while and see what the wiser folks do.
Dennis

[mgb260]

If you don't have a super powerful (over 300HP) V8 you may get by with the NWC 83-84 Mustang T5. It had the 2.95 first and some had the .72 OD. Probably hard to find and I would still do a rebuild, use Synchromesh fluid and a aftermarket shifter with stops.

[IaTR6]

Rob, Look at this link, it refers to a Pathfinder with a high ratio in the 3. something range.
More research to see if the info is valid!
http://zilvia.net/f/showthread.php?t=267957
Dennis

[mgb260]

Dennis, Good find! 3.113 ratio. That would be 10.43 combined with the 3.35 first you already have. Rob would be lower with his 23" diameter tires at 10.82.

https://www.ebay.com/itm/2012-NISSAN-PATHFINDER-4-0L-REAR-CARRIER-ASSEMBLY-DIFFERENTIAL-RATIO-3-13/162679881226?hash=item25e079fe0a:g:x6AAAOSwD5ZZwWh-&vxp=mtr

[IaTR6]

Oh, something else that popped into my head was the notion that the point of greatest torque multiplication has the greatest stress.
I may be wrong on that, and someone can jump in here, but a numerically high rear ratio would move the stress to the transmission,
which in the case of the T5 is around 300 ft lb. in the better models. Higher capacity can be had for a price of course.
So, I'm leaning toward a 2.95 1st gear and leaving my 3.54 ratio R200 as is. That's still 10.4 overall.
Dennis

[rficalora]

I've been researching the Pathfinder 3.13 - seems like it only came in an open differential.  No LSD.  Anyone familiar with Phantom or Traction Concepts? They advertise these things that can be installed to give it LSD...  https://www.ebay.com/itm/Nissan-Pathfinder-fits-R200-diffs-Limited-Slip-Differential-Conversion-Kit/252021217093?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

[mgb260]

Rob, Those limited slips work at first, then the springs weaken and blocks wear and then become a open diff again. 2004-2007 Pathfinder diff should be Viscous Limited Slip.

[rficalora]

That's great if true.  So far the Nissan boards haven't been able to confirm.  There is a salvage yard near me with a 2005 2wd pathfinder with 3.13 gears; I may just have to drive out & look at it (supposedly there's an orange sticker labeled "Use LSD Oil only" that survives the age).

[mgb260]

Rob, The orange sticker should say Viscous LSD. It is a separate sealed unit with thick silicone in the diff. You would use conventional lube in the rear. There was a thread where a guy removed one and switched to a clutch type rear. The Pathfinder rear has a larger pinion and 13mm bolts on ring gear vs 12mm on yours. The axle stubs from 5 to 6 bolt may swap if yours is VLSD too. Also the rear cover will have to be swapped. The front mount spacing may also be different.

[rficalora]

Jim, your ability to find this stuff continues to amaze me!

So, if I'm following, 2004-2007 2WD is viscous limited slip.
*  Need to verify if front mount spacing is the same or different so might need to modify IRS cage to accomidate.
* Need to swap rear covers (presumably to get same mount bolt spacing/size?  If not that, why swap the rear cover?
* May be avle to swap my VLSD axle stubs (if not, I'd simply need to replace my Nissan 5-bolt to Porche 930 CV adapters with new ones that go from Nissan 6 bolt to the 930).

[mgb260]

Rob, You got it. Probably not all are VSLD. My guess was optional. Ebay has new OBX Helical gear type posi's (Tru-Trac/Quiaiffe type)for $388 and used Viscous LSD for $119 to $ 190.  I still would switch to the 2.95 T5 because of your lower tire diameter. Pic of Viscous LSD: