Gear ratio calculator, rear gears, and transmission ratios

[rficalora]

Did some more research and finding that 3.54 was the tallest gear Nissan offered in an R200 with LSD.  So now trying to figure out if I can use the ring/pinion from a 3.13 in my Skyline diff.  Or if I can use my Limited slip (or one of the ones you listed above in a pathfinder diff.  I'm just worried there may be a reason they never put limited slip in the 3.13 or 2.95 diffs.  Thinking something might not fit?

[mgb260]

Rob, The Infiniti automatic G35 3.36 are pretty common with VLSD. The Pathfinder has a larger pinion and won't interchange. I think your best bet is the Infiniti G35 3.36 and 2.95 T5. Here is the  thread where a guy took the VSLD out of a Pathfinder 3.13 and installed a clutch type LSD:

http://zilvia.net/f/showthread.php?t=267957

[IaTR6]

I have followed this discussion with considerable interest, since I am not entirely satisfied with my 3.35 low gear and 3.54 diff.
I believe, that changing the rear ratio to solve the 1st gear issue may be disappointing since doing so will effectively reduce the overall
ratio on every gear. This may be most apparent in 5th, where the rpm would lower also, perhaps to a value too low. This would
mean the cruising rpm would result in sluggish acceleration in that gear, and possible sluggish performance on hills. (maybe not an issue in the South?)
Anyway, I am happy with my 5th gear cruise rpm, and would only change to a 2.95 1st gear trans. I do know that the 5th will change to .62,
but there are few options around that.
Dennis

[mgb260]

Dennis, you can simply change the 2 OD gears to .73 if you went to the 3.36 rear and in my opinion would be perfect with the 2.95 first T5. I conversed with Carl awhile back on the tooth count of the gears. I'll do a search to find the thread.

[mgb260]

Dennis, I found the thread:

http://www.mgexp.com/phorum/read.php?40,3265232

[rficalora]

Making progress -
* Have a transmission guy in Austin area who said he could build me a T5 with the longer SN95 input shaft like I have, but the same gears as a T5Z.  Price is $1295; no core; no shipping (I travel to Austin pretty regularly).  I never told him I want it, but he sent me a note last night saying he's built it & sent pics.  What should I ask to get a feel for quality of what he did?  Pics below.  See anything odd (I see some rough edges on some of the gears & what looks like wear on the ends of some, but having never rebuilt a transmission, I have no idea if those are concerns)?

* On the rear end, Narrowing in on 3.36 or 3.13 (3.36 better for my current tire size; 3.13 better if I go back to 225 or 235/50/15's.  3.36 has LSD options; 3.13 less clear but am connected with a Nissan diff guy who believe's it's doable... But, I'm going to hold off getting parts for this till I have the transmission swapped and figure out if I want to go back to 24" tires.  Also, considering a cam swap to shift torque lower in RPM range.  Want to decide that too before I do anything with the rear end.  Kelley Stevenson had a comp cam XE264HR-14; 2.95 1st gear, 3.55 rear gear; and 24" tires (same as 225 or 235/50/15) & thought that combination worked very well.  So, may not need to change the rear axle.

For now, I have plenty to do:
* Install Edelbrock EFI system I got (means I have to fix my exhaust leaks & figure out how to fit the big cap distributor due to clearance [lack of it] to my air cleaner)
* Swap transmissions
* Fix my cracked windshield
* Align my doors (they're not aligned right & that's bugged me since day 1)

[rficalora]

Changed the subject on this thread since it's evolved past just the initial calculator question.

[mgb260]

Rob, I think you got the ratios switched for tire size. Ford Racing E303 cam has excellent midrange and designed for fuel injection. I have a Desktop Dyno program and can run simulations for you on  different cams. If your existing cam is not already, you can advance it 4 degrees to lower the torque curve.

[rficalora]

Yes Jim - I got the ratios switched for tire size.  Existing cam is not advanced.  I'll take you up on your desktop dyno offer as soon as I've narrowed 2-3 options.

Anyone have thoughts on the transmission - what questions to ask to figure out if quality components were used &/or thoughts on condition of the gears in the pics?

[MGBV8]

Maybe Jim B will pop in.  He tore into the MG Roadmaster T-5 earlier this year.

In my book, a 2.95 1st & .72 or .73 5th gear with a 3.5 rear gear is about perfect for a LBC V8.

What about the Mighty B Cam?!

[rficalora]

RE: 5th -- I'm already checking with him on that.  I have .68 currently & that puts me a little low in the RPM range.  But, from what I've read, the only options with the 2.95 1st is either .59 or .63.

RE: Mighty B cam --  I'll likely also swap cams.  Have been on the road this week; no time to call Comp Cams or others to narrow down options.  Goal will be more lower end torque.  Will also look at effect of advancing current cam per Jim's earlier note.

[BlownMGB-V8]

"All Hail the Mighty "B" cam!!"

I did what to the Roadmaster? Oh. The T-5, yep I did. Replaced a couple synchros.

Now the RM is a special case I think. It has that thunderous 455 BBB, and that makes it perfectly happy with about any gearing you can stuff in it. I think the axle ratio is about 2.88 or 2.87 and that works just fine. The rear tires are a little larger too. And it's still getting about 20mpg. But I wouldn't use that ratio in my car I don't think. I can give my impressions as soon as I get to drive it with the new transmission though, might be another week or two. 3.27 1st gear, 0.68 OD I think, 3.54 axle gears and 25.7" rear tires. That is about equivalent to 3.08 gears with 24" tires which a 350 cid engine should easily support. Should be a pretty good combo I think. Lively off the line. Overall 1st gear ratio is 11.5 which would be equivalent to 10.8 with 24" tires.


Carl would know what the 1st gear ratio in the RM would be. If it's that 2.95 that gives a 8.5:1 overall ratio plus the taller tires. I don't recall at the moment their diameter but it is a bit larger, maybe not much. The RM feels like it is geared about perfect, though you have to remember the massive torque.

Jim

[mgb260]

Rob, the 2.95 T5 has a OD available of .73(.72?) also. It was in a few Mustang and Camaro's.If you go to the 3.36 gears the .63 will be pretty tall. Check out the link above regarding tooth count. A lot of guys like the earlier HO cam with 1.7 rockers too.

[MGBV8]

Or a .80.

http://www.allfordmustangs.com/Detailed/349.shtml

The MG Roadmaster has 2.95 1st & .63 5th gears.

[mgb260]

Carl, I forgot about the Ford .80. I think it may be better for racing. I like the lower RPM's for cruising on the Interstate. Just not too low  in the hills.

[mgb260]

Rob, Here are examples for the cams I mentioned above. The HO cam with 1.7 rockers only makes sense if you already had that cam. The E303 beats it in lower RPM TQ and is about a tie at upper RPM. EDIT: 272 TQ on HO cam.

[mgb260]

B303(your cam) Advanced 4 degrees moves TQ curve from 5000 RPM to 4500 RPM. Surprisingly the mildest HO cam still is at 5000 RPM when 4 degrees advanced.

[IaTR6]

Jim, I am curious, since Larry Shimp changed from the B cam to Comp's XE264HR. If I recall correctly,
it has 212/218 duration @ .050 and would have .512 lift with 1.6 rockers. Would you plug that in to see?
(truth in advertising, or whatever-it's what I have)
Thanks,
Dennis

[mgb260]

Dennis, Here you go! This is fun but rather addictive! It looks very similar to the "B" cam advanced 4  degrees. The same cam Kelly has. I don't know why the bottom of the chart is cut off but, max TQ is at 4500 RPM, HP is at 6500 RPM.

[MGBV8]

Kelly's cam is ideal for fast street.  I have never had so much fun passing cars in places mere mortals wouldn't even consider!  :-0

[ex-tyke]

All hail the mighty 'B' cam!

[kstevusa]

Here's copy from earlier pages of this forum.  These pulls were for different timing settings.  the most advanced was the great fuel mileage.  the other pull was for max power.  These points were determined over time from different dyno sessions.  The A9L (std Trans.) (A3M ?? A/T) ECM was near top of chart  for OBD1 technology. Time dims my memory, but was into Ford Tech at that time. Total package  for my car, weight 2440# wet, no driver,T5Z (Ford racing), 3.55 Ford 8.8 Trac Loc,Ford Focus wheels w/205-50R16 tires 24.1" Dia, Similar engine configured to Factory Crate with Hyperutetic pistons, X-303 heads, XE-264-HR Cam, Roller Rockers 1.6 ratio, 65 mm T/B, Pro-M MAF on GT40 Tubular Intake ported Lower by T. Moss, March serpentine pulley system,& Explorer T/C & Crank Damper. Donor car odometer read 118K miles when I got the package to begin my conversion.  Carl did initial run at Townsend 2006 after the Terre Haute unveiling in  2005. Usually returned 27-28 MPG at interstate speed with adequate performance.  ;-)
Tx 2012 Dyno results.jpg

[mgb260]

Kelly's pic is not showing. Here is the thread.

 http://forum.britishv8.org/read.php?10,26772,page=2

Good HP at the wheels and  max TQ 700 RPM lower than the simulation. I used Rob's engine specs's for the cam comparisons. I picked the Performance Trends program because it doesn't show inflated numbers like some. Those simulations would be at the flywheel with open headers, electric water pump and no accessories. Typically chassis dyno's show peak HP and TQ 500 RPM's lower than engine dyno's. Deduct 20% from the engine simulations above to get approximate @ the wheels.

[rficalora]

Here's the chart for Kelley's car...

[rficalora]

Jim - do the simulations change if you assume my motor but with the Edelbrock Pro-Flo EFI system?  It has a different intake & of course throttle body vs. carb.