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tips, technology, tools and techniques related to vehicle driveline components

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mgb260
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 10, 2017 07:41AM

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
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator
Posted by: rficalora
Date: November 10, 2017 12:39PM

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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 10, 2017 03:48PM

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.
viscous.jpg



Edited 1 time(s). Last edit at 11/10/2017 03:50PM by mgb260.


rficalora
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator
Posted by: rficalora
Date: November 10, 2017 04:40PM

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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 10, 2017 04:47PM

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:
viscous 2.jpg



Edited 1 time(s). Last edit at 11/10/2017 04:48PM by mgb260.


rficalora
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator
Posted by: rficalora
Date: November 13, 2017 09:58PM

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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 14, 2017 01:25AM

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:

[zilvia.net]



Edited 2 time(s). Last edit at 11/14/2017 05:54AM by mgb260.



IaTR6
Dennis Costello
Central Iowa
(114 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6

Re: Gear ratio calculator
Posted by: IaTR6
Date: November 14, 2017 12:06PM

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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 14, 2017 03:50PM

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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator
Posted by: mgb260
Date: November 14, 2017 04:44PM

Dennis, I found the thread:

[www.mgexp.com]


rficalora
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator
Posted by: rficalora
Date: November 15, 2017 09:10AM

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)



IMG_1993.JPG
IMG_1994.JPG
IMG_1995.JPG
IMG_2002.JPG


rficalora
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: rficalora
Date: November 15, 2017 10:21AM

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


mgb260
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: mgb260
Date: November 15, 2017 03:41PM

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
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: rficalora
Date: November 16, 2017 08:13AM

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
Carl Floyd
Kingsport, TN
(3232 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: MGBV8
Date: November 16, 2017 11:14AM

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?!



Edited 1 time(s). Last edit at 11/16/2017 05:46PM by MGBV8.



rficalora
Rob Ficalora
Cypress, TX
(2377 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: rficalora
Date: November 16, 2017 11:52AM

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
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5343 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: BlownMGB-V8
Date: November 16, 2017 11:53AM

"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
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: mgb260
Date: November 16, 2017 02:31PM

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.



Edited 1 time(s). Last edit at 11/16/2017 02:33PM by mgb260.


MGBV8
Carl Floyd
Kingsport, TN
(3232 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: MGBV8
Date: November 16, 2017 05:50PM

Or a .80.

[www.allfordmustangs.com]

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


mgb260
Jim Nichols
Sequim,WA
(1804 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gear ratio calculator, rear gears, and transmission ratios
Posted by: mgb260
Date: November 16, 2017 05:59PM

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.
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