As written; you (I) have more than one differential...what gears do you put in it?

In my car; I have a 2.59...great for highway since I can get 30 to 33 MPG at around 68 MPH.

but I have a spare diff. sitting in my shop, I was thinking a 3.55 or 3.73 that I can swap out when I want to go sporting.

I did a dyno-tune and was easily putting down 330+ HP at the wheels, my tuner did a kick down to spike true HP estimation (if geared correctly) and spiked 406HP at the wheels.

Since these diffs. are easily swapped...what gear ration would you select?

I believe the sport diffs. were 3.08 which was a great medium choice for highway or sport.

I am not interested in medium, but at the same time I am not looking into a 4.11 or 4.56 that limits me.
My L82 has a 3.55 diff. and I believe it would do just Ok with an OD tranny..

With the 2.59 diff. presently in the car I can barely lock up the torque convertor at 2000rpm, going around 68 to 70MPH.


And back to the question, you have one diff. with 2.59, its great for highway, the engine has plenty of get-up-and-go to beat stock C5's as is with this diff., and now you want to build a spare diff. that takes you beyond beating stock C-5's.
I am currently running 12.90's with the 2.59 diff, and 18" wheels

Specifics:
460LE tranny, well built (for up to 550hp)
2000rpm stall convertor
LT1:
bored
stroked
splayed 4bolt main
heads ported and shaved
block decked
roller rockers and lifters.
 healthy cam
windage tray
headers, blah-blah-blah
almost 10:8.1CR and tune set @ 13.7 to 1 fuel mixture



What gear ratio do/would you install?



Jim

I'm also in the same pickle.  1995 LT-1 with a 2.59.  After all the reading and research I've done to date, I've been thinking of a 3.45 or a 3.54 (seems to be the best choices for kick in the pants feel plus decent highway manners).  Plus with the D36 housing it works.  With your RWHP, will the 36 stand up to the torque with the 3.73?  And you are a braver man than me saying that the swap is easily done, I think it's a PITA

I am not sure the spare diff. is a D36 (my luck; probably is)....but; I am thinking anything close or at the 3.5 turn ratio would be OK for occasional use. *crosses fingers*
If it does OK, I would make that my primary diff. and swap to the 2.59 for trip, or even put taller gears in that diff......I'm so confused......

Compared to my C3,5, the C4 batwing diff. swap is a snap....especially if the spare tire components are already gone.



Jim


[QUOTE=jimmymack]I'm also in the same pickle.  1995 LT-1 with a 2.59.  After all the reading and research I've done to date, I've been thinking of a 3.45 or a 3.54 (seems to be the best choices for kick in the pants feel plus decent highway manners).  Plus with the D36 housing it works.  With your RWHP, will the 36 stand up to the torque with the 3.73?  And you are a braver man than me saying that the swap is easily done, I think it's a PITA [/QUOTE]

I've got a friend with a 94 LT-1 stock and the 3.54.   I can REALLY  feel the difference between his and mine off the line.  He revs higher at 65 MPH and gets about 3-4 MPG less than me on trips down the Jersey shore, which is a acceptable swap to me.  There's an old thread on another forum that let's you calculate all kinds of spec's for gear swaps, (just plug in values).  I'll look for it and post it if I can find it again.  Anyway, once I find a D36 chunk with those gears, I'm swapping them out. If you are doing serious strip runs, maybe a D44 with serious gears is a better choice for you? Either way, keep us informed, sounds like a fun project to cap off your ride.

[QUOTE=jimmymack]  There's an old thread on another forum that let's you calculate all kinds of spec's for gear swaps, (just plug in values).  I'll look for it and post it if I can find it again.[/QUOTE]

Thanks; I do have the time to wait....I dont want to rush into something and have to settle....I like to do things one time.




[QUOTE] If you are doing serious strip runs, maybe a D44 with serious gears is a better choice for you? Either way, keep us informed, sounds like a fun project to cap off your ride.[/QUOTE]

Yeah; I know where there is a few of them (4 x D44 last I saw)...I just dont know what years each of them are, nor do I know "direct bolt on" compatibility per model year .
I'm thinking all LTx's are direct bolt on with each other, even with factory upgraded suspensions.
And a good chance older models are a direct bolt on as well; I just dont know for a fact.

I am gonna do serious strip runs (when I do run), but, the car is not going to be a dedicated strip car in any way shape or form....its too comfortable, almost perfect interior and exterior, a perfect DD if a person wanted (I have my Silverado for that)...it could pass as a 5y/o car instead of a 13y/o car. 
So; if I was to put lets say a 4.56 set, that would really limit me except for lower speed trips or track running...also considering a set that would work decently for auto-X, but primary racing sport would be 1/4mi, not 1/8th.

This is what these forums are for; tech, swaps, and sharing experiences.
I like to go with experience on some things vs. "opinion".

So this is the dilemma:
Diff.-A/primary
1-must do 1/4mi. respectably.
2-be capable of having *fun* if auto-X'd.
3-must have decent road manners when not sporting.

Diff.-B/secondary
1-tall gears for highway.
2-see #1

[QUOTE]  Anyway, once I find a D36 chunk with those gears, I'm swapping them out.[/QUOTE]

Are you saying you are looking for a D36 with any gear set so you can swap?

or

Are you saying you are looking for a D36 with a specific gear set already installed?



Thanks!! 


Jim

Looking for one with the gears already installed.  I'm waiting on a friend who has the setup, he's going to a D44 (this summer supposedly) and I have first dibs.  I've looked at converting mine but every shop that is reputable or has a decent reputation for doing it right, wants an arm and a leg to do the setup, even with me furnishing the gear set.   Just biding my time

I think your d36 will take upt to like 500hp for sure unless you are geting traction.  I have 3.75's to put in, and I am expecting much more fun than the 2.59 crap.  I have been in many and with many gears, you will love anything other than 2..... series crap, but I loved the high 3's gears in a vette, I would swap it out with anything you have if you have the menas and trust your parts.

[QUOTE=pologreen1]I think your d36 will take upt to like 500hp for sure unless you are geting traction.  I have 3.75's to put in, and I am expecting much more fun than the 2.59 crap.  I have been in many and with many gears, you will love anything other than 2..... series crap, but I loved the high 3's gears in a vette, I would swap it out with anything you have if you have the menas and trust your parts. [/QUOTE]


Been looking into it more...there are certain items to buy and weld to help strength.

For all around fun with the auto tranny, my best bet is to set up one of the D36's with 3.55/4(range) and keep my 2.59 and my 30 to 33 mpg handy.

As Polo stated, with traction I'll break parts with too much torque....I have the HP, the 2.59 limits the torque.....Its that or buying a D44 or race specific chunk.

I can afford to blow at least one diff since I have a spare.


Choices, too many choices...


Thanks,
Jim