rear diff

[Britishstev56]

well after doing some math my rear gear is a 3.46 ,I'm thinking of going down to 3,15 less rpm on highway I'm at 3000 at 77mph ,what does any body think

[spdbrake]

If your going from an open diff to a LSD its a good time to kill two birds....
There should be a metal tag on the aft diff cover, left side. An "S" = LSD, No "S" = Open diff. in both cases always followed by your ratio.
(http://i18.photobucket.com/albums/b1...eese/Diff4.jpg)

I take it your using a calc like this one.
(Gear Ratio Calculator)

It is doable but your only going to drop 200-300 or so rpm. Don't know what rpm your shooting for. An example:
(http://i171.photobucket.com/albums/u.../DSC_0929.jpeg)

This may help in your source search for a LSD with the right gearing.
(http://i714.photobucket.com/albums/w...erentieels.jpg)

A 3.15 LSD on EBay right now....
(BMW 325i E36 3 15 Limited Slip Differential LSD Diff | eBay)


In my search for a reputable diff shop I'm leaning towards:
(https://www.turnermotorsport.com/BMW...aring-upgrades)
On my wishlist as I have an open diff.

[Britishstev56]

thank u for the info I will use looked all over rear could not find my car is 10 years old,maybe never on when bd built it.The place where was finished is now gone and bd does have a record

[eschaider]

Try using the Second Strike Gearing Calculator, click here => Second Strike Gearing Calc.

It should make short work of the research phase of your project.



Ed

[Gaz64]

What transmission do you have?

Gary

[Mark IV]

Originally Posted by Gaz64

What transmission do you have?

Gary

BINGO!

TKO? .62 or .84? T5?

[eschaider]

Hey guys, it doesn't matter!

The calculator models all of them. Just go to the Second Strike Calculator and it will take out all the guess work and unfounded opinions. Leaving only answers you can depend on.


Ed

[Britishstev56]

Thanks guy it looks very much like a t5,5th gear unknown rpm does not drop far from 4th to 5th 3000 rpm on the interstate for 3 hours is bit much I could live with 2500

[Mark IV]

If you have T5 you have one of these ratios:
Racing.


RATIOS
1ST 2ND 3RD 4TH 5TH REVERSE
'83-'84 2.95:1 1.94:1 1.34:1 1.00:1 0.72:1 2.76:1*
'85-'89 3.35:1 1.93:1 1.29:1 1.00:1 0.68:1 3.15:1
'89-on 3.35:1 1.99:1 1.33:1 1.00:1 0.68:1 3.15:1
Tremec 500 3.27:1 1.98:1 1.34:1 1.00:1 0.68:1 3.01:1
Tremec 600 2.87:1 1.89:1 1.28:1 1.00:1 0.64:1 2.56:1
Tremec 600 2.87:1 1.89:1 1.28:1 1.00:1 0.82:1** 2.56:1

*Ford also offered a 0.63:1 Overdrive ratio in 1983.

[spdbrake]

Originally Posted by Britishstev56

well after doing some math my rear gear is a 3.46 ,I'm thinking of going down to 3,15 less rpm on highway I'm at 3000 at 77mph ,what does any body think

I came across these folks today in my Diff searches.
E36 Diffsonline Custom Performance Differential

I also thought this cover quite nice.

Rogue Engineering E36 Differential Cover

[Xmas]

Originally Posted by Britishstev56

well after doing some math my rear gear is a 3.46 ,I'm thinking of going down to 3,15 less rpm on highway I'm at 3000 at 77mph ,what does any body think

I have seen a few 3.23s on eBay that are LSD. I'd probably not go lower/higher than that.

[Britishstev56]

Thanks I did see them too,but if I'm going to change may go lower say 3.15 3000 rpm is just to high on the interstate

[RallySnake]

I think your diff ratio is the best available, leave it alone. Find a 5 speed with an overdrive like the Tremec TKO wth a 0.68 or 0.63 5th gear. Then, you will keep your great acceleration and have low RPM cruising. I run a 3.73 rear end and with the TKO's 0.68 5th gear I cruise the freeway at 80 and 2700 RPM. I kinda wish I had gone with the 3.50 rear end for even better gas mileage on long runs. You must have the 0.83 5th gear and that's the problem. It may be possible to swap the 5th gear in your trans.

[Britishstev56]

thanks yes but rear end can be had for $300 trans $ 800 plus ,for a few rpm .I do c your point I wonder how hard it is to change out 5th gear

[RallySnake]

I believe that you stated that you have a T5 rear? I happen to have one under my workbench with the .68 5th gear. I took it out of the Cobra because the oil leaked out of it and the tail shaft bearing wore out causing a bad driveshaft vibration. I could not bring myself to throw it away. You can have it and combine the best parts together to achieve your goal. I am on the north side of Los Angeles. Where are you?

RS

[RallySnake]

I meant to say: I believe that you stated that you have a T5 transmission. That's what I have.

RS

[Britishstev56]

thank u very much for the offer but I live Tampa fl ,in between a rock and hard place change out rear end gear or trans