318is Diff in my Ti

[brotherkimball]

I just got a 98 318ti a few months ago and i love it, i wasn't sure at first, but i love it. i just came across a 4.10 L.S.D. from a 91 318is (for free) and i'm thinking about putting it in my car.
My questions are:
How easy is this, is it a straight bolt in or do some pieces have to be replaced (back plates?) etc...
Has anyone does this swap..any comments?
What is the stock diff in my car, i'm pretty sure its a base model, it HAD steel wheels when i got it, no fog lights, no OBC, has sunroof. I want to know this so i can think about how much of a difference this will be.
any imput helps, thanks,
tyler

[SDKmann]

If its free and from a E30 then grab it right now. Im not sure about instalation but there may be a DIY here or on Bimmerforums. You dont have a LSD in your car so this will definitly be an improvement. Many people have done the swap so Im sure there will be someone who can give more details. Sorry, wish I could be of more help.

[brotherkimball]

to clarify i can swap identical diffs no problem i'm wondering how much "jerry-rigging" is required to do this thanks

[larryn]

Since it has the e30 diff cover, it will bolt right in to the same mounting locations.

It will also bolt right in to your drive shaft. However, you have a couple of options on the output (half) shafts.

The E30 has a different bolting arrangement from the output flange of the diff to the half shafts, than the e36 318ti. You can do one of two things.

1.) Pop the output flanges out of the existing 'ti diff and put them in your new 4.10:1 diff. They physically fit, but do not insert all the way into the diff splines as far as the e30 ones do. So, it will work, but it's not optimal.

2.) Source the E30 half shafts, and replace the ones in your 'ti with those. This is the better of the two options, since you will be able to use the E30 output flanges, which extend all the way into the diff spline area.

If you go with option #2 (as I did), make sure you get the half shafts that are from an ABS equipped car. They have a grooved section on the outboard side of them that the ABS sensor on the wheel yoke will use to sense slippage.

Btw, this isn't a Jerry-rig. Our cars have an E30 rear suspension, so it's a direct OEM diff swap.

[brotherkimball]

thanks a lot for that info, it sounds easy, does anyone have the 4.10 in their car? i think it might be to low for everyday driving since the stock is 3.45...

[larryn]

Originally Posted by brotherkimball

thanks a lot for that info, it sounds easy, does anyone have the 4.10 in their car? i think it might be to low for everyday driving since the stock is 3.45...

I drove a 318is this past weekend on an autocross course, that had a 4.10 in it, and 1st gear was a joke. It certainly took off quickly, but you have to shift to 2nd almost immediately. I think 2nd gear topped out at 45mph, iirc.

I bet 5th gear @75mph will be around 4500rpm too. Just a thing to think of.

[zboot]

Write up: http://www.318ti.org/notebook/diff_c...ion/index.html

It's not too onerous a task. The stock diff is a 3.45. I'm not sure what the size diff is for the 4.10. I recently swapped to a 3.73 which is larger and heavier than the stock diff. I was able to get the stock in and out of my car by myself and only needed the floor jack to support it while unbolting. Once free of bolts, I was able to pull it out by hand. The 3.73 was way to heavy to manipulate myself. I'd suggest having a friend on standby in case you need the extra help.