e30 Diff Swap

[L84THSKY]

Andy, do this simple measurement.

Measure the width flange to flange of each of the two diff in the picture, with the stock flanges. Then take the ti flanges out and put them in the E30 diff, and measure the width flange to flange.

The problem with everyone throwing their insight into the mix is, they are confusing the issue.

Anyone who has ever done an experiment knows, if you change two variables, you won't know which one did what. By swapping the SAME flanges in two DIFFERENT diff housings, we can do a proper measurement.

I keep hearing, the shafts are longer/shorter so that means ........
The flanges are longer/shorter, so that means ...........
The bodies of the diffs are wider/narrower, so that means........

It don't mean ****, if people keep comparing multiple issues and trying to come to a conclusion.

PLEEEEEZE, some one just compare the flange to flange width of an E30 diff with ti flanges, and a 318ti diff with ti flanges.

If I leave my shafts in, and remove the diff, the car will expect the diff I put in to have the same width to fit. So I don't car about the shafts, just the flanges and diff. The diff/flange combination I replace must have the same width as what was in there. The only way I will know is to do what I'm asking.

Thanks
Eric

Originally Posted by andy

http://www.318ti.org/gallery/showgallery.php?cat=600

1. The output shafts' flanges' holes are indeed further apart than the stock unit. I assume this is where swapping flanges comes in.

[HigH RevZ]

Originally Posted by cali-ti

if you can find a ti or 1.8/1.9 z3 auto that had a LSD (again, this is a small case diff), it will bolt right in with no issues (and be the same 4.44 ratio as your current automatic open diff). it's going to a large case diff where you run into fitment issues (although not too big of issues).

So I would have to find a sport Ti to get the lsd, correct.

[cali-ti]

it was standard only on the 95 club sport, optional on other 95s and early 96s (i believe) until ASC+T became standard. after that, i don't believe it was even an option. likely the same with the 1.8/1.9 z3s.

[andy]

I shall, I shall! I got busy last night, and I have to take the gf out tonight, but I've got all the parts sitting on my garage floor ready for measurement. Comparing the pics from the other thread, they do look shorter, but wasn't that a 5 series diff?

Originally Posted by L84THSKY

Andy, do this simple measurement.

Measure the width flange to flange of each of the two diff in the picture, with the stock flanges. Then take the ti flanges out and put them in the E30 diff, and measure the width flange to flange.

Thanks
Eric

[andy]

Yep, it was a $550 option on my non-club sport package '95...I still have the window sticker around somewhere.

If someone wanted to make their automatic faster (or if you were a complete nut that only drove on tight roads) you could find a small case auto diff from an older 318 auto; I believe they came with a 4.88. A search on RealOEM would tell for sure.

Originally Posted by cali-ti

it was standard only on the 95 club sport, optional on other 95s and early 96s (i believe) until ASC+T became standard. after that, i don't believe it was even an option. likely the same with the 1.8/1.9 z3s.

[mischief]

all you most click on this link if u havent seen it allready will tell you all you need to know now click on the link
http://www.emotors.ca/articles/7.aspx

[andy]

Here is a picture of the e30 diff with one ti flange and one e30 325 flange stuck in it.

http://www.318ti.org/gallery/showpho...o=1816&cat=600

Long and short of it is that they stick out nearly exactly the same distance; possibly less than a millimeter difference. Both measurements are 14.5mm, from the centerline of the diff to the edge of the flange.

I read through the link in the last post, and I think this guy's on to something here. Going to be busy this week, but I'll check in when I get the chance.

[L84THSKY]

Andy

I think you missed the point. Your comparision doesn't help. I asked for a picture of the stock ti diff with stock flanges, compared to the E30 diff with ti flanges.
You are comparing two flanges on the same diff, that tells me nothing. Since the E30 diff is wider, I still can't draw any conclusions from your comparision.

Can you please just measure the ti diff flange to flange with stock flanges. Then remove the ti flanges and put them in the E30 diff and measure flange to flange. If you do that, there will be absolutely no confusion, missinterpretation or false conclusion drawn. That is the ONLY way to know for sure.

Originally Posted by andy

Here is a picture of the e30 diff with one ti flange and one e30 325 flange stuck in it.

http://www.318ti.org/gallery/showpho...o=1816&cat=600

Long and short of it is that they stick out nearly exactly the same distance; possibly less than a millimeter difference. Both measurements are 14.5mm, from the centerline of the diff to the edge of the flange.

I read through the link in the last post, and I think this guy's on to something here. Going to be busy this week, but I'll check in when I get the chance.

[andy]

L84THSKY - I see, I thought it was obvious from the pics, but yes, there is a lot of conflicting information out there.

These measurements were from outside of the output flange to the outside of the output flange, for each diff.

318ti flanges in a 318ti diff (168): 25.5 cm
318ti flanges in an e30 325is (188) diff: 28.25 cm

The e30 diff is definitely wider (by about 2cm) and while the ti flanges do sit in nice and snugly, they don't sit in further to fully account for the difference in size of the 188 diff. Note these aren't super-exact measurements, I don't have any fancy calipers to measure these at home, just a few straight edges and a tape measure.

Interestingly, I swapped the flanges back afterwards, and the e30 flanges in the e30 diff were the same as the ti flanges in the e30 diff.

So, it's the above article talking about only swapping the inner e30 cv joints onto a ti axle? That'd theoretically leave us with an axle that's about a cm too long, right? Unless the hub has enough play to accept the extra axle when tightening the collar nut. Hmm....

[L84THSKY]

Thanks Andy. That is exactly what I wanted to know. Now the question is, will the E30 diff work wih ti flanges, and the stock halfshafts? I've heard people say yes. I also saw the writeup on the website that Constant Yu swapped inner CV joints from an E30 halfshaft.

That is what I'm not sure about now. Do I keep ti flanges and inner CV joints, or must I swap to E30 flanges and E30 inner CV joints.

From what you said E30 diff with ti flanges is almost 3cm to wide, as opposed to swapping to E30 flanges and E30 CV joints; which is only 1 cm too wide.

The truth is, I have heard of people doing both, with no problems. That leaves me with doubt about what is true.

Originally Posted by andy

L84THSKY - I see, I thought it was obvious from the pics, but yes, there is a lot of conflicting information out there.

These measurements were from outside of the output flange to the outside of the output flange, for each diff.

318ti flanges in a 318ti diff (168): 25.5 cm
318ti flanges in an e30 325is (188) diff: 28.25 cm

The e30 diff is definitely wider (by about 2cm) and while the ti flanges do sit in nice and snugly, they don't sit in further to fully account for the difference in size of the 188 diff. Note these aren't super-exact measurements, I don't have any fancy calipers to measure these at home, just a few straight edges and a tape measure.

Interestingly, I swapped the flanges back afterwards, and the e30 flanges in the e30 diff were the same as the ti flanges in the e30 diff.

So, it's the above article talking about only swapping the inner e30 cv joints onto a ti axle? That'd theoretically leave us with an axle that's about a cm too long, right? Unless the hub has enough play to accept the extra axle when tightening the collar nut. Hmm....

[andy]

Originally Posted by L84THSKY

The truth is, I have heard of people doing both, with no problems. That leaves me with doubt about what is true.

Well, the situation is probably what can be made to fit, vs. what is optimal given the different dimentions. If it's off enough on the axle to fit, yet might be causing undue wear on the diff, hub, or CV joints, then that's not something someone would discover until further down the road. There could be enough play in the system to handle a cm on each side, but we don't know that yet.

Also, I was thinking, since the 188 diff output flanges are placed further back than 168, then that could mean less of a straight shot, and a longer distance to cover making up for the wider diff.

[andy]

Okay - finally got this to work.

1. Swapped the e30 inner joints into my ti axles. I could get them to fit in, however, when put the car back down on the ground, the axles did bind up and interfere with the suspension's travel.

2. Swapped the ti inner and outer cv joints onto the e30 axle. The entire setup was noticibly shorter than the ti axle setup. The outter CV joints are quite difficult to get undone, and we destroyed the inner clip ring getting them off. However, this did allow me to keep ABS (the old e30 axles did not have ABS) and come up with a setup that fit.

Here are the part numbers I used:

01 FINAL DRIVE 3,73 09/1988 33101211960 (from a '88 325)
01 OUTPUT SHAFT 33211226333 (from an '84 318i)

I may go with a 4.11 in the future, this is a race car afterall. But I think this should be a good start.

[jonchino]

ok so is this what worked?

Ti's inner and outer cv joints on the E30s axle.?

plus the Ti's flanges on the E30 Dif..?

and you got the ABS to work..?

thanks
Chino

[andy]

It was

'87 e30 325 diff and output flanges
84 e30 318i axle (all the e30s appear to use the same axle)
e30 inner cv joint, mated to the e30 diff
ti outter cv joint, mated to the ti hub as usual

Removing the outter cv joint from the ti axle was a treeemendous pain; it doesn't have a lock washer like the other end. I realize some of the writeups seem to show the e30 axle isn't longer than the ti axle. I found the e30 axle (just by itself, no cv joints on it) to definitely be noticibly shorter.

Oh, and because I did keep the ti outer joints, abs is fine.

Originally Posted by jonchino

ok so is this what worked?

Ti's inner and outer cv joints on the E30s axle.?

plus the Ti's flanges on the E30 Dif..?

and you got the ABS to work..?

thanks
Chino

[97BlueTI]

Hello

I am looking to also do this diff swap for my 97ti, I already have the E30 differential but I am in need of the inner CV joints to put on the ti axels. Could anyone let me know where I could find some?
Thanks 97BlueTI
dvanlengen@mchsi.com