My not-so-great Ebay Diff...

#1

Well - looks like I got “taken” on my great “3.73 LSD” Diff. Got it yesterday, unboxed it tonight. It does appear to be an LSD because both outputs turn the same direction when you spin the input but…

About 3 1/4 turns of the input(3.23? or 3.25?) equals one turn of the outputs… DAMN IT

I suppose there was also a 3.23. or 3.25 LSD diff in the E30s? No doubt it is an E30 diff - JUST THE WRONG RATIO !!!

So much for getting my car back together over the 3 day weekend… Now to see if the seller responds to email…

Does anyone know of a part number on the diff that would verify the ratio ???

Thanks

Jim

#2

this sticky page at E30Tech does not list a 3.25 or 3.23 E30 ratio available in the US E30s…

WTF???

http://www.e30tech.com/forum/showthread.php?t=1863

#3

Did you actually read the stamped metal tag on the diff? It should say that it is a LSD and give the ratio numbers.

#4

There is no stamped metal tab on the diff - seller claims he had to reseal the diff cover and left it off… It did say “S3.73”… again, according to him…

He also claims the diff came from his 89 325IC - and that he replaced it with a 4.10 LSD

Is my test valid? Can’t you just count the number of input turns required to produce 1 output turn - or am I smoking dope?

I will confirm my test method on my 3.73 Non-LSD diff - but I don’t see what I’m missing here… I think I have a 3.25 diff - I guess they were available on the 5 series - and maybe it got swapped over to this guy’s car???

Jim

#5

The 3.25 was very common on the E28s and swaps are fairly common as well. The count-the-turn test is valid–might help to mark TDC with a paint pen on both the input and output where you start.

#6

Yeah - I marked input and output so I know I’m relatively close on my ratio… and guess what?

The seller claims that he has no knowledge of a diff swap in his car - so it looks like I’m stuck with a 3.25 LSD diff…

So now what? I really wasn’t looking forward to diff surgery but I guess I could swap the 3.25 LSD diff carrier over to my 3.73 non-LSD case, right? As long as I’m using the 3.73 ring/pinion/case - I don’t think the backlash should change, right? The sad part is that the 3.25 diff only has 75K miles on it - and my 3.73 diff has 200K+ miles on it…

DAMN IT !!!

#7

Before giving up the differential try the whole turns test. 41 turns of the input shaft should result in 11 turns of the output if it is a 3.73 ratio.

#8

This diff don’t pass the test:

41 turns of the input = 12 5/8 turns of the outputs - looks like 3.25 to me…

I’m going to tell the seller that it’s worth $50 to me - because I can swap the LS diff carrier over to my diff with my ring & pinion - but damn that’s alot of work…

Or… anybody wanna buy a “cheater” diff for Road America ??? :slight_smile:

Sure would be nice on that mile long back straight… I won’t tell anyone - just PM me…

B)

#9

Take the rear cover off, turn the diff until the code is visable on the ring gear, it will be a “k” code, a K with 2 numbers, What is it?

AL

The way you describe the turn and count test may not be the reliable way…

#10

L8Apex wrote:

[quote]Or… anybody wanna buy a “cheater” diff for Road America ??? :slight_smile:

Sure would be nice on that mile long back straight… I won’t tell anyone[/quote]

Hit up Steve DeVinney, #410. He’ll probably want to add this to his collection :laugh:

#11

TheRedBaron wrote:

[quote]L8Apex wrote:

[quote]Or… anybody wanna buy a “cheater” diff for Road America ??? :slight_smile:

Sure would be nice on that mile long back straight… I won’t tell anyone[/quote]

Hit up Steve DeVinney, #410. He’ll probably want to add this to his collection :laugh:[/quote]

Hey Mickelson! What are you doing on this Putt Putt course of smack talk? You can do better. Or can you?

Steve D.
Hero to the Differentially Challenged Worldwide

#12

oh wow - obviously some spec E30 history here I need to catch up on… or not…

Way off topic, but I did see a guy get “sent home” from the SCCA Runoffs for cutting big slots in the teeth of his ring gear (less hydro pumping losses in the gearbox you know) - and you guys thought you had spec class rule cheaters… you’ve got some things to learn still from the FV guys, but they’ve been doing it for 45 years…

Back on topic - pulled the rear diff cover - Pinion = 12 teeth, Ring = 39 teeth, I’ve only got a BS in engineering but I think that’s darn close to a 3.25 diff ratio…

So I am screwed for sure. I’ve started the paypal dispute process but the seller is playing dumb as expected. Even if I win, Paypal makes you pay the return shipping - so that’s $70 I’m out already… (paid $101 +$70 shipping for everything)

Also - on the ring gear, here’s the part number: H34 11 5553

On the diff carrier housing: 4061006389 434490 S25

If anyone can link me to a web page that will link this gear to a 3.25 ratio diff - that would be great - I’ll need it for my paypal case. Also thinking that I can reverse charges on my credit card but that shuts down the paypal appeal - so I’m going to wait and see what they come up with.

More fun coming tomorrow - I told you boys that my build would be a soap opera… and it is…

#13

L8Apex wrote:

[quote]oh wow - obviously some spec E30 history here I need to catch up on… or not…
[/quote]

I unknowingly ran a 4.10 diff at NASA nationals (my first race in an E30 - a new build of an auto-to-manual swap) and at Road Atlanta last year. After I posted some video of the Road Atlanta race, my competitors asked if I was running a different diff because my shift points were strange. Turns out, I had used a reference source on the interwebs that indicated that all 1989 is cars had the 3.73. But the autos actually had 4:10s. Unsatisfied with the tremendous amount of flak I caught, I took the suggestion to get 410 as my permanent number to keep the lovefest going.

I accuse Geegar of being Racer X. He accuses me of being a cheater. All in good fun, not serious at all.

Steve D.

#14

Not sure if my number should be 325 or LSD - I think taking LSD would be helpful after my two frustrating days of wrenching on rusty E30 suspension parts…

Front is mostly done - just got started on the rear… rear half of rusty exhaust is gone - looks like the front half needs to go too so I can drop the driveshaft…

FUN FUN FUN

#15

Been there and done that on my 1 month old build. I was able to get the driveshaft out just by removing the hangers on the exhaust and bending it down without removing any of the exhaust. I did later pull the exhaust off though to make putting the new driveshaft in easier. Just waiting on my Autosolutions shifter to put her all back together and see if my $800 car runs worth anything. I learned this weekend that the 32mm fan nut sucks. I spent an hour on it with an adjustable wrench and got no where. Then went on Amazone and ordered one of the 32mm flat wrenches for bicycles. So just remember we all struggle with the build, keep at it.

#16

If there’s a decent bike shop in your area - they will have the flat 32mm wrench - I got one for about $10…

I found a posting either on here or on E30tech about looking at a bike shop - and I get to use mine AGAIN since my water pump didn’t seal properly to the block - I’ve got a water leak - so get to do it all over again…

My “Cat-back” pipes were full of tiny rust holes and not worth saving. Now it looks like I get to drop the front pipe and cats too since they cover the drive shaft tunnel - the fun never stops…

Jim

#17

I called 4 local bike shops, and none of them had one. In fact most thought I was crazy for asking for a wrench that big. I paid $20 for mine, and it shipped yesterday, so I hope I get it this weekend. Also have my 16" electric fan, Red Line tranny, and diff oil on the way from Summit.

#18

Strange on the 32mm wrench - I think it is popular for headsets or crankset nuts…

I got mine at the local outlet of Performance Bike (performancebike.com) - but Austin is a Biking Mecca - thanks to Lance Armstrong - so maybe I’m spoiled…

And… Paypal says I’ve won my case - so all I have to do is ship BACK my Diff - and they will refund my $171… I need to read the fine print - do they really refund it from their paypal funds - or does the seller have to have funds in his account that they transfer back to me? I have to pay for shipping it back - so there’s the potential that I could get stuck for even more $$$…

Jim

#19

Ok - I need to start at the beginning again.
1.Bought 325i
2.Jacked up rear wheels
3.Spun one wheel - other side turned opposite. (have no idea if I was in gear or ebrake on or off (in fact I think one of my ebrakes are partially seized). This indicated I had an open diff.
4.Thinking I had an open diff - I bought my awesome “3.73 LSD” off Ebay. Of course it was really a 3.25 LSD (see above)
5.Yesterday - finally drop the original diff on my car, clean the crud off the metal tag - and it says “S3.73” I turn the input and both outputs spin the same direction. The following P/N is stamped on the diff carrier: 4061006389 824812 S25 - can anyone confirm this is an LSD?
6.Won my paypal case and shipped back my 3.25 diff to “Jose” in Florida. Cost me $50 Fed Ex ground to get my $171 back but I guess I learned my lesson about Ebay and guys named “Jose” who live in South Florida…
7. Did being in gear or having one of my ebrake drums seized or dragging make my LSD diff test invalid?
8.I’ve installed my powerflex diff bushing and I’m going to put my diff back in the car - the ring and pinion really look great for 2xx K miles on it.
9.Too damn hot down here in Texas now - working on the car is no fun at the moment. It may be time to go into Summer hibernation. See you guys in October…
10. King Tut - sorry to hear about your bum tranny - based on my experience I would try a local BWM repair shop or pick & pull yard- ask around the local BMWCCA or autocross clubs - someone should know a good source for a used unit that you can inspect before you buy (and ship across the country).

Jim

#20

Per the tag (S3.73) you have a limited slip differential in the car. You can assess the condition of the clutches by measuring the torque required to turn one wheel with the other locked. With one wheel on the ground use a torque wrench on the axle nut of the other wheel. A diff in great condition will require 65ft-lbs to turn the wheel.