Author Topic: Differentials: Open vs Rebuild kit vs Torsen vs Welded?  (Read 18178 times)

PumpItUp

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Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« on: October 27, 2013, 06:46:36 AM »
Any experience with welded diffs? It can't be worse than my current (original) LSD. I was even considering an open-diff for a while (to save money and for the reliability). Now I read many Z3's particularly the later models came with torsens and they swap onto an e30, but how does one distinguish them from clutch pack cases if sourcing from a wrecking yard?
Quote
The internal BMW tech literature very clearly states that MZ3's came with a special standard type LSD (clutchpack) except that it has 25% lockup under acceleration and 40% lockup under deceleration which is what differentiates it from an E36 M3 LSD that is 25% lockup both ways. The same literature states that the 1999+ Z3's have a "special design" LSD (Torsen).

"The smaller case was used on 4 cylinder and 320i cars, and has a crown wheel of 168mm."

Small case (168mm) vs Medium case (188mm):
http://84.45.115.78/e30zonewiki/index.php/Differential
http://www.e30zone.net/e30zonewiki/index.php/Limited_Slip_Differential

Medium case (188mm) vs Large case (210mm):
http://www.bmwfanatics.co.za/showthread.php?tid=1374
http://forums.bimmerforums.com/forum/showthread.php?1470479-Nitty-gritty-on-Large-vs-Medium-case-diff-swap

Info on rebuilding LSD:
http://www.r3vlimited.com/board/showthread.php?t=207170
http://e30performance.info/viewtopic.php?f=22&t=939

PDFs:
http://e30eta.com/wordpress/wp-content/uploads/2010/12/Know-your-Differential-EC-12.97.pdf
http://www.metricmechanic.com/pdf/Differentials.pdf

And installation/removal (diff-swap) tutorials:
http://www.esatclear.ie/~bpurcell/318isfaults.html#differential
http://www.318ti.org/notebook/diff_conversion/index.html
http://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Slip_Differential_Swap.htm
http://www.youtube.com/watch?v=CM1QE3T6Guc

Some links for parts:
http://www.pelicanparts.com/BMW/catalog/shopcart/BE30/POR_BE30_TRANSM_pg5.htm
http://www.turnermotorsport.com/BMW-E30/c-37-bmw-differential-upgrades-and-parts.aspx
http://www.ebay.com.au/itm/BMW-E28-E30-E34-E36-LSD-Diff-Rebuild-Kit-/230653176264

After-market differentials (new but pricey):
http://www.kaazonline.com/899.html / http://www.kaazusa.com/lsd_bmw.html
http://www.vacmotorsports.com/catalog/kaaz---limited-slip-differentials-lsd-for-bmw.htm
http://www.vividracing.com/catalog/1991_BMW_3-Series_cusco-typemz-2way-lsd-bmw-318i-is-ti-e36-9198-p-151969.html

Rear-end ratios (these lists are not always completely accurate):
http://en.wikipedia.org/wiki/BMW_3_Series_%28E30%29#Differentials

Quote
U.S. E30s:

318i/is
1984-1985 - 3.64 (84 open for Auto)
1991 - 4.10 (Manual)

318ic
1991-1992 - 4.27 (Manual w/ LSD option)

325
1988 - 2.93

325e/es
1984 - 1985 - 2.79 w/ LSD option
1986 - 1987 - 2.93 (es = LSD)

325i/is/ic
1987 - 1988 - 3.73 (is = LSD)
1988 - 3.73 (Automatic; iS = LSD)
1989 - 1993 - 3.73 (Manual; is = LSD)
1989 - 1992 - 4.10 (Automatic; is = LSD)

325iX
1988 - 3.91
1989 - 1991 - 3.91 (Manual)
1989 - 1991 - 4.10 (Automatic)

M3
1988 - 1991 - 4.10
1988 - 1991 - 4.45 (rare)

325i Touring
3.91 (LSD = option)
« Last Edit: October 27, 2013, 10:32:44 PM by PumpItUp »

DesktopDave

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #1 on: October 27, 2013, 08:53:48 AM »
I thought the Torsen diffs were only offered on the six-cyl Z3, around the turn of the century.  Might have been '99 and later, after the update to the TU motor. The tag and case should have an 'R' instead of an 'S' IIRC.

***EDIT:
Now that I've done a bit more research, I'm not too sure about that.  Here's a good read; apparently the later diffs may have no tag at all.  Worse, a torsen diff will act as an open diff unless under load.  So the usual "spin one wheel" test does not work.  I'd pull the cover in all cases.  A new diff gasket is cheap, and you'll be changing the oil anyway, right?
« Last Edit: October 27, 2013, 10:25:38 AM by DesktopDave »
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

wazzu70

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #2 on: October 27, 2013, 09:38:46 AM »
What is the intended use for the car?

A welded diff is pretty bad at everything unless you only go in straight lines.
-Nick
91 E30 M42 with VEMS

PumpItUp

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #3 on: October 27, 2013, 09:52:42 PM »
What is the intended use for the car?

A welded diff is pretty bad at everything unless you only go in straight lines.
Well I was speaking in general terms but as far as my situation goes that depends as much on the parts I can or can't affordably source as any planned intent. What are the pro's and con's of a torsen? I know it sounds funny but the E30 is kind of a hog at least compared to similar cars of the 1980s. I'm not complaining as there are clearly benefits to the added size and weight like safety and roominess but I'm not sure where the E30 particularly the 318 hits its stride. It wears me down on long trips with its ride and road noise and it's too fat and neutral to be an ideal throw around car. It doesn't get 35mpg like FWD econoboxes of the same era do but it seems to overtake about as sluggish as one. I can look for the 4.27 lsd from the convertible, spend the money on rebuilding it and have the car set it up for thrills, or get 3.73 lsd for its highway "overdrive" 5th gear and put back the stock springs with new sachs struts, and maybe buy some sound dampening material and get more comfortable seats.

An open-diff regardless of ratio is a bit depressing. Years ago at ~$200 they were a risk-free replacement over used lsds which were more expensive and of questionable condition. But now as the prices are similar and if one does the labour themselves, the only real reason to look for one would be to weld it, and a welded diff seems to be for full blown drifting or drag racing. If I could afford to do donuts all day and ruin my ride because I had a spare it would make more sense to preserve the e30 and thrash the spare, a lighter car (like a 2002) or a Japanese RWD more suited to drifting and high angle powerslides than a BMW. I guess to truly enjoy the e30 and gear it towards one direction one needs a second daily driver, either a more comfortable commuter like an e28/e34/e39 just to name a few, or a sportier weekend racer like a Miata or RX7 to make uncomfortable. In the meantime I'll be looking through torsen ratios but the simplest solution seems to be to rebuild the 4.10 factory LSD at home or with a skilled friend though I'm not sure about the parts and where to get them.

The tag and case should have an 'R' instead of an 'S' IIRC.

I'd pull the cover in all cases.  A new diff gasket is cheap, and you'll be changing the oil anyway, right?
Interesting and good point although I'm not sure how a dismantler would react if I started pulling apart cases I wasn't going to buy. Maybe I should bring spare gaskets along ;D to appease them. I found this, not sure about its accuracy:
Quote
E30 318i, M10, 1984-1985 : M168 ring gear, small case diff, shared with 318ti, and Z3 with 1.9 engine

E30 325ix, M20 : M188 ring gear, medium case diff, viscous style LSD

E30 318i, 325, 325e, 325i, 325ic, M3, M20, S14, M42 : M188 ring gear, medium case diff, clutch style LSD also used in Z3 with M50, E28, E24(83? and newer)

swap info: use an E30 rear cover, and E30 output shafts, which just slide in, and there are many medium case diffs that fit an E30.

In 1998-2002, the Z3 2.8/3.0 Coupe, came with a Torsen(similar to Quaife) style diff. Gear ratios are:
2000-2002 Z3 3.0 Coupe, manual had 3.07, auto 3.46
1998-1999 Z3 2.8 Coupe, manual had 3.15, auto 4.10


If you like the diff ratio, you can directly swap one of these into your E30. If you don't like the diff ratio, you can use a 3.23/3.46 and have 3.73 or 4.10 gears swapped on by a differential rebuild shop, and have a Torsen diff in your E30 for fantastic traction.
Also, you can use a 3.07 Z3 Coupe diff, and swap on 2.93 or 2.79 gears for ultimate Eta MPG and traction.
Source: http://www.unofficialbmw.com/phpBB/viewtopic.php?t=32354&sid=1e496132226dafbf5b5a0812a75f0f16

Info on speedometer sensor: http://www.bimmerfest.com/forums/showthread.php?t=5078

E30 turbo with a torsen doing donuts: http://www.youtube.com/watch?v=TNU06icVyPE
E30 M3 making good use of a functioning LSD: http://www.youtube.com/watch?v=OtWUJL7ukLo
« Last Edit: October 27, 2013, 10:15:26 PM by PumpItUp »

DesktopDave

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #4 on: October 30, 2013, 03:53:11 PM »
Well I was speaking in general terms but as far as my situation goes that depends as much on the parts I can or can't affordably source as any planned intent. What are the pro's and con's of a torsen? I know it sounds funny but the E30 is kind of a hog at least compared to similar cars of the 1980s. I'm not complaining as there are clearly benefits to the added size and weight like safety and roominess but I'm not sure where the E30 particularly the 318 hits its stride. It wears me down on long trips with its ride and road noise and it's too fat and neutral to be an ideal throw around car. It doesn't get 35mpg like FWD econoboxes of the same era do but it seems to overtake about as sluggish as one.

If I could afford to do donuts all day and ruin my ride because I had a spare it would make more sense to preserve the e30 and thrash the spare, a lighter car (like a 2002) or a Japanese RWD more suited to drifting and high angle powerslides than a BMW. I guess to truly enjoy the e30 and gear it towards one direction one needs a second daily driver, either a more comfortable commuter like an e28/e34/e39 just to name a few, or a sportier weekend racer like a Miata or RX7 to make uncomfortable. In the meantime I'll be looking through torsen ratios but the simplest solution seems to be to rebuild the 4.10 factory LSD at home or with a skilled friend though I'm not sure about the parts and where to get them.

Might just be that your LSD clutch pack is worn out.  Rebuild parts are available from BMW, there are a lot of rebuild guides out on the Google.

 How new are your bushings & struts?  If any of those are worn out, the car just won't be running at its best.

I'm not sure about your info...IMHO the E30 isn't that heavy at all.  It feels solid, but that's just a clever illusion.  Drive an early 90's M-B 190e, then get back in to the E30.  It'll feel downright light and tinny!  I'm told an E30 M42 trimmed for action is ~2500 pounds.  My sedan is only a few pounds heavier, and I've loaded it up with goodies.  That's only 300 pounds heavier than an '02 - and even the tii made less power!

Comparative sporty cars of the time were similar.  I took a look and compared a few of the cars I've known and owned in the past...none of them really stand out.  I'll stick with sporty sedans and coupes (a real sports car is an entirely different beast).  Let's review them, shall we?
 ;)
VW GTI?  The Mark 2 is nice and light at 2300 pounds, but the tweaked SOHC 1.8 only pushed out 105HP.  Even the rare 2.0L GTI/16v was only good for 134.  Although my Golf was fun to drive, it was a handful at the limit.  It was oh-so-easy to lift the inner rear wheel on anything resembling a turn...not confidence inspiring, that's for sure.
A Honda Civic Si or CRX Si was light - also about 2300 pounds, but their 1.6 was good for only 108HP...and you had to rev the heck out of that car to get some torque.  As far as handling, I have never driven a pre-2000 Honda that really felt planted.  Fun? Yes. Solid? No.
My old Nissan 240sx had more power (155 HP) and a bit more torque, but it was an easy 300 pounds heavier.  The truck engine KA24DE made it easy to drive, great low-end grunt, but it just plain hated revs (shame they didn't import the CA20DET, eh?).
Even the drifter darling AE86 is only a hundred pounds or so lighter than our 318iS.  The Toyota's chassis dynamics are great (except for the live rear axle) and the 4A-GE is a great motor, but it's down a bit on power compared to the M42.
The awkwardly-styled SAAB 900 turbo was good for 160hp.  Great handling, solid car.  Unfortunately it ran about 2700 pounds.  The Volvo Turbos are great cars too, running near 200HP.  Unfortunately they're also 3000 pounds.

I left my favorite for last, had to mention it.  My flyweight '82 Toyota Starlet (hilarious car, BTW - 1.2L carb pushrod with a 5-speed & RWD) was a whopping 800 pounds lighter than an E30 but only had half the power - maybe 70HP.  I ride motorcycles that feel more secure!
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

PumpItUp

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #5 on: October 30, 2013, 07:36:05 PM »
Drive an early 90's M-B 190e, then get back in to the E30.  It'll feel downright light and tinny!
True, but it will also make the E30 feel downright shitty, along with pretty much anything else that's not a 1980s Mercedes. The Cosworth 190 is one of the best cars I've driven even if it was gutless and sometimes felt like driving a city bus because of it. The thing is it did some things so well that I could ignore its other failings. Where the m42 powered E30 doesn't have any one thing to make you love it.
Comparative sporty cars of the time were similar.  I took a look and compared a few of the cars I've known and owned in the past...none of them really stand out.
I agree, but at the same time out of all those cars listed the E30 (m42 or even m20) is in my experience the most boring to drive, barring major upgrades like an S50 swap of course. However m20 E30s have torque to enjoy, a more quiet and solid ride and that great engine noise. Emissions standards brought detuned imports to the American market and really killed the fun for cars with small engines, and the jumps in power every few years couldn't keep up with the jumps in weight and safety. But out of all those cars it's the 318 that's begging the most for increased displacement. With a 2.0 it could have been a legend, instead it's just a wannabe, a "girl's car" for those too poor to afford an inline-6. Of course guys who speak like this tend to be massive idiots basing their opinions on preconceptions and see cars as status symbols and penis extensions, but even those idiots have kind of got a point. It's just a "spirited" commuter, but could of been much more.

The E30 M3 was a very successful race car and perhaps the 318is is even quicker, but so is any modern family sedan. When rating "sports" cars in the context of a daily driver, it's not about theoretical performance, specs on paper and/or Nurburgring lap times. It's about thrills, reliability and of course money. Can you say the 318is delivers more thrills and more miles per buck than those Japanese models listed (or even the ancient but non-carbureted 2002)?

Slowered318

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #6 on: October 31, 2013, 09:51:00 AM »
I've been running an 8 bolt 4.10 LSD for the past 10 years. It's overkill for a 4 cylinder, 2600lb coupe but firmly plants the rear end especially in bad weather. If I didn't spend so much money initially and on rebuilds over the years then I would happily try out another small case, I remember the car felt a bit more nimble/fun before the swap. That being said the ideal diff would be a 3.91 or 4.27 8 bolt LSD/Torsen, depending on the build of your 318. I would certainly go with a fully rebuilt unit by one of the reputable companies before spending $600+ on a diff of questionable condition.

Most European and Japanese cars are 4 cylinder by default, I don't see how anyone can say an old BMW is a feminine just because it's 4 cylinder. I don't know many women who like the boxy styling, prefer RWD over trunk and leg room, truly appreciate standard transmission, or can tolerate constant maintenance. If that's not enough you can beef up the suspension, upsize the wheels, throw in a short shifter and lightened flywheel, aftermarket exhaust, rip out some sound deadening, delete the power steering and poly bushings. Respect to your woman if she still wants to drive it!  LOL

DesktopDave

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #7 on: October 31, 2013, 05:26:05 PM »
I don't know many women who...can tolerate constant maintenance.

I know a few women who tolerate constant maintenance very well!   ;D   My (nearly-perfect) wife only has that one nagging flaw - she hates driving my car!

I've been running an 8 bolt 4.10 LSD for the past 10 years. It's overkill for a 4 cylinder, 2600lb coupe but firmly plants the rear end especially in bad weather. If I didn't spend so much money initially and on rebuilds over the years then I would happily try out another small case, I remember the car felt a bit more nimble/fun before the swap. That being said the ideal diff would be a 3.91 or 4.27 8 bolt LSD/Torsen, depending on the build of your 318. I would certainly go with a fully rebuilt unit by one of the reputable companies before spending $600+ on a diff of questionable condition.

I agree, rebuilt is best.  I swapped in a medium case LSD when I bought the car, but the clutch pack was shot.

BTW, you (hopefully) can't imagine the racket a bad diff bearing can make...sounded like it had a trunk full of loose lead shot.  My wife thought I was insane the first time I took her out in it!
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

Slowered318

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #8 on: November 01, 2013, 09:29:34 AM »
Hahaha!

I agree, rebuilt is best.  I swapped in a medium case LSD when I bought the car, but the clutch pack was shot.

BTW, you (hopefully) can't imagine the racket a bad diff bearing can make...sounded like it had a trunk full of loose lead shot.  My wife thought I was insane the first time I took her out in it!

I don't have to imagine the bad bearing sound, experienced it first hand last summer! :-\

Fortunately I haven't burnt out my clutch pack but I have replaced the bearings twice and seals three times. Despite this I still get a few drips from the CV shafts, any advise on preventing that? I'm not entirely confident in the shop that last rebuilt it, I was unable to deal with them directly.

80% sure my diff is a LSD, on the bench it almost feels like it's welded but I was told it came off a 325ix. Can you verify the tag markings S for LSD and R for Torsen?

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #9 on: November 01, 2013, 04:28:35 PM »
80% sure my diff is a LSD, on the bench it almost feels like it's welded but I was told it came off a 325ix. Can you verify the tag markings S for LSD and R for Torsen?

I can 100% verify the 'S' is on diff tags and painted on the top of all the clutch-pack LSD (Salisbury type).  I don't think the Torsen has any markings, I only found one reference about any letter.  IIRC the newer diffs all have printed labels that tend to fall off.  I'm still researching that.  It's all hearsay until I see it with my own eyes.
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

wazzu70

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #10 on: November 06, 2013, 05:37:25 PM »
The IX diffs are viscous, not clutch or torsen.


From reading this, I think you need to learn how to drive :)

If you want your car to handle crappy (like a drift mobile) upgrade the rear sway bar to a stiffer unit. You will have no issues having the rear end pass you.
-Nick
91 E30 M42 with VEMS

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #11 on: November 08, 2013, 06:59:36 AM »
The IX diffs are viscous, not clutch or torsen.

I thought the rear diff on the iX was a clutch pack type?  If it's a viscous, that's one more good option for our little cars.  None of them are perfect, but they all provide better solutions than an open diff.
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

colin86325

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Re: Differentials: Open vs Rebuild kit vs Torsen vs Welded?
« Reply #12 on: November 08, 2013, 09:10:34 AM »
Yep, iX uses a viscous type.