Author Topic: LSD Differences... (Read 4102 times)

ZeroG · « **on:** March 19, 2007, 09:42:06 PM »

Maybe you guys can help out a little as the guys on BFC seem to be worhtless.

Does anyone know why you would prefer a Variable Limited Slip Diff vs. just a LSD with an increase lock up say 40%? I believe that the factory LSD lock up was 25%. So what is gained by increasing to 40% and what is gained by going to a VLSD?

I would think that if the course is tight and you have too much lock you would scrub some speed.

b318isp · « **Reply #1 on:** March 20, 2007, 07:28:48 AM »

With the 40% lockup you will get better traction in a straight line, however I'd think that you would get a lot more understeer and less adjustability as it can be handy to get one wheel to break traction a bit.

Gunni · « **Reply #2 on:** March 20, 2007, 07:45:40 AM »

25% refurbished is all you need,
if you know you need 40% then asking us isn�t what you would be doing,

What are your intentions

ZeroG · « **Reply #3 on:** April 15, 2007, 09:05:20 PM »

Quote from: Gunni;21779

25% refurbished is all you need,
if you know you need 40% then asking us isn�t what you would be doing,

What are your intentions

I really don't know that much about LSDs. I currently have an open 3.45 in my 318 track car and I was thinking of purchasing a purpose built LSD and was trying to figure out which was the best set up.

From what I have heard a VLSD is the way to go, it will be like 25% when you turn in and 100% when you go straight.

jetteman · « **Reply #4 on:** April 15, 2007, 10:01:48 PM »

from what i know a vlsd stands for a viscous unit. if so i dont like them for the fact that the fluid packs tend to be useless after being applied a couple times back to back, then you have an open until it cools slightly. i would just go with a rebuilt medium case 4.10 clutch type.

ZeroG · « **Reply #5 on:** April 15, 2007, 10:30:51 PM »

Quote from: jetteman;23855

from what i know a vlsd stands for a viscous unit. if so i dont like them for the fact that the fluid packs tend to be useless after being applied a couple times back to back, then you have an open until it cools slightly. i would just go with a rebuilt medium case 4.10 clutch type.

Interesting.. I thought VLSD = Varriable LSD

jetteman · « **Reply #6 on:** April 16, 2007, 03:51:14 PM »

i have been reading and it definitely means viscous limited slip differential. it works with a viscous fluid between two slotted plates and as the fluid is heated up from the friction of the slipping discs (when the car spins one tire) the fluid applies pressure to the plates thus locking the two axles together. so one of the many problems is the time it takes the fluid to lock the two together, also the fact that they become useless when heated continuously until cooled. this diff is an option on many factory cars as a means to deal with wet and snowy roads not really a good option for the performance oriented driver. in addition i do not know of an e30 with this diff. the only other option i would think about would be a torsen unit which gives power to which ever wheel has more traction from companies such as quiafe and kazz (SP). at least thats my $0.02

cecotto · « **Reply #7 on:** April 16, 2007, 03:56:21 PM »

Quote from: jetteman;23888

i have been reading and it definitely means viscous limited slip differential. it works with a viscous fluid between two slotted plates and as the fluid is heated up from the friction of the slipping discs (when the car spins one tire) the fluid applies pressure to the plates thus locking the two axles together. so one of the many problems is the time it takes the fluid to lock the two together, also the fact that they become useless when heated continuously until cooled. this diff is an option on many factory cars as a means to deal with wet and snowy roads not really a good option for the performance oriented driver. in addition i do not know of an e30 with this diff. the only other option i would think about would be a torsen unit which gives power to which ever wheel has more traction from companies such as quiafe and kazz (SP). at least thats my $0.02

The 325ix came with a viscous locking unit.

jetteman · « **Reply #8 on:** April 16, 2007, 05:25:40 PM »

good call i forgot about the awd would be kinda hard to drive without the slip in the middle

dlmrun2002 · « **Reply #9 on:** April 16, 2007, 06:29:49 PM »

The 325ix viscous... Isn't that for the front to rear torque? Not the rear diff?
dlmrun2002
1974 2002 L Jetronic efi
1989 325iX "SNOW DAWG"
1991 318is mmmmmmm42

jetteman · « **Reply #10 on:** April 16, 2007, 08:29:57 PM »

yes it allows slip between front and rear if not the drive line would bind up on hard corners. the viscous is the biggest difference between a 4wd and an awd vehicle. also the car would chew the hell out of the tires without the viscous.

ZeroG · « **Reply #11 on:** April 16, 2007, 09:02:00 PM »

This is the unit that I am thinking of getting..

http://www.metricmechanic.com/pdfs/Differentials.pdf

MM Variable Limted Slip

jetteman · « **Reply #12 on:** April 16, 2007, 09:45:34 PM »

from what i get from the site is that it is a clutch type lsd but it is more of a 1.5 way as opposed to a one way, meaning that it locks always on acceleration and about half the time on deceleration. this would be a good choice but a stock medium case lsd will give you alot of the same operation at a lot less out of pocket. i would recommend a stock lsd that was just freshened up with new clutches. if you want more lockup than stock you can remove one of the steels and use one of the old clutches in place of it (this is what i will be doing). this will increase lockup to about 35% or so. sorry about the confusion

Author Topic: LSD Differences... (Read 4102 times)

ZeroG

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