STOCK VLSD vs WELDED DIFF for the track ?
10-15-2008, 06:04 PM
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STOCK VLSD vs WELDED DIFF for the track ?
ok so i drive a 240sx with a sr in it. i recently turned up the boost to 14 psi on the stock t25 and i loose traction at around 4 or 5k when all the boost builds in 1st and 2nd gear. when i first take off my tires dont spin. its only when i hit full boost. right now i have a stock vlsd and one wheel spins. im going to the track on friday to try and run a 12. should i keep the vlsd or buy my friends welded differential ? the track is going to be much stickier i understand, but should i just pay 50 bucks for the diff and be sure ?
how does the car ride, i know its easy to get sideways, but i herd the rear end skips when you make u turns and stuff.
how does the car ride, i know its easy to get sideways, but i herd the rear end skips when you make u turns and stuff.
10-15-2008, 06:56 PM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
I wouldn't even bother with a welded diff on the street, it's a lot of drivetrain stress that you don't need, and the stickier the tires the greater the stress. It only really makes the car decent in a straight line, and even though it makes it easy to break traction during turns it is completely uncontrolled. Not a good drift setup in other words. Too many downsides for something that only actually works at the track.
10-15-2008, 07:03 PM
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10-15-2008, 07:20 PM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
I wouldn't even bother with a welded diff on the street, it's a lot of drivetrain stress that you don't need, and the stickier the tires the greater the stress. It only really makes the car decent in a straight line, and even though it makes it easy to break traction during turns it is completely uncontrolled. Not a good drift setup in other words. Too many downsides for something that only actually works at the track.
10-15-2008, 07:25 PM
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10-15-2008, 07:47 PM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
Right, and I'm saying it's going to be a big pain in the ass on the street just to take it to the track every once in a while. I'm assuming that's why you asked how the ride was and how it behaved in turns....?
Sucks on either type, live or IRS.
A welded diff/spool in a live axle is usually worse on the street than a welded diff/spool in an IRS car. It's all about how the tires can move in relation to the chassis (and in relation to one another) during weight transfer in corners. Live axles are generally less predictable because they don't have any camber gain and the entire axle assembly tends to flutter up and down from one side to the other as the tires break and regain traction. Kind of like a dragster when the wheels break free and both oscillate up and down, but in this case the left and right wheels alternate. The forces aren't the same left to right in a corner, so the motion isn't really symmetric.
IRS setups tend to have much better control of the random movement of the tires as they break and regain traction, and the contact patch is different because of the camber gain with weight transfer. It really just isolates the motion of the wheels much better.
You'll tend to break one tire free with IRS setups, but both tires free with a live axle just because of how the movement of one wheel affects the other. These are all generalizations and there are exceptions to everything, like the horrible IRS on (IRS equipped) Mustangs. There's also other stuff thrown in, like tire traction (width, aspect, compound, etc.) and the unsprung weight of that corner (or some combination of both corners on a live axle setup).
None of this matters at really low speeds obviously, or if you're applying enough power to actually drift. If both tires are sliding you don't have intermittent grip/slip problems, but you still don't have the control that you would with an LSD. This is a good exercise in finding the weak parts of your drivetrain and transmission though, and a live axle can usually take a lot more abuse without breaking a shaft or joint.
A welded diff/spool in a live axle is usually worse on the street than a welded diff/spool in an IRS car. It's all about how the tires can move in relation to the chassis (and in relation to one another) during weight transfer in corners. Live axles are generally less predictable because they don't have any camber gain and the entire axle assembly tends to flutter up and down from one side to the other as the tires break and regain traction. Kind of like a dragster when the wheels break free and both oscillate up and down, but in this case the left and right wheels alternate. The forces aren't the same left to right in a corner, so the motion isn't really symmetric.
IRS setups tend to have much better control of the random movement of the tires as they break and regain traction, and the contact patch is different because of the camber gain with weight transfer. It really just isolates the motion of the wheels much better.
You'll tend to break one tire free with IRS setups, but both tires free with a live axle just because of how the movement of one wheel affects the other. These are all generalizations and there are exceptions to everything, like the horrible IRS on (IRS equipped) Mustangs. There's also other stuff thrown in, like tire traction (width, aspect, compound, etc.) and the unsprung weight of that corner (or some combination of both corners on a live axle setup).
None of this matters at really low speeds obviously, or if you're applying enough power to actually drift. If both tires are sliding you don't have intermittent grip/slip problems, but you still don't have the control that you would with an LSD. This is a good exercise in finding the weak parts of your drivetrain and transmission though, and a live axle can usually take a lot more abuse without breaking a shaft or joint.
Last edited by Fabrik8; 10-15-2008 at 08:08 PM.
10-15-2008, 07:57 PM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
You want to run 12s...aka drag race. Put the welded in.
If you were trying to drift I'd recommend a real LSD over a VLSD or a welded. If the VLSD works properly it'll be great for drifting but they wear out easily as they're based on viscosity and that changes with heat.
You can most definitely drift and road race with a welded, plenty of people do it (dent sport garage 240 at VIR recently for one, several people in Spec E30 as well). It makes the car behave completely differently though. I've drifted and done some spirited driving with a 1.5way (current), welded (before that), and 2-way (before that). I like the 1.5way the best personally - but it's a 1200 dollar diff compared to a welded compared to a 800 dollar diff.
The biggest thing you'll find with a welded diff compared to a LSD is some entry understeer with corners. This goes for drifting and grip. The car will push before it rotates - nothing some gas petal can't fix (even N/A KA) but you definitely have to drive differently then you do with a LSD.
Bottom Line:
Welded - great for drag racing, OK for drift/grip
VLSD (working properly) - sufficient for drift/grip, OK for drag
LSD (clutch type)- Best for drift/grip...if it boasts 100% lock up like my 1.5way does then it would also be best for drag
A 2-way LSD is very sketchy for high speed grip driving......just thought I'd put that out there.
If you were trying to drift I'd recommend a real LSD over a VLSD or a welded. If the VLSD works properly it'll be great for drifting but they wear out easily as they're based on viscosity and that changes with heat.
You can most definitely drift and road race with a welded, plenty of people do it (dent sport garage 240 at VIR recently for one, several people in Spec E30 as well). It makes the car behave completely differently though. I've drifted and done some spirited driving with a 1.5way (current), welded (before that), and 2-way (before that). I like the 1.5way the best personally - but it's a 1200 dollar diff compared to a welded compared to a 800 dollar diff.
The biggest thing you'll find with a welded diff compared to a LSD is some entry understeer with corners. This goes for drifting and grip. The car will push before it rotates - nothing some gas petal can't fix (even N/A KA) but you definitely have to drive differently then you do with a LSD.
Bottom Line:
Welded - great for drag racing, OK for drift/grip
VLSD (working properly) - sufficient for drift/grip, OK for drag
LSD (clutch type)- Best for drift/grip...if it boasts 100% lock up like my 1.5way does then it would also be best for drag
A 2-way LSD is very sketchy for high speed grip driving......just thought I'd put that out there.
10-15-2008, 08:12 PM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
shim a VLSD, you can make them act close to a welded diff
nissan sells the shims for cheap too
14 psi on a T25, GD get something bigger
nissan sells the shims for cheap too
14 psi on a T25, GD get something bigger
Last edited by 88SinZ; 10-15-2008 at 08:17 PM.
10-16-2008, 03:36 AM
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Re: STOCK VLSD vs WELDED DIFF for the track ?
Right, and I'm saying it's going to be a big pain in the ass on the street just to take it to the track every once in a while. I'm assuming that's why you asked how the ride was and how it behaved in turns....?
Sucks on either type, live or IRS.
A welded diff/spool in a live axle is usually worse on the street than a welded diff/spool in an IRS car. It's all about how the tires can move in relation to the chassis (and in relation to one another) during weight transfer in corners. Live axles are generally less predictable because they don't have any camber gain and the entire axle assembly tends to flutter up and down from one side to the other as the tires break and regain traction. Kind of like a dragster when the wheels break free and both oscillate up and down, but in this case the left and right wheels alternate. The forces aren't the same left to right in a corner, so the motion isn't really symmetric.
IRS setups tend to have much better control of the random movement of the tires as they break and regain traction, and the contact patch is different because of the camber gain with weight transfer. It really just isolates the motion of the wheels much better.
You'll tend to break one tire free with IRS setups, but both tires free with a live axle just because of how the movement of one wheel affects the other. These are all generalizations and there are exceptions to everything, like the horrible IRS on (IRS equipped) Mustangs. There's also other stuff thrown in, like tire traction (width, aspect, compound, etc.) and the unsprung weight of that corner (or some combination of both corners on a live axle setup).
None of this matters at really low speeds obviously, or if you're applying enough power to actually drift. If both tires are sliding you don't have intermittent grip/slip problems, but you still don't have the control that you would with an LSD. This is a good exercise in finding the weak parts of your drivetrain and transmission though, and a live axle can usually take a lot more abuse without breaking a shaft or joint.
Sucks on either type, live or IRS.
A welded diff/spool in a live axle is usually worse on the street than a welded diff/spool in an IRS car. It's all about how the tires can move in relation to the chassis (and in relation to one another) during weight transfer in corners. Live axles are generally less predictable because they don't have any camber gain and the entire axle assembly tends to flutter up and down from one side to the other as the tires break and regain traction. Kind of like a dragster when the wheels break free and both oscillate up and down, but in this case the left and right wheels alternate. The forces aren't the same left to right in a corner, so the motion isn't really symmetric.
IRS setups tend to have much better control of the random movement of the tires as they break and regain traction, and the contact patch is different because of the camber gain with weight transfer. It really just isolates the motion of the wheels much better.
You'll tend to break one tire free with IRS setups, but both tires free with a live axle just because of how the movement of one wheel affects the other. These are all generalizations and there are exceptions to everything, like the horrible IRS on (IRS equipped) Mustangs. There's also other stuff thrown in, like tire traction (width, aspect, compound, etc.) and the unsprung weight of that corner (or some combination of both corners on a live axle setup).
None of this matters at really low speeds obviously, or if you're applying enough power to actually drift. If both tires are sliding you don't have intermittent grip/slip problems, but you still don't have the control that you would with an LSD. This is a good exercise in finding the weak parts of your drivetrain and transmission though, and a live axle can usually take a lot more abuse without breaking a shaft or joint.