Quamen

iTrader: (14)

You sir are a D-bag... Considering I have the fastest 60ft time out of all verified Z's right now (using stock VSLD!), i would say the OP will be fine on a VSLD and will save money.

djamps

iTrader: (1)

+1. Tires and driving skill should be the main concern, not sinking a stupid amount of money into the diff.

binder

iTrader: (8)

especially on a mild hp car with only occasional drag strip visits for fun. At least that's what I gather is being done based on the OP's first post.

terrasmak

iTrader: (8)

Wheel spin will change, in your case you would actually put power to both rear tires. 30% max lock on the VLSD, what a joke.

For the OP, yes dedicated drag tires would be nice for only trips to the strip. The diff will help on the strip and his where dedicated drag tires will suck.

Quamen

iTrader: (14)

Wow.... you know more than all the big names on this forum do considering almost all of us run stock differentials.

Also note that the main purpose of a differential is to compensate for difference in wheel speed which include traction loss. Further note that traction loss is a result of poor tire contact. For drag racing our cars A differential is like swatting flies and the garbage is the tires and driver skill.

binder

iTrader: (8)

I have never broke only 1 single tire loose, track or street. You are thinking of a base rear end with no LSD.

PracticeDrifter

I hate to come in here and tell all you 'big names' that you are wrong about the quaife differential that you have never tried, but you are.

I had the VLSD and it sucked. At first I thought I had an open diff cause I would lay just one strip of rubber to start, which means only one tire was moving me forward (the one not slipping). Of course throttle modulation could get them back together... but it sucked. I took it to the shop and they said my made sure the VLSD was working fine. VLSD, like any wheel-speed or friction-based LSD will only start to do its job once your wheels are moving at different speeds. This is after you already lost traction to a wheel, and the wheel has had time to accelerate to enough of a different speed for the diff to step in. It is like the diff has a lag before it kicks in.

I got a Quaife, and man do I have more traction! I immediately tested it out by laying 2 neat strips of rubber with a chirp and I get traction back. What surprised me was how quickly the diff reacts to a loss of traction. The quaife is a torque-biasing differential, meaning that it transfers force back and force between the wheels based on how much they resist turning. So if a wheel starts to slip, the differential transfers the torque before it really speeds up. There is no delay at all. Once it breaks free, both tires are maintained at the same speed with much more lockup (wheels are the same speed) than the VLSD ever did, and because they are going the same speed they both connect back up at the same time at the end.

It may not help me in a drag race in the dry as much as slicks, but that diff has helped me win races against AWD cars on the street in the rain where slipping is unavoidable. Do you guys just drive around in slicks or what? The OP is not asking what the best mod for drag racing is (tires, duh), but what the best DIFF is for drag racing and spirited street driving. In my experience and with normal street tires, this quaife differential makes a huge difference in both straight line grip and for control at the limits around corners. Drag racers have so much rubber that they will not slip and will not benefit from this kind of differential, but if you have any slip then you will benefit.

The best thing about the Quaife for me is drifting with it, but that is another story.

jerryd87

iTrader: (4)

want proof you dont need more then the vsld? notice how both strips are the same length(start watching at 20 seconds)? and i know for a fact it hasnt been serviced in 15k miles and likely never(car has over 115k on it now.)
thats after only my initial baseline dyno the car makes MUCH more power now, anyone who says it dosnt work eiter has a base model diff and dosnt know it or are having a placebo effect.

disclaimer: i always did the speed limit in the following video lol

Quamen

iTrader: (14)

My comment was not about the Quaife differential, it was about the stock VSLD being more than adequate for the spirited driving and light track use. Also, the title clearly states "Best differential for drag racing in 350z"...

The point is that the OP is better off buying a stock VSLD and saving the money towards something else that will have a better impact. There are plenty of good street tires that can put down 500-600whp on a VSLD that aren't slicks.

Nealoc187

Quaife is nice, I have one, and used to have VLSD, and open diff before that. It's definitely not necessary though if drag racing improvement is you primary goal.

btw a VLSD can not be serviced - it will become less effective over time. how quickly its effectiveness deteriorates depends on a lot of factors.

topnotchg

iTrader: (5)

Quaife

binder

iTrader: (8)

It can be serviced. recommended oil changes will keep it functioning properly. I run redline oil in mine and have always spun both tires at the same time, track or street.

As for the person doing a 1 wheel burn out with the VLSD: yours might be worn out or damaged. If the oil wasn't properly serviced it would allow it to slip.

Nealoc187

that is wholly inaccurate. you can NOT change the silicone fluid inside the viscous coupler in a VLSD (unless you have customized yours). it is a sealed unit in the 350z (and virtually every other car out there, though there are a few that have relief ports on them that can be used to drain and refill if you really know what you're doing). changing diff oil is NOT the same as changing silicone fluid inside a viscous coupler. the fluid inside the coupler is, and always will be, the fluid that was in there when it was manufactured (unless you are one of those rare few who knows where to get dimethicone, and knows the proper ratio of dimethicone to air - if you fill your viscous coupling with the improper ratio you just made it ineffective - if you can customize your viscous coupler in such a way that you can drain and refill it, etc. i know you didn't do that because you have never done custom modification of a viscous coupling - your post makes that quite obvious).

this is why VLSDs fail over time, because they are almost entirely unserviceable (they are not designed to be serviced, though as i stated a few people have developed methods to service them, with questionable results).

if you would like me to point you to some viscous coupling SAE papers and analysis of them by other engineers i can do that, if you are so inclined.

3hree5ive0ero

iTrader: (95)

^ +1

And another +1 for VLSD. If all you're doing is drag racing and some light, spirited driving, you don't need any more than that. Of course, getting an aftermarket diff will of course help you put your power down better, but the value won't be there (unless you plan to do other types of motorsports that require turning more often).

Nealoc187

one of the cool benefits of the VLSD in the R200V rear end by the way, is the fact that it as 4 spider gears instead of two that the open diff has, making it much less susceptible to breakage. even if your VLSD is entirely worn out and ineffective, you still have a rear end that will handle more power than the base one will (not that breaking rear diffs has been a very prevalent problem for 350Zs).

andre12031948

I'm no expert but as an owner of an 08 350z with some bolt ons for over 3 yrs, having a daily driver & a few times a weekend drag racer using 10" slicks, I've found no problems with my stock vlsd. The only thing I recomend is if you have slicks or real sticky tires, start warming them up/spinning the tires in the water box. It's easier to get both wheels spinning & puts less stress on the stock vlsd. I find it funny when people with 13/14 seconds cars spend a fortune on vlsd's, 1,200 hp axles, & multi-disc clutches, then they go to the track & turn 13/14 seconds Minus 5 grand of course.

djamps

iTrader: (1)

Some tracks have d!ck officials that won't let you start in the box or barely put any water down. That said I get both wheels spinning just about anywhere with a 2nd gear clutch dump from 5krpm LOL.

bbs350z

iTrader: (85)

the factory vlsd is suitable for your application. while a viscous type isnt anywhere near as good as a clutch type, they can handle the abuse. the last thing you want is some crazy full lock on a daily car. besides, z's are garbage out of the hole anyways. if your seriously building your car for drag and want 600+hp etc, get a 3.3 and pull ecu pins (i believe 103, and 104 so you can brake boost, do a still burnout) or invest in a linelock.

Quamen

iTrader: (14)

Well look who it is.... My Z isn't slow out of the hole

djamps

iTrader: (1)

The combination of strong low end TQ and driving skill (at the same time) just isn't always there. The drivetrain and chassis (including stock VLSD) is more than capable as Quamen has shown. I couldn't get below a 1.6 without a big shot of NOS or real antilag setup.