vrooompssssht

why the hell would you spend $500 on an OEM helical? You were more than half way to a gear or clutch type lsd that would send more power to the wheel with traction

and your car is not losing traction due to ONLY having 255s, unless you are pushing 400wheel, which you arent on 0.6 bar

work on other areas of the car first

nlzmo400r

first off, 'gear' types, are helical or mechanical types, dumbass. And the 'LSD' im using sends more power to the wheel with traction, thats the point of my 'torque biasing differential'..... dumbass. You obviously have no idea wtf is going on. Also, my car isn't on .6bar anymore, I just haven't updated. Last time I dyno'd I was at 371whp 375tq on 16lbs.

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nlzmo400r

if youd prefer a welded differential to a helical type for roadracing, or anything other than drifting, then you have no idea how to drive a vehicle. The welded differential obviously keeps wheels going the same speed the entire time, causing understeer at both corner entry and exit, unless of course you power over and slide it out (i.e scrub speed off)

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KA24DESOneThree

If chmercer brings the Saturn (provided it's not a Sky), I'll bring the Hoosiers and I'll outgrip the thing on my RE01-Rs. Tires are a big part of the equation, but they can only get so far.

I've been trying to find the pics of the black coupe at an autocross running 275/40R17s all around. If I remember correctly, he had some issues with them fitting, i.e. he was running stock bodywork and they stuck out by a couple inches.

However, here is a hatch with 275/40R17s under some 30mm bolt-on flares:
http://www.pdm-racing.com/features/imag/DSC06714.jpg

From:
http://www.pdm-racing.com/features/240sx4.html

I hope that will be of some help.

nlzmo400r

Im very curious as to whay offset those wheels are. They would have to be about a (+5) or so to clear the front dampers. So im assuming those are the +12s with a 7mm or so spacer front and rear

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Maximamike

275's on a 10" wheel. Doesn't look like it sticks out that much. I PM'd him for more info.

vrooompssssht

sorry, i never read up on the "helical" oem lsds, not even worth purchasing one to me, so i did not know what type they are.

i meant more power than your s15 lsd sends

what is your suspension setup like? spring rates and sway bars?

McRussellPants

Thats funny, because I'm sure JGTC cars run spools in the dry and 99% of other sanctioning bodys that don't allow Electronically controlled VLSDs use 2-ways set up to be nearly 100% locked.

Hell, alot of GT Porsches run spools as well.

Consistancy >>>>>>>>>>> Mild Entry understeer thats easily tuned out.

Racecar Engineering had an artical about how worthless Helicals are. You should pick it up. They're too inconsistant to be a good choice for any thing other than old man willows 7/10ths windy road mobile.

ryan hagen

my problem is turbo power, when the boost hits, the boost burnanates tires the ra-1's in a slide i think are more predictable than the 615's they tended to all of sudden grab again making it a ruff transition while the ra-1 were really smooth. but they booth still broke traction about the same.

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KA24DESOneThree

That's not the car. I was talking more about the front fitment, also. Thanks, though, for helping with the search.

It was a stock-looking black car with gold pinstriping, I believe. I think he was running a forged wheel with R-comps. There might have been a bridge abutment in the background.

n1smo400r, I'd recommend shooting an e-mail toward PDM. I'm sure they can clue you in as to the offset.

McRusselPants- You know what else is funny? JGTC cars are purpose-built race cars and share very little with street cars. They're also running what, thirteen inches of slick up front and like fifteen inches out back?

The 935 ran a spool, but it also had turbo lag like you wouldn't believe coupled with '70s suspension and tire technology.

chmercer

but, shouldnt we be striving to make the most out of our street setups? or.. . what?

smelly240

you do realize that the JGTC cars use spools then... The Audi R8 uses a 2 way clutch type that has something in the vacinity of 1800lbs of turning force (almost a spool) - u should see them try to roll those things around in hte pits.


I raced before you were born, btw (january 3'rd will be 20 yrs since i got my 1st qurater midget) - Helical LSD's arent the best for a high power RWD setup - its a known fact (they used it in the Bentley lemans car bc the car wouldnt steer with the disc type they even tried open diffs like whats in hte elise - its a bandaid bc the car's flawed by design with parts of the chassis neglected in hopes to lowe rhte cars CofG).

The JGTC cars with those big slicks would have way more scrub with them sticky tires and a spool - so looks like your comment contradicts itself KA24desonethree. Anyway, nizmo... you bring your 285's and your helical and we'll have at it with my smaller tires and i'll even put a welded diff back in hte car. The thing about a HLSD is - it NEEDS to have traction on one tire to work... or it acts silly.

charlie and superpants are gonna get on ya dude... and you're starting to seem like a nub. I smell fire...

jmauld

Why do you guys constantly bring up the JGTC cars, like they are the god's gift to racers? What do you really know about their setups. Real racers here in the US use Quaiffe LSDs and love them.

For whoever referenced the Lotus, be sure to check out the LSD that they offer for their cars. Yep, it's a Torsen...

The problem that 240sx owners have with the Helical diffs is that they have chosen poor parts to setup their cars. If you're lifting the inside rear tire, than you have introduced a problem with your choice of suspension components. Don't blame that on the LSD.

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'95 240sx SE

chmercer

um, ok, how about like tons of scca cars run heavy locking 2 ways. is that a better example than jgtc cars for some reason? i dont know why it would be.

helical diffs never wear out

because they dont work

ps smelly240 do jgtc cars really have that much scrub, seems like they wuold just run super high offset and really long control arms.

McRussellPants

The GT Porsches I was refering to useing a spool race in US series if that helps you sleep a night.

Racecar Engineering "[Clutch diffs will not wear as quickly and have more tuning options compared to HLSDs]" paraphrased, but its in there V16N5.

Point in fact, your using a diff built for old man willow's 200whp Silvia on 205 tires. Not gonna work fresh on a 285/35 Tire'd 10kg sprung car.

England's GT2 350Z crew bragged about the only driveline modification being a clutch and Nismo GT-Pro LSD.

"Helical for Racing, Clutch for Drifting" is just some stupid quip people jerk themselves off with to pretend they know anything about how cars work.

turtl631

Man, I love how far off the original topic this has gone. Honestly nlzmo400r, if you really want to do this, you might just have to buy some wheels and make the car fit them. FG overfenders dont really add that much room, especially up front, and you would probably be better off with either pulled stockers or arch flares. I don't think that huge r comps are going to give you significantly better corner exit grip with 375 whp. It might just come down to not crushing the titty. And maybe PM some guys like racingSWH to see how they're doing (SRX cup guys).

smelly240

LOL @ crushing the titties!!!! im so sending my dad a copy of this thread - i swear he'll post it on one of his old man dirt track forums or somewhere.

If anyone wants to get their kids into racing - i got a million things you can tell a kid to help them learn. my mom made little songs and stuff for my sisters, and so we wouldnt be afraid to hit curbing on road courses; when it was nice out we rode to the track in the back of teh truck - and our parents would go off the edge of the road and hit the rumblies. I miss bein a lil kid

seriously nizmo - the problem with u exiting th corner is between the seat and the steering wheel.


Does anyone even make a spool an R200 diff?

KA24DESOneThree

Not scrub radius, but tire scrub from having to drag one tire around the corners.

articdragon192

Your local welder.

Wiisass

Wow, I was going to try and get involved in this, but this thread is all over the place. I'll give it a shot anyway.

Preloading a linear spring does not change the rate. You still have to input the same force to move it one inch no matter if it's at its free length or compressed an inch already. Of course this depends on the quality of the spring. A good truly linear spring will behave this way. A cheap linear spring probably will not. And what's more important than spring rate is the linearity of the installation ratio anyway. And than can be either linear, rising rate or falling rate. But that's in the suspension geometry and a little harder to adjust without doing some real work.

Smelly, what calcs are you doing to show a change in spring? I'm just curious as to why every guy with a roundy-round dirt racing back ground seems to think that it increases the spring rate. The only way it could would be based off of suspension geometry and installation ratio as I previously mentioned and possibly positioning the suspension in a different part of the curve. But let me know, please.

About fitting the tires, you might just have to try and do it. I'm planning on running some stupid sized rubber. I am thinking about running a 315 on an 11.5 in the back and a 275 or 295 on 10.5 in the front. It's probably overkill but if I'm not heating them up then I'll mess around with size or compound. But I will be running hoosiers for hill climb, road race stuff. We'll see how it works out, if tire temps are too low, I'll change, but I would rather do the work to make sure the biggest tires I want to run fit rather than fit a smaller tire and have to mess with the bodywork more to get something bigger on there. And for all the talk of unspring weight, my wheels both weigh about 17.5lbs each. Not too bad for the size. I'll probably get a set of RPF1's in 18x10.5 later on and those are only around 19lbs and then run a 285 or 305 on them and see how they do.

Ideally, I would like to get a tire temp measuring setup on my car but it's a little more money than I can spend right now and would eat up all the analog inputs on the data acq. I would be using IR temp sensors and I know some people will say that they won't tell you the actual temperature of the core, which is the important part, you will be able to get a lot of valuable information out of it and it will all be real time and can be compared with acceleration and shock travel and I will be able to have a lot of fun analyzing data for a few days after the race, but it would be pretty awesome.

Unsprung weight is an issue, but some weight in needed. I mean if you're that concerned with it, then run the smallest brakes you can get away with, and do other stuff like that. Damper valving is part of the issue, but heavier unsprung mass will actually work better with the damper than lighter. Most of the dyno plots I've seen have too stiff of a compression curve and with a heavier mass at the bottom the damping ratio will go down.

So if you're getting this serious then custom valved dampers are the way to go. There's no point trying to do all this work and then going with a crappy off the shelf setup. And anyone that claims to revalve the dampers and doesn't give you a real CVP dyno plot didn't do shit. Be careful of that. I've seen the insides of what people say are some of the better JDM dampers and they look like the insides of cheap mountain bike shocks.

Diffs are an issue, it depends on how the car is setup. A good torsen based diff can be a good thing but it depends on the diff and like Jmauld said it also depends on the suspension. If you're lifting a wheel, you need to figure out why that is happening before throwing away the diff because of it. I personally like clutch-type diffs and will be running that next season, but there are many successful people running good torsen diffs in racing. It all depends on how the diff is setup. But for what's available and in the same price range a good clutch-type is the way to go for these cars. I've used both types and although very different applications, I never had any problems with the torsen diff, but then again, the suspension was well sorted and we set the car up the right way everytime we drove it. And it was a real torsen diff and not some OE crap.

Well that's just my input from what I remember from the last 3 pages.

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jmauld

Not trying to be a smartass, but if you're trying to make a point in that post, please try to make it coherent.

Also, take note, that I am not bashing the clutch diffs. I'm saying that the argument based on what so and so is using, is a weak argument. Clutch diffs are wonderful things! They work great, they're cheap and they do a great job of covering up mistakes that the majority of people make with their suspension setup.

My guess is that you've never driven a car with a properly working suspension and torsen?

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'95 240sx SE

jzr

Good post Wiisass. I'm running a 315/30-18 and 285/30-18 r/f setup on 12.5" and 11" wide wheels (CCWs, coincidentally) on an S13 hatch.

Nismo, my rear wheels have 8" backspace and need only a small spacer to clear inboard. The fronts have 6" backspace. I'd recommend running 2.25" or 2" diameter springs up front, along with some extended strut ears, to give more inboard clearance. One benefit of 18" wheels in the rear is the ability to go further inboard without interfering with the LCA and in my case, the knuckle (HICAS car). I try to keep the car as narrow as possible for a given wheel/tire size.

In trying to go fast we want to maximize grip. Minimizing unsprung weight is good in that it allows the tire to better follow the contours of an uneven surface. The benefits of this weight reduction must be evaluated against the defecit of running a smaller wheel/tire combination than may have been possible. In my experience, with a vehicle the size and weight of a 240sx, the negative effect of a bigger wheel/tire combo's additional unsprung weight will be more than offset by the combination's increased grip in any situation other than pure straightaways. Sure, the car may not feel as "light on its feet" with the bigger shoes, but where cornering speed is paramount (track/auto-x) it will be faster.

How wide to go depends on power level. For a KA with bolt-ons, I'd say 285/30-18 (or perhaps the new 275/35-15 when it's out next March/April) all around would be a good choice. For 300+whp I'd be looking at at least 315's in the back, and 335's for 400+whp. A little more front tire would be helpful since the 240 tends to be a little more nose heavy than is ideal, the problem is there aren't any good tires wider than the 285/30-18 that aren't also taller than 25", which is a limiting factor for the front wheelwell of an S13.

Diff discussions are academic, just like turbos, in that what's ideal for a person is very specific to their application. I happen to think that for autocross and most track use a Torsen T2R (helical with preload) is great, but since it isn't made for the 240, I've "settled" for an ATS 1.5-way.

Happy motoring all,

smelly240

i welded 2 myself - ones still sitting here - but i was hoping something maybe lighter? LOL - i like melted the entire shits together with these other ones and they're HEAVY.

ryan hagen

i ve driven a welded,h-lsd, v-lsd, clutch type, open etc, i like the h-lsd the best, i got one for my car, next would be the clutch type. welded i didnt like you had to slide and stay on the power to get it to turn, if not it shaved your front tires off. h-lsd i liked but i messed with my sways bar too much and now i lift a wheel so i have to put it back to how it was. a clutch type a little looser than my freinds would be great for road raceing too though. v-lsd is waste of $ and welded is too hardcore for me.

i run a spec stage 2 z32 clutch on my ka-t powered car, and 275-40-17/275-35-18 tires, my clutch is shit with that, 285 on a ka with bolt ons? say good good by to the clutch and alot of other stuff thats alot of strain on a basically stock low powered motor. the place i work at is the largest buyer of wrecked vipers in states, and a 335 is not going to fit a 240 even with 50mm over fenders. i get to to play with viper tires alot

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vrooompssssht

jzr

Heh, well you don't have to believe me. I spent all of 2006 competitively racing my 240 with a KA with bolt ons, and that's what I'd run if I were in a class that allowed it (DSP, for instance). The 285/30-18's are a good width for something of the 240's weight, and they're the same height as the HICAS car's stock tires (~25"), so they don't kill gearing.

For street use something that big is likely "overkill" but for getting around a track as quick as possible I think that's the best bet amongst DOT tires for a ~170whp 240, at least until the new 275 Hoosier comes out. Anecdotally, the success of the DSP E36 3-series BMWs of similar weight and power on those same tires provides some credence to the theory.

And who says the tires have to fit in the fenders?

Wiisass

Speaking of fenders, what are/were you running with the CCW's on the car? I'm trying to figure out what I can get away with for 10.5 in the front and 11.5 in the back. I was originally thinking of something like a -20 in the front and a -3 in the back. But I might be changing plans if I can fit a +32 in the back and then a -4 in the front. And tire size will probably be 275 in the front, maybe 295, and 315 in the back. They're 17's and I want to run Hoosiers so I don't have any choice on aspect ratio.

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jzr

Just these little bolt-on flares:
http://www.raceonusa.com/index.asp?P...OD&ProdID=3777

They cover the 315s in the rear okay, and would probably cover 335s okay as long as I don't go any wider with the wheels.

The front is another story. My struts are actually in now getting re-worked to try and get some additional inboard clearance. The little bolt-on flares don't quite cover the 11's, so in the long run I'll probably go with some 20 or 30mm wider front fenders and then attach the bolt-on flares to those, which should be close enough.

My wheels are 18x12.5" with 8" backspace and 18x11" with 6" backspace. That works out to about +32 offset for the rear and +12 for the front. With my old strut setup I needed about 15mm of spacer to clear in the front, but hopefully that requirement will mostly go away with the strut re-work. In the rear I'm using about 6mm, but when I get some adjustable rear LCA's I'll adjust everything outboard and get rid of the spacer.

Wiisass

Are you sticking with the Koni's and just redoing the lower bracket? Any concern with the force line of the spring and adding bending in the strut? I know it's not ideal no matter what with the big wheels, larger scrub radius and just the fact that it's a MacP setup.

I think we're going to have a couple sets of different style fenders around the shop in the next couple weeks, so hopefully I can order my tires and put them on the car and see how things are going to sit. The nice thing is they're two different 3-piece wheels with the same outer bolt pattern. So I can mess around with backspacing.

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jzr

Hey, where did I say I was running Konis?

Yep, I am sticking with them. Struts do suck though when it's time to do big tires. At least it's only the front...

For those still reading along, note that another benefit of a 3-piece race wheel like the CCWs vs. a 1-piece is the ability to play with the width and offsets (or repair damage) relatively inexpensively through the purchase of additional rim-halves, which cost much much less than a complete wheel. Of course, if you know the exact dimensions you want and know you won't ever play around with the dimensions or hurt any part of the wheel, a 1-piece can be lighter.