bolt in s13 quick change

[kingkilburn]

http://instagram.com/p/hjKc6Jg6I_/#



Chris Forsberg's MA Motorsports offers a bolt in S13 subframe for a Winters quick change.

I don't know much of anything about the rules sets of various classes but this seems like a potential big deal to me and I'm sure I don't have to explain to you guys why that is.

[Matt93SE]

Need to make it for S14!!

But yeah, that's nifty. I wondered how hard it would be to make one fit. Didn't figure it would be too hard- just needed someone with the money and inclination to make it work.

Unfortunately I can't use one in STU. You can use them in GT classes though and I know several folks in S-chassis that use them. They're all tube-frame cars tho.

[Def]

QCs sound cool, but man does it get pricey. Plus what do S chassis guys end up doing or axles?

[kingkilburn]

Drive Shaft Shop makes axles for it in S chassis specifically.

[kingkilburn]

At least that's what I'm hearing.

[Def]

Are there any good salisbury diffs for these? I searched a bit and found a bunch of lockers (who the F would use one of those in a quick change??? midget cars or something?), and some versions of helicals - one that you could adjust which seemed cool. But strangely didn't find much for salisbury diffs.

[PerilousActs]

Here is what Bill W. is running in the 240rs maxi http://icpcitation.com/variloc_theory.htm

[djsilver]

Variloc LSD's are also available for the Ford 9", in case someone wanted to mount an aluminum IRS 9" pumpkin in the 240sx subframe. ;-)

I found these when Def was talking about using a BMW 5-speed transmission. The problem is that they have really short gears and no OD. The tallest BMW diff is a 2.93, but you can get Ford 9" gears taller than that.

[Def]

Why would you want taller than a 2.93 with a 1:1 5th? That's a mighty long gear.

[djsilver]

Why would you want taller than a 2.93 with a 1:1 5th? That's a mighty long gear.

You are correct. I was looking more at 2nd gear for autocross use.

[Def]

Why not go shorter then use a 3rd gear that's as long as you want it, then you also have a 2nd gear that's got a much shorter spread between it and 3rd if you need to grab a lower gear for a hairpin.

Something like a 50 mph redline for 2nd and 75 mph redline for 3rd or so?

[djsilver]

Why not go shorter then use a 3rd gear that's as long as you want it, then you also have a 2nd gear that's got a much shorter spread between it and 3rd if you need to grab a lower gear for a hairpin.

Something like a 50 mph redline for 2nd and 75 mph redline for 3rd or so?

That could work but I'd end up with effectively a 4-speed.

To get back on track; There are several companies that make IRS pumpkin setups for the Ford 9" (Currie, Heidt, etc) using either universal joints or Porsche CV's. I was looking because the Variloc appears to be much more tuneable than the "Yo JDM" diffs we've been talking about (OSG, Cusco,etc)

So, if someone wanted to use a Variloc in the 240sx, you'll need a Winters IRS Quick-change, an IRS Ford 9", or have them make a custom unit to fit the R200.

[Def]

A Variloc is just a salisbury diff. In fact it seems like the cheaper JDM units with belleville washers/cone springs to provide preload. They just seem more open to having a bunch of ramp angles for you to play with.

I'm not sure if I'm confused by their tuning info or what, but it seems they have some of the advice backwards according to popular theory. More locking action is going to make the car want to go straighter off power, and rotate better on power. I guess that holds true unless you have an absolute ton of lockup on decel where the car will feel super loose on corner entry like a spool can make a car feel (it goes from understeer initially, then once you get the car turned the rear just wants to keep going around).

Don't you autocross your car? Or do you drive it on track?

For an autocross car I don't see the advantage of using gears 2-3 other than the norm seems to be using just 2nd gear and hoping you never need to toss it into 1st because it's borderline unusable at higher power even with a longer diff. The gaps between 1st and 2nd are just huge on OEM transmissions.

[djsilver]

A Variloc is just a salisbury diff. In fact it seems like the cheaper JDM units with belleville washers/cone springs to provide preload. They just seem more open to having a bunch of ramp angles for you to play with.

I'm not sure if I'm confused by their tuning info or what, but it seems they have some of the advice backwards according to popular theory. More locking action is going to make the car want to go straighter off power, and rotate better on power. I guess that holds true unless you have an absolute ton of lockup on decel where the car will feel super loose on corner entry like a spool can make a car feel (it goes from understeer initially, then once you get the car turned the rear just wants to keep going around).

Don't you autocross your car? Or do you drive it on track?

For an autocross car I don't see the advantage of using gears 2-3 other than the norm seems to be using just 2nd gear and hoping you never need to toss it into 1st because it's borderline unusable at higher power even with a longer diff. The gaps between 1st and 2nd are just huge on OEM transmissions.

I do mostly autocross, but also occasional track days, so it's nice to have useable gears. There was a "road race" version of the T-5 for a Mustang, with a 2.93 first and .83 overdrive, but it's not offered anymore. The T-5 is comparable in weight to the OEM trans, but a good bit stronger. The T56, T-6, 300ZXTT 5-speed, and 350Z 6-speeds are all ~30-40lbs heavier.

I have an S5W71C from an S14 SR20DET with the .83 OD, but it would be nice to have a higher first gear as well.

It's like everything else; you can get what you want if you spend enough money...,

[Def]

If you don't make a ton of power a 4.9 might give you the autox gearing you need in 2nd and 3rd and still work on track if you're not buzzing it up to 150+ mph.

Mike (Tower240SX) is working on putting a T5 WC behind his SR20VET. I'd be more interested in that if the transmissions with decent gears weren't $$$. I think for the price difference I'd rather just get a Z33 6 speed and deal with a little bit of weight penalty and not worry about trans reliability ever. The ~0.8 6th seems like a pretty good track setup with a 4.63 from my calcs. So it'd be a mostly 4-6 gear trans, with the occasional shift to 3rd on the tighter stuff.