Based on some discussion in the past, I thought I would see if we could get something going for this - I have a feeling this will only work if we more or less get a lot of people to support it.

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Can we get that petition going this year for STU/X AWD cars to be able modify/upgrade one of their LSDs? I think there is definitely potential here to get this rule updated.

This doesn't just benefit evos, but maybe for all AWD cars in an ST class that may or may not have fallen in the wayside with competent 2WD cars being able to upgrade to whatever LSD they want. If they can upgrade their LSD, I don't think it's so unreasonable for an AWD car to be able to upgrade just one of its LSDs.

I think with the way things are now, a competent FWD or RWD car with aftermarket LSD has the potential to outperform whatever AWD car. Apparently the rule was made to handicap AWD cars, but I think that handicap is a bit much - especially for any AWD car that has all open diffs - not to mention AWD cars are already handicapped by weight.

I think it would be fair to petition to allow AWD cars in ST classes to upgrade one of their differentials - obviously in our, and most other AWD cases, rear diff would probably be the way to go. It'll make the car faster, way more fun to drive, and may make up for shortcomings in other cars - i.e., the earlier 8s that have open front and viscous center, and they can't touch their drivetrain - makes it harder to compete with IXs that have helical in front and ACD in the center, and in general, for other AWD cars that may have open diffs.

More info on rear diffs: https://www.evolutionm.net/forums/ev...ound-here.html

Prior discussion bits (all regarding petitioning to allow rear diff mods in STU):

Maybe after we compile some data in this thread we can write a more formal letter to the SCCA.

Any input?


Result:

#10334 Differential Allowance Proposal
The STAC believes the current restrictions on limited slip differentials for AWD vehicles are appropriate.

 

How will they even know? I mean, you can swap in a 100% modded diff and ACD controller that looks totally stock.

I don't think it's right, but I can see it being very hard to regulate.

 

you mean how do they know right now if people have those upgrades already? it's a good question, i don't personally know - i think the same would go for stuff like cams, i guess part of it depends on good faith?

maybe if an STU evo power-oversteered out of a corner they might call something into question lol

 

aside from the additional cost of having this mod in STU, i think it's a great chance for all those STU evos that have wanted this rear diff mod but haven't been able to out of preference of running in STU to get in on the power oversteer action

 

When setup right, a STU Evo9 can easily over-steer out of corners. Opening up differentials in cars with 3 of them will only increase the expense of the class. The basis of the class is suppose to be low level cost.

Looking back, Evo 8's have won at Nationals a number of times. They don't seem to be at enough of a disadvantage that a great driver can't make up for.

 

I'd be all for it IF it was only to allow the VIII to ADD a front diff. Puts it more on an even keel with the IX.

 

you don't think a rear diff would be more beneficial for the car overall?

Seems in general though, the consensus is against this move.. oddly enough. oh well

 

The 04 and 05 VIIIs have a different front diff from the 03 that is closer/same to the one in the IX. Not sure how stringent these rules are but by already having that front diff in the later VIIIs does that allow you to "back port" it into the 03?

Edit Wikipedia claims the helical front diff is only in the 04 RS

The American 2003 and 2004 GSRs are without the helical limited-slip front differential and 6-speed manual transmission. The 2004 US spec RS models, however, do have a front helical limited-slip.....The 2005 US spec RS and GSR have the ACD standard, and the front helical limited-slip differential is now standard on all models.

http://en.wikipedia.org/wiki/Mitsubi...ncer_Evolution

 

These things aren't usually democratic. In other words, more letters does not always make it more likely to happen (to a point).

You need to explain in such a letter why this is a good thing for the category. If you break it down by class:
STC / STS don't really have any AWD cars
STR, I think the Audi TT is legal, still not going to be competitive

If I was on the STAC, I would be afraid this would screw up STX more than anything, i.e. the WRX could come back. With 3 diffs it would be a lot faster. I don't think just the rear would be enough to make a dent though. The WRX is still plenty heavy. I think this would increase its competitiveness without upsetting the "applecart".

As far as STU goes, I think there is a good argument that a real rear diff wouldn't cost much. If you believe that the class is balanced correctly as it is though (since an E36 just won), then this would not help that. You also need to argue that it's not going to screw up the balance between the STi and the Evo, which it shouldn't really.. the 04-06 STi's have a clutch diff in the rear already, so this would just let the 07+ models that have a Torsen swap to something more effective.

I was kind of against this until I started writing this post. Now I kinda think there's a good argument for it

edit: and actually, STU has a bit of a long term problem. The most competitive cars in the class currently are the 06 and before cars. Opening this up would potentially put the 07+ STis and 09+ WRXs in better shape.

 

Here's the rule:

I guess the proposal would be to amend the red part to something like this?
"AWD vehicles may add one aftermarket LSD, or may change one OEM LSD to an aftermarket LSD". I dunno, that feels clunky, but we can probably come up with something decent.

 

i was thinking it would be with just one diff, i.e., how the sway bar rule for stock class recently changed to front or rear sway bar. obviously hard to enforce for diffs, but the same applies now anyway.

 

I dont disagree with you however personally I dont think it'll happen. The way I see it they need to draw the line somewhere. Its never gunna be a perfect system. For example my car has HKS 272 cams. Those automatically threw me into SM. Is that fair? A stock cammed IX will make the same power as my VIII with the HKS cams. So what gives?

The point I am making is that while I see your argument, I dont think its feasible to expect everything to be perfectly fair.

 

yeah i'm hoping but not expecting there to be action on this. i guess the most ideal system would be a points-based system like in nasa tt (i believe)

 

^ why not just make the rule so that "all cars in ST* may be allowed to add one aftermarket LSD". i think that would cover everything, a concise, simple rule.

 

Stupid question, when you look at the fasttracks they always reference a proposal number but they never really say what was in the proposal. Is there anyway to read the actual proposals? Sometimes they do give enough information but other times its just "Thank you for your input" which is quite annoying to read lol.

As for the actual LSD proposal. I somewhat have to agree that not having the allowance would be better for the class. As it stands rearranging the stock diff helps a bit and is legal, allowing full modification of one diff would introduce quite a bit of cost increase.