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One more time....Front LSD


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First off, I searched....supposily impossible to do with factory parts.

 

Phantom grip sucks. I know this from many ppl I know who have/had them and they suck and fall apart easily. I know the guy who builds the Miata spec racer rear LSDs personally and he will make me a front, center and rear custom diff, planetary with any TQ split I want, or clutch type LSD...but I dont have any cash at all to spare for that

 

What I do have to spare for experimentation is a RX box, an XT FT4WD box, and a 3.70 LSD diff.

 

I want to retro the rear LSD into the front of the RX box.

 

WHY do I NEED a front LSD? I could have picked up 1 more second at the last autocross....that second was lost due to INSIDE FRONT wheel spin out of corners....one section was a long-off-camber-uphill...if I could have got all the power down, that section alone was worth 1/2 a second or more.

 

WHY can this NOT be done?

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i THINK you can do what your saying.

 

 

Basically take the lsd "cartridge" from a rear LSD and install it in the front.

 

They are supposed to be the same..but who knows.

 

a front LSD would help a pile.

 

From what i've heard, given the conditions, and the springs you use a Phantom Grip does work...for how long..who knows.

 

For the rear....man...you should be able to slip in just about any plate type diff from a WRX or GC8....you'll have to change the ring gears....but thats not a huge deal.

 

The center...just lock the stupid thing and be done with it. you'll have to drive it a little harder and "chuck" it more...but it's worth it.

 

give it a shot throwing the rear lsd "cartridge" in the rear, and let me know if it works...it's cheap and will work. If it won't work and you gotta do something else $$$$$$ i'd prolly spend more time and money on better tires, brakes, and suspension. Those will gain you more than 1/2 second...no matter what the track. the rear lsd, and locked center is more than ok. Especially since no matter what....anything decent...anywhere (front, rear, center) is going to cost you upwards of a grand.

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I could easily pick up 1~2 seconds from suspension bushings, and D2 coil overs. :brow:

 

Better tires...? well, thats about 1g right there. I'd need some 13x9 Diam racing wheels...for the 235/45/13 Khumo Ecsta V700's...Im already running those, but in 215/50/13. They are just now reaching optimal dry race 'tread' depth.

 

Ive got GR2's front and stock RX (like new when i got them) rear dampers with 350/450 springs...works fine for autox speeds, no bounce...but yes its underdamped.

 

Right now getting the power down is what Im concerned about...the next thing will be the busihngs and D2's once I figure out about the Front LSD.

 

As for locking the center diff....I rarely even lock it for launches. With the race tires on the car...im sure to break an axle or something else in the drivetrain on the dry tarmac. If it were rallyx...i'd be locked all the time. :headbang:

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i seriously doubt you'd break an axle.

 

with the center diff locked...there is really no more extra stress on the front or rear axles (maybe marginally more) . the stress is on the Main prop shaft and the center differential.

 

with the open center diff. going up a hill, out of a corner under hard accelleration....your getting a good majority of the power to the front inside tire (hence your tire spin). If you had that center diff locked you'd have 50 % of the power at the rear wheels and you'd just tear up the hill!

 

when i had the center diff open on my RX it was good...but messy. Once i locked the diff...man a world of a difference..thing would just go sideways nicely, behave under power...not pull anywhere

 

remember...3 wheel drive is better than 2 ;)

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Hey WJM This is Jerry, you need to find a tranny like i have setting in my yard. I have 2 from a 88 RX 5 speed dual range with center diff lock. With that type of tranny lock up the front and no more 1 wheel spin. Thanks Jerry

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The dif lock is for the center diff not the front.

 

Will, try contacting Randy's Ring and Pinion. They are on line. They are in Washington state. They do alot of custom stuff but I don't know if they build custom one off's though.

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Someone told me if you take a rear LSD and put it in the front (the RX style clutch pack) that it would not function correctly because it would be spinning in the oppisite direction... I never really cared at the time as I really have no urge to pull my car apart again at the moment, but why would that be? I also would like a front lsd, but I'm FWD so it would be more fun.

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Randy's doesn't do one-off custom stuff. I asked them about a different project about a year or so ago and they kinda looked at me funny and said "Uh...no.". However, there is a place just up in bremerton that does and another up in Poulsbo. Forgotten the name of the one in Bremerton, but the Poulsbo place is called Jantz Engineering. Their web site is http://www.jantz4x4.com/. I've talked to them and they are really friendly and do excellent work (this judgement made through observations of work done on other people's rigs, not mine...yet).

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damnit justin. the engine is fine as it is. If I were doing something else to it, like 19 PSI, a turbo...or something else....Id need to do EM right now. THe enigne is fine right now, the most IMPORTANTA mod that I need to take care of next is the COOLING system. Bigger rad and good coolant is going in it this weekend, along with dual electric fans.

 

Otherwise...getting ALL the current power to the ground and making the car hookup better is on the top of the list after the cooling system.

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You had a '88 RX with 2 transmissions? That is a pretty rare car, you should post some pictures.

 

 

 

Hey WJM This is Jerry, you need to find a tranny like i have setting in my yard. I have 2 from a 88 RX 5 speed dual range with center diff lock. With that type of tranny lock up the front and no more 1 wheel spin. Thanks Jerry
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Someone told me if you take a rear LSD and put it in the front (the RX style clutch pack) that it would not function correctly because it would be spinning in the oppisite direction... I never really cared at the time as I really have no urge to pull my car apart again at the moment, but why would that be? I also would like a front lsd, but I'm FWD so it would be more fun.

 

A clutch type LSD uses ramps to apply pressure to the clutch packs, the angle of the ramps is often different for forward and reverse torque. So depending how the parts are installed it might not function as intended.

 

I know the front and rear ring gear carrier are not the same, but there might be a way to adapt the clutch parts into the front carrier with some creative machine work. If somebody has a trans and LSD diff they will let me take apart I’ll see what can be done.

 

Gary

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damnit justin. the engine is fine as it is. If I were doing something else to it, like 19 PSI, a turbo...or something else....Id need to do EM right now. THe enigne is fine right now, the most IMPORTANTA mod that I need to take care of next is the COOLING system. Bigger rad and good coolant is going in it this weekend, along with dual electric fans.

 

Otherwise...getting ALL the current power to the ground and making the car hookup better is on the top of the list after the cooling system.

 

I'm gonna have to disagree...do something about engine management. We've run these motors at a lower state of tune that you have yours, and we blow them up.

 

I believe we blew up 2 motors this year....and that it was a good year....we've blown many more in the past.

 

I've yet to put my Wideband on one of them...but i'm fairly sure they are running too lean. and it's somewhat obvious from your dyno curves that it is too lean. I should have the wideband on my friends street car in a couple weeks.

 

get some more fuel to it...in some way shape or form...Even if it's just an additional injector or two, with a circuit that turns them on at "X" amount of boost.... you need more fuel. You can rig up an additional injector set up fairly cheap....find some injectors from a junk yard...then just make a simple circuit....doesn't have to be 1000 times adjustable..just get some fuel in there.

 

telling ya...it's a ticking time bomb...and i speak from our experience with these things. If it's not the pistons that you blow..it'll be a Head gasket...even the Subaru gaskets won't hold.

 

I hate to be telling you that....but, no sense putting the power down...because you can't make any power when you got a hole in a piston

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thats what I'm waiting on before I go back. and even if it is "good enough" with the stock stuff, imagine it with out fuel cut, better ign stuff, and FULL tuneablity. now think of the HP and TQ, for the driveablity, power band, and like everything. I could go on and on but I think you get my point.

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