View Single Post
Old 01-09-2014, 05:20 PM   #50
jlangholzj
Scooby Newbie
 
Member#: 377640
Join Date: Jan 2014
Chapter/Region: MWSOC
Location: Lincoln, NE
Vehicle:
2014 WRX hatch
DGM

Default

Quote:
Originally Posted by memmek2k View Post
I don't doubt that an LSD will help OP at all, but I'm afraid that OP's setup won't fully take advantage of the LSD, and it will just mask bad driving and suspension habits. Not knowing alignment specs and throwing a bunch of suspension mods at the car all at once are red flags for me. Eventually, OP will need good LSDs all around to take full advantage of the car for sure. It's kind of up to OP for their own build philosophy - I don't like to buy new parts until I know I'm taking full advantage of the old ones and still having issues.
You sir know where it's at. I've got a few questions I'll post towards the end here that I would LOVE you to look at.

Quote:
Originally Posted by jackolafedon View Post
I currently autox my 07 2.5i with similar problems and much less torque available (currently about 155 wheel tq). On long sweepers under power the front doesnt lift, just unloads enough that the open diff spins the inside, the rear has enough weight on it to hook up what power is there. I do have enough photos and spotter feedback to be sure about it. Thus I 100% agree with the diff being the fix, not more suspension tuning.
WRONG. in fact, it means that there's more suspension work that needs to be done.

Quote:
Originally Posted by memmek2k View Post
Torque-sensing differentials (Quaifes or OBX) will still not help if you are actually lifting a tire - http://mgaguru.com/mgtech/rearaxle/ra302c.htm . If the tire is just scrabbling, it will help then. But you yourself have said you're not entirely sure.
I'll put one little correction in here and then we can get into the fun stuff :P A traditional manual quaife differential WILL help if you're lifting a tire. However a clutch-type LSD will not. This is because of how the differential works. I WILL put a disclaimer on this however in that most of the quaife's ive worked with allow a 20-80 maximum split. The center spring disks in the center with the keyway shouldn't allow for a full unlock, which is what makes the quaife so awesome!

anyway.....back to VD stuffs.

I'm new in the subie field, not so much in the race world. Granted they're on different chassis but a lot of the same stuff will still apply. I'll put a second disclaimer on here that I only know enough about VD to make me dangerous.....Start talking about engine/drivetrain/electrical or tires though....now you're in my ballpark! Anyway, since we're already on the topic of lifting the insides i thought I'd put this here....but If I need to move it I will.

Sounds like to me that a lot of guys will put the frame and fender stiffening braces on without much consideration for what else is going on here....is the flex in the chassis really THAT bad? Frame stiffening aside I'd tend to believe that if you're lifting a front inside tire you should be understeering like an SOB.

typically what I've run is~ -2.5* camber in the front, -0.5-0.75 in the rear. Also for our application we'd run somwhere's in the range of +6* front caster. Granted the kingpin angles and IC's for the geometry so this won't hold true. Another item that is of concern that nobodies answered yet is your toe angles on the front and rear. we'd typically toe out on the front by ~3* and then toe in the rear by ~0.5. Having the rear toe'd in will help considerably with stability but I'm not even sure if we can adjust rear toe on these cars.

The fact that it's lifting on the front under acceleration has me a little concerned. Thinking about the load paths on that particular setup, the outside rear tire should be the heaviest loaded....which....if it were too soft, would lead to a front lift IF the front had too stiff of a ARB on it. PLEASE NOTE.....a lot of these things work together. Can't just slap stuff in and hope it works. I'm wondering if a less-stiff ARB in the front with some adjustemnt in the rear would help the problem??? ...again....I'm not real familiar with these chassis.

I am glad that k2k brought up tire pressures. These will make A LOT more difference that what you'd like to admit. One thing that he DIDNT bring up however (I'm assuming you're a he??? if not...I'm single) are corner weights. If you've just thrown everything to the max and not actually balanced out the camber,caster, toe, etc to be even, I'm assuming that your corner weights are nowhere NEAR close. Again, not real familiar with the chassis so this may or may not be a problem on the scoobs.

another thing that I'm a little worried about is that if the camber/caster/toe hasn't been aligned the fact that you're putting in a kit that changes not only your roll center but also the anti-dive (the ALK) which in turn ALSO changes the roll IC.....

Lastly why was it changed from stock? This is the big question. I'm betting the answer most will give to that question is "to make it faster....duuuh". Well.....in order to make it faster you need to know why.

to give an example......my old POS mustang had some massive body roll....and it also had some major tendency to dive on braking. Added some stiffer springs in....now we're fantastic...I could see a little body flex through corners which is really the only reason why I added the front brace bar...but I did notice a little better turn-in on the car.

I'm still seeing some squat under acceleration and it needs new rear springs anyway so....those are next. However almost all my oversteer is gone and I'm excited to see what new rear springs will do.

I digress....

The point was, I recognized what problems I had with the car, did research and then addressed those specific problems. This is typically a good approach to any tuning

anyway...sorry for the blab....maybe after looking over this i should move it to its own thread.....
* Registered users of the site do not see these ads.
jlangholzj is offline   Reply With Quote