felix_is_alive

ok
i have been trying to figure this out , but cant seem to get with the program on this one
maybe someone with more experience on the subject could chime in
Here is my dilema :
installed my 20B engine with subframe and bumpsteer correction kit
but when driving now , i feel the rear end feels "loose" and twichy ,kinda like floating
checked the tire pressure was a bit high , ..lowerd it to 32psi ...runs better but still not as it should
i do remember i installed some time ago the pettit trailing arms (which now i`ve been told are crap) before i put in the 20B , car didnt drive bad back then ,
when i installed drove the car for the first time with the 20b i had a noise coming from the back , as soon as i try and lift the clutch no matter how soft you can hear it , and of course going over potholes and crap , its a full concert of clunking in the rear

i checked my pillowbals , but didnt feel any play , i could move some of them quite easy though (they turn)
but i am not to shure about the pettit trailing arm crap
could that be causing this ?
could i still have bump steer , regardless of the bumpsteer kit ?(car was alligned many times ,i have an allignment shop)
could my pillowballs be doing this?
i have a full set of superpro bushing that i am going to be installing over these days could that help?
what do you guys think ?
this is a nasty problem for me as i want to increase boost , but with an unstable car i dont know if thats a good idea
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Falcoms

The clunking sounds like the sub frame mounts are going bad, or possibly the differential mounts. The twitchy handling in the rear would also probably be related to the sub frame shifting about due to bad mounting bushings. Also, if the suspension bushings are all worn out (which the added torque/horsepower of the 20b would most certainly exacerbate), then I wouldn't be surprised if your problems went away.

If you change out the bushings and problems still persist, then start looking into suspension tuning. Firstly, the rear suspension can have bump steer, so don't be too quick to rule that out. The first thing I'd do, though, would be to soften the rear anti-sway bar as much as possible if it's adjustable. If the rear sway bar is not adjustable, then if you have adjustable height coil overs, raise the rear end to get some more weight on it. I know that may sound backwards, but if you read up on it, it'll make sense. Just make sure you raise the suspension equally left to right, especially if you had it corner-weighted at some point. Ideally you would want to do this on the scales to make sure your corner weights remain similar, just biased to the rear more

Also, I don't pretend that I know about FD's very much, but these are all the same basic principals to follow with an IRS car, at least in my experience with road course racing.

ptrhahn

iTrader: (9)

I don't think these cars have subframe bushings to go bad, do they?

felix_is_alive

thanks for the replies guys
my car went to the body shop today to have my rear wing mounted
i have already taken my original traling arms and mounted the superpro bushings on them
i will change all the bushings i have , and see what happens
Falcoms , i have height adustable coilovers , i will try and lift the car a bit to see what happens
i can also adjust the stifness of front and rear shocks , what do you recomend doing with those ?
thanks
mike

Falcoms

in regards to stiffness settings on the shocks, leave the fronts if the car has good initial turn in bite but still goes over minor bumps somewhat decently, but I'd soften the rear shocks a little so the tires stay in contact with the road. In regards to shock and spring settings, it used to be that racers set the suspension way stiff, but now the setups have changed to setting the suspension to the point that it can go over the bumps on a track without bouncing the wheel into the air, and compensating for softer springs with stiffer sway bars and they adjust the turn in with sway bar stiffness and pre-load.

t-von

iTrader: (8)

1. The pillow ***** wear out at about 70k. Replace them if you haven't. Trust me it's a night and day difference and will make the car seem brand new again.

2. Replace your diff mounts with the solid units. Too much diff movement will change the rear geometry and make the rear wander around too much.

3. Do you notice a lot of tranny movement while accelerating? If so, remove your PPF and use two metal pry bars to twist the PPF from each end. This is how you check it to see if it's cracking. If it is, reinforce it (like i did mine) or replace it.

You wont believe the difference these mods will make to the car.

ReZ311

iTrader: (4)

^^ What TVON said, also:

Tighten up the wheel bearings, loose front bearings will give a rear floaty feeling.

Check the alignment cam bolts on the control arms. If they are loose they will cause the rear end to do weird scary stuff.

Most likely it's the pillow bushings and or the suspension bushings.

felix_is_alive

i`ve already reinforced my ppf , since the 2 rotor days , i ve seen too many of them fail , going to change all the bushings now , since i have them anyway ,