car pulls to the right when braking

[A1337STI]

So my rally car is pulling to the right under braking, also rather interesting when you release the brakes the steering wheel moves. (like it moves left then back to right) upon brake release. movement is pretty small 5 degrees of a 360, but very pronounced

I do have a failing or missing A-arm bushing on the passenger front... my rally crew noticed the passenger wheel physically moves (rearward?) under braking even at low speeds ... So that might be the entire issue ... just seems to have gotten really bad (course i don't know what is left of that bushing after Gorman) and that side wheel bearing is going out .... (have replacement knuckle with a good bearing, and replacement A-arm with ... good for pick n pull bushings)

but i think something else is going on. anyone want to tell me what i should be looking for?

I'm sorta thinking "sticking caliper" but i dunno ...

[sperry]

It's the A-arm. Stop driving the car until it's fixed... or else.



Before mine went at the track, I was getting a hard pull right under braking. One of the welds on the LCA had failed, allowing the other to flex toeing the left tire in and turning the car right. I noticed the issue and checked the car out in the pits but couldn't see the failure when the car was static... it only took like 3 more slow laps and then it failed completely. I was lucky to be at a race track with runoff and at only around 40mph when it let go... if it had occurred on the street, or on the freeway heading home, it would have been a huge mess.

[A1337STI]

Thanks!! I'll swap it out before driving it anymore.

Think I've only driven it 2 days since the rally (one was to go to the pick n pull)

Eeeks!!! even on a race track i don't want that to happen, and on the highway would be epically bad.

[A1337STI]

I went to swap the A-arm and spindle last night and it appears i damaged the threads for the A-arm mounting bolts.

I'm talking about the 2 Large 19mm bolts , they are the rearmost bolts for mounting an A-arm, the bolt on the far outer edge of the car will go about 3 turns and then won't budge. I don't want to damage it further as i'm sure there will be more A-arm swaps in the future.

obviously i'm wondering how to fix it .
Do I just run a tap to repair the threads?

Also I'm wondering if my process of A-arm removal caused the issue. I was lazy and decided to remove the A-arm while attatched to the spindle. I removed the axle nut, brake caliper , swap bar , Then the outer rear A-arm bolt with a rattle gun. the A-arm moved down as i removed it so maybe there was some unwanted foces at work ? i then removed the A-arm from the subframe. removed the inner rear A-arm bolt. then i unbolted the spindle from the coilover and pulled it all out.

for re-install I attatched the A-arm to the subframe. I put the rear outer A-arm bolt in a few turns, but then took it out as i realized it was just making the subrame bolt harder to line up. i then attatched the swaybar because it was lined up perfectly. moved over to the rear A-arm bolts and the outer one won't go in. I put the Inner one in about 95% in. it has a few turns left to go.


Was it my methodology that caused this problem? I've done a few A-arm swaps (and removed a bunch at the pick n pull) I ran into a similar issue on my STI when i was doing an A-arm swap , it was caused by doing the bolts in the wrong order/ fighting with it too much.

Oh and the rear bushing is completely destroyed and i think nut with a large shoulder has been backing off on that A-arm. what's left of the bushing was allowing a crazy amount of movement.

[khail19]

Never changed one before, but I would think you should leave the swaybar disconnected until everything else is done.

[sperry]

Sounds like that LCA bushing is the culprit causing your issues, assuming the rest of the arm is in good shape. You shouldn't need to take the arm off to get at that bushing... just the bolt thru the bushing first, then two bolts into the chassis to remove the LCA bushing and mount. Then press a new bushing into the mount and re-install.

To remove the whole LCA, I don't bother with the axle/spindle. I just disconnect the sway bar, remove the upper half of the ball joint from the spindle, then remove the front bushing bolt and the two rear attachment chassis bolts from the LCA to take it off. Reverse the order to reinstall, but make sure to leave everything a little loose until it's all lined up. Then tighten in the order from the manual (which I don't remember off hand). I think the car is supposed to be on the ground when torquing things down.

I'm assuming the '02 WRX service manual procedure is the same on your impreza: http://www.seccs.org/tech/

[A1337STI]

Perfect, so i was doing things in the wrong order ... D'oh

thanks, that order does make sense now that i think about it. I was replacing the spindle at the same time due to a bad wheel bearing, and having a stack of spindles with "better" bearings
Ya i would think the 02 Torque specs will be good.


So What do i do about the bolt that won't go back in? use a Tap to chase the threads, and avoid the rattle gun to put it back in?

[sperry]

Originally Posted by A1337STI

Perfect, so i was doing things in the wrong order ... D'oh

thanks, that order does make sense now that i think about it. I was replacing the spindle at the same time due to a bad wheel bearing, and having a stack of spindles with "better" bearings
Ya i would think the 02 Torque specs will be good.


So What do i do about the bolt that won't go back in? use a Tap to chase the threads, and avoid the rattle gun to put it back in?

If it's just the few starting threads that are chewed up, you should be okay to clean the bolt and chassis up with a tap and die. But if the whole thing is stripped, well, you may be looking at drilling it out and using a heal-a-coil, or you might need to cut the car open and weld in a new backing plate with a new captured nut or something.

Oh, and there's basically never a situation where you should be using an impact wrench during re-assembly. Those are for taking things apart. Period.

[A1337STI]

the bolt goes in by hand for 1 or 2 turns, and an other 3 turns with out much effort with a wrench, then just stops and appears to damage the threads on the bolt at that point...

I know Tom B has the correct tap (i bought it for him when we were working on my STI) but he hasn't been responding to texts. anyone else happen to have that Tap?

Hopefully i can just re-tap it. if its a worst case scenario would it be best to drill out the hole enough to weld in a long nut , or even a blank tube that i tap out ahead of time? (hopefully its not that bad)

and good to know, no more impact wrench on re-assemblies, think i did that to the other side.

[sperry]

Originally Posted by A1337STI

the bolt goes in by hand for 1 or 2 turns, and an other 3 turns with out much effort with a wrench, then just stops and appears to damage the threads on the bolt at that point...

I know Tom B has the correct tap (i bought it for him when we were working on my STI) but he hasn't been responding to texts. anyone else happen to have that Tap?

Hopefully i can just re-tap it. if its a worst case scenario would it be best to drill out the hole enough to weld in a long nut , or even a blank tube that i tap out ahead of time? (hopefully its not that bad)

and good to know, no more impact wrench on re-assemblies, think i did that to the other side.

Make sure when tapping it that you're cleaning up the bad threads and not just using the tap to propagate the crossed threads into the good ones. The last thing you want is to go and torque this down and find out the bolt threads nice and smooth now, but is crooked.

[Dean]

I can't remember. Can you get to the back of that nut? If so, tap it from the back where the threads are known good.

And clean up the threads on the bolt too.

[MPREZIV]

Originally Posted by Dean

I can't remember. Can you get to the back of that nut? If so, tap it from the back where the threads are known good.

Remember the blue WRX that was on my lift one day when you came by Dean? They had broken that captured nut off, and we deduced that the only way to get to it was to cut into the uni-body...


Better than a tap would be a thread chaser. Taps can actually cut the existing threads slightly larger at times, and cause even the correct bolt to be too loose in there.

Let me look through my stuff and see if I've got the correct size chaser for you Alex.

[Dean]

Originally Posted by MPREZIV

Remember the blue WRX that was on my lift one day when you came by Dean? They had broken that captured nut off, and we deduced that the only way to get to it was to cut into the uni-body...


Better than a tap would be a thread chaser. Taps can actually cut the existing threads slightly larger at times, and cause even the correct bolt to be too loose in there.

Let me look through my stuff and see if I've got the correct size chaser for you Alex.

I wasn't positive which bolt he was talking about. If it is that captive bolt with no access, BE VERY CAREFUL! You do not want to be in the same situation the guy Cory is talking about was!

Chaser would be better.

The problem with all situations like this is getting lined up with the original not munged threads. Angles are critical! Take your time!!!

I always thought a cool tool would be a camed chaser that could be inserted past the mangled threads and then would expand and chase the threads as you backed it out of the hole. If you designed it right, a single thread pitch chaser might work in multiple diameter holes.

[A1337STI]

Tom stopped by with the Tap and he carefully re-tapped the damaged section of threads (only seemed to be about 2 turns of bad threads)

Tap went in completely straight , small amount of metal dropped out for the bad section. I need to get a good thread cleaning Set (as i'm sure continued part swapping won't be great on the threads)
i think i should have gone that route first... but i didn't ..

I'm not sure if i should torque it down to the spec or a bit under now ... ?!?
Currently the bolt is only set at 100 ft pounds, the specs say 184 ft/lbs I'm going to put the spindle (and tire) back on tonight and drive it over to Tom Scalzis for an exhaust fit (oops) and maybe we will swap knock sensors (or just check if its tight)

Also when my off season starts (October) I'm thinking I should use a helicoil to repair the threads back to OEM specs..

thanks for the help btw. car it at least able to be put back together.

[Dean]

IMHO, Torque it in there if it cleaned up that easily. if it holds, you are done if it strips then you can helicoil or whatever.

Don't wait for it to fail on a stage!

[A1337STI]

Okie Dokie. there is still time for other drastic repair options if torquing it down strips it out.

[A1337STI]

Finished putting the car back together last night, got a bit dumb and decided to up the torque by 10 to 110 Ft/lbs and it felt normal , turned a little bit before my torque wrench gave me the "click click" so i called it good.

quick quick test drive up and down the street and the pulling to the right under braking is gone. no weird steering wheel shake on brake release either. and wow the bushing (what's left of it) is really destroyed. i should post a pic. now the car is back to just 1 loose nut as an issue (well that and a gaping hole in my exhaust and missing a muffler) meh ... small issues

[MPREZIV]

Originally Posted by Dean

I always thought a cool tool would be a camed chaser that could be inserted past the mangled threads and then would expand and chase the threads as you backed it out of the hole. If you designed it right, a single thread pitch chaser might work in multiple diameter holes.

They make them, but they're fucking expensive to get decent ones. They can't do multiple size holes of the same thread pitch though. I have one in O2 sensor size.