STi brakes, the brute force way!

[Cam]

I believe you are onto something with the steering rack. I have not had this happen to me but if everything else is tight down there, that is the first place I would check.

[92 SVX]

could it be the upper strut mount? I had that happen on a 2000 grand am, they use a pivoting upper mount though.

[sperry]

Originally Posted by 92 SVX

could it be the upper strut mount? I had that happen on a 2000 grand am, they use a pivoting upper mount though.

That's a good idea too.

Since the spindle conversion pushed the struts out a bit from their stock position, I could be torquing the rubber strut top more than it's happy with. If I tore something up there, that very well could be the play I'm feeling through the steering.

Unfortunately, if that's the case, the "fix" it likely building some coilovers... not something I was looking at spending money on right now.

[sperry]

I jumped back under the car at lunch today after checking the strut tops (they looked fine). The steering rack was nice and tight.

While under there I grabbed the sway bar and twisted it... sure enough, that was it. The passenger side end-link was a tiny bit loose where it attaches to the strut, allowing a nice clunk when it moved up and down. When I had checked it earlier once side at a time, the bar was under tension so I couldn't get it to clunk with my hand. But from under the car w/ both wheels in the air, it was easy to reproduce the noise.

I tightened up the bolt, and checked all the others while I was under there and the car is back to normal. What I thought was some slop in the steering was just the normal tendency of the wheel to not center due to the -2 deg of camber on the front end with no toe-in. I never really noticed how dramatic the effect of the camber was before since I always just center the wheel while driving. It's no where near as bad as the WRX (it's a -4 deg and you can leave the car tracking through a turn with no hands on the wheel ), but it's noticeable if you're looking. I really wish I could run -1.2 to -1.5 on the camber... but I'll need to revise the ball joint adapter design to get there.

So, good news... the problem was a benign as they come, and I'll be tracking the SVX tomorrow!

[92 SVX]

very good news.

[Cam]

That's a relief. You seem to have had some trouble with loose bolts...still reusing those locknuts huh?

In all seriousness though, I am glad that it was not your struts or rack, both could have been potentially pricey.

[NeedForSpeed]

One of the best projects here,

[sperry]

Originally Posted by Cam

That's a relief. You seem to have had some trouble with loose bolts...still reusing those locknuts huh?

In all seriousness though, I am glad that it was not your struts or rack, both could have been potentially pricey.

Actually, I replaced the bolts and locknuts on the ball joint adapters with brand new ones. They're on there plenty tight now.

The endlink's were only tightened with a pair of open ended wrenches... so they weren't exactly torqued down all that hard.

I think the reason I'm fighting so many loose bolts is just that I'm taking things on and off the car every 3 days. I stopped bothering to carefully torque everything down and just put a little elbow into it and called it good because I'm just going to have to pull it back off to check on things on the next weekend. Not exactly the ideal method for putting things back together, I know. But I did go over everything carefully w/ a long handled wrench before heading out on track!

Speaking of the track:

I'm not super happy with the car on track. First, with those wheel spacers pushing the front wheels outwards and the super soft stock suspension, I'm actually rubbing the shoulder of the tire on the rubber fender liner under hard turning. It's actually minor enough that I can probably just pull off the liner strip... but if I'm going to do that, I'll probably also put a really minor roll on the front fenders as well just to be sure.

Second, the car pushes like a plow... I mean sure, it's not any worse than the car was before the new front knuckles/brakes, but I was really hoping the additional camber up front was going to help a little... but with a 70/30 weight bias, I don't think the SVX is ever going to be super fun on track... it's probably always going to be a bit gruesome in the slow corners.

Third, and this is the most disconcerting, I've got a weird shimmy in the steering on corner exit. I don't know how to explain it better than to say that if feels like a speed-wobble on a motorcycle. Basically, as you feed in power exiting the corner, if you hit even a minor bump, the steering starts to shudder back and forth. Just backing out of the throttle a tiny bit stops it, but leaving your foot on the floor allows the shudder to worsen. My best guess is that the car has a bumpsteer issue that coupled with my 231,000 mile old struts can put a wobble in the steering. Hit a bump with the car's weight shifted off the wheel, and the bumpsteer pushes the steering one way, then the strut starts to oscillate on the one corner and as the wheel travels up and down it pushes the steering back and forth. And I think the -2deg of camber probably allows the shudder to self perpetuate, as the wheel turns back and forth just a little bit, the camber keeps the strut from ever damping the vibration out. The only thing that stops it is lifting a little and shifting some weight back on the strut.

The problem there is that I don't think there's really anything much I can do about a bumpsteer issue. If the geometry of the SVX vs STi knuckles are different enough to induce bumpsteer, I'm basically going to have to model both the suspensions in order to figure out how to get the STi knuckle in the correct position to match the SVX... which will likely mean raising or lowering the STI's ball joint. And now that ball joint adapter might need to be drastically more complicated in order to put a vertical offset into the mounting point. Worst part is that I don't even have a guess as to which way it may need to move... Somewhere I've got a simple suspension modeling program around here... if I can find the disk, maybe I can take some measurements of everything and sort it out. But more likely, I may just decide the SVX shouldn't be taken to the track.

The good news is... the new brakes worked phenomenally. To put it simply, my car simply is not fast enough to be able to out drive the brakes. Not matter how hard I pounded on the braking zones, the brakes just shrugged off the abuse. No fade, no shudder, no drama... not even any pad knock-back, which I was expecting because I'm still on some old high-mileage rear wheel bearings. It was completely the opposite from the last time I had the SVX on track where one hard braking zone and I was fearing for my life as the brakes faded before the corner.

Which reminds me, I wanted to mention the pads I ended up putting on the car. I got a set of the new StopTech street performance pads. They are *awesome*. Performance-wise they remind me of the EBC YellowStuff pads... a little bit poor with the cold-bite... but work really well once they start to heat up. Street pads, but able to handle some mild track time. But the StopTech pads have just like 1/10th the dust of the EBCs and are dead silent, even on noisy race calipers. I was kinda skeptical and even had a set of YellowStuff to go on the car but there was no need, as the StopTech pads handled the track w/o breaking a sweat.

[Johnybeas]

interesting finds, however I don't think you should give up on the SVX on the track especially if you're using stock old ass suspension. A Bontrager rear sway bar some koni gc's or another strut/coilover option may just refresh your idea of the svx on the track. Just my .02

[sperry]

Originally Posted by Johnybeas

interesting finds, however I don't think you should give up on the SVX on the track especially if you're using stock old ass suspension. A Bontrager rear sway bar some koni gc's or another strut/coilover option may just refresh your idea of the svx on the track. Just my .02

True. A lot of my handling issues are likely due to the worn struts. But I still would like to address the bumpsteer issue as best as possible if I'm doing one more revision of the BJ adapter, if for no reason than to make the front tire wear better.

[sicksubie]

If you make another revision, please let me know.. I would love to get my hands on a set. I could also give you feedback aas to whether or not I have the same issues with my coilovers vs. your old stock suspension.

[Johnybeas]

progress?

[sperry]

Originally Posted by Johnybeas

progress?

Sorry, nothing lately. Was pretty busy with the wedding. And since then, playing catch-up at work.

The car is driving well on the street, but still has the bumpsteer/shudder issue at the track. I've just been driving the WRX for track days, so I haven't been in any great rush to get back to the SVX. I still want to get some adapters cut on the waterjet with some minor revisions for clearance and bumpsteer... but without the proper tools to measure and understand my bumpsteer issue, I'm not totally sure how to proceed.

So, sorry to be slacking, but I will update as soon as I've got more info.

[Johnybeas]

Bump, getting close to buying wilwood fronts with some Hawk rear pads. Any progress on this??

[sperry]

Sorry for the long delay... not a ton to report, I've just been living with the car half done, since my issues aren't really affecting me much just driving to/from work. Until tonight... since we're getting some crazy T-storms and possible snow in the high altitudes, I figured today's as good a day as any to swap on the new winter tires.

Since the stock SVX wheels won't clear the new brakes, I scored a cheap set of semi-beat up '05 STi BBS wheels over the summer and ordered up 4 Dunlop Wintersport M3's on special from TireRack (245/45/17) for 'em a few weeks back. When I put them on this afternoon I learned a two things:

1) The wobble at the race track, and possibly my whole roll/bump steer issue may be 100% attributable to some loose tie-rods. Once again, apparently I failed to tighten some important bolts and ended up with a loose nut on the tierod/spindle junction. Now, I *know* they were tightened to spec when I put them on initially, because I had to ream out the holes to match the SVX tierod ends. And they were tight when my mechanic aligned the car. And the were tight the first couple of times I disassembled and reassembled various bits on the front knuckles. But when I was pulling the front tires off, I noticed a bunch of play (1-2 degrees perhaps?) that wasn't turning the steering wheel. So I re-tightened that up. I just hope it's not an issue with the reamed out taper mismatching the tirerod end taper, which might mean this will just come right back after driving on it some more. Either way, with it tightened, I'm hoping my wobble and rollsteer issues go away.

2) "Normal" sized wheels/tires probably aren't going to fit on the car after this conversion without spacers. ("Normal", as in popular wheels for STi's.) When I put the STi wheels on the car, I figured I'd be able to forgo the spacers that I needed in order to get my 17x9 RPF1's to clear the brakes. However, the STi wheels (17x8+53 if my memory serves me) put the inside of the tire just up against the struts. Granted, I'm running some *massive* 245/45/17 snow tires, so it may be possible for some 225/45/17's or other more "normal" sized tires to clear, but it'll probably be close. Narrower or lower offset wheels would work as well. But if anyone's planning on doing this mod, be aware you'll likely need some spacers if you want to run big tires on STi sized wheels. I ended up putting the spacers for the RPF1's on there and everything fits again.