Z Steering Part II

[Ron Earp]

This weekend at VIR the #38 260Z had some serious steering rack issues.

The car behaved well in practice and qualifying. Jeff started the ECR1 on Saturday and did a fantastic job of moving through traffic. The car behaved well and seemed to have no problems other than the dreaded hot re-start issue.

I got into the car at the 45 minute mark or so and then had a couple of laps under caution. Car was okay. Once the course went green I had about 2.5 laps with a “good” car, and then everything went south.

Coming into turn three I tried to turn left and the car didn’t turn much at all. More steering input got the car to turn, but I had to put a full 120 degrees wheel input in to make the turn. This problem continued to various degrees all over the course and for the rest of the race. I seriously thought I’d have to come in but I managed it after a bit. During the uphill esses you’d have to put in about 110-130 degrees left wheel sometimes to make the second left esse. Left turns were far more hairy than right turns, but in either one you never knew what to expect for steering. To make turn four required slightly more than 180 degrees of input, arms fully crossed.

Sunday morning we investigated the car in the light and found a loose jam nut on the driver’s steering arm. The Parrishes helped us get that fixed and string the car and we thought all was good for the SARRC.

The SARRC kicked off and I was happy on the pace lap with the way the car felt. However, at Oak Tree on the outlap the problem came back worse than before. Same symptoms, but, the effects in corners was more pronounced and the car was extremely hard to drive. Lap times suffered but I managed to finish the race.

I checked the car again at home and there are no loose tie rod ends. It seems I have some sort of steering problem that can develop after the car gets hot? I’m not sure exactly what is going on. The rack seems stable when examined with a helper turning the wheel. But maybe it will not stay stable when warm?

This thread I started back in June and we ended up putting some metal shims in the bushing and it seemed to hold well. At least it held last month at Roebling.

Steering Rack Issues (http://itforum.improvedtouring.com/forums/index.php?showtopic=11681)
http://itforum.improvedtouring.com/forums/...showtopic=11681 (http://itforum.improvedtouring.com/forums/index.php?showtopic=11681)

[pballance]

Ron,
Check the coupler bushing under the brake M/C. Just a hunch that the bolts may have wallowed out the poly bushing if you have installed it. It would also be consistent with "heat soak" if the OEM bushing is in place and has broken loose from the bolts.

Just something to check. I would also look at the lower "U" joint in the column and check that the splines haven't been stripped.

[kthomas]

Is the steering wheel back to center to track the car straight? If so then it's proly not anything splined. I'd run the whole gamut of checks (and frankly, if one of my drivers experienced that on a track they would have parked the car).

1. Check alignment. Is it what you had before the weekend started? If so, we know the innner and outer tie rods aren't stripped.
2. Is the steering wheel where it was before the weekend started? If so, we know the upper and lower steering sector splines aren't stripped, and the rack isn't slipping past the pinion.
3. If both of those are true, then you got big deflections somewhere. Could be coupler, but proly more like something cracked- frame, strut, control arm, wheel, or bolts.

Don't limit your inspection to just steering components, you could have something big cracked far away.

Best of luck, let us know what you find.

[Parrish57]

Yeah... What they said. And, if you have eccentric bushings on the front make sure that they are not spinning. Whatever it is, get it fixed. Steering issues are about as scary as fire.

[Tom Donnelly]

Ron,

A loose steering rack will do what you described. The rack slips back and forth between the bushings. at least it happend to me once and we shimmed the rack and cranked down on the bolts. Didn't come back.

Ditto to what Keith and Steve said. Get off the track. I had a tie rod bend and almost hit someone just trying to limp back to the pits with unpredictable steering. The car jerked around and zig-zagged down the back straight at the end of a practice session and a friend thought I was trying to run him off the track.
I got a real WTF look before I explained what happened. Coulda been worse.

Just call for a tow next time, its cheaper.

Tom

[Ron Earp]

I hear you fellows. However, if I thought I was in danger or putting others at risk (rarely around anyone in my stints, especially in the SARRC) I'd definitely come in. Hard to drive is true for sure, but I don't think it was uncontrollable dangerous. Good points, all of them and looking back on it it'd probably have been better to have not raced and parked it. It is odd how Jeff only experienced a single episode or two of it during his drive, but I had it full blown within 8 minutes or so of swapping drivers.

I don't know what it is yet, but we're going to find out and make the steering the way it should be, simple and direct. We will check the entire system and figure out what where the problem is. I've ordered a lot of new parts for it already. I'm not made of money, but I figured that many of the parts original to the car when it was built in 1992 and some probably original with the car I'm sure from 1974. I'd feel better knowing what I had in there.

I'll report back on the issue and hope we find a definite cause and not a "hope we got it" sort of solution.

Oh, Got to meet Riely from Lynchburg Nissan this weekend. It was a pleasure putting a face to a fellow who has been so helpful over the phone. Got some nice tshirts too!

Ron

[joeg]

Tires? Tire pressure?

[pballance]

Did you find anything yet Ron?

[Cobra Tim]

Are you sure the rack sint moving in its mouts as someone posted previously.

You can check this with the hood open and the car on a solid surface. Have someone sit at the wheel and turn it from side to side (as if you were warming tires on a pace lap) Keep your eye on the rack itself and see if it moves.

What bushings are you running in your rack?

[JeffYoung]

Tim, thanks on that. Yes, we are sure. We've had that issue before and corrected it. This is something else; we think it is internal to the rack.

[Ron Earp]

Not sure what is up with it. On dry pavement with lots of traction the rack does not move when the wheel is turned. But clearly it does under race conditions. I'm going to replace the rack, use some hard bushings, do the metal tab trick, and replace the steering coupler.

It is frustrating to have a fun car that does fairly well but have an intermittent problem like this rack issue.

Tire pressures were fine before and after the racing.

Ron

[kthomas]

Not sure what is up with it. On dry pavement with lots of traction the rack does not move when the wheel is turned. But clearly it does under race conditions. I'm going to replace the rack, use some hard bushings, do the metal tab trick, and replace the steering coupler.

Ron
[/b]

Okay, yer scaring me now. You still don't know that the rack is moving under race conditions. No reason for it to not move just sitting there, but move in the race. I doubt the loads on the rack are higher at speed versus sitting on the garage floor (the loads are certainly higher on control arms and chassis, but the forces on the steering wheel thru the rack aren't). And even if they were, the movement if it was bushings or coupler is just a matter of degree. Your problem sounds non-linear, as in CRACK or some other mechanical failure.

I wouldn't put this thing on a track until I found THE problem. Sure, replace the rack if you want, but I'd tear the old one apart and magnaflux everything or whatever. Without finding the actual cause you don't know that the problem might migrate from "hard to steer" to "can't turn at all" at 125 mph.

[Ron Earp]

I wouldn't put this thing on a track until I found THE problem. Sure, replace the rack if you want, but I'd tear the old one apart and magnaflux everything or whatever. Without finding the actual cause you don't know that the problem might migrate from "hard to steer" to "can't turn at all" at 125 mph.
[/b]

It is not going anywhere until we can find the issue. Like I said, we are not sure why it does it but I think while we are disassembling these parts we will find the problem.

But it appears to not move on dry pavement. And you know on dry pavement with the Hoosiers there is a lot of force to make that thing turn.

Ron