SmokingClutch

I have a 1988 GTU. The suspension is unmodified, the rims are stock and the tires are the stock size. The only modification in the suspension are Energy Suspension urethane bushings for the rear lower control arms. I do have slightly different front calipers than stock, they have Mazda embossed on them, and they're aluminum 4-pots, but they're slightly beefier than stock and they aren't the usual RX-7 part though they do fit. I have no idea what vehicle they would have come from.

Problem #1: At highway speeds, the car feels unstable. The car wanders from side to side (no consistent pull to either direction) though it almost feels like it's not coming through the steering wheel, almost like it's the back end doing the steering. It's almost like a "dog walk." If you hit imperfections in the pavement it sometimes goes very wild, requiring constant steering corrections. It might be my imagination but it seems worse the colder it gets outside. The speed at which this happens changes but it's most consistent above 65 mph, but it does come and go.

Problem #2: At parking speeds, at full lock or near full lock it feels like the wheels or tires are continually "catching" and then "jerking loose." It doesn't happen constantly but it is very annoying.

I have already done the following:

- Checked tire pressures
- Gotten a four wheel alignment

Turbonut

iTrader: (1)

If four wheel alignment done and no worn parts found??? Hopefully alignment specs were done correctly. Did they give you a readout of specs-before and after?
A lot of cars with wide tires will create a wandering condition caused by the road imperfections, but you probably have the 205's on the car. Tire pressure @ 30lbs? No noticeable uneven tire wear? Check rear DTSS bushing to be sure they arn't worn.
Also when you have the wheel turned to the fullest the 2 front tires are not compatable from an alignment standpoint, so may see a small amount of scrubbing.

SmokingClutch

They didn't give printouts, truth be told they're not all that much of a shop, they can handle most stuff and I figure they can handle putting things back to manufacturer's spec.

The tire wear is a bit odd on the car, I'm not sure how to describe it but on one of the front tires the tread is sort of "pulled" up at the edges, though I suspect this happened when I used the car on the track (Charlotte Motor Speedway and a local very small road course). Needless to say the tires on it now are not the best for on track work so I think they overheated.

I keep pressures higher than mfg. recommendations for that same reason - if you run 32 PSI on the track you'll be rolling over the sidewalls. I usually run about 40 PSI.

The scrubbing in the front end seems a bit more than minor and I don't remember the car always having it.

How would I check the DTSS bushings... how can I tell if they're worn?

Trav

Problem #1: I would definitely stick to near-normal tire pressures when not at the track... I'm not extremely familiar with suspension setups yet as that is on my list of jobs to tackle -- however, have you checked your rear shocks? If your back end is "loose" I would wonder about those.

Turbonut mentioned the DTSS bushing -- definitely a culprit although I would think it would have to be basically gone for it to be this bad, although it's all relative...

Sounds like you already started replacing some bushings, might just go ahead and do em all back there to be sure.

One last idea but it's a stretch... I'm assuming that since you're going to the track that you have quality tires on the car. Sometimes the "cheap" tires can feel like it gives the car a lot of steering play. Or like the car will follow ruts a lot more than usual -- or like it's being affected by crosswind. I had a car that had some old cheap tires (namely bias ply, not radials). I went through all of the steering etc. and it turned out to be the tires.

Problem #2: Sorry, don't really have an opinion -- I've never heard of such a problem except on 4WD vehicles.



P.S. -- If you have any question about the quality of work done by the shop (and it sounds like you might), take it elsewhere.

Turbonut

iTrader: (1)

If your running 40 on the street I'd say that's a problem.
The DTSS bushings are on the front side of the rear hub assembly at about 3 o'clock. I would jack the car up under lower shock support and then see if any play in that bushing by moving the wheel/tire back and forth.

Hot_Dog

For problem #1, it sounds like it's your rear steer bushings. My 90 did the same thing. The parts manager at my local Mazda dealer told me that those rear steer bushings go bad all the time. I've replaced mine with the polyurethane busings (i.e., rear steer eliminator bushings). The car steers muvh more precise now. The poroblem was that when I would be driving straight ahead there would be instances where I'd have the wheel off center left to go straight and other times I'd have to have the wheel off center right to go straight. Elimanating the rear steer bushings fixed that problem. Also, check your inner and outer front tie rods for looseness/wear.

For problem #2, it sounds like your front lower control arm bushings are worn, especially the big inner bushings. Also, check the upper strut mounting blocks for wear.

After Christmas, I'll be replacing the rear trailing arm bushings on my 90 GXL with polyurethane. I was wondering what difference I would notice with the new bushings? Any noticable difference in ride harshness?

Thanks,
Hot_Dog
90 GXL
02 RSX-S

Nick86

iTrader: (1)

Does your car have power steering? If so, check the fluid levels, and belt tension. I had a similar problem: every time I went around a corner, my steering would suddenly go really light in the middle of the corner. I had a PS pump fluid leak - so when I would go around a corner, was the only time the pump would work.

I also had that wandering feeling on the highway - especially over expansion joints. The culprit was worn rear shocks (something that wouldn't have shown up during an alignment). A new set of Tokiko rears, and it was as good as new.

Matlock

Check your tie-rods. Those can cause similar systoms of #1. They do in my case.

daceo215

You described this problem very precisely, I have the exact same suspension issues w/ my 7... I was pretty sure that the shocks are bad (96K and still stock) but I recently decided to replace all the bushings also... My car wanders considerably and when I hit a bump in the road it can even jump a few inches to one side or the other...

Any information on the best/cheapes way to correct this is very helpful, I'm going to price the bushing mentioned above now! - Thanks guys!

Hot_Dog

If your car is approaching 100K miles, than it's highly likely that your shocks need replacing. The original Mazda shocks are fairly decent. I replaced the original shocks on my 90 GXL with Tokico Illuminas at around 120K miles. I have nearly 100K miles on the Illuminas. I've bought a set of KYB AGX's, and will be putting them in after Xmas. I'll also be putting in new upper strut mounting blocks, and polyurethane bushings on the lower control arms.

When I first put in the Illuminas several years ago, I also changed the upper strut mounting bolcks and the lower control arm bushings. The upper strut mounting bolcks is actually a bearing that is set in a rubber bushing. As this bearing starts to fail, the top of the strut will become loose and will affect your car's steering. These bearings cost only about $35 each, and should be replaced with the struts.

The problem that I had with my GXL was that if the road had had ruts, even mild ruts, the car would track in the ruts, and was hard to keep under control. After I changed the control arm bushings, that problem disappeared. I believe the cause of this problem was due the rear rubber bushing on the control arm had deteriorated. If you were to look at the bushing, it would look as if it were very badly weathered. Well, after I changed these bushings, the problem went away. When I put the AGX's in my car, I'm also going to replace the control arm bushings, but this time it'll be with polyurethane.

Hot_Dog
90 GXL
02 RSX-S

600HP CLUB

They're from a TURBO RX-7..turbo has 4-piston up front and 2 pistons out back.

-mike

Nick86

iTrader: (1)

So does the GXL.

Jahoo88

Sound slike you had too much toe out at the front. I had teh same problem and found i was drivign at like 3/4" of toe out at the front. It will cause wandering liek you describe. Without moving the wheel the car will be all over lane at hwy speeds.

SmokingClutch

Thanks for the help, and I'm glad to see I'm not the only one with this problem - I was starting to wonder if I had something seriously messed up.

The tires on it now are Dunlops on one end (I forget the model but while not great they're not bad) and Yokohama Avid H4s on the other.

Sounds like it's bushings, then, not a biggie, since the rear ones were worn to the point of causing a "clunk" in the rear it does not surprise me that the rest are bad.

As for the difference, when I had the bushings installed it definitely positively affected the handling (til this new problem cropped up about two months later). There's a noticable amount of extra stiffness in the rear but even on PA's pockmarked roads it's not bad at all. I'm going all urethane on the new bushings.

The 88 GTU already had aluminum 4-pot calipers identical to the TurboII's calipers... these are slightly larger (more aluminum, not bigger pistons) and the ones previously on the car, which were original, did not have the Mazda logo on them.

I would think the front toe should be fine since the car was aligned - and there's no good reason it should be out of alignment, I did nothing to the front end of the car yet and this problem is new. It's possible my mechanic didn't set anything right, of course.

The struts were replaced by the previous owner about five years ago - that's a route I'll take if the bushings don't help.

As for recommendations on struts - is it worth it to get performance springs and shocks or is it better to just go coilover?