Fixing a Month-Long Blonde Moment

[Ash]

I finally hit upon an epiphany today that took 6 weeks too long to figure out. Took a couple weeks to get used to the little weirdisms that come along with a new (to me) car and finally started noticing stuff.

1) The car liked to shimmy in the back end whenever I hit a rut or bad road-worm. It would wobble side to side and it felt like the bushings were going on my steering rack. (Had this happen with my Mustang last fall after I took it off-roading.)

2) Put a small flat-shaved spot on one of my tires a couple weeks ago (stopping for deer on the highway at 130 km/h). After that there was a noticeable thumpthumpthump. I thought a wheel bearing packed it in.

3) At low speeds, in second gear, I would get lash out of the back end; it felt like my U-Joints were going.

4) Car has Potenza dampers/springs all the way around, and the car seemed rather harsh, even for an aftermarket system. Pot-holes and railroad tracks made it sound like the car was bottoming out. Actually it felt like the coils were coming right off the car.

5) And today I noticed that my tires were starting to wear funny on the shoulders, but not the rest of the tire (Sumo Firenzas, 205/50R17).

Apparently the wear was because my tires were underinflated. Regular checks on my tire pressure told me that I had 32psi all the way around. This was a consistent number, no changes or leaks for the last 6 or 7 weeks, but I couldn't figure out why that number seemed funny. Then I remembered.

I had these same tires on my Mustang last year and I was running 42/46psi fr/rear.

So I promptly added more air to the 42/46psi set-up and it feels like a whole new car!! No shimmy, vastly reduced lash (now it feels normal), the flat-spot is almost not noticeable anymore and the suspension now feels stiff without being paralyzing.

I'm gonna keep and eye on the tires just to make sure that the pressure I'm running isn't going to screw-up something else though.

Thoughts? Experiences? Am I just talking crap with no idea what I'm talking about?

 

[LilMissMkIII]

:biglaugh::biglaugh::biglaugh::biglaugh::biglaugh::biglaugh:

And I thought I was a blonde

 

[Guyana00]

This is pretty funny, but I would still do a full inspection on all of the components of the car. Proper tire pressure could have hidden some of the symptoms and problems could still be there. There are probably other problems you don't notice either.......not yet anyways

Feels good when you go through the whole car, know everything wrong and even better when you fix it all. On the inside, and on the road

 

[Ash]

This is pretty funny, but I would still do a full inspection on all of the components of the car. Proper tire pressure could have hidden some of the symptoms and problems could still be there. There are probably other problems you don't notice either.......not yet anyways

Feels good when you go through the whole car, know everything wrong and even better when you fix it all. On the inside, and on the road

Took me a bit to sort the flat-spot. My brakes locked up stopping for those damn deer:3d_frown: and it was the front right tire. I figured out it was the tire and not a wheel bearing when I put the spare on and the thump was gone. So I switched the fronts and rears and I'm hoping that the (now)rear flat spot will wear down a bit. While I was nosing around looking for the source of THAT problem I had a decent look around narrowing down problems.

I think.

 

[Clueless]

how many psi in the tire??!

 

[Ash]

how many psi in the tire??!

I was running 32psi, and it never occurred to me that it might be too low (I try to check my tires once a week, and that's where I had my blonde moment: they were all the same and I didn't think about how much was actually in there).

Now it's 46 in the rear and 42 in the front.

 

[IJ.]

I always use the max on the sidewall

 

[Clueless]

I was running 32psi, and it never occurred to me that it might be too low (I try to check my tires once a week, and that's where I had my blonde moment: they were all the same and I didn't think about how much was actually in there).

Now it's 46 in the rear and 42 in the front.

I've never ran past 35psi, I consider it a hazard. But it sounds like the suspension is wacked....

 

[Ash]

I always use the max on the sidewall

Now...is that sarcasm? I'm going to call a hunch and guess yes...
(And because I'm kinda gullible - if you do mind if I ask why?)

I've never ran past 35psi, I consider it a hazard. But it sounds like the suspension is wacked....

My max psi rating for these tires 51psi, so I think I'm okay. I didn't have any problems at this psi on the last car I ran these tires on.

And I agree with you about the suspension being whacked. The car is a japanese import, and had the Potenza's on it when it came over, so I have no way of knowing how old they are. I've never had aftermarkets coilovers before, but common sense tells me they shouldn't sound like squirrels on meth falling in a barrel everytime I hit a bump.

 

[IJ.]

Ash: Nah being serious I run the Max as while it's a bit of a harsher ride the tire holds it shape and side walls better and doesn't bottom out and destroy rims as often (35 series rubber)

If it's a JDM import has it been realigned for the US roads?

 

[Rennat]

i go by whats on the inside of the door... sometimes even a 2-3psi lower...

and stock tire size is 225/50/16... not 205's.

 

[Ash]

Ash: Nah being serious I run the Max as while it's a bit of a harsher ride the tire holds it shape and side walls better and doesn't bottom out and destroy rims as often (35 series rubber)

If it's a JDM import has it been realigned for the US roads?

That's a good question. I bought the car off a kid whose brother bought it from an import garage in BC (I live in Canada). Bro drove it for a year, Junior drove for what I think was about two months and then parked it for a year before I bought it.

In order for an imported car to meet Canadian Motor Vehicle standards it needs to be certified so I would assume it was aligned at the time of import/inspection. But three years is a long time for things to go out of alignment (especially when the kid that sold it to me doesn't know shit for cars).

I'm thinking another alignment can't hurt. $70 and the peace of mind seems like a small investment to me.

 

[Rennat]

hopefully that $70 doesnt turn into an expensive job...

do you have any way of jacking it up and inspecting everything pre-alignment? just so you have an idea of what shape everything is in?

 

[Ash]

i go by whats on the inside of the door... sometimes even a 2-3psi lower...

and stock tire size is 225/50/16... not 205's.

The inside of my door is Kanji (and I can't read that yet), but good to know on the stock tire size, thank you. I thought 205's seemed a bit small, but those were on the car too when I bought it.

Ah, the joys of buying a used sports car: you get to spend your time chasing/fixing someone else's mistakes.

Would having 205's have a negative (mild or otherwise) impact on the handling?

 

[suprarx7nut]

How do the JDM and US alignments differ? My roommate had said something about cars being aligned slight right so sleeping drivers are less likely to go head on. Any truth to that?

Ian, shed some light for me!!!

 

[Ash]

hopefully that $70 doesnt turn into an expensive job...

do you have any way of jacking it up and inspecting everything pre-alignment? just so you have an idea of what shape everything is in?

Yes I do, and I'm thinking that's a good idea, from some of the stories I've heard in my small town. And this means of jacking up the car is in the shop at my brother-in-law's place, run by a mechanic I can trust. He can do alignments though.

Worst case scenario - after pre-checking everything first of course - there is a tire shop I trust two hours away so I may go that route.

 

[IJ.]

I have my car set up slightly asymetrical so it doesn't want to follow the camber of the road to the kerb, a RHD car on the other side of the road crown drives horribly by comparison and that's basically what you have if the car isn't realigned on all 4 corners.

I also use a bit of extra castor so it returns to centre, this means more steering effort but I can live with that for the extra stability at high speed.

 

[jugodegolf]

I always use the max on the sidewall

Where's my litte notepad...:biglaugh:

None of those sound normal to me.

 

[dumbo]

Interesting thread, I must say...

A easy way to get rid of flat spots, burn em off, and get rid of those pizza cutters lol. Good to see some more :canada

 

[honestabe]

My Goodyear Eagle F1 GS-D3's and Toyo T1R's run at 50 PSi (max is 51) and I have no issues. The old rule of 32 PSi is out dated. Go by what the tires say, not the old rule. Hell, my Geo had tires that ran at 44 PSi. I'd only run 32 PSi if I were drag racing. Then again the front tires would be over inflated and the rear tires would be under inflated.