firemn131

I put the Cup II back on and the condition is gone.

Difference
* Tires on the cups are worn
* Cups offset is 52
* twist offset is 55
* Cup tires 225 40
* twist tires 205 50

What's the problem?
Tire size?
Or
The offset?

Thanks for playing along..

J

hacker-pschorr

Could still be a bad tire(s) or a wheel is bent our way out of true.

Swap twist wheels from left to right, see what changes.

As far as offsets go, 55 is better up front. Stock is 65 so closer to that the better.

Tires...some of us run 245's on the street and others 265 or bigger on the track.

jcorenman

You checked tire pressures, right?

I am not a big fan of 205's on these cars, but I don't think that would explain it...

firemn131

Yup,
Tire press right on 50.

I will try the swap tomorrow. But it they were bent or out of true I would imaging I would feel it during driving. Not a shimmy at 100.

hacker-pschorr

Why 50? That's a bit on the high side. Possible wear issues due to over inflation..?

See this thread:
https://rennlist.com/forums/928-foru...your-tire.html

Maybe that thread needs a spring bump....

firemn131

Tires call out 50.

That's ok, I went out to pick up the male child...
Car wont start..

Man this gets old!!

hacker-pschorr

Read the thread I linked to.
The PSI on the tire is not what you should be running at. That is the max pressure the tire is designed for, it's a safety maximum load rating.

If you are using stock tire sizes, you should be setting the psi (cold) which is listed on the fuel filler door. My S4 says 34F / 44R.

The confusion starts when you run something other than stock. Typically not far from the stock rating though, many run less psi with larger, lower sidewall tires.

firemn131

will do.

So what is the relay that I hear clicking behind the glove box?
FP relay swapped, still no start.

jcorenman

Try 34 / 34, there is no reason at all to run 44 in the rear.

Smell the exhaust after cranking for 10-15 seconds, if it smells like gas then it may simply be flooded.

FredR

John,

205 front tyres running at 51 psi cold- I take it you are a fan of roller skates? Does the car have a tendency to go straight on when you apply the brakes?

1. Dump the front 205's ASAP- 225's are barely adequate, 235 better if the wheel used can take it.
2. The 928S4 should run with 400kg on each wheel. For a given 205 section tyre a good starting point is to look at that tyre's rated conditions typically specified at 51 psig- maximum rated load will be around 550kg. To find a working pressure [i.e. when hot] divide the actual load by the max load for the tyre and multiply by 51- for the case in hand this works out at 37 psig so a cold pressure would be roughly 34 psig allowing 3 psi for warm up. Wider tyres typically have higher working loads.
3. For my first 928 [90S4] the RDK system demanded soemthing like 44 psig n the rear to keep the warning light off- this was nonsense- I figured the front 225 needed something like 36 psig and the rear 245x16 a tad less at 35 psig. There is no "one size fits all" as things like driving style can influence the need. I currently run a 255x35x18 section on the front at 35 psig and a 285x35x18 on the rear at 33 psig. If I was going to the track I would run a bit lower cold.

Rgds

Fred

firemn131

Thanks Corenman, Fred,
Amazing how much I still learn about this car in general.
So, the no start was an alarm kill.
I actually thought that I disarmed it 7 years ago.
I locked my door while my daughter still had hers opened.
That disabled the start.

Had dinner thought about it and remember reading years ago about something similar.

When and inserted the key, locked and unlocked. Start right up..

Now on to tire shopping..

So the turbo twist are ok wheels to use?
Front 7 1/2 x 17 with offset at 55.
Rear 9 x 17 with 47 offset. Need to find a spacer.

squid42

I suggest to get a quality laser distance meter and measure distance between the wheels, on forward and backpoint points, for both sets.

You said that you aligned the wheels yourself, maybe you already got one.

FredR

John,

The Turbo twist is a very nice design and looks well. The front offset will work- to a point - but will never be the equal of the stock design. Without trying both back to back difficult to say whether in practice you would notice the difference.

Regarding rubber you can probably fit a 235 section up front and a 265 section on the rears should you feel so inclined. I suspect that combination will not need a rear spacer but that would have to be proven.

jcorenman

I thought the twists were 7" wide in the front? That will work OK with a 225/45R17 in the front, 255/40R17 rear. I would not go wider with a 7" front rim. No spacer needed on the rear.

FredR

John has been a bit inconsistent with the width of the turbo twist front rims. If they are 7 inch then they will be limited to a 225 section.