tii Wheel Offset and Scrub Radius

[Beaver's02]

Any suspension guru out there? Couple of questions I haven't been able to find an answer for.

1). Does anyone know what the offset is for the stock 13"x5" steel wheel that came on a tii?

2). Any one know what the Factory Scrub Radius is set at (negative or positive) and what the Steering Axis Inclination (angle) is?

I am currently running a set of e30 basketweaves (6.5X14 et30) with mediocre results in the steering 'feel' department. I believe the poor steering feel is due to a Scrub Radius problem caused by the increased offset of the e30 wheel. I figure I can fix the Scrub Radius difference with a wheel spacer, but I need to know how much. I know the factory alloys came with offset et27, but is that the same as the factory steel 13X5 wheel? By knowing the Scrub Radius and Steering Axis Inclination, I can calculate any additional offset for tire diameter differences.

Thanks in advance for any help.

[Conserv]

The factory 5x13 steelies for all U.S. square taillight cars are ET29. I can't imagine that the factory 5x13 steelies for round taillight tii's are much different. In short, the offset is going to be pretty close to your ET30 rims.

Steve

[c.d.iesel]

6.5" wide is a bit chubby for a street o2 - plenty reason

for 'loss of steering feel' with that

and what size tires do you have ?

++++++++++++++++++++++++++++++++++

stock steering specs (2002 & 2002tii)

rim offset ET29

readings with 150 lbs on each front seat,

150 lbs centered on back seat,

46 lbs in center of trunk,

FULL tank of gasoline

front:

Camber +0* 30' (+/-30')

Caster +4* 0' (+/-30')

Toe-in total 1.5mm (+1mm/- .5mm)

Kingpin inclination 8*30'

track 1348mm

rear:

Camber -2* (+/- 30')

Toe-in 1.5mm (+/- 1.5mm)

track 1348

[Beaver's02]

C.D., thank you for the information.

The tire size I am running on the car is: 195x60x14 which is 30mm wider in section and 11mm smaller diameter than the stock (assuming a 165x82x13 stock tire). Not an atypical tire size for a +1 application (e30 'bottlecap' and 'basketweave' wheels).

Do you happen to know if the standard 2002 steering geometry is set with negative, zero,or positive Scrub Radius?

Thanks again.

[c.d.iesel]

sorry - can't find the answer to that .......... at the moment

for the rest of the class to think about:

http://en.wikipedia.org/wiki/Scrub_radius

[Mike Self]

Carbureted roundie US 2002s used a 4.5 inch wide wheel, and the outer lip of the wheel cover was flush with the outer edge of the wheel. Tii wheels were a half inch wider, and the wheel cover was inset a half inch. Thus the offset is to the outside.

cheers

mike

[Beaver's02]

Thank you for the information Mike.

What is interesting, is your observation that the additional 1/2" wheel width increase on the tii is entirely to the outside of the wheel. This would reduce the offset from the stock 4.5"x13" et29 wheel by half the width increase or .25" (6.3mm) making the 5"x13" tii steel wheel offset et23. Hmm.

All things being equal, less wheel offset makes for a more positive Scrub Radius, which would mean a tii has a more positive Scrub Radius than a standard 02, unless the tii strut was geometrically set up differently (different kingpin angle or different hub flange to steering axis distance).

Anyone out there know about strut geometry differences (stock vs. tii)?

[Conserv]

Someone here (c.d.?) can confirm the factory ET for the 4.5" rims. The ET29 of the later 5x13 rims (i.e., square tailight) appears to be the same as the ET for the earlier 5x13 rims (i.e., round taillight ti and tii): 29mm. And, in line with Mike's observation, the additional 1/2" width of the earlier 5" rim is largely to the outside. The 4.5" rim must then have an ET in the 35mm range.

(I just took a quick, and no doubt inaccurate, measurement of a '67 4.5" rim and a '72 5" tii rim and came up with ET37 and ET27, respectively. This difference, directionally at least, fits with what one might expect.)

Steve

[c.d.iesel]

(I just took a quick, and no doubt inaccurate, measurement of a '67 4.5" rim and a '72 5" tii rim and came up with ET37 and ET27, respectively. This difference, directionally at least, fits with what one might expect.)

look at those two rims again , please

the ET is always stamped on the rims

I'm pretty sure you wont see a ET37

[Conserv]

(I just took a quick, and no doubt inaccurate, measurement of a '67 4.5" rim and a '72 5" tii rim and came up with ET37 and ET27, respectively. This difference, directionally at least, fits with what one might expect.)

look at those two rims again , please

the ET is always stamped on the rims

I'm pretty sure you wont see a ET37

c.d.,

Stamped ET's become common on German rims beginning in the mid-'70s, but you're darned lucky to find a stamped ET on a late-'60s, early-'70s steel rim. I haven't owned a roundie in the last 37 years, so I'm down to my last 5 roundie rims. They date from 2/67 to 2/73, 4 are Lemmerz, 1 is Kronprinz, but there's not a stamped ET among them.

No one worries about ETs on 4.5" rims because clearance is rarely (never?) an issue. But somewhere there is a factory ET for them. It's an academic exercise at best, but I am curious. (I'm not vouching for 37 precisely -- my calc. of the 5x13 ET was off by 2mm -- but if the 5" is ET29, I believe the 4.5" is greater.)

Regards,

Steve