Technical What eLearn says about 18" wheels

[neilshep]

Interesting to see on the eLearn CD that the steering rack travel for 18" wheels is 140mm, but for 15", 16" and 17" its 148mm. The full paragraph on the steering says:

eLearn - Contents
CONSTRUCTION SPECIFICATIONS

The steering wheel structure is made from magnesium to reduce its weight and improve its strength. Axially and height adjustable steering wheel. The steering column is supported by a steel mounting, in turn secured to a steel bracket.
The stiffness of these components contributes significantly to minimising steering wheel vibrations.
The steering column is a sliding telescopic structure, in order to improve safety.
The steering box is the constant ratio type (51mm/fixed rev) whilst the servocontrol is the electric type located on the steering column.
The steering box has a different arm length and travel according to the size of tyre requested:
- 148mm rack travel with 15" - 16" - 17" tyres
- 140mm rack travel with 18" tyres.

So if you change your wheels to 18" from something smaller, probably wise not to use full lock!l

 

[neilshep]

Also:

Details (steering box employed with 15" - 16" - 17" tyres)
- splitter ratio equal to 51 mm/fixed revolutions
- steering wheel angle/wheel angle ratio equal to 16°/1° (referring to rack centre)
- steering wheel turns: 2.9 for a rack travel of 148 mm
- turning circle between pavements: 10.4 m.
Details (steering box employed with 18" tyres)
- splitter ratio equal to 51 mm/fixed revolutions
- steering wheel angle/wheel angle ratio equal to 16°/1° (referring to rack centre)
- steering wheel turns: 2.745 for a rack travel of 140 mm
- turning circle between pavements: 11 m.

 

[Hellcat]

Muchas Gracias. Useful info

 

[neilshep]

Muchas Gracias. Useful info

My pleasure, but the thanks are due to Tiramis for posting the links to the eLearn files.

 

[mikem1989]

Hey guys, reviving an old thread because I've just found this and I'm planning to add 18" wheels myself.
Has anyone here added 18"s to a Bravo that originally came with 16" or 17" and how did it go, did you have any problems?

 

[fovargue12]

Hey guys, reviving an old thread because I've just found this and I'm planning to add 18" wheels myself.
Has anyone here added 18"s to a Bravo that originally came with 16" or 17" and how did it go, did you have any problems?

Hi mate I had 17s and now have 18s, I have no problems at all ! Obviously you don't always use full lock but forme it isn't a problem. Sometimes when I reverse with full lock I here a bit of a judder but that could have happened before I'm not sure. The conclusion is for everyday driving I don't see any issues with the 18s.

 

[mikem1989]

Hi mate I had 17s and now have 18s, I have no problems at all ! Obviously you don't always use full lock but forme it isn't a problem. Sometimes when I reverse with full lock I here a bit of a judder but that could have happened before I'm not sure. The conclusion is for everyday driving I don't see any issues with the 18s.

Coool! Nice to know. Thanks for the info mate!

 

[rossocorsa]

Comical the Italians one has to wonder why they didn't simply standardise the shorter travel rack across the whole range? I have a delta with 18s and can't say that I find the turning circle excessive so there's really no reason. Have wondered as 18 is a 'sport' wheel option if there are other setting differences but probably not.

 

[Fergie]

They were maybe worried about the wear / stress on the car under full lock on 18s?

The 20vt Coupe has the turning circle of a bus for the very same reason.

I've never had any problems rubbing and I doubt many people would be accelerating hard under full lock...