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Old 26th May 2009, 14:28   #1
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Question Shorter wheelbase but large turning radius...WHY?

Fiat cars (Petra & Palio) have wheelbase of 2373 mm (shorter than most of the cars of same size). Despite their shorter wheelbase, these cars have large turning radii. Why can't Fiat do some changes to reduce the turning radius?

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Deepak
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Old 26th May 2009, 16:56   #2
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The turning radius of a car is dependant on 3 factors - the wheelbase, the gearing of the steering (how many turns lock to lock?) and the overhang of the bodywork.

Firstly, the Palio has the largest overhang as compared to its Peers - Swift and Getz. The length of the Palio is 3763mm and wheelbase is 2373mm, giving an overhang of 1390mm. The Swift is much better placed in this respect (L = 3695mm, WB = 2390mm, hence OH = 1305mm).

Secondly, I'm not sure, but I think the Palio steering is also higher geared.

This should answer your query.

Last edited by predatorwheelz : 26th May 2009 at 16:57. Reason: Proper punctutation
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Old 26th May 2009, 17:48   #3
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Quote:
Originally Posted by predatorwheelz View Post
The turning radius of a car is dependant on 3 factors - the wheelbase, the gearing of the steering (how many turns lock to lock?) and the overhang of the bodywork.

Firstly, the Palio has the largest overhang as compared to its Peers - Swift and Getz. The length of the Palio is 3763mm and wheelbase is 2373mm, giving an overhang of 1390mm. The Swift is much better placed in this respect (L = 3695mm, WB = 2390mm, hence OH = 1305mm).

Secondly, I'm not sure, but I think the Palio steering is also higher geared.

This should answer your query.
Thanks predatorwheelz! Overhang of bodywork is understandable as it is not easy for any company to keep changing basic platform (and hence the WB) of a car but why can't they change the gearing of the steering?
Almost all Fiat owners complain about large TR of their cars. Is Fiat simply not listening or is there anything more to it?

Cheers,
Deepak

Last edited by deepgautam_qa : 26th May 2009 at 17:49.
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Old 27th May 2009, 13:32   #4
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Quote:
Originally Posted by predatorwheelz View Post
The turning radius of a car is dependant on 3 factors - the wheelbase, the gearing of the steering (how many turns lock to lock?) and the overhang of the bodywork.

... ...

This should answer your query.
Predatorwheelz,

That's a crisp post, but i have to point out that there are a few errors in your answer.

Wheelbase, agreed, is part of the equation. (and you could also say so is track)

Overhang
, thats a good point you bring up (this only affects the wall-to-wall turning radius, not the kerb-to-kerb).

Wall-to-wall - imagine you are turning in an alley with walls on both sides, no footpath/kerb.

Kerb-to-kerb - imagine you are turning on a road with low footpaths/kerbs on both sides. (ie the front overhang will move above the curve without touching)

I'm not sure which figures manufacturers quote, but wall-to-wall surely makes more sense in India, though given that kerb-to-kerb is smaller, they probably quote that figure!

Gearing of the Steering - this one is incorrect. The gearing, or "steering ratio" just affects how much the wheels turns per turn of the steering. Eg, with one turn of the steering, the angle of the front wheels might change 15* on one car, and 19* on a car with a more sensitive/higher-ratio steering. (A higher ratio steering will typically have less turns lock-to-lock).

But in the end, when you reach the steering lock - what matters is how far your wheels can turn (not how quickly they got there). If im not mistaken, this is known as the wheel-cut. Ie the angle to which the wheel can turn. (Not sure if its called something else as well?)

It would be interesting to compare the wheel-cut of the palio to other cars that size. I think this is where it loses out, since wheelbase/track/overhang aren't really issues.

Heres a related thread : http://www.team-bhp.com/forum/modifi...ible-mods.html (How to decrease the Turning radius(Any Possible Mods)??)


Quote:
Originally Posted by deepgautam_qa View Post
Almost all Fiat owners complain about large TR of their cars. Is Fiat simply not listening or is there anything more to it?
I wonder if this is in part something to do with the original design - and how they probably thought the car wouldn't really need a smaller turning radius in the context it was originally designed for?

cya
R

Last edited by Rehaan : 27th May 2009 at 13:35.
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