Front wheel drive gear box

Gearbox questions & answers etc..

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coachgeo
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Front wheel drive gear box

Post by coachgeo » Thu Jun 03, 2010 3:49 pm

how does a conventional front wheel drive car layout work. Tranny lies below engine?, Slightly in front of engine or rear of it.??? with two axle shafts going to each wheel?

IgorVigor
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Re: Front wheel drive gear box

Post by IgorVigor » Thu Jun 03, 2010 4:02 pm

it depends on the FWD car...

if you mean a transverse engined car, then the gearbox is usually to one side of the engine, basically the same to look at as a rwd car, just turned 90 degrees...

the main difference is the output shaft (propshaft/driveshaft).

in a FWD car, the driveshafts are usually lower down, more under the gearbox, but some have them right up in front and some have them behind the gearbox.

and they incorporate a diff at the bottom of the engine...

there are some exceptions to the rule though.

Audi keep the engine longitudinally mounted, with a front wheel drive gearbox, so basically instead of a single shaft running inline with the crankshaft, you have 2 driveshafts, one going to each wheel.
the other main exception are old renault's (Renault 4, early Renault 5's for example). They have the gearbox at the very front of the car, and the engine between it and the bulkhead/firewall...

Hope that helps...

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coachgeo
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Re: Front wheel drive gear box

Post by coachgeo » Thu Jun 03, 2010 8:16 pm

Transverse engine- tranny is driven only by one side of engine? As in their is not power pulled from the engine on both ends of the crankshaft right? Just one side is feed into a gear box and that gear box has axle shafts for both sides... incorporated somehow for these shafts is some form of differential.

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Re: Front wheel drive gear box

Post by TedV » Fri Jun 04, 2010 3:29 am

Yup, trans on one side, air conditioner compressor, alternator, power steering pump, etc are usually run off the other siide. Timing belt diesel fuel pump and waterpump too depending on design. This is generalizations, exceptions to them all.

;edit; forgot the diff is in there too. Most all are open withvery few limited slip. You can find a spool or locked diff for some cars, usually from the drag race croud.

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Re: Front wheel drive gear box

Post by IgorVigor » Fri Jun 04, 2010 7:35 pm

the engines are exactly the same as a rwd car, they only change the gearbox.

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coachgeo
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Re: Front wheel drive gear box

Post by coachgeo » Fri Jun 04, 2010 9:29 pm

Differential? part of Tranny case usually? or is it a separate box? As in say you want to remove tranny from FWD car and use CVT..... do you then have to come up with some alternative differential for the two wheels cause diff. was integral to the tranny?

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Re: Front wheel drive gear box

Post by IgorVigor » Sat Jun 05, 2010 3:09 pm

yes the diff is usually built into the gearbox...

this diagram might help you understand:

http://www.icarumba.com/shared/image/re ... 52LG09.gif

if the diff was a separate unit, it would be sooo much easier to fit one into a motorbike...
sadly, because its cheaper to manufacture a single casing, and fit the diff into it, it makes like harder for bike builders to use the gearbox as a welded diff is required...

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coachgeo
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Re: Front wheel drive gear box

Post by coachgeo » Sat Jun 05, 2010 6:04 pm

ok thank you for the information. Didn't want to assume anything but thought as described above is the setup, but it twas only a guess. If I was wrong then the leading thought into my question would be pointless. Sooo.... since it is not.... what I was leading up to.....

now needs to be asked

so, the new question.......

with out further a do.......
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See the CVT Forum question :arrow: :mrgreen:

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