Re: [DML] Re: Gearboxes!

[Martin Gutkowski <webmaster@xxxx>]

Hi John

Lowering the final drive ratio means putting a larger crown gear on the (sorry, not sure
of the correct term) central driveshaft - the one that translates the longditudinal
rotation of the engine and gearbox to the transverse rotation of the driveshafts. This
means all five gears will have a higher ratio - ie more rotations of the engine per
rotation of the wheels. This improves accelleration but at the detriment of top speed.
You'd get the same effect by putting smaller wheels on the back (no, I'm NOT suggesting
this!).

Whether with a stock or modified engine, it all comes down to personal preference. The
DeLorean has extremely tall gears - this was to bring the cruising RPM down and get the
car the mpg figures they needed. IIRC this was part of the deal that got DeLorean all his
money.

Since the first day I started driving, I've owned diesel cars. The disadvantage with a
diesel is the engine doesn't rev as high as a petrol engine. The advantage is you get
shedloads more torque (remember power is torque x speed). My 2.0l HDi Xantia is 110bhp
and cruises at 90mph at 3000rpm. This is because Citroen gave it very tall gears to make
use of the torque.

Driving my DeLorean for the first time pleased me greatly because of the tall gearing. I
would like it to be a bit quicker off the line, but as you know my long-term plan
involves some engine mods by a company I found, and it's basically up to me what I want -
ie torque or power. It seems to me that in a car with tall gears, you need more torque
rather than power. I'm no expert but it makes sense to me.

I am not planning to get anything done to my car till my finances are more healthy and I
sort out some of the other problems with the car, like the non-functioning drivers side
lock, the faded fascias, and the tatty interior. The gearbox is a possibility, and the
bloke I spoke to can do far more than just lower the final drive. He can interchange
ratios to (for example) give you lower/closer 1-3, a mid range 4th and stock 5th so you
get better accelleration but retain motorway cruising economy and top speed.

Martin
#1458
www.delorean.co.uk

PS Thanks!

John Dore wrote:

> Hi list,
> Martin and others, can you tell me if modifying the final drive ratio
> (see Martins post below) would be only good for a low powered
> DeLorean, i.e. stock engine, or would there also be benefits for the
> DMC Hi-Po engine upgrade? Maybe the stock final drive suits the car
> better when it has more BHP? Are you going to do this modification to
> your DeLorean Martin? If it would allow the car to accelarate faster,
> would it lose some top speed?
>
> Thanks,
> John.
> PS Martin, Congratulations on buying your DeLorean!