4x4 cosworths again

just checked a set of drop gears, 26 teeth and 24 teeth, the 24 tooth gear is splined to fit the end of the centre diff/ output shaft , so the 26 would be on the front prop,

would this make the front prop spin faster or slower than the output shaft ?

 

 

if the diff end turned once 24 teeth,then the prop end would turn 24 teeth,leaving 2 teeth not used= prop turning slower.

 

ok this is very confusing now,

the actual scenario, i thought i'd sussed it, but looking at the driven gear from the diff to the prop makes no sense,

front diff - 3.62:1
rear diff - 4.27:1

so to match the front speed to the rear speed, surely i need to up speed the front prop ?????????

but if my driven gear from the gearbox out put shaft is smaller than the one on the front prop surely the front prop will be slower

or ............................


does the gearbox, actually drive thr front prop direct via the chain, and the vc drive the rear diff hmmmmmmmmmmmmmmmmm too confusing for this time the night

 

up for Markk

 

I am not a gearbox expert, but if your rear diff has a shorter ratio than the front, than the front prop must be driven slower to match speeds.

I am almost sure the rear prop is direct driven, the front via step off chain.

Don't know if the ratio's are correct though??

 

You need to match ratios

front diff - 3.62:1
rear diff - 4.27:1

At a given speed the two props will be turning at different rates, and that needs reconciling by the transfer chain ratio, to prevent the centre diff being made to slip.

The maths:

4.27 divided by 3.62=1.179, you therefore need a drop gear ratio of 1.179:1

You have a drop gear set of 24/26 (24 on the driver, 26 on the driven)

Divide 26 by 24=1.083, which will not work.

To find out what it is for...

Multiply 3.62 by 1.083=3.92.

The drop gears you have are for 3.92:1 rear diff

 

front diff isnt it?

 

I don't think so, Bernie's started with the 3.6 front, and multiplied by the difference in the gears

 

Fuck I don't know now

EDIT: It is right.

 

Of course it is

 

off topic i know..,

gearboxman,

did u get my email about my 4x4 gearbox problem?

cheers, dave.

 

I know, but Gareth had me all confused.








Easy done

 

cheers for the replies chaps

so we actually 'underdrive' the front diff, i.e the bigger pulley on the front prop, small pulley on the VC, hence slowing the front diff down ? does that make sence ???

bernie , iknow the step offs i have are 3.9's but always thought that the larger gear was to go onto the VC until i looked at it properly then realised it couldnt

the actual ratios im hoping to use on this drivetrain are

front - std ( 3.62:1 ?or is it 3.64:1 )
rear 4.55:1

so 4.55/3.62 = 1.257

so if i have a 32 for the VC , and i have a 26 for the front prop (assuming i can get a chain to fit )

32/26 = 1.231 (pretty close ?)

differance in front/rear 1.257
differance in step offs 1.231
= 0.026

that will sort me for the 4.55:1 rear on the step offs

 

im confused all day long

 

Wrong way round Mark

Always divide driven by driver

26/32=0.8125

hmmm....

3.62x0.8125=2.94125

Nope!

 

so to get the underdrive to the front prop, it must always have the bigger gear on the prop shaft end, and the smaller one on the vc ?

 

Yes, that's right.
You are going to struggle to match 4.2, although if purely on gravel you could use 27/31 (4.1:1), but not on tarmac or you will go through VCs at an alarming rate

 

Mark,

Get your hand in your pocket and buy a 7 1/2" front....9" rear....50/50 split in the box.....all on 4.4:1.... job sorted....

Ian

 

is that what your buy me for my birthday?

 

i think your right ian, might as well just go and ring barra, order a sequential 6 speed and fully active, whilst im at it


im waiting for your car to be ready before i commit myself, i'll decide once ive give it a shakedown in grizedale this november, make sure its in full gravel trim for me will you

 

Mark,

Ł2K and the bond you can take it....arrive and drive like a prince....i'll even service for you... will that be hard or soft compound for the long stage?

Ian

 

can you make the difference up with some different profile tyres maybe?

i'm just clutching at straws her tho...

 

i'll have soft compound there only 9 miles each, so 18miles for the 1st time through, a new set for the short dunnerdales, then we will see how they go for the last two in the dark, i hope youve got bumper pods for me as well !!!

 

jim , your clutching at straws