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post #1 of 8 (permalink) Old 10-31-03, 04:16 AM Thread Starter
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Change diff gearing?

My 'new' XE ghia (302C / C4) has (according to my transmission guy)
a tight diff. Not having owned Ford V8 power before I was wondering what sort
of rpm should I be doing on a flat freeway.

I took some figures down - 100kph @ 2500rpm / 130kph @ 3000rpm

Should I be getting lower rpm with a stock diff? If so, what would that ratio
be. I want cruise mode when on the highway, not something that revs harder
than it should.

Also the 3 speed is a real short shifter. In top before I get to 60 kph,
and really clunks through the gears

I had it serviced and box appears to be in good order, but the bent metal (kickdown?) rod from carby to box has been disconnected.

Any help would be much appreciated.


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post #2 of 8 (permalink) Old 11-01-03, 04:17 AM
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Re: Change diff gearing?

Depends on your tire size and profile, what rim and tire combo are you using? 2500rpm@100 would be no less than a 2.92 or 3.0 with a 302, I think the 302 cam std with either.

I have a 2.75 with 14'rims I do around 2300 at 100kph

2500 is about right with your 302 if you go 2.75 you might not have enough torque at low speed.

Not sure about the auto, I'm a manual ford owner.
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post #3 of 8 (permalink) Old 11-01-03, 02:04 PM
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Re: Change diff gearing?

Last time I heard "tight diff". It meant the LSD clutches were tight causing the LSD to act similar to a minispool.

I have a "tight diff" myself a few workshops have comented on it.

That diff of your LSD??


XB Fairmont (street car) 11.07@123.02mph.
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post #4 of 8 (permalink) Old 11-01-03, 02:37 PM
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roll Re: Change diff gearing?

I had a standard XE 302/C4 & it had 2.75:1 rear diff ratio. (Not the quickest thing off the mark though.)
Is your dog a good driver?
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post #5 of 8 (permalink) Old 11-02-03, 04:09 AM Thread Starter
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Re: Change diff gearing?

Clevo, Rims are 15in / tyres are 65 series.

Brendon, The diff is LSD but is not a 9inch

You can spin the wheels real easy in this car - if you want to.

The gearbox is a bitch with the harsh changes - anyone got any solutions?

Fat100 - In regards to the beagle being a good driver, I'm not sure, but it does enjoy gettin' in the car at any opportunity. Leave a window down and it's in like flyn!
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post #6 of 8 (permalink) Old 11-03-03, 03:48 AM
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Re: Change diff gearing?

s-pak, you could have a 3.25 the higher the tire and rim combo the lower the rpm.

I would find out what ratio you have: Jack the car up and mark a point on the tire at the top and a mark on the tail shaft.

Turn the the tire around until the mark on the tail shaft has made one complete turn.

Remember how many turns your tire has gone around, if you went 3 * you have a 3.00, if you went 3 and 1/4 you have 3.25 etc

Do the test a few times to make sure, let me know your results.

While the car is up test your LSD with a torque wrench, one wheel off the ground the other fixed on the ground, see how much it takes to turn the wheel off the ground you'll soon know if you have a good LSD or need it adjusted. Some people think they have a single spinner when they actually have an LSD with no clutches left or not tightended up.
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post #7 of 8 (permalink) Old 11-03-03, 08:16 PM
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Re: Change diff gearing?

You could always get under and read the tag on the diff assuming it hasn'r been removed
amongst the crap you should see something like xxx2L92xxx or xxxx3L23xxxx which will tell you.
If your kickdown cable has been disconnected then the auto will shift in grandpa mode forever.
I would reconnect the rod (assuming there is nothgin wrong with it ) and adjust it properly and I think you will find that it will hold gears a lot longer.
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post #8 of 8 (permalink) Old 11-06-03, 07:11 PM
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Re: Change diff gearing?

There is a program called Gear Head, its an american program so tyre hieght is in inches and speed in miles per hour
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