Diff ratio

Includes clutch, transmission, propeller shaft,
universal joints, differential and rear axle.

Moderators: reidy, Blacky

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Wag62
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Re: Diff ratio

Post by Wag62 »

My son has a worked 202 and 4 speed with a 336 lsd doesn't rev too hard on the highway and has heaps of grunt off the mark tyres are 225/60/13.

My hyromatic grey motor is now running a 355 with 185/80/13 tyres and is perfect all round.

My wifes 3 speed grey is now running a 336 with 205/60/13 tyres and it is perfect all round.

Hope this helps.
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(AUST)Mod
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Re: Diff ratio

Post by (AUST)Mod »

I have a 186/powerglide/3.08 LJ diff and 205 55 15 tyres on the back and my freeway revs are nuts - over 3000rpm! I am hoping to fit a trimatic - will this bring my revs down?
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Blacky
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Re: Diff ratio

Post by Blacky »

(AUST)Mod wrote:I have a 186/powerglide/3.08 LJ diff and 205 55 15 tyres on the back and my freeway revs are nuts - over 3000rpm! I am hoping to fit a trimatic - will this bring my revs down?

ummmmm ...... no. The final drive ratio of both boxes is 1:1 so you wont gain anything up top.
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Devilrod
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Re: Diff ratio

Post by Devilrod »

(AUST)Mod wrote:I have a 186/powerglide/3.08 LJ diff and 205 55 15 tyres on the back and my freeway revs are nuts - over 3000rpm! I am hoping to fit a trimatic - will this bring my revs down?

Are you sure its a 3:08 diff gear? Sounds more like 3:55 or lower.... My old FC had 3:55 and 245/50/14's and it was just over 3000 at 60mph.
Speed and Style........... One day I'll get the speed bit.
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(AUST)Mod
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Re: Diff ratio

Post by (AUST)Mod »

Devilrod wrote:
(AUST)Mod wrote:I have a 186/powerglide/3.08 LJ diff and 205 55 15 tyres on the back and my freeway revs are nuts - over 3000rpm! I am hoping to fit a trimatic - will this bring my revs down?

Are you sure its a 3:08 diff gear? Sounds more like 3:55 or lower.... My old FC had 3:55 and 245/50/14's and it was just over 3000 at 60mph.
Well it was sold to me as a 3.08:1 :roll: by a reputable Perth business :?:

Ah well, guess I will just have to pass on driving it to the nats haha.
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Stygian
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Re: Diff ratio

Post by Stygian »

(AUST)Mod wrote:
Devilrod wrote:
(AUST)Mod wrote:I have a 186/powerglide/3.08 LJ diff and 205 55 15 tyres on the back and my freeway revs are nuts - over 3000rpm! I am hoping to fit a trimatic - will this bring my revs down?

Are you sure its a 3:08 diff gear? Sounds more like 3:55 or lower.... My old FC had 3:55 and 245/50/14's and it was just over 3000 at 60mph.
Well it was sold to me as a 3.08:1 :roll: by a reputable Perth business :?:

Ah well, guess I will just have to pass on driving it to the nats haha.
You can pull it out and have a look. If I remember correctly, the ratio is stamped on the crown gear.
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Trev
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Re: Diff ratio

Post by Trev »

Don;'t pull it out, the ratio is stamped on the plate behind the uni-joint.
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Devilrod
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Re: Diff ratio

Post by Devilrod »

And if not jack it up and spin a wheel and count the revolutions of the tailshaft or vice versa.
Speed and Style........... One day I'll get the speed bit.
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Stygian
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Re: Diff ratio

Post by Stygian »

Trev wrote:Don;'t pull it out, the ratio is stamped on the plate behind the uni-joint.
I've never noticed that...the things you learn...
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Re: Diff ratio

Post by (AUST)Mod »

Trev wrote:Don;'t pull it out, the ratio is stamped on the plate behind the uni-joint.
Awesome thanks mate!
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Brodie
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Re: Diff ratio

Post by Brodie »

Andy, with a 3.08 ratio and your tyres, 3000revs in top is 69mph (111kph)
Same with 3.36 gears would be 63.5mph (102kph)
And with 3.55 gears it would be 60mph (96.kph)

Hope that helps man
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(AUST)Mod
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Re: Diff ratio

Post by (AUST)Mod »

Brodie wrote:Andy, with a 3.08 ratio and your tyres, 3000revs in top is 69mph (111kph)
Same with 3.36 gears would be 63.5mph (102kph)
And with 3.55 gears it would be 60mph (96.kph)

Hope that helps man
Cheers Brodie,

I can't remember the exact revs, but it sounds like my diff is actually a 3.36 or 3.55.
Craig wrote: Andrew you have a red so I wouldn't race it :wink:

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