the best differential ratio

[schipps]

I am using a 4.11 :1 R33 rear end behind the T56. I have done just over 25,000 kms and not once have i wished for a different ratio.
It takes off brilliantly and cruises at 100km/hr sitting on abt 1850 rpm.

regards

Mick

[1 TUF AC]

Originally Posted by schipps

I am using a 4.11 :1 R33 rear end behind the T56. I have done just over 25,000 kms and not once have i wished for a different ratio.
It takes off brilliantly and cruises at 100km/hr sitting on abt 1850 rpm.

regards

Mick

What tyre size are you running in the rear? And what your overdrive ratio in 6 gear?

[schipps]

Originally Posted by 1 TUF AC

What tyre size are you running in the rear? And what your overdrive ratio in 6 gear?

I have 275/40/17 rear tyres and as to the final ratio on 6th...not really sure.

Sorry that doesn't help you, I got my T56 from Mal Wood a few years ago and I thought it was the .5 , however I just looked on Mal's website and he lists .5, .56 and .62. (So its one of these 3...which ever one it is, its really good..


regards Mick

[Dominik]

You raised a good point about the amount of shiftts to get to a certain speed. I always put some value to that too, i.e. I aim to get to 100kph (or more) in 1st, 160kph in 2nd, and 200kph (a decent 1/4-mile speed) in 3rd. If you build an engine to cover each gear in 4 seconds, you're on the right path ;-)

[Wazza]

Just got all new diff today for the 8.8 Thunderbird IRS.

And Changed from 3.2 to 3.7, and it's bloody AWESOME.

The old "reconditioned" one was not healthy at all.....should've used Brand New from the start.....it was about the only "used" bit on the whole car when it was built...and I always felt I was going to regret it....I was right.

New one is as Smooth as silk, and sixth gear at 110 k.p.h. Is around 2,000 rpm.....just hummin'.

Fixing/ replacing the diff was a bit last minute...but the Nationals road trip/drags/sprints had used up what ever life the old diff had.

Mad panic over the last few days waiting for all the new bits to arrive, picked it up in Brisbane as soon as they finished it today (12 o'clock )....

Back to Scott Hampsons place....put the whole arse end back together...

take it for a 20 Klm's test run...( Brilliant)

Go and get the trailer organised, load and back to Gold Coast...so I can START getting my $hit together for a week on the road.

Packing at the moment,as we are off to the "COOMA Summit To Surf" run at 8.00 am tomorrow.
Really been looking forward to this...and...touch wood...the weather looks tops.

(Don't ya just LOVE trying to pack for two people for a week on the road...and getting it to fit in the Cobra?)

The tip is lots of "little" bags...and then it sort of goes together like a big puzzle...and then the last bit is standing there trying to fill any "gaps" with shoes.

Should be great......

What could go wrong....right??!

Cheers,
Warren

[YerDugliness]

Deleted by YerDugliness

Forum glitch...posted three times, didn't show until 3rd try, then all three were shown.

Gonna delete the next one, too.

Dugly

[YerDugliness]

Forum glitch with posting...deleted by YerDugliness

[YerDugliness]

I'm not using a T56...but i have some experience with a T-5 World Class. The problem with the T-5 is that the first gear is useless except for parades and doing burnouts across intersections. I run a 3.70 gear in the differential and if I start out in 2nd gear the car leaps off the line like an electric car...the engine is a Ford 5.0HO from a 1989 Mustang GT that has been converted to carb. As for road use the T-5 has a very tall overdrive (I think it's a 0.63 gear) and that high gear combined with the 3.70 in the differential puts the engine right at the low end of the power band at highway speeds.

I hope to find a 1/8 mile dragstrip sometime to compare 60 foot times between 1st gear and 2nd gear starts...I bet the 2nd gear starts beat 1st gear by a significant amount, as I lose time to tire spin and have to shift if I start out in 1st, but in 2nd the car hooks up with little spin and there's no need to shift, as I'm already at the end of 60' about when the engine hits the redline.

So...the best advice I could give would be to use one of the calculators and pick a rear end gear ratio that provides a highway speed RPM slightly higher than the lower limit of your cam's power band, Tire size plays an important part in that.

Cheers!

Dugly

[guye]

Originally Posted by YerDugliness

... the first gear is useless except for parades and doing burnouts across intersections ...

The way you wrote that, Dugly, you make it sound like a bad or unnecessary thing? I'm confused...

[Aussie Mike]

You cant really compare rear end ratios between a T5 and T56. The T5 runs a 3.35:1 Ratio first gear where the T56 runs a much taller 2.66:1 ratio first gear. The spread of ratios from 1st to 5th in the T56 is actually closer than the spread from 1st to 4th in a T5. This means you can use much shorter ratio rear end gears and still have a usable 1st gear with a T56

3.7:1 and 3.9:1 work fin with the T56 boxes for daily driver duties.

Common T5 ratios
1st-3.35:1 2nd-1.93:1 3rd-1.29:1 4th-1.00:1 5th-0.68:1

Common T56 ratios
1st-2.66:1 2nd-1.78:1 3rd-1.30:1 4th-1.00:1 5th-0.74:1 6th-0.50:1

Cheers

[YerDugliness]

As I suspected, Mike...those ratios look much better than my T-5...that T56 is a much closer ratio gearbox...and that TALL .50 sixth gear will really get those highway RPMs down...is it usable? It looks like the RPMs might be below the power band...I know the power band in my mild 5.0HO begins to build decent power at about 2,000 RPM and by about 5500 it's all over, even with the Performer intake, 550 CFM carb and one of K&N's X-Stream filters.

I get what you mean about 1st gear, though...like I said, even from an idle in first gear all it takes to break 'em loose is to put your right foot down. That 3.35 1st gear, combined with the 3.7 in my differential, offers incredible torque multiplication. I'd rather have the usable 1st gear in the T56.

Cheers!

Dugly

[YerDugliness]

I can still do the burnouts and poke along in a parade if I launch in 2nd gear...in fact, if I don't use some restraint with the right foot the 2nd gear burnouts are even more impressive (LOTS of tire smoke, but a much better hookup...probably b/c the tires heat up better with the increased rear tire RPM rate).

I still think my 60' time would be better with the 2nd gear start due to the better hookup (the 1st gear burnout goes all the way to the redline, the 2nd gear burnout creates some traction before the engine reaches redline) and the fact that I don't have to short-shift.

Gotta love the burnouts, though. Most of the time I launch from a stopsign or light with 2nd gear...first is so low that I really need to shift quickly, sometimes before I'm across the intersection.

My engine is pretty much a stock 5.0HO from a 1989 Mustang GT, just converted to a carb with an Edelbrock Performer intake and sidepipes. I suspect it is possibly putting out 250 horsepower. I frequently say that more power=more tire smoke, not necessarily a faster car...that's based in large part on my experiences with the 1st gear vs. 2nd gear launches and their respective torque multiplications.

...but, yeah.....the burnouts are much more fun than I expected...and much easier. I don't need to slip or pop the clutch in 1st...just get the car rolling from an idle and then plant the right foot. I need to give the throttle a bit of a nudge to get the burnout from a standing start in 2nd...but it either hooks up better or (if I give it too much throttle) the rear end of the car just hops sideways.

I think I need stickier tires! (mine are BFG's 295/50X15's, I think..I know about the BFG's...not highly recommended. That's an issue for another thread, though.)

Cheers!

Dugly

[Bernica]

Lose the BFG's unless you just want to die.
For me, 3:31 and a 4 speed WR toploader are just fine.
Old school!

[T.L.]

I have TKO600 and have 3.27 in the rear I think!, cant remember was a while ago when I put it all together.

At 100kmph(62mph) it is doing 2100rpm in 5th, just off cam but takes off from there though.