[plum-crazy]

Hello guys.
At this time the 3.23 sure grip is dead. The powerful hemi wins the 38 aged locker.
I'm looking for a new 489 case with a good locker unit.
Mancini racing is selling a 489 nodular case with posi auburn diff locker.
What do you think about it?
Is really better nodular units?
I'm thinking in 3.55 ratio.
What do you think about disc locker, like power lok? Maybe auburn is not enough?

[fbernard]

A buddy of mine bought a complete 489 center section with Truetrac differential (a Torsen setup), 3.55 gears, and tried it on the highway, racing a bit, and on the strip with drag slicks last week-end at Santa Pod.

Works like a charm (open diff when stret driving, locks up when under torque, no wear parts). I bought the same thing for my car and installed it last week.

You may want to contact DrDiff (guy's name is Cass Eslick, e-mail is doctordiff@centurytel.net) and ask him.

[plum-crazy]

Thanks for info fbernard.
What's the difference between true track and power lock?
I just emailed him to ask for it.

[fbernard]

Thanks for info fbernard.
What's the difference between true track and power lock?
I just emailed him to ask for it.

From what I see on internet, the Power Lock is a rebuildable clutch unit similar to the OEM piece. The Truetrac has no wear parts.

[plum-crazy]

Cass went to mopar nats and he will come back on 18th august.
Now I'm trying to choose the best one, 3.55 or 3.73, I'm not sure.

[fbernard]

Cass went to mopar nats and he will come back on 18th august.
Now I'm trying to choose the best one, 3.55 or 3.73, I'm not sure.

Depends on what you want to do with the car, and your transmission.
If you have a transmission with a 1.0 final ratio, and you want to drive your car on the street, the 3.55 is the higher I would go (it's already a bit high for highway use).

If you have an overdrive transmission (Gear Vendors OD on a TF727, or Tremec 5-speed, Passon Performance Overdrive gears in a A833), you can go higher (3.73 or 3.91).

If you want to go drag racing, and have the torque converter that goes with it, take a 4.10 (or a 3.91 with short tires).


The 3.55 is a pretty good compromise for a street/strip car.

[dave-r]

Because you mainly use this car on the strip you should go for the gear that gives you your redline rpm at the finish line of the track.

[plum-crazy]

I will use the car mainly on the street but want to make a good et times twice or three times in a year.
I will purchase the 3.55.
The car weights 1650 kgs without driver + 80 with me inside.
If the engine produce about 630 hp at flywheel I think I will arrive almost at red line (5900) at 1/4 mile with a 26" tires and 3.55 ratio.

[fbernard]

The car weights 1650 kgs without driver + 80 with me inside.
If the engine produce about 630 hp at flywheel I think I will arrive almost at red line (5900) at 1/4 mile with a 26" tires and 3.55 ratio.

A friend of mine, in a 1973 'cuda, with a 3.55 Truetrac, a stroked small-block (416ci) giving 500HP, and a Tremec 5-speed manual transmission, did 12.59 at Santa Pod this year, on 26" x 8.5" slicks (Mickey Thomson 3052).
He only used the 3 first gears, redlining at the end.
If you have a Torqueflite (2.45:1 first gear, 1.45:1 second gear, and 1.00:1 third gear), I don't know whether it's better to plan on using all 3 gears or just 1 and 2 (Dave will know).
You will need a converter with a high stall speed, too.

All I know is you may want taller tires for the street. With a 1.00 final transmission ratio and a 3.55 rear-end, you'll be at 110km/h at 3000 RPM.
That's acceptable for cruising, if you dont do too much highway.

[dave-r]

How many gears are best depends on the power curve. As a general rule the steeper the power curve the more gears you need to keep up at peak power.

However the more power you make the less you need gears. Top Fuel cars for example don't use many gears and when I was a young lad some of the early funny cars used direct drive with no gears at all.

Personally I would use at least three gears. But make sure you are at peak HP as you cross, or just before, the finish line. Even if you have another gear left.

[plum-crazy]

Hello again.

My converter is a Dynamic 9.5", the stall is around 3500 rpm and now i'm covering the 1/4 mile at 5000 rpm with the 3.23 and 26" tires.

I need to practise more and more but we haven't tracks to do it, but I'm on the way.
First of all I will order the 3.55 power loc and will try again, on the other side I want to go to the dyno once the new case installed and get info about the engine curve.

Thanks.

[dave-r]

Another option would be to use 4.30 gears and a GV overdrive like I do.

That way you can effectivly switch between 3.30 and 4.30:1 gears.

[plum-crazy]

Sure dave but is not the moment to do it, i have no money. Other parcels of my life are requiring money.
Now I just need to put the car on the street again spending the minimum.
The challenger issue arrived at the end for fun, in the future the car will receive all the attentions if something breaks, but no more.

[plum-crazy]

You may want to contact DrDiff (guy's name is Cass Eslick, e-mail is doctordiff@centurytel.net) and ask him.

Hi fbarnard.

I ordered him the center section with 3.55 ratio, nodular iron case and power lock unit.
Maybe it's on the way, but I have just one question.
The credit card charge shows quality body shop instead something like doctor diff. Ovbiously the amount is the same he told me few days ago, but I'm surprised.

[fbernard]

The credit card charge shows quality body shop instead something like doctor diff. Ovbiously the amount is the same he told me few days ago, but I'm surprised.

Yes, that's the name of his business. DrDiff is a nickname I believe.

[plum-crazy]

I think the diff is flying to barcelona today.
This weekend we have a meeting with a track times and all sort of performance cars.
If we have enough time I will try to fight with them.
Anyway there's a guy who will come with a supra modified, It's a 10 second car, unbeatable.

[plum-crazy]

Well the centersection is installed and some noise is coming from the transmission.
We go to check it and noise increase. Finally the car arrives hardly and we need to disassemble the transmission to check.
The hemi torque has broken something behind the valve body.

It's neverending story.

[dave-r]

Oh dear.

Transman on here should have the parts you need to take the power.