Rearend size - some like'm big - some like'm small - your o-pinion?

[Daytona Guy]

My Hemi has 713 HP and 750 trq @ 4g and I want to drive this car on long trips. I have 3.23's in my yellow Daytona and freeway driving at 75 mph seems to wind the thing up too high for that long. I was thinking with 2.94's in my new blue Daytona with this trq it will have no problem moving off the start, even lighting it up, and driving at a cruse altitude of 75 mph @ 2800-3000 rpm's would make for a more enjoyable trip.

Rearend size - some like'm big - some like'm small - your o-pinion?

Dane

[cdr]

overdrive 

[JB400]

Looks like you're gonna have to keep them small if you want to drive them.  I don't see gas prices getting any cheaper now.

[ODZKing]

I will never take them to the track but we do take trips.
2.94 in the 67(383) and 2.71 in the 73(400hp)

[Daytona Guy]

overdrive 

Agreed, but ridiculously expensive.   

Dane

[Daytona Guy]

I will never take them to the track but we do take trips.
2.94 in the 67(383) and 2.71 in the 73(400hp)

With your 2.94's @ 65 mph what is your rpm's. My rpm's can't be too low for my cam .557/.526 -- .235/.249 @ 50 (converter will be 2300-2500).

Dane

[ODZKing]

I will never take them to the track but we do take trips.
2.94 in the 67(383) and 2.71 in the 73(400hp)

With your 2.94's @ 65 mph what is your rpm's. My rpm's can't be too low for my cam .557/.526 -- .235/.249 @ 50 (converter will be 2300-2500).

Dane

As I recall 55 was just under 2000.  65 I want to say 2200 or so.  Right around there.
I get 17-18 mpg with the 67 on trips.  For a 383 4bbl - I think that is OK.

[cdr]

overdrive 

Agreed, but ridiculously expensive.   

Dane

its not that bad cost when going to a518 trans. i have about 1200.00 for everything,still gotta build a cross member

[cdr]

unless you already had your 727 built, it cost me about 300.00 more to do the 518 over doing a 727

[Dino]

I have 2:96 with near 26" tires and it's pretty good on the highway, not all that high in rpm but I couldn't tell you how much it is.  The 727 needs to go though, I need more gears.  It's very easy to light em up with these gears but I only have 225 wide tires.  I had 3:55 before which makes it much quicker off the line but anything above 45 mph was just too annoying.

[Mike DC]

                
Overdrives are ridiculously expensive but 700hp Hemis are ridiculously expensive too.   I can't see that motor happening for less than 5 figures.

Dropping a couple grand on a nice overdrive setup to enjoy it better and make it last longer . . . not a bad deal in the big picture IMHO.  



IMHO even an overdrive setup could still use relatively tall axle gears, especially with a modern tranny that has a low 1st gear.  Seriously, what good is a 1st gear ratio low enough to spin 5000 rpm at walking speed?  It's worthless for anything other than tearing the tires off the back wheels, and you can still do that with higher gearing when you've got so much motor.  

Meanwhile I think it really makes a difference when you can get the cruise RPM down low on the freeway.  If big engines & tall gear ratios cost nothing then we would all want to have the option of going down to 1500rpm @ 75 mph.

[Cooter]

overdrive 

Agreed, but ridiculously expensive.   

Dane

Did I read this correctly??? You have a 713 HP HEMI, clearly by the standards of the board here in the 5-speed from Passion Perf., you should be able to afford a newer 5-speed easily....Yet, you say they are rediculously expensive...

[Daytona Guy]

When you reach your limit - you reach your limit. The overdrive and all the electrical lockup - and cost and hastle I just want a happy medium - cant stand manuals they drive like a truck. Plus when I'm driving down the freeway and want to get on it - tall (high) gears just go nowhere - I want to leave the fart cars in the dust

Money is always an issue on any build - Hemi or not. Without a lid cars sit in a gaurage for years waiting for that next part they can't afford.

Dane

[Dino]

Although not the fastest, with my combo I have no problem going from 70-100 in very little time.  Torque will do that.  On the rural roads here the limit is 55, with my daily I pass one car at a time, with the Charger 3 or 4 in less time.  Torque is my friend.    

The a518 would have been a nice option for you Dane but your hemi might tear that thing up.

[Mike DC]

           
Yeah, if I had 700 hp then I wouldn't compromise the gearing to make it any faster.  Just gear it tall for cruising and let the engine do the work when you wanna go fast. 

[Daytona Guy]

So 3.23's or 2.94's

Does anyone know a formula? Tire size, gears, 1 to 1 3rd gear trany, RPM = Speed? There has to be...

Dane

[Dino]

So 3.23's or 2.94's

Does anyone know a formula? Tire size, gears, 1 to 1 3rd gear trany, RPM = Speed? There has to be...

Dane

This may help:

http://vexer.com/automotive-tools/speed-rpm-calculator

[JB400]

I'm with Cooter on this one.  If you can afford a 700hp+ engine, you can afford to put a 5-6 speed gear banger behind it.  But, if your just going to put put around town and take the kids to the park, 450 hp is plenty and keep the 3 or 4 speed.  Otherwise, your literally just wasting money that can be more better spent on other things.

[1974dodgecharger]

LMAO, thinking the same thing talking about expensive, but yet saids he has a hemi with 700hp plus.

overdrive 

Agreed, but ridiculously expensive.   

Dane

Did I read this correctly??? You have a 713 HP HEMI, clearly by the standards of the board here in the 5-speed from Passion Perf., you should be able to afford a newer 5-speed easily....Yet, you say they are rediculously expensive...

[Dino]

So you guys have unlimited funds?  Money does run out you know.  Besides the guy asked a question, not our opinion on how to spend his money.

[Daytona Guy]

I guess I can always do the trany overdrive later - and change the ring gear out (250.00) - But for now I just have to make do. The idea is to cruse, and go fast, and sound crazy good. No gear is going to stay locked in with this car at 700 HP even with my 12' wide back tires.

About the money - that reasoning makes no sense. That is like saying, "If you have enough money to buy a $40,000.00 car, you have enough for a 42,000.00 car". No, 40K is the limit. I have chosen for now to put it in the motor, because if you don't go big, you go home. Once you buy a 426 425HP (or so), you can't take it to 572 later, while I can do a trany change down the road

The issue is 3.23's or 2.94's and does anyone have any used 2.94's ring and pinion I can buy? Can't find them at all.

Dane

[Dino]

2:94's and similar can be found in the plain mopars.  Mine came out of a 65 Coronet.  Be aware that they likely are all 741 cases although I haven't had an issue with mine behind a 440.

I know of one 742 case with open 3:23 for sale in Detroit but he's asking $300 which is close to sure grip money.

Any junkyards with old mopars near you?

[JB400]

If you go big, you stay home.  You can't afford to pull it out of the driveway.







Just pickin on ya

[1974dodgecharger]

Good point, but I still think he knows what to do he is just bored so he is asking questions while he sits and looks at his beauty of a engine he has in his charger 

2:94's and similar can be found in the plain mopars.  Mine came out of a 65 Coronet.  Be aware that they likely are all 741 cases although I haven't had an issue with mine behind a 440.

I know of one 742 case with open 3:23 for sale in Detroit but he's asking $300 which is close to sure grip money.

Any junkyards with old mopars near you?

[Cooter]

So you guys have unlimited funds?  Money does run out you know.  Besides the guy asked a question, not our opinion on how to spend his money.

Certainly not Dino, but While i'll most likely "Never go big or go home", I DID reply in that Passion 5-speed thread about how "Rediculously overpriced" it was and got handed the ol "If you have enough money for a high end car, you have enough for the tranny" response....

Yes, he did ask a question, but also made a statement about how overpriced the OD was. THAT was what I was replying/implying to....


IMO, if you spent a sh*tload on the engine and have nothing left for the trans, then someone made a mistake somewhere. Too much engine? Too much paint job? Too much whatever. I don't think a 700 HP HEMI will have very good street manners in OD in the long run anyway. It takes ALOT of camshaft to make those numbers without forced induction of some sort, Even in a Hemi. Ever tried to drive a Big cammed engine in OD? I have and it SUCKS fuel, Drives like it has NO balls as it's out of it's power band, Lopes uncontrollably, etc.
So to offer my input on the OD? Simple...Don't do it.