Yup, try running 4.86 on the interstate, people just look at you in disbelief as they go by because it sounds like your doing 120
Overdrive options
- Thread starter WCMachine
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67Dart273
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Well I'll tell you guys...........while you are all pattig yourselves on the back, there ARE inherent problems running too low a gear with a tall OD. That driveshaft is STILL spinning whatever RPM it was OD or now, and that ring and pinion are STILL REALLY churnin up the oil and makin' HEAT. Will "in a previous life" experience with friends and Jeeps with stuff like 5:38s (not all that low with big *** tall tires!!) There CAN be problems doin' "80" on the hiway!!
Yeah, but it's fricking BOSS until it let go.
roccodart440
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Must be why my cummins ram has a double OD and 4.10 gears from the factory and 258k miles.
This theory has been brought up before and dispelled by numerous professionals in the business.
famous bob
mopar misfit
how could the driveshaft be still spinning at the before rpm, when the final drive out of the trans is reduced , slowing everything down ??? lost me there !
67Dart273
Well-Known Member
The gearing in the trans and OD have no bearing, if the pinion was spinning at "X" rpm at 75mph with say, 4.56 gears, then the shaft is STILL spinning that fast with an OD in front of it
And that myth has NOT been dispelled, and I'm not talking about paltry 4.11's. You get up into 4.89--5x ratios and start spinning them long distances down the highway at 75mph, you are eventually going to have a problem. I'm talking about passenger cars with typical "short" tires. Your pickup is an exception due to large tires. My 2500 is 4.10, it runs just over 3K at 70mph (with OD locked out). That is not a problem.
roccodart440
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According to GVOD and Strange engineering it isn't. I've brought it up with both of them. Now mine specifically is a 4.56 gear with the OD. I'm assuming most guys aren't going to far past that. I don't know what else to tell you. mines been together for the better part of 2 decades and drag week and power tour speak for themselves. I run 28" tires for reference since I didn't mention that.
I don't really see the need to go higher than 4.56's unless your car turns high RPM through the traps or had really lack luster HP. If I had to do it again I'd run 4.30's. 4.56's are on the edge of too much gear for my existing combo. I may got to a 29" tire though.
I don't really see the need to go higher than 4.56's unless your car turns high RPM through the traps or had really lack luster HP. If I had to do it again I'd run 4.30's. 4.56's are on the edge of too much gear for my existing combo. I may got to a 29" tire though.
jbc426
Well-Known Member
I chose a built 2004R for my '68. I would never go back to a non-overdrive, so any overdrive is a good choice in my book, but it is all dependent on what matches best with your combo, wants and needs.
If you really want to blow your mind with modern upgrades, add fuel injection to your overdriven car.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I have been running the GVOD since 2004 behind my 367 in a 68 Barracuda with a stick. I have run so many different rears I have lost track of them all. And yes, even 4.86s.
The nice thing for me was rewiring it to run as a gear-splitter. With the right mainbox, this keeps my little engine on the pipe, making it trap as tho it had a lot more cam. This may not apply to your combo I just thought I'd throw that in.
It traps at 93 mph(1/8th) which would be second-over @ 6400, with 3.73s. And the starter gear is 3.73 x 3.09=11.53 which with an automatic would be like 11.53/2.45=4.70s. And the hiway gear is 3.73x.78=2.91, making 65=2350.
But I run 3.55s now.
And thinking about putting the 3.23s back in. ( which with a 727 would be like 4.07s)
I love my GVOD.
My 4.86s are for sale.......5.13s busted,3.91s busted...........4.30s sold,4.11s traded away. The 4.88s in storage, with the 3.23s,2.94s,and 2.76s..........Sheesh, I almost forgot all the crap I ever tried.
The nice thing for me was rewiring it to run as a gear-splitter. With the right mainbox, this keeps my little engine on the pipe, making it trap as tho it had a lot more cam. This may not apply to your combo I just thought I'd throw that in.
It traps at 93 mph(1/8th) which would be second-over @ 6400, with 3.73s. And the starter gear is 3.73 x 3.09=11.53 which with an automatic would be like 11.53/2.45=4.70s. And the hiway gear is 3.73x.78=2.91, making 65=2350.
But I run 3.55s now.
And thinking about putting the 3.23s back in. ( which with a 727 would be like 4.07s)
I love my GVOD.
My 4.86s are for sale.......5.13s busted,3.91s busted...........4.30s sold,4.11s traded away. The 4.88s in storage, with the 3.23s,2.94s,and 2.76s..........Sheesh, I almost forgot all the crap I ever tried.
Whew! Good thing you have a 8 3/4!
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Yeah there was this one summer..............
famous bob
mopar misfit
I re-thot this, they are running the same speed, but the engine is running slower . DUH! But rear gear heat has never been a problem to me. p.s.- I don`t have an overdrive, but would if I could afford one. I run 30" tires on the street, w/ a 3:73 rear gear, will probly run a shorter tire if I ever get around to taking it to the strip.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Wow! 30s and a 3.73. Congrats on making that work.
famous bob
mopar misfit
approx. 700 h.p., 727, dana 60, 35-3800 convertor, 295 65 15 d. radials, approx. 3100 lbs., very docile till u stick ur foot in it. "Does like gasoline", even w/ the fuel inj. Would love to have a g.v. overdrive! Retired, guess I`ll have to get a part time job to afford one. LOL
famous bob
mopar misfit
Can a 200r4 be built to handle 700ish h.p. ?
wireweld
Well-Known Member
Yes. Extreme Automatics builds them to handle 1000 hp.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Say Bob
What about going down something like 10% in rear gear? To maybe 3.23s.
This would drop your hi-way Rs that same percent, and you can still hit 60 at the top of first gear.
With that loose TC I wonder if you couldn't still make it work.
You probably already thought of that, I guess. And with a Dana it's not just a simple swap out, for a testrun.
In any case, I got no experience with that kind of power. I try to stick with SBMs at below 400/450.
I had this one 367,lol, tho once, that pulled the equivalent of a 1.97 finaldrive, and still went 12.9 with a 2.2 60ft, but it had a clutch. Yeah it was mine,lol.
With 700, I have no idea.
What about going down something like 10% in rear gear? To maybe 3.23s.
This would drop your hi-way Rs that same percent, and you can still hit 60 at the top of first gear.
With that loose TC I wonder if you couldn't still make it work.
You probably already thought of that, I guess. And with a Dana it's not just a simple swap out, for a testrun.
In any case, I got no experience with that kind of power. I try to stick with SBMs at below 400/450.
I had this one 367,lol, tho once, that pulled the equivalent of a 1.97 finaldrive, and still went 12.9 with a 2.2 60ft, but it had a clutch. Yeah it was mine,lol.
With 700, I have no idea.
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fishy68
Tyr Fryr's Inc.
I'm rebuilding a GM 2004R for a guy down the street from me for his 69 Camaro. They are a good trans if you put quite a bit of money in them. One of the biggest costs is a billet or hardened forward drum. They can be built to handle 1000 HP according to Art Carr but that takes some doing (money). IMO, if you have something making over 400 hp by the time you buy a 2004R core and build it to withstand the power your throwing at it and buy the adapter to make it work your better off with a A500. The only disadvantage to the A500 is you have to massage the trans tunnel to get it in. In both cases (2004R vs. A500) you will be modifying the TB crossmember. JMHO
famous bob
mopar misfit
Back to the gearvendors.
roccodart440
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Turns 2500@60mph
Sounds pretty ideal to me for street use. It's like my car with the OD turned on.
famous bob
mopar misfit
I haven`t driven it much, life has been in the way, If I remember right, around 72ish at 3000/3100, my speedometer bounces around about 5 mph. I need to get the engine fully broke in , still don`t know if I can trust it yet, LOL . Still experimenting w/ the tune /what little I`ve messed w/ it. Seems like I need a one step hotter plug. I have a fair reading on # 7 plug, the rest look rich as he--. I did put some seafoam in the last tank of gas, was thinking one of the eight injectors might be plugging up in the throttle body. Seat of the pants feels better. Planning on driving it again today, and prayer breakfast next Sat., if not raining.-------to be continued------
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