Woods74
Broke Senior
:d
rear gearing with a four speed A833.
- Thread starter alpha13
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A definite sign of the times is thinking 3000-3500 RPM cruising speed @60-65 MPH is Way to high! When in fact these were acceptable perimeters back in the 60's - 70's and even into the 80's. Now days with the younger generation use to 5,6,8,9 speed transmissions and every car/truck coming standard with tachs. The thinking is that a car/truck needs to turn 1500-1800 RPM @70 MPH to be "right".
This is why I drive my 07 4x4 CTD when towing or traveling. But when I drive my 500 cu.in Dart to cruise nights, I really don't care about the RPM's @60.
Don't worry RRR, your still on my Christmas card list. LOL
This is why I drive my 07 4x4 CTD when towing or traveling. But when I drive my 500 cu.in Dart to cruise nights, I really don't care about the RPM's @60.
Don't worry RRR, your still on my Christmas card list. LOL
I agree with you. I was simply trying to help make sense of the OP's convoluted post. My truck is a 75 F250, 351M, borg warner T18 4 speed and 3.73 gears. It has no tach but I am sure it is twistin around 3K at 60.....the rare times I accidentally hit 60. LOL
nm9stheham
Well-Known Member
The Dart Lites and Featehr Duster /6's came that with the 4speed OD had a 2.94 or 2.76 rear gear fromt he factory. I drove one for about a quarter million miles and it was not problem to get moving at all, living in the mountains here and the 360 will be even less of a problem if a stock or torque cammed engine.
The newer Challeger 6 speed manuals have 5th and 6th gears as OD. 5th is a .83 ratio like the A833 OD, and 6th is an 0.5 OD; it wil run at 1750 RPM on the interstate at 70 MPH with NO problems and even will drive up 95% of the mountain interstate grades here in VA/WV with no lugging.
So, based on this, the OP should not at all afraid to use an A833 OD and a rear gear ratio around 3; it will get going just fine. BUT it will be 'good' but not be optimum for sprited street driving in hills and mountains ( missingthat 4th non-OD gear will show up there) and not be the best (at all) for drag racing. So if he is OK with that, then go with the lower gear + OD if wanted. All the above assumes a stock or mild torque cam so that low RPM torque is usable. Any level of aggresive cam will make it harder and harder to move out.
The newer Challeger 6 speed manuals have 5th and 6th gears as OD. 5th is a .83 ratio like the A833 OD, and 6th is an 0.5 OD; it wil run at 1750 RPM on the interstate at 70 MPH with NO problems and even will drive up 95% of the mountain interstate grades here in VA/WV with no lugging.
So, based on this, the OP should not at all afraid to use an A833 OD and a rear gear ratio around 3; it will get going just fine. BUT it will be 'good' but not be optimum for sprited street driving in hills and mountains ( missingthat 4th non-OD gear will show up there) and not be the best (at all) for drag racing. So if he is OK with that, then go with the lower gear + OD if wanted. All the above assumes a stock or mild torque cam so that low RPM torque is usable. Any level of aggresive cam will make it harder and harder to move out.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Hey, Rusty
As you may know, I love math.I plugged your pick-up numbers into the formula and with a typical P225/75-15s(89"roll-out), and 3.73s; 60mph comes to 2655rpm. Sounds like a reasonable place to be.
I also find myself cruising at sub-60mph, now, as I get older.Whats the hurry, I say.But if I get too slow, I get sleepy. On long trips, and as may be permissible,I like to boot it up to where Im wide awake, somewhere north of 75. At 85 on the Interstates, I can stay awake for hours and hours. At 50, sometimes 10 minutes and Im done.
As you may know, I love math.I plugged your pick-up numbers into the formula and with a typical P225/75-15s(89"roll-out), and 3.73s; 60mph comes to 2655rpm. Sounds like a reasonable place to be.
I also find myself cruising at sub-60mph, now, as I get older.Whats the hurry, I say.But if I get too slow, I get sleepy. On long trips, and as may be permissible,I like to boot it up to where Im wide awake, somewhere north of 75. At 85 on the Interstates, I can stay awake for hours and hours. At 50, sometimes 10 minutes and Im done.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Say, Alpha,
-I was re-reading this thread, and I came across something in post 14, that I missed the first time. In it you mention that you feel like your engine is wrapped up too far in first with 3.55s and that your car loses too much momentum, going into second. This is typical of wide ratio boxes, like most all 3 spds, including the 3+1 O/D box. It gets aggravated with engines that are not tuned for stump pulling;ergo,your 360. The problem wont go away until you go to a 4 speed or more.No amount of rear gear fudging will get you out of this situation.
-The 4 speed boxes tighten up all the splits, so that the revs dont fall so far between shifts. So #1 you dont have to rev it up so high in 1st, to grab a comfortable 2nd. Or #2, If you do rev it out higher in 1st, then 2nd will pull harder, right away.
-The early 4spds with the 3.09 low, have a medium sized 1-2 gap(similar to your A-230) of 61%. The 2.66 low box has a regular gap of 72%. And the T/A box has also about 72%, but has all the other gears tightened up as well. The O/D box is the worst with 54%.
-So I see only 2 possible solutions for your 1-2 gap complaint:
. 1) Find a trans with a tighter 1-2 split, or
. 2) Increase the off-idle torque of your engine, or
. 3) Switch to an autotrans, or
. 4) Contact the guy in a previous post with the tractor teener, and clone his torque monster.
Ok, well thats 4 options.
-After all the box swapping in my combo, I settled on the 3.09/direct box. The 3.09 to 1.92 split at 62% is liveable, and lets me run highway-friendly gears of 3.55s or 3.23s with my 230* cam. With a stockish cam, you should be able to pull 2.94s Ok , and maybe even 2.76s.
-One more general observation, on starter gears(low ratio x diff ratio):
. . . For 360s with street cams; a brisk pull away needs ratios of 9.5 to 10.5. The lower is acceptable, the higher is busy. At 8.5 I didnt like it at all. At more than 11 it becomes a race starter.If you have the lower gear in the trans, you can move up the scale, to help with 2nd.
-I am very happy, finally, with the 3.09/direct box and 3.55s(10.97 starter, the equivalent of 2.66 x 4.12s).
-Happy swapping, AJ
-I was re-reading this thread, and I came across something in post 14, that I missed the first time. In it you mention that you feel like your engine is wrapped up too far in first with 3.55s and that your car loses too much momentum, going into second. This is typical of wide ratio boxes, like most all 3 spds, including the 3+1 O/D box. It gets aggravated with engines that are not tuned for stump pulling;ergo,your 360. The problem wont go away until you go to a 4 speed or more.No amount of rear gear fudging will get you out of this situation.
-The 4 speed boxes tighten up all the splits, so that the revs dont fall so far between shifts. So #1 you dont have to rev it up so high in 1st, to grab a comfortable 2nd. Or #2, If you do rev it out higher in 1st, then 2nd will pull harder, right away.
-The early 4spds with the 3.09 low, have a medium sized 1-2 gap(similar to your A-230) of 61%. The 2.66 low box has a regular gap of 72%. And the T/A box has also about 72%, but has all the other gears tightened up as well. The O/D box is the worst with 54%.
-So I see only 2 possible solutions for your 1-2 gap complaint:
. 1) Find a trans with a tighter 1-2 split, or
. 2) Increase the off-idle torque of your engine, or
. 3) Switch to an autotrans, or
. 4) Contact the guy in a previous post with the tractor teener, and clone his torque monster.
Ok, well thats 4 options.
-After all the box swapping in my combo, I settled on the 3.09/direct box. The 3.09 to 1.92 split at 62% is liveable, and lets me run highway-friendly gears of 3.55s or 3.23s with my 230* cam. With a stockish cam, you should be able to pull 2.94s Ok , and maybe even 2.76s.
-One more general observation, on starter gears(low ratio x diff ratio):
. . . For 360s with street cams; a brisk pull away needs ratios of 9.5 to 10.5. The lower is acceptable, the higher is busy. At 8.5 I didnt like it at all. At more than 11 it becomes a race starter.If you have the lower gear in the trans, you can move up the scale, to help with 2nd.
-I am very happy, finally, with the 3.09/direct box and 3.55s(10.97 starter, the equivalent of 2.66 x 4.12s).
-Happy swapping, AJ
Yeah AJ, we talked about this stuff between PMs. Like I said before, you offered Alot of good useable real world advice. Yes that split from 1st to second kinda blows... but I could live with it if I had to for a lower rpm at 70. What I NEED is a 5 speed lol. BUT that's not in the cards right now. This car spends most of its time on the street so I would rather be more comfortable cruising than being able to blow the doors off of every car that pulls up next to me. Of course I'm trying to find that middle ground. I think what I'm going to end up doing is using the OD box with my current 3.55s.:burnout: I've still got plenty of torque for the 1st to second shift. It's just when I'm hot rodding it it seems to run out of steam quick. Which we talked about as well. Every time I think about this gear and tranny situation, the more I realize the only REAL problem solver is to run a five speed. Everything else just seems to be a bandaid. Some day! Lol I know a lot of guys are alright running high RPM. I'm just not part of that bandwagon. I feel that anything really over 2600rpm at 70 is just a waste of fuel and shortens my engine life. I figure at 70 the OD ratio of .73 and a 25.6 inch tire will get me just under 2500 rpm. Which I feel will be fine seems how at 70 your not really looking to hot rod it in OD anyway. Ka boom!! I feel if I don't have torque coming on at 2000 rpm it's not really a good street engine. Especially one with street gears. Like I said I don't want high rpm at cruise. Some of you guys though I'm sure are fine with 4.10's and power not coming on til 3500 rpm. Just not my idea of a street engine is all.
I would also like to point out that in modern times lower RPM is the norm because we no longer rely on technology from the 60's and 70's. vehicles make plenty of power with low RPM. It makes for a longer lasting engine and drivetrain as well. Now when people look at cars with 100,000 miles they feel they have a low mileage car. In the seventies though, low mileage was like 30,000. Why do you think 70's tech engines are wore out after 100'000 miles. As technology advances people find they can have their cake and eat it too. Which means we can have low rpm, be comfortable and still make power. Oh also, check out variable valve timing. What an innovation in technology. Like I said, have your cake and eat it too. That's just an example.
Mine was just a guess on RPM on my truck since I don't have a tach. It also has 245/75/16 tires on it. They must be a dead match diameter wise to the originals because we have posted LED speed signs in the county and it is dead on it.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Alpha
Your thinking is a lot like mine.
Id like to respond to the questions about long engine life.
Todays modern engines last longer for mostly 2 reasons; 1)better oils, and 2) MPFI. Fuel injection is better able to control the fuel charge and therefore a lot less of it sneaks past the rings and into the pan.When the oil stays on the cylinder walls, the rings dont chew them up.And with the oil in the pan being now mostly oil, the bearings last a lot longer as well.Prior to about 1970/71, our Mopes did not have the hardened valve seats. When these engines were forced to run on unleaded fuel, the soft seats had a much reduced life. So typically, those older engines would be well past there prime by 100,000 miles, and looking for retirement by around 140,000 or so.Timing chains were often done a lot earlier.Now modern engines, with electronic controls are also better able to control ignition as well.
-All this leads to the right amount of fuel being in the chambers more of the time, and all of it being burned more of the time.
-If you would take one of those early engines, install hardened seats, and MPFI, and load it similarly to a modern cars loading; Id be willing to bet that its life would on par with modern technology engines.
-Conversely, if you were to take a modern engine, slap a carb on it,take away its computer timing controls, and load it up like the old days; I am pretty sure it would die as early as they used to.
-I think this longer lasting business was a side benefit we got ,due to the struggle with pollution control.Pollution control demanded better fuel control and better fuel economy. This led to longer life, lighter cars,and lower gearing
At least thats how I see it.
-And youre right on target;To be competitive in every arena; performance, economy, long life,etc., we need more gears. VVT would also help
Your thinking is a lot like mine.
Id like to respond to the questions about long engine life.
Todays modern engines last longer for mostly 2 reasons; 1)better oils, and 2) MPFI. Fuel injection is better able to control the fuel charge and therefore a lot less of it sneaks past the rings and into the pan.When the oil stays on the cylinder walls, the rings dont chew them up.And with the oil in the pan being now mostly oil, the bearings last a lot longer as well.Prior to about 1970/71, our Mopes did not have the hardened valve seats. When these engines were forced to run on unleaded fuel, the soft seats had a much reduced life. So typically, those older engines would be well past there prime by 100,000 miles, and looking for retirement by around 140,000 or so.Timing chains were often done a lot earlier.Now modern engines, with electronic controls are also better able to control ignition as well.
-All this leads to the right amount of fuel being in the chambers more of the time, and all of it being burned more of the time.
-If you would take one of those early engines, install hardened seats, and MPFI, and load it similarly to a modern cars loading; Id be willing to bet that its life would on par with modern technology engines.
-Conversely, if you were to take a modern engine, slap a carb on it,take away its computer timing controls, and load it up like the old days; I am pretty sure it would die as early as they used to.
-I think this longer lasting business was a side benefit we got ,due to the struggle with pollution control.Pollution control demanded better fuel control and better fuel economy. This led to longer life, lighter cars,and lower gearing
At least thats how I see it.
-And youre right on target;To be competitive in every arena; performance, economy, long life,etc., we need more gears. VVT would also help
Yes you are correct about fuel and oil control. And even though they are a big contributor I didn't want to mention them because I was talking about rpm. I suppose they go hand in hand but I still from an engineering standpoint. The less Times the engine goes around the longer it will last haha. I will mention though that even though oil and fuel control is better I have witnessed relatively fast engine wear from a Ford 4.0. 150,000 and it uses a quart every 1000 miles. It's in my brothers Mazda b4000 pickup. I told him to buy Mopar lol.
jpl572103
Well-Known Member
66 dart 4 speed od transmission 225slant 2.92 diff 7 1/4. Plenty of pull and torque in 1st gear, take off is fine up to 30 mph with the 3.09 1st gear. It will squeal the right side 235 60 14 tire to death but The car has no balls from 2nd-4th gears. It's ok but it just lacks. The rpm's are slow to reach 4500. Heavy slow crank? But I think if the diff gear were lower, it would help. And the transmission is just not geared right. I know it's a truck,van transmission but its now a 66 dart transmission and I want this thing to scoot a little bit better.
It's not a higway car. Just a light to light around town car.
Here are some options I was considering.
68 B body 489 8 3/4 2.76 open gear with brakes. $650
It will need shortened. Dr. Diff axles with bearings $305. Housing ends $85 and perches $15. Cut the driveshaft $200. Ujoint $50 and
get it all welded $300-$500? So $1500-$1800. And the 2.76 would need to be changed to a 3.55 $200 and possibly a spool $100 and install kit $100.
$2200 approximate.
I also found a dana 60 already modded for a 70 nova with drum brakes. $500 has 4.10 posi Probably too much gear for my transmission.
It will need shortened. Will need Dr. diff axles $305, housing ends $85, perches $15, driveshaft cut $200, joint $50, welding $500.
$1655 approximate. And if I change the gear to a 3.54 figure another $3-400. So $2000 approximate.
And I found a 68 mustang 8" 2.80 gear with brakes non posi for $150. Supposed to be a drop in. No cutting of the driveshaft. 59 1/4 axle flange to flange.
I think this will need shortened also. So Dr diff axles $305, ends $85( not sure if the 9" housing ends will work) perches $15. Ujoint $50 Welded $500. Gear/install kit/spool $500
$1600 approximate.
And there's a $1000 A body diff for sale on this forum from Colorado plus shipping I"m guessing $300?
But its a 741 with 2.94 open. So I would need another $500 for 3.55 gear and spool plus $200-$500 misc shoes,cylinders,cables,?
$2000-2300 approximate.
I think I read from another member that any way he priced it , was all about the same price. Looks like the Dana is the better build.
It's not a higway car. Just a light to light around town car.
Here are some options I was considering.
68 B body 489 8 3/4 2.76 open gear with brakes. $650
It will need shortened. Dr. Diff axles with bearings $305. Housing ends $85 and perches $15. Cut the driveshaft $200. Ujoint $50 and
get it all welded $300-$500? So $1500-$1800. And the 2.76 would need to be changed to a 3.55 $200 and possibly a spool $100 and install kit $100.
$2200 approximate.
I also found a dana 60 already modded for a 70 nova with drum brakes. $500 has 4.10 posi Probably too much gear for my transmission.
It will need shortened. Will need Dr. diff axles $305, housing ends $85, perches $15, driveshaft cut $200, joint $50, welding $500.
$1655 approximate. And if I change the gear to a 3.54 figure another $3-400. So $2000 approximate.
And I found a 68 mustang 8" 2.80 gear with brakes non posi for $150. Supposed to be a drop in. No cutting of the driveshaft. 59 1/4 axle flange to flange.
I think this will need shortened also. So Dr diff axles $305, ends $85( not sure if the 9" housing ends will work) perches $15. Ujoint $50 Welded $500. Gear/install kit/spool $500
$1600 approximate.
And there's a $1000 A body diff for sale on this forum from Colorado plus shipping I"m guessing $300?
But its a 741 with 2.94 open. So I would need another $500 for 3.55 gear and spool plus $200-$500 misc shoes,cylinders,cables,?
$2000-2300 approximate.
I think I read from another member that any way he priced it , was all about the same price. Looks like the Dana is the better build.
michiganpat
Well-Known Member
have you looked at an XJ cherokee rear axle? they had chrysler 8.25's or dana 35's. manuals had 3.07 gears and autos had 3.55's, with 3.73's available with the tow package I believe. XJ cherokee width drum to drum is 59.5", so about 2" wider than an A body, or an inch narrower than a B body.
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