Re: 276, 294, 323 rear gear
[Re: Moparmaniacc]
#2976917
10/21/21 06:25 PM
10/21/21 06:25 PM
|
Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
I Live Here
|
I Live Here
Joined: Jan 2005
Posts: 12,424
Kalispell Mt.
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: 276, 294, 323 rear gear
[Re: HotRodDave]
#2976941
10/21/21 07:29 PM
10/21/21 07:29 PM
|
Joined: Jan 2005
Posts: 4,463 Michigan
MarkZ
Worthy
|
Worthy
Joined: Jan 2005
Posts: 4,463
Michigan
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio My Fifth Avenue had 2.24:1 from the factory with 205-70-15 tires. It could wind out first gear to 45mph. I couldn't imagine driving a 1.9:1 ratio with truck tires.
1987 Fifth Avenue - 512/518/D60
|
|
|
Re: 276, 294, 323 rear gear
[Re: MarkZ]
#2976992
10/21/21 09:09 PM
10/21/21 09:09 PM
|
Joined: Mar 2011
Posts: 3,113 Michigan
A727Tflite
master
|
master
Joined: Mar 2011
Posts: 3,113
Michigan
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio My Fifth Avenue had 2.24:1 from the factory with 205-70-15 tires. It could wind out first gear to 45mph. I couldn't imagine driving a 1.9:1 ratio with truck tires. And probably had a 998/999 with the 2.7 low gear on it.
|
|
|
Re: 276, 294, 323 rear gear
[Re: Moparmaniacc]
#2977283
10/22/21 03:20 PM
10/22/21 03:20 PM
|
Joined: Dec 2003
Posts: 22,783 Bitopia
jcc
If you can't dazzle em with diamonds..
|
If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,783
Bitopia
|
I believe they also made a 3.08 gear, for Nascar? back in the day, I have tried for over a decade to locate such gear, but have come up zero.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
|
|
|
Re: 276, 294, 323 rear gear
[Re: A727Tflite]
#2977299
10/22/21 03:55 PM
10/22/21 03:55 PM
|
Joined: Jan 2005
Posts: 4,463 Michigan
MarkZ
Worthy
|
Worthy
Joined: Jan 2005
Posts: 4,463
Michigan
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio My Fifth Avenue had 2.24:1 from the factory with 205-70-15 tires. It could wind out first gear to 45mph. I couldn't imagine driving a 1.9:1 ratio with truck tires. And probably had a 998/999 with the 2.7 low gear on it. Yes, and it was horrible. If HRD has a 518 in his truck and not the 500 then he doesn't even have the lower first gear. Just makes the problem that much worse. Then a taller tire on top of that? Ignoring city street driving, a 30" tall tire and a 1.9 final ratio puts you at like 1500 RPM on the highway. It just seems way too numerically low to me.
1987 Fifth Avenue - 512/518/D60
|
|
|
Re: 276, 294, 323 rear gear
[Re: MarkZ]
#2977305
10/22/21 04:04 PM
10/22/21 04:04 PM
|
Joined: Mar 2011
Posts: 3,113 Michigan
A727Tflite
master
|
master
Joined: Mar 2011
Posts: 3,113
Michigan
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio My Fifth Avenue had 2.24:1 from the factory with 205-70-15 tires. It could wind out first gear to 45mph. I couldn't imagine driving a 1.9:1 ratio with truck tires. And probably had a 998/999 with the 2.7 low gear on it. Yes, and it was horrible. If HRD has a 518 in his truck and not the 500 then he doesn't even have the lower first gear. Just makes the problem that much worse. Then a taller tire on top of that? Ignoring city street driving, a 30" tall tire and a 1.9 final ratio puts you at like 1500 RPM on the highway. It just seems way too numerically low to me. I bet you would find yourself taking it out of OD a lot, I doubt it would handle a grade without lugging. And if a lockup, I’m betting it would drive you right out of the truck.
Last edited by Transman; 10/22/21 04:06 PM.
|
|
|
Re: 276, 294, 323 rear gear
[Re: MarkZ]
#2977307
10/22/21 04:13 PM
10/22/21 04:13 PM
|
Joined: May 2019
Posts: 6,357 nowhere
Sniper
master
|
master
Joined: May 2019
Posts: 6,357
nowhere
|
Most likely 2.76. I have never seen a 2.45 before the mid 1970s
I have a 2.76 I am thinking about putting in my 93 318 2wd dakota, combined with the OD trans it should cruise real nice highway cruiser with a 1.90 final drive ratio My Fifth Avenue had 2.24:1 from the factory with 205-70-15 tires. It could wind out first gear to 45mph. I couldn't imagine driving a 1.9:1 ratio with truck tires. And probably had a 998/999 with the 2.7 low gear on it. Yes, and it was horrible. If HRD has a 518 in his truck and not the 500 then he doesn't even have the lower first gear. Just makes the problem that much worse. Then a taller tire on top of that? Ignoring city street driving, a 30" tall tire and a 1.9 final ratio puts you at like 1500 RPM on the highway. It just seems way too numerically low to me. I fixed that problem in my 87 Diplomat. I got rid of the 318 and put in a 360, then I axed the rear axle with the 2.24 ratio and put an 8 1/4 with a 2.94 rear ratio from a cop spec M body, then I put an A833 in it. Which is how Dodge should have built it. But they cheaped out to meet CAFE by not putting a 4 speed OD auto in and a better rear gear.
|
|
|
Re: 276, 294, 323 rear gear
[Re: Sniper]
#2977312
10/22/21 04:23 PM
10/22/21 04:23 PM
|
Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
I Live Here
|
I Live Here
Joined: Jan 2005
Posts: 12,424
Kalispell Mt.
|
It does have the 518 now but I already have an A-500 for it, just one more thing to get around to. Also if it drops in and out of OD too much I can just wire up control of those for me to handle. The tires on the truck are brand new 235-75-15s so they will be there for a while and are not very tall. The 318 in my cuda had a low gear 904 and similar height tires and was bareable on the low end, on the highway it still wanted another gear. I am 100 miles from cities in 3 different directions where I live now, tons of driving on mostly flat ground 75 MPH.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: 276, 294, 323 rear gear
[Re: 360view]
#2977328
10/22/21 05:35 PM
10/22/21 05:35 PM
|
Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
I Live Here
|
I Live Here
Joined: Jan 2005
Posts: 12,424
Kalispell Mt.
|
I find it is much, much better to talk about MPH per 1000 rpm instead of differential gear ratios.
If you are turning 2000 rpm at 80 mph your ratio is 40 MPH per 1000 rpm, etc
Doing it this way combines tire size, overdrive ratios, and differential gear ratios.
In highway driving there is considerable fuel economy improvement up to a ratio of 40 MPH per 1000 rpm, slower improvement above 40. I like this thought... but I like to take it another step and figure displacement per mile. Right now I am a hair over 2000@60mph. so about the same displacement per mile as if I had a 159 CID engine running 4000@60mph. if I slow it to 1500@60mph it is like the 159 running at 3000RPM at 60mph witch is close to what my neon was running in displacement per mile with tiny tires and no OD 122 CID at just over 3000 RPM, so actually I would still be slightly more displacement per mile so I don't think it is un doable, I know it is a truck but not a very big or heavy one at all by todays standards. The long term plan is to do some stuff to increase the low end TQ like zero deck the pistons and take about .030 off the heads and better spray pattern injectors... maybe a bely pan and some other aero tweaks.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: 276, 294, 323 rear gear
[Re: TJP]
#2977389
10/22/21 09:32 PM
10/22/21 09:32 PM
|
Joined: Jan 2003
Posts: 10,668 Freeport IL USA
poorboy
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,668
Freeport IL USA
|
OK, so what am I missing? I have a 96 Dakota 4x4 chassis (under my 49 Dodge truck body) with a 318 OD auto (I assume its a 518, factory stock 46000 mile drivetrain) with 3:55 rear gears and 235 75 15 tires. it is not a lightweight truck. According to the factory tach, the motor is turning right at 2,000 rpm at 70 mph on the interstate in Iowa. The truck pulls a pretty consistent 18 mpg at 70-75 mph, and is pretty fun around town.
If the stated 318 is doing 2000 at 60 with an od trans and 3:23 gears, something isn't working, like maybe the OD trans. 2,000 rpm is about what my truck is pulling at 60 before it shifts into OD. Gene
|
|
|
Re: 276, 294, 323 rear gear
[Re: HotRodDave]
#2977469
10/23/21 06:49 AM
10/23/21 06:49 AM
|
Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
|
Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
|
Displacement (and volumetric efficiency aka “breathing”) does play a part.
If you attach a vacuum gauge and it reads less than 6 inches Hg at your flat level highway cruising speed, your engine displacement is matched pretty close to the Horsepower need to go that MPH. ( but you cannot climb a noticeably steep hill without downshifting, or have an electric booster motor kick in)
Another factor is piston ring friction due to average linear speed up and down the bore.
Stay below an average ring speed of 1200 feet per minute, unless you have super hard and slickly polished bore walls (plasma sprayed on or a hi tech liner) or extremely thin high tech rings.
New tech may have pushed optimum ring speed up maybe 1500 feet per minute.
MDS as done by Chrysler on Hemi V8s proves that their engine to drivetrain matching for highway cruise is off by 50% or more.
Or... on these 10 speed automatic transmissions the top 6th, 7th, 8th, 9th, and 10th gears should be progressively lower overdrive ratios.
Scientific knowledge of many car buyers is so low that they think a vehicle that shifts to climb hills is “weak” and CVT is “weird” hence MDS.
You do not see MDS on big truck diesels, but you have seen truck diesels that can idle on 1 or 2 cylinders although APU’s to stop idling are now the norm thanks to CA.
|
|
|
Re: 276, 294, 323 rear gear
[Re: 1969ronnie]
#2977986
10/24/21 08:26 PM
10/24/21 08:26 PM
|
Joined: Dec 2004
Posts: 733 Northern Virginia
Moparmaniacc
OP
super stock
|
OP
super stock
Joined: Dec 2004
Posts: 733
Northern Virginia
|
I do have short 245-60-15 BF Goodrich rear tires, Ronnie. Come to think of it, the car does sit pretty low. So which taller tires would do the job and still look relatively good on my 70 Challenger R/T, for the rear? And would you get a different size for the front? (It would make my manual steering easier thats for sure).
Another approach would be to keep these tires and use the 2.76 sure grip I have. Or expensive option is to replace my 833 with a 5 speed...
And finally, see the attachment on full size Dodges in 1970. Cars usually got 2.76 or 3.23
thanks...
Last edited by Moparmaniacc; 10/25/21 08:17 PM.
|
|
|
Re: 276, 294, 323 rear gear
[Re: HotRodDave]
#2978757
10/26/21 09:59 PM
10/26/21 09:59 PM
|
Joined: Mar 2010
Posts: 1,061 Atlanta, GA
mgoblue9798
super stock
|
super stock
Joined: Mar 2010
Posts: 1,061
Atlanta, GA
|
I find it is much, much better to talk about MPH per 1000 rpm instead of differential gear ratios.
If you are turning 2000 rpm at 80 mph your ratio is 40 MPH per 1000 rpm, etc
Doing it this way combines tire size, overdrive ratios, and differential gear ratios.
In highway driving there is considerable fuel economy improvement up to a ratio of 40 MPH per 1000 rpm, slower improvement above 40. I like this thought... but I like to take it another step and figure displacement per mile. Right now I am a hair over 2000@60mph. so about the same displacement per mile as if I had a 159 CID engine running 4000@60mph. if I slow it to 1500@60mph it is like the 159 running at 3000RPM at 60mph witch is close to what my neon was running in displacement per mile with tiny tires and no OD 122 CID at just over 3000 RPM, so actually I would still be slightly more displacement per mile so I don't think it is un doable, I know it is a truck but not a very big or heavy one at all by todays standards. The long term plan is to do some stuff to increase the low end TQ like zero deck the pistons and take about .030 off the heads and better spray pattern injectors... maybe a bely pan and some other aero tweaks. I had a 93 Dakota with 5.2 518 combo. Picked up nearly 1mpg average on interstate driving just by adding a tonneau cover.to the bed.
|
|
|
Re: 276, 294, 323 rear gear
[Re: mgoblue9798]
#2978805
10/27/21 08:52 AM
10/27/21 08:52 AM
|
Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
|
Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
|
I find it is much, much better to talk about MPH per 1000 rpm instead of differential gear ratios.
If you are turning 2000 rpm at 80 mph your ratio is 40 MPH per 1000 rpm, etc
Doing it this way combines tire size, overdrive ratios, and differential gear ratios.
In highway driving there is considerable fuel economy improvement up to a ratio of 40 MPH per 1000 rpm, slower improvement above 40. I like this thought... but I like to take it another step and figure displacement per mile. Right now I am a hair over 2000@60mph. so about the same displacement per mile as if I had a 159 CID engine running 4000@60mph. if I slow it to 1500@60mph it is like the 159 running at 3000RPM at 60mph witch is close to what my neon was running in displacement per mile with tiny tires and no OD 122 CID at just over 3000 RPM, so actually I would still be slightly more displacement per mile so I don't think it is un doable, I know it is a truck but not a very big or heavy one at all by todays standards. The long term plan is to do some stuff to increase the low end TQ like zero deck the pistons and take about .030 off the heads and better spray pattern injectors... maybe a bely pan and some other aero tweaks. I had a 93 Dakota with 5.2 518 combo. Picked up nearly 1mpg average on interstate driving just by adding a tonneau cover.to the bed. I had a very similar experience - 1995 Ram Club Cab 5.9/518 3.21 picked up 1 MPG with an ARE fiberglass tonneau at 70 MPH on my “test track” of I-40 from Durham to Wilmington and back. Lost 1 MPG when I removed the Tonneau. GM has a very interesting US Patent on a Tonneau for the S-10 pickup. https://patents.google.com/patent/US4573730A/en?oq=4573730Knowing that there is a “horizontal tornado” behind the rear window helps a lot in understanding the drag reduction graph in the GM patent. There is a similar “horizontal tornado” behind the tailgate “Wheeler Vortex Generators” create tiny double horizontal tornados. Airtabs are molded plastic improvements on the Wheeler originals.
|
|
|
Re: 276, 294, 323 rear gear
[Re: jcc]
#2978816
10/27/21 09:49 AM
10/27/21 09:49 AM
|
Joined: Jan 2003
Posts: 10,777 North Dakota
6PakBee
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,777
North Dakota
|
I believe they also made a 3.08 gear, for Nascar? back in the day, I have tried for over a decade to locate such gear, but have come up zero. In the AMC world they had a 3.15 ratio for the AMC 20 rear end. A great highway/town gear.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
|
|
|
Re: 276, 294, 323 rear gear
[Re: 360view]
#2979287
10/28/21 03:43 PM
10/28/21 03:43 PM
|
Joined: Jan 2005
Posts: 12,424 Kalispell Mt.
HotRodDave
I Live Here
|
I Live Here
Joined: Jan 2005
Posts: 12,424
Kalispell Mt.
|
You guys can keep your tonnoue covers, I am constantly putting things in and out of the bed so that's a no go, I have had em on trucks I bought before and HATED them!
My truck has 3.55 gears, don't know why anyone assumed 3.23s? The tach is reading a little higher on the dash than it is with the scanner hooked up but still, just over 60 it hits 2000 rpm verified by GPS. Trans works great.
When I had a 318 4wd dakota I had zero issues running it down to 1000 RPM in 5th around town and got nearly the same MPG in town lugging it like that as I did on the highway where I could not lug it because it was turning too many RPM, that truck had 3.55 gears but taller tires, they were 17 R/T wheels but don't remember the exact size. It was a bigger heavier truck with much taller tires and I still found myself wanting a higher gear, maybe I should swap in a 6 speed Manual with a .50 OD ratio instead. Leaving the 3.55 in there would give me a 1.77 final drive ratio where the 2.76 a-500 only gives me 1.90 final drive. Some cars in the 80s had 2.20 ratios with less tq, 318 magnums easily have enough TQ to work that low and like I said I can easily add a few more foot pounds of torque. Now to find a 6 speed...
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
|
|