Those Running 3.73 And a TF w/ LockUp.. What's your highway Driving Like?

[junkyardhero]

I like the idea that you did so much highway time with the 3:23. I'll have to think on the 3.08 and do some reading.. As I mentioned, I'll eventually put something an OD in. So, I'm not sure what final drive etc is with something like a 46rh

Thanks for the input!

to be fair, i was a lot younger then. but i still wouldn't hesitate to get in the warhorse and do a california turnaround to pretty much any NA point today. currently the tires are 26.5 so it brings the R's down to a "reasonable" level. i'm not saying it's perfect, but it's about the best compromise. also, i don't care about laying rubber, ET & trap speed or trying to hustle some crap can one stop light to the next on friday night.

3.55's with 25" tall tires was a level of: i can stand this for about 2.5hrs, but super fun in town with a deep 1st 4spd.

anyway, the 46 has the same gear spread as a 727 and the OD is .69 so you'll likely want something in the 3.9X~4.1X ratio in that a 4.1X would effectively become 2.8X at cruise.

a 3.7X with the right tires might put the cruise RPM in the 1800~2200 sweet spot for a G3 hemi tho.

 

[DionR]

I'll have to think on the 3.08 and do some reading..

Just something to think about, but the later model cars with an 8HP run a 3.06 for the performance ratio and that is with an almost 29" tall tire. Those 8HP's have some really deep first gears and (I don't think) work well with the normal idea of a performance ratio. I think I settled on a 2.94 with a 26" tire when I was looking at doing one. A 3.08 with a 26" tire might work, but seems like the 3.2x ratio was actually starting to get too deep.

I guess the issue is even the computer can't keep up and shift fast enough when the rear gear get's too deep, and the cars hit the rev limiter sometimes. Plus with a 4.70 1st and 3.2x gears it is like a 727 and 6.20 setup. Might as well not even use first, probably shifts into second in the first 10 feet.

Doesn't really matter now, but maybe it is something to factor in if you do look at an 8 speed later.

Edit - I guess you have an 8 speed and 3.55's so you have probably thought about this some already. Nevermind.

 

[MopaR&D]

2.74 x 3.08 = 8.44
2.74 x 3.27 = 8.96
2.74 x 3.55 = 9.73
2.74 x 3.73 = 10.22

2.54 x 3.08 = 7.82
2.54 x 3.27 = 8.31
2.54 x 3.55 = 9.07
2.54 x 3.73 = 9.14

I realized since you have a lockup 904 you have a lower 1st gear than an earlier non-lockup 904 or 727 (2.74:1 1st vs. 2.54:1). Above shows some quick math for the starting ratio. General consensus is a 3.2x final drive ratio is the ideal compromise gear on muscle-era cars with the taller 1st gear autos but with your lockup 904 your starting ratio is actually a tad deeper than that with 3.08 in the rear end. The lower 1st gear basically makes the starting ratio the same as one step "up" in final drive ratio. With that in mind, I'd go with 3.08 in a heartbeat. That will also match up well with an 8-speed down the road as @DionR pointed out. Not to mention doing ring and pinion changes in an 8.8" isn't as easy as in an 8 3/4" with its dropout center section so picking the right ratio the first time will save a good amount of work later.

 

[Dantra]

to be fair, i was a lot younger then. but i still wouldn't hesitate to get in the warhorse and do a california turnaround to pretty much any NA point today. currently the tires are 26.5 so it brings the R's down to a "reasonable" level. i'm not saying it's perfect, but it's about the best compromise. also, i don't care about laying rubber, ET & trap speed or trying to hustle some crap can one stop light to the next on friday night.

3.55's with 25" tall tires was a level of: i can stand this for about 2.5hrs, but super fun in town with a deep 1st 4spd.

anyway, the 46 has the same gear spread as a 727 and the OD is .69 so you'll likely want something in the 3.9X~4.1X ratio in that a 4.1X would effectively become 2.8X at cruise.

a 3.7X with the right tires might put the cruise RPM in the 1800~2200 sweet spot for a G3 hemi tho.

Maybe I'm using the calculator wrong.. I'm coming up with right around 2k at 70mph with a 46RH and 3.08s at 70mph.. 1500 at 55. 3.73 will raise those RPMs by 300. Kind of a double edged sword that I'm playing with here. If I do go to 3.08, chances are that I'll want to regear if I end up going with the 46.. 8Hp might like it. I guess I'll have the gears on the shelf if I do go 46

Been playing with this.. has some trans options preloaded
Gear Ratio Calculator

Just something to think about, but the later model cars with an 8HP run a 3.06 for the performance ratio and that is with an almost 29" tall tire. Those 8HP's have some really deep first gears and (I don't think) work well with the normal idea of a performance ratio. I think I settled on a 2.94 with a 26" tire when I was looking at doing one. A 3.08 with a 26" tire might work, but seems like the 3.2x ratio was actually starting to get too deep.

I guess the issue is even the computer can't keep up and shift fast enough when the rear gear get's too deep, and the cars hit the rev limiter sometimes. Plus with a 4.70 1st and 3.2x gears it is like a 727 and 6.20 setup. Might as well not even use first, probably shifts into second in the first 10 feet.

Doesn't really matter now, but maybe it is something to factor in if you do look at an 8 speed later.

Edit - I guess you have an 8 speed and 3.55's so you have probably thought about this some already. Nevermind.

Dude, I always love reading your responses.. your OCD/ADHD just shines through as you try to help problem solve. Always makes a guy think.. regardless of what they have, what their experience is or whatever.

You are correct.. I have the 8 with 3.55s and first gear is pretty worthless. I can bounce off the rev limiter through about 5 gears, pretty damn quick! But it is fun when the tires chirp in town after 10 or 20 feet from a stop, with very little to no effort lol. I don't remember what my tire height is on Hoopty but the 55s are pretty sweet for every other gear and on the highway but it can be a bit aggressive on a kick down. I may have to keep an eye out for a 3.08 or 2.94 center section for Hoop.. It's an open diff now, so I'd settle for another open.. Thing gets stupid AF when both tires decide to spin! I really never even thought about doing it.. even knowing the LX cars are 3.08

2.74 x 3.08 = 8.44
2.74 x 3.27 = 8.96
2.74 x 3.55 = 9.73
2.74 x 3.73 = 10.22

2.54 x 3.08 = 7.82
2.54 x 3.27 = 8.31
2.54 x 3.55 = 9.07
2.54 x 3.73 = 9.14

I realized since you have a lockup 904 you have a lower 1st gear than an earlier non-lockup 904 or 727 (2.74:1 1st vs. 2.54:1). Above shows some quick math for the starting ratio. General consensus is a 3.2x final drive ratio is the ideal compromise gear on muscle-era cars with the taller 1st gear autos but with your lockup 904 your starting ratio is actually a tad deeper than that with 3.08 in the rear end. The lower 1st gear basically makes the starting ratio the same as one step "up" in final drive ratio. With that in mind, I'd go with 3.08 in a heartbeat. That will also match up well with an 8-speed down the road as @DionR pointed out. Not to mention doing ring and pinion changes in an 8.8" isn't as easy as in an 8 3/4" with its dropout center section so picking the right ratio the first time will save a good amount of work late

After some reading, my 904 is pre 80. That means that my 904 gears are 2.45/1.45/1. In 1980 they changed to 2.74/1.54/1. I'm staring to lean towards the 3.08 set but how much will the 2.54 come into play? The way I'm looking at it now is the 3.08 will be a nice gear for the open road plus if I go 8HP, It'll be fine there too. If I go 46, I'm probably gonna have to go back to the 3.73 regardless. But I'll at least try the 3.08s before swapping back.

 

[volaredon]

I wouldn't want more than a 3.23 with the 3 SPD trans (727/904) w/o the OD anymore unless I could run 32" or taller tires (like a truck)

 

[Dantra]

to be fair, i was a lot younger then. but i still wouldn't hesitate to get in the warhorse and do a california turnaround to pretty much any NA point today. currently the tires are 26.5 so it brings the R's down to a "reasonable" level. i'm not saying it's perfect, but it's about the best compromise. also, i don't care about laying rubber, ET & trap speed or trying to hustle some crap can one stop light to the next on friday night.

3.55's with 25" tall tires was a level of: i can stand this for about 2.5hrs, but super fun in town with a deep 1st 4spd.

anyway, the 46 has the same gear spread as a 727 and the OD is .69 so you'll likely want something in the 3.9X~4.1X ratio in that a 4.1X would effectively become 2.8X at cruise.

a 3.7X with the right tires might put the cruise RPM in the 1800~2200 sweet spot for a G3 hemi tho.

Just read up on 8HP70.. Final Dive isn't that much different than the 46. 8th gear is .6667 (first is 4.6957 lol)

 

[DionR]

For what it's worth, here are the numbers I worked up when I was looking at an 8HP

	8HP70 w/ 245/45R20	8HP70 w/ 275/35R18
1st	4.69	4.69
2nd	3.13	3.13
3rd	2.1	2.1
4th	1.67	1.67
5th	1.29	1.29
6th	1	1
7th	0.84	0.84
8th	0.67	0.67
Final Drive	3.06	2.71
MPH
20 (1st)​	2245	2229
65 (8th)​	1562	1551
75 (8th)​	1802	1790

So functionally, an 8HP70 with a 2.71 rear gear and a 25.6" tire would feel about the same as a 2015-23 Challenger with the same trans and a 3.06 gear.

Here is the same comparison but with a 235/60R15 and a 3.08 gear:

	8HP70 w/ 245/45R20	8HP70 w/ 235/60R15
1st	4.69	4.69
2nd	3.13	3.13
3rd	2.1	2.1
4th	1.67	1.67
5th	1.29	1.29
6th	1	1
7th	0.84	0.84
8th	0.67	0.67
Final Drive	3.06	3.08
MPH
20 (1st)​	2245	2483
65 (8th)​	1562	1727
75 (8th)​	1802	1993

 

[DionR]

To be clear, I think the biggest potential issue with an 8HP is more if you run a motor that is a little high strung and carb'ed. The deep first gear of the 8 speed kind of forces you into running a taller rear gear, but that can result in highway RPM's that aren't to the liking of the motor. But if you gear it down so it is in a better range on the highway, you might lose the use of 1st gear. The other way to do it is leave the gear tall and just not use 8th. Either way, if your motor wants to run at 2,200 rpm for example on the highway, it get's hard to make both ends work well.

Bolted behind a G3? Other than rev'ing too fast or some kind of built G3, seems like it is hard to beat.

The nice thing is, you end of potentially chasing gear ratios people are usually trying to sell cheap or throw away. But it also means you can't buy the gear set new, even for an 8.8. At least the last time I looked anyways.

 

[Dantra]

For what it's worth, here are the numbers I worked up when I was looking at an 8HP

	8HP70 w/ 245/45R20	8HP70 w/ 275/35R18
1st	4.69	4.69
2nd	3.13	3.13
3rd	2.1	2.1
4th	1.67	1.67
5th	1.29	1.29
6th	1	1
7th	0.84	0.84
8th	0.67	0.67
Final Drive	3.06	2.71
MPH
20 (1st)​	2245	2229
65 (8th)​	1562	1551
75 (8th)​	1802	1790

So functionally, an 8HP70 with a 2.71 rear gear and a 25.6" tire would feel about the same as a 2015-23 Challenger with the same trans and a 3.06 gear.

Here is the same comparison but with a 235/60R15 and a 3.08 gear:

	8HP70 w/ 245/45R20	8HP70 w/ 235/60R15
1st	4.69	4.69
2nd	3.13	3.13
3rd	2.1	2.1
4th	1.67	1.67
5th	1.29	1.29
6th	1	1
7th	0.84	0.84
8th	0.67	0.67
Final Drive	3.06	3.08
MPH
20 (1st)​	2245	2483
65 (8th)​	1562	1727
75 (8th)​	1802	1993

I came across this calculator this morning and I like that it has side by side comparisons
Gear Ratio Calculator

I put the 46 on one side and the 8hp on the other. Since 3rd on 46 and 6th on the 8 are 1:1, I can look at those columns and know thats what my 904 will be at...

Talking with a few guys with Hemi swaps and 3 speeds and they like their 3.23 (3.27 Ford). Other future factors to consider tho

 

[Last of the Fast]

Doing a rear-end swap.. The one going in is a 3.73 and I'm just not sure if I'm going to like that gear. It'll see a little bit of highway time but not alot.. car shows, occasional drive to work etc. Possibly Power Tour..

69 Dart with a 6.4 Hemi and a 904 lockup.. Just a driver and not a track car. I know a 904 LU isn't ideal, but it is what it is for this year. I did have it beefed up with new bands/reds/steels/4.2 etc. Tires are (will be) approx 25-26 tall. Looking at about 500hp when it's all said and done. I'll go 8 speed or 46RH next winter.. maybe.

I know there are all kinds of calculators and guys that can dazzle me with math but I'd really like to hear some real world stories before I go throwing money at 3.27s

Thanks Guys!

My '70 Duster 340 has 3.55:1 rear gears with the 4 speed and gets 8mpg. Also, I do not recommend those gears for freeway use.

 

[John S]

I've run 24.5" diameter w 3.91 rear and highway driving was "not fun". Rev'd up to 3000 rpm+ at 55 mph, noisy, too much engine braking, can't hear anybody talking, has bad milage. Makes you not want to take the car any distance that requires interstate or even 55 mph back roads.
Recently switched to 28" diameter tires and added a Gear Venders w same 3.91. Cruising at 55 MPH is better in 3rd but your starting to feel like it needs another gear. Activating the OD brings the rpm down to about 2200 and it makes the ride much more enjoyable. That combo is supposed to give a final ratio of about 3.05 but the convertor will slip a little. With this setup, I can take it on the highway and run 60- 70 and it is tolerable for long drives.

 

[Dale Davies]

Doing a rear-end swap.. The one going in is a 3.73 and I'm just not sure if I'm going to like that gear. It'll see a little bit of highway time but not alot.. car shows, occasional drive to work etc. Possibly Power Tour..

69 Dart with a 6.4 Hemi and a 904 lockup.. Just a driver and not a track car. I know a 904 LU isn't ideal, but it is what it is for this year. I did have it beefed up with new bands/reds/steels/4.2 etc. Tires are (will be) approx 25-26 tall. Looking at about 500hp when it's all said and done. I'll go 8 speed or 46RH next winter.. maybe.

I know there are all kinds of calculators and guys that can dazzle me with math but I'd really like to hear some real world stories before I go throwing money at 3.27s

Thanks Guys!

My Chev 1/2 truck has 3.73 gears and an OD trans. 16" wheels and 75 series tires. Cruised on the highway at about 1800 RPM in OD.
I don't know whether the extra complexity of the 8 spd is worth any benefit. Extra weight and size. Personnaly I would go with the 3.73 and next winter channge to the 46RH trans. 3.55 gears may be a good option also.
Most of the 4 spd auto OD transmissions seem to have the OD gear about .7:1. 3.73 × .7 gives about 2.6 final drive. Gives good and easy acceleration while cruising with a quiet and low RPM good for fuel economy.

 

[Dale Davies]

I came across this calculator this morning and I like that it has side by side comparisons
Gear Ratio Calculator

I put the 46 on one side and the 8hp on the other. Since 3rd on 46 and 6th on the 8 are 1:1, I can look at those columns and know thats what my 904 will be at...

Talking with a few guys with Hemi swaps and 3 speeds and they like their 3.23 (3.27 Ford). Other future factors to consider tho

Very common now in Ford axles is the 3.31 gears with traction loc. Many Ford Exploders had 3.55 gears in them with the 4R70W trans.

 

[peachtop]

I have 3.73 gears in my '47' Canopy. I'm running a 46rh behind a 340 and I cruise at 60 mph all day and the RPM is 2000. My tire diameter is 27". The only problem I see is very little torque at that rpm so it takes a little more throttle when going uphill. The gas mileage isn't that great. I thought it would improve when I replaced the 727, but it actually went down. If I was you, I would jump to 3.92's, but do the calculations using your tire diameter to see what your RPM's will be. Use the calculator given 'DANTRA' above to get your engine speed.
Some of the responses on this thread recommend going to 3.32 or 2.76. Do the calculations. When I put me 46RH in, I was running 3.55 gears and at 60 mph I was only running 1800 rpm. I don't care what v8 you're using, none of them have any torque at that rpm unless you are running with a very small cam and a very light car. The engine has to have a decent amount of torque to keep the vehicle moving into a headwind. I know because my truck is like a 4/4 piece of plywood pushing air down the road. By the way my mileage with the 727 and 3.55 gears was 15 on the road. The mileage with 46RH and 3.55 gears was 13. Go figure. I think it's because of the low RPM's and less torque. I don't have enough mileage on the 3.73 ears to give an estimation yet. I just put the 3.73 gears in last fall.

 

[MopaR&D]

I have 3.73 gears in my '47' Canopy. I'm running a 46rh behind a 340 and I cruise at 60 mph all day and the RPM is 2000. My tire diameter is 27". The only problem I see is very little torque at that rpm so it takes a little more throttle when going uphill. The gas mileage isn't that great. I thought it would improve when I replaced the 727, but it actually went down. If I was you, I would jump to 3.92's, but do the calculations using your tire diameter to see what your RPM's will be. Use the calculator given 'DANTRA' above to get your engine speed.
Some of the responses on this thread recommend going to 3.32 or 2.76. Do the calculations. When I put me 46RH in, I was running 3.55 gears and at 60 mph I was only running 1800 rpm. I don't care what v8 you're using, none of them have any torque at that rpm unless you are running with a very small cam and a very light car. The engine has to have a decent amount of torque to keep the vehicle moving into a headwind. I know because my truck is like a 4/4 piece of plywood pushing air down the road. By the way my mileage with the 727 and 3.55 gears was 15 on the road. The mileage with 46RH and 3.55 gears was 13. Go figure. I think it's because of the low RPM's and less torque. I don't have enough mileage on the 3.73 ears to give an estimation yet. I just put the 3.73 gears in last fall.

Lots of factors involved... You mention running a 340, those tend to have less grunt than 360s. I'm wondering if you're getting into the power enrichment opening the throttle that much when it's in 4th, might be better off downshifting to 3rd when you need any extra acceleration. I know the stock-cammed 360 in my D200 makes peak torque not much over 2000 RPM and would probably work well cruising at 1800; it currently spins at 2800 around 75 mph with a 727, 3.55 gears and 33" tires... I think it would be a good candidate for a 46RH. The Magnum engines that were in front of the RH/RE transmissions from the factory had gobs of torque right off idle so unless your engine is a stump-puller it would probably want higher cruising RPMs.

 

[junkyardhero]

at 2K rpm you probably don't have enough timing (especially if you have stock components) and that's why your mileage is down. couple that with what R&D said about being just into the enrichment at steady cruise and that would certainty explain the drop in mpg.

 

[a70duster]

This was years ago but 3.91 and ~26" tires (auto) at sustained 60 mph was not fun!

 

[peachtop]

I respect the replies. My 340 when built in 1996 an had had 360hp, but the torque band didn't come on till 2600rpm. It has a purple shaft that I think has 460 lift. Think back 20 years and the parts available then. It has an air gap intake and a 750 Edelbrock from back then. Mechanical advance at 2000rpn is 35 degrees. I can't go any more or it knocks. I'm stuck with what I have. By the way, the vacuum is low, 7 pounds and I have a vacuum pump to run the brakes. It probably should be pulled and rebuilt, but I'll leave that to my son after I kick the bucket.

 

[DionR]

I have 3.73 gears in my '47' Canopy. I'm running a 46rh behind a 340 and I cruise at 60 mph all day and the RPM is 2000. My tire diameter is 27". The only problem I see is very little torque at that rpm so it takes a little more throttle when going uphill. The gas mileage isn't that great. I thought it would improve when I replaced the 727, but it actually went down.

Exactly my point in post #33 in regards to an A8. If your motor won’t work well at the lower cruise RPM’s that the taller rear gear and OD offer, it can make the car worse. And sometimes it isn’t tuning but more just the engine build.

I don't care what v8 you're using, none of them have any torque at that rpm unless you are running with a very small cam and a very light car. The engine has to have a decent amount of torque to keep the vehicle moving into a headwind.

Just have to point out that a 2015+ 6.4/A8 runs at 1560 RPM or so at 65, and sometimes in 4 cylinder mode. And they make 485 HP, so I don’t think it would be considered a “very small cam” motor nor is a Challenger/Charger a light car. And it pulls fine and gets something like 23 mpg.

Not saying it is an apples to apples comparison, but pretty sure the ‘73 Duster I am going to put a 5.7/T56 in will be fine cruising at 1600 RPM just like the ‘15 R/T did before I sold it.

 

[peachtop]

Exactly my point in post #33 in regards to an A8. If your motor won’t work well at the lower cruise RPM’s that the taller rear gear and OD offer, it can make the car worse. And sometimes it isn’t tuning but more just the engine build.



Just have to point out that a 2015+ 6.4/A8 runs at 1560 RPM or so at 65, and sometimes in 4 cylinder mode. And they make 485 HP, so I don’t think it would be considered a “very small cam” motor nor is a Challenger/Charger a light car. And it pulls fine and gets something like 23 mpg.

Not saying it is an apples to apples comparison, but pretty sure the ‘73 Duster I am going to put a 5.7/T56 in will be fine cruising at 1600 RPM just like the ‘15 R/T did before I sold it.

Like I said My engine was built in 1996. There is a huge difference in technologies between then and now. I speaking about my situation, not anyone else's so don't shoot the messenger. If you don't like what I said you don't have to respond negatively. Just keep your negative thoughts to yourself. I thought I was giving thoughtful advice with my life experiences with the OD transmission. It's sad to see that the so called experts can't accept a journeyman's opinion without whining about your expert opinion. From now on don't expect anything from me. You so called experts can do everything. I have been involved in MOPAR's since 1967 and really that's what I love. Maybe you youngsters with your GenIII hemi's need to do a little research on the older engines to see where you came from. I'm in my 70's and don't need a new hemi to toot my whistle.

 

[AJ/FormS]

Listen, I know some of you are gonna hate me for saying this, But I once got my HotRod 367 combo up to 32 mpgs. and it still got into the 12's with 245 tires, spinning most of the way.
This is not a brag.
This is a statement of fact.
and it was running 3.55s with an A833d and a GVod behind that for, Seven useable and sequential gears-ratios.
The trick is to know your engine, and feed it the ignition advance it so desperately needs at low rpm.
With this combo, the ratios were
3.09-2.41-1.67-1.30-1.00-.78od-and .55 od
With 3.55s; 65= 1590 rpm, 75=1840, 85= 2060
The ignition timing needs to follow.
In my case, it required high 50s to low 60s, depending on the cruising speed/rpm. After that, I just leaned out low-speed circuits, until is began to hunt, then threw a lil fuel back in.

But, getting back to the question, I have nearly always had, since 1970, a 4-speed A-body in the driveway. and for the most part, they have always had 3.55s, in fact my current 3.55s may have been out of that 1970 Swinger 340. and, for the most part, I have always run the tallest tires that fit on the car, usually around 27/28.
But I have always hated cruising those 3.55 gears cuz 65= about 2900, even with the current combo which is very well balanced. About 10 years ago, I got me that GVod, and so with the latest trans combo, she cruises at 65= 2240, still with the 3.55s. ....Which is infinitely better.
I would and have cruised at lower rpms but, that iteration that cruised at up to 32 mpgs, dropped lobes in 2004. The cam that replaced it, can't touch that 32 mpgs no matter how hard I have tried. So, the 3.55s get me to 65=5520 in Second, or to 60=6400 in First-over, which is fairly ideal, so, the 3.55s have stayed.
But man, those gears are tuff, I bet they have a half a million miles on them or more.

BTW, I have tried nearly every combination of rear gear that Mopar makes, with every fine-spline A833 she makes, and I can tell you that no matter what I ran, a starter gear of about 11/1 is all my HO-6liter ever wanted, and not any more. down to 10/1 with this latest cam is Ok too. but no less than 9/1. This is not for lack of power mind you, but the slowest my engine will idle in gear is about 500; which with 3.55s gets me 3.6 mph, to parade at. Any less gear will just increase the slowest speed higher than I want to idle around at.
With an auto trans, obviously, this is not a consideration for you.

BTW-2
I'll never run 3.55s again without an overdrive. I have never liked it, and at age 70 now, I can't imagine cruising at much over 2200 ever again. When I ran 3.55s alone, I usually ran at about 55= 2450

 

[junkyardhero]

Like I said My engine was built in 1996. There is a huge difference in technologies between then and now. I speaking about my situation, not anyone else's so don't shoot the messenger. If you don't like what I said you don't have to respond negatively. Just keep your negative thoughts to yourself. I thought I was giving thoughtful advice with my life experiences with the OD transmission. It's sad to see that the so called experts can't accept a journeyman's opinion without whining about your expert opinion. From now on don't expect anything from me. You so called experts can do everything. I have been involved in MOPAR's since 1967 and really that's what I love. Maybe you youngsters with your GenIII hemi's need to do a little research on the older engines to see where you came from. I'm in my 70's and don't need a new hemi to toot my whistle.

 

[DionR]

Like I said My engine was built in 1996. There is a huge difference in technologies between then and now. I speaking about my situation, not anyone else's so don't shoot the messenger. If you don't like what I said you don't have to respond negatively. Just keep your negative thoughts to yourself. I thought I was giving thoughtful advice with my life experiences with the OD transmission. It's sad to see that the so called experts can't accept a journeyman's opinion without whining about your expert opinion. From now on don't expect anything from me. You so called experts can do everything. I have been involved in MOPAR's since 1967 and really that's what I love. Maybe you youngsters with your GenIII hemi's need to do a little research on the older engines to see where you came from. I'm in my 70's and don't need a new hemi to toot my whistle.

I wasn’t trying to be negative, not really sure how you read that into it. Maybe you missed that I was also agreeing with you? Your “life experiences” are exactly my hesitation with an A8 and most builds on here.

And to be clear, the 6.4 reference is pertinent as the OP has that exact motor in his car.

Pretty cool to be called a youngster. While I’m not in my 70’s and certainly don’t have the wealth of experience you do, I’m pretty far from being a “youngster”.

 

[Dale Davies]

Listen, I know some of you are gonna hate me for saying this, But I once got my HotRod 367 combo up to 32 mpgs. and it still got into the 12's with 245 tires, spinning most of the way.
This is not a brag.
This is a statement of fact.
and it was running 3.55s with an A833d and a GVod behind that for, Seven useable and sequential gears-ratios.
The trick is to know your engine, and feed it the ignition advance it so desperately needs at low rpm.
With this combo, the ratios were
3.09-2.41-1.67-1.30-1.00-.78od-and .55 od
With 3.55s; 65= 1590 rpm, 75=1840, 85= 2060
The ignition timing needs to follow.
In my case, it required high 50s to low 60s, depending on the cruising speed/rpm. After that, I just leaned out low-speed circuits, until is began to hunt, then threw a lil fuel back in.

But, getting back to the question, I have nearly always had, since 1970, a 4-speed A-body in the driveway. and for the most part, they have always had 3.55s, in fact my current 3.55s may have been out of that 1970 Swinger 340. and, for the most part, I have always run the tallest tires that fit on the car, usually around 27/28.
But I have always hated cruising those 3.55 gears cuz 65= about 2900, even with the current combo which is very well balanced. About 10 years ago, I got me that GVod, and so with the latest trans combo, she cruises at 65= 2240, still with the 3.55s. ....Which is infinitely better.
I would and have cruised at lower rpms but, that iteration that cruised at up to 32 mpgs, dropped lobes in 2004. The cam that replaced it, can't touch that 32 mpgs no matter how hard I have tried. So, the 3.55s get me to 65=5520 in Second, or to 60=6400 in First-over, which is fairly ideal, so, the 3.55s have stayed.
But man, those gears are tuff, I bet they have a half a million miles on them or more.

BTW, I have tried nearly every combination of rear gear that Mopar makes, with every fine-spline A833 she makes, and I can tell you that no matter what I ran, a starter gear of about 11/1 is all my HO-6liter ever wanted, and not any more. down to 10/1 with this latest cam is Ok too. but no less than 9/1. This is not for lack of power mind you, but the slowest my engine will idle in gear is about 500; which with 3.55s gets me 3.6 mph, to parade at. Any less gear will just increase the slowest speed higher than I want to idle around at.
With an auto trans, obviously, this is not a consideration for you.

BTW-2
I'll never run 3.55s again without an overdrive. I have never liked it, and at age 70 now, I can't imagine cruising at much over 2200 ever again. When I ran 3.55s alone, I usually ran at about 55= 2450

I am also 71. My POS Dakota with 3/4 V8, auto OD trans, 3.55 gear and 235/75-15 tires is reving right about 2000RPM at 100kph or 62 MPH.

 

[Dantra]

I wasn’t trying to be negative, not really sure how you read that into it. Maybe you missed that I was also agreeing with you? Your “life experiences” are exactly my hesitation with an A8 and most builds on here.

And to be clear, the 6.4 reference is pertinent as the OP has that exact motor in his car.

Pretty cool to be called a youngster. While I’m not in my 70’s and certainly don’t have the wealth of experience you do, I’m pretty far from being a “youngster”.

Damn Whipper Snappers..

Time to go drink some Whipple!!!!

BTW.. I ordered some 3.27s. If I have to change again when (if) I do an overdrive.. It is what it is.