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1969 Newport Custom final drive ratio?

Old 10-05-2016, 08:26 PM
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1969 Newport Custom final drive ratio?

Greetings Crew Members.

So what IS my final drive ratio, 2.73 or 3.23?

My "boat" has the mighty D32 option heavy duty (trailer package) 727 torque flight automatic transmission.

I'm considering changing the "locker" for better acceleration without changing intake and carb, kickdown linkage, exhaust, cam and torque converter. The car weighs almost 500lbs more than a Charger.

I want to keep the pleasant "street manners" high and the cost low.

Share the knowledge, Captain Chrysler
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Old 10-06-2016, 11:50 AM
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Originally Posted by Boompy View Post
Greetings Crew Members.

So what IS my final drive ratio, 2.73 or 3.23?

My "boat" has the mighty D32 option heavy duty (trailer package) 727 torque flight automatic transmission.

I'm considering changing the "locker" for better acceleration without changing intake and carb, kickdown linkage, exhaust, cam and torque converter. The car weighs almost 500lbs more than a Charger.

I want to keep the pleasant "street manners" high and the cost low.

Share the knowledge, Captain Chrysler

Differentials usually have a tag under there that give you the ratio. You may have to hunt for it, and clean/degrease.


Another way is to get an electronic tach on there (about $40 on any auto part store) and an accurate GPS speedometer. From the two, and tire size, we can see if you have 3.23 or 2.76 (not 2.73, I think thats a chevy ratio).


Do you have 383 2bbl? I think changing this into 4 bbl is really by far the easiest and most effective way to get the car go fast, and may improve gas mileage when driven carefully. That year BB's had the same cam for 2bbl or 4bbl. This is very cheap too, much more so than messing with the gear ratio.


And, BTW, you can also help acceleration by using lower profile tires. But I prefer the 4bbl option, and let the revs be low at speed. I have 2.94 and 235/75/15, and via GPS confirmed many times 90 at 3000 rpm.
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Old 10-06-2016, 08:26 PM
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B -

If the car has a tach, and you think the speedo is accurate (you can check the speedo against another more modern car), run the car at 40, 50, and 60 mph (as a check) and compare the rpm to mph. There are rpm calculators all over the net. You'll need the tire diameter as well.

For a quick an dirty check, chock the front wheels and jack up the rear by the diff housing. With the tranny in N, rotate the rear wheels 360* and see how many times the drive shaft rotates. (marking both at bottom dead center makes it easier to see). That will get you close enough for factory gearings.

3.23 or 3.55 are optimal street/highway gears. Going to higher ratios makes the car peppier, but may limit high way cruising at speed. 3.91s are about as high as I'd go.

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Old 10-06-2016, 08:45 PM
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easy way... Best guess... >>>>>>
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Old 10-08-2016, 03:09 PM
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Originally Posted by demetri View Post
Differentials usually have a tag under there that give you the ratio. You may have to hunt for it...Do you have 383 2bbl? I think changing this into 4 bbl is really by far the easiest and most effective way to get the car go fast, and may improve gas mileage when driven carefully...And, BTW, you can also help acceleration by using lower profile tires. I have 2.94 and 235/75/15, and via GPS confirmed many times 90 at 3000 rpm.
Hey Demetri, thanks, I'll look for the tag.

Yes, I have the 383 2 barrel.

See, I'm leary about starting on motor work.

First, the money.
I could probably afford the new intake and carb. I looked into the Edelbrock set-up, roughly $300.00. I'd still need some type of kickdown linkage.

Second, the money.
If I can suddenly flow more mixture, then I need to flow more exhaust.
Those factory cast manifolds are awfully restrictive, and I currently have the single pipe exhaust system. At the moment, I'm actually wasting H.P. pushing exhaust out the back.
So I'd need headers designed to fit my C-body (without shim this/alter that...) and the complete duel exhaust system with crossover pipe.

Third, the money.
How could I slam all that into all those performance upgrades and not change the cam? An RV cam would be my choice, with a little lope from the new duels.

All that makes me nervous!

My tires are Hankook 235/75/R15. What kind of C-body do you have?

Sorry for all the bla-bla, Boompy
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Old 10-08-2016, 03:29 PM
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Originally Posted by Archer View Post
B -
For a quick an dirty check, chock the front wheels and jack up the rear by the diff housing. With the tranny in N, rotate the rear wheels 360* and see how many times the drive shaft rotates...3.23 or 3.55 are optimal street/highway gears. 3.91s are about as high as I'd go.
Archer
Hey Archer, I don't have a tachometer.
I'll try the wheel/drive shaft spin test if I can't find the tag on the differential housing.

I'd think 3.55 would be optimal. I don't go fast at highway speeds. Just be nice to get my boat moving a little easier, sooner.

Quicker, Boompy
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Old 10-08-2016, 04:24 PM
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Originally Posted by RacerHog View Post
easy way... Best guess...
Thanks for the helpful video RacerHog.

Regards, Captain Chrysler
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Old 12-29-2016, 03:24 PM
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Boompy,

I have a 68 and a 70 Newport. Both started as 383 2bbls.

I strongly agree with demetri. Do a 4bbl swap with a Lo-kar linkage and then do a dual exhaust off the factory manifolds. Bang for your buck that will be your best bet. From there you can go crazy but it all can start to snowball. It is worth the money in the end though. My 68 is a blast to drive now.

Gary
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Old 12-29-2016, 04:36 PM
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3.55 are the way to go.
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Old 12-29-2016, 06:39 PM
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Originally Posted by 70newport View Post
Boompy,

...Both started as 383 2bbls.

I strongly agree with demetri. Do a 4bbl swap with a Lo-kar linkage and then do a dual exhaust off the factory manifolds...It is worth the money...

Gary
Thanks for your reply Gary. Yes, Demetri makes good points.
I have a few questions...

How many miles on your 383?

Did you convert to electronic ignition?

What 4bbl carb and manifold did you install?

Is your 727 "healthy"?
Mine works well unless you really stand-on-it. The clutches are worn-out and it "grabs" on hard acceleration from a standing stop. Roughly $1500.00 for a rebuild from a local shop.

Was the Lo-Kar linkage difficult to dial in?

Did you look into headers that actually fit? For that reason alone I'd consider using the stock manifolds. I've been trying to find headers that absolutely fit with no shimming, cutting, redesigning, relocating, cursing or tool throwing.

Did you consider a cross-over pipe for the new duel exhaust system, or is this an unnecessary extra cost?

What mufflers did you use?

Did you change your cam?

Sorry for all the bla-bla, I tend to dream out loud.

Took "The Ghost" to the Mopar Nationals this past July. It was the only one like it there. Swarmed like ants at a picnic.

Happy New Year, Captain Chrysler
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Old 12-29-2016, 06:45 PM
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Originally Posted by Iowan View Post
3.55 are the way to go.
Thanks for your reply Iowan. I agree.

Happy New Year, Captain Chrysler
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Old 12-30-2016, 03:43 PM
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With a tow package it probably has a 3.23 I had a 69 Chrysler that I bought for parts had a 440 / and a 3.23 sure grip...If you are replacing the gears I would think about a 3.90 and a 518 / 42Re overdrive trans...
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Old 12-30-2016, 04:34 PM
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Back at you with the Happy New Year!
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Old 12-30-2016, 06:24 PM
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Originally Posted by TVLynn View Post
With a tow package it probably has a 3.23 I had a 69 Chrysler that I bought for parts had a 440 / and a 3.23 sure grip...
Thanks for your reply TVLynn. Happy New Year.

My Wife, out of the blue, ask me what it would cost to install a manual transmission in The Ghost!
I love this woman!

Hit the switch, Captain Chrysler
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Old 12-30-2016, 09:41 PM
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She a keeper..... My wife hates all my cars..... Dont know what she seen in me, I been working on cars my whole life.. Sure going to miss her if she leaves...
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Old 12-31-2016, 05:35 AM
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Originally Posted by RacerHog View Post
She a keeper..... My wife hates all my cars.....
Thanks for your reply RacerHog. Happy New Year.

Speaking of "all my cars", don't remember if I posted anything about it, this July my Wife let me buy the neighbor's 1986 Dodge D100 pickup! I've had my eye on this truck for years. It never moved. 225 slant sickness with the "agricultural" 4-speed. Great shape with the most beautiful sun burn. Stole it for $1000.00!

Now I want a GTX to complete the Mopar trilogy.

Yeah, She's a keeper.
Regards, Captain Chrysler
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Old 12-31-2016, 08:06 AM
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I don't know how this got on women on new years eve but the ones I held on to I should have walked away from and the ones I should have held on to, well that's life.
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Old 12-31-2016, 03:25 PM
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Originally Posted by Iowan View Post
...the ones I held on to I should have walked away from and the ones I should have held on to...
Sounds like some of the cars we used to have...
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Old 12-31-2016, 04:12 PM
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Originally Posted by Boompy View Post
Sounds like some of the cars we used to have...
Lol, I have better luck with cars.
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Old 01-03-2017, 09:02 AM
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Originally Posted by Boompy View Post
Thanks for your reply Gary. Yes, Demetri makes good points.
I have a few questions...

How many miles on your 383?
Mine Now has around 150,000 Miles but I did recently have the block machined .30 over

Did you convert to electronic ignition?
I have a stock replacement distributor with electronic internals rather than points now

What 4bbl carb and manifold did you install?
Holley 670 street avenger. Not in love with this carb but it gets the job done. I have a 770 sittin in my garage im going to mess with this summer. If your looking for a great simple easy to tune carb I think the street avenger is the way to go.

I have my carb on an Edelbrock performer intake with a 1" open spacer.


Is your 727 "healthy"?
Mine works well unless you really stand-on-it. The clutches are worn-out and it "grabs" on hard acceleration from a standing stop. Roughly $1500.00 for a rebuild from a local shop.

Was the Lo-Kar linkage difficult to dial in?

My 727 was rebuilt a bit ago with a shift kit and a 2800 stall. its not a crazy built one by any means but handles the 383 well. the lo-kar linkage was pretty straight forward for me.


Did you look into headers that actually fit? For that reason alone I'd consider using the stock manifolds. I've been trying to find headers that absolutely fit with no shimming, cutting, redesigning, relocating, cursing or tool throwing.

They are expensive but TTI is the only way I would recommend to go for a c body. you do have to lift the engine a bit to get them in and go at a steep angle bringing them in from the bottom so they are not "easy to install" but they fit and are a great set.


Did you consider a cross-over pipe for the new duel exhaust system, or is this an unnecessary extra cost?
What mufflers did you use?

I do not have an x pipe currently but Will probably do one when I do cutouts in the spring just as a fun option to annoy my neighbors. But IMO dual 2.5" with stock heads is plenty. I have edelbrock alluminum heads right now and am still running the 2.5"

Did you change your cam?
I did go to a comp cams 23-223-4. It is a great cam. slightly choppy idle. I had a 21-215-4 at first and wanted to go a little more aggressive. If money was no object I would go to a roller cam but I did not have the funds to do that.

Sorry for all the bla-bla, I tend to dream out loud.

Took "The Ghost" to the Mopar Nationals this past July. It was the only one like it there. Swarmed like ants at a picnic.

I love c bodys for the fact that nobody has them. they might not be the coolest to some people and may not be the fastest but they are a blast to own that i know for sure!


feel free to message me about anything. I have made a lot of mistakes over the 10+ years I have owned c bodies and love seeing these boats on the road!

Happy New Year, Captain Chrysler
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Old 01-03-2017, 12:43 PM
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Great reply!
Lots of useful information from someone who has been there/done that.

I'll look into all the pieces/parts you mentioned.
Thanks for the post.

Regards, Captain Chrysler
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Old 02-01-2019, 09:35 AM
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Originally Posted by demetri View Post
...see if you have 3.23 or 2.76 (not 2.73, I think thats a chevy ratio).
Greetings.
You were correct, I do have the 2.76 gear ratio. D51 axle listed on the broadcast sheet.

Regarding your 2.94 gears, is that ratio a noticeable improvement over the 2.76 gears?
For all the effort I'd like to see a "useful" difference when pulling out of busy intersections.
I really don't drive fast on the superslabs anymore but I don't want excessive RPM at 65MPH either.

If the 3.23 ratio isn't too buzzy, what cars should I look for when searching for donor rear gears?

Thanks, Captain Chrysler
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Old 02-01-2019, 09:25 PM
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Originally Posted by Boompy View Post
Greetings.
You were correct, I do have the 2.76 gear ratio. D51 axle listed on the broadcast sheet.

Regarding your 2.94 gears, is that ratio a noticeable improvement over the 2.76 gears?
For all the effort I'd like to see a "useful" difference when pulling out of busy intersections.
I really don't drive fast on the superslabs anymore but I don't want excessive RPM at 65MPH either.

If the 3.23 ratio isn't too buzzy, what cars should I look for when searching for donor rear gears?

Thanks, Captain Chrysler
theres a name we haven't seen in awhile.
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Old 02-02-2019, 05:31 AM
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Originally Posted by Iowan View Post
theres a name we haven't seen in awhile.
Greetings Iowan! Glad you're still here .
Let's say I've been putting out other fires.

My big old Chrysler turned 50 on January 31st. Yesterday I retitled "The Ghost" as an antique.

This is the year I iron-out all the little gremlins that are keeping my Newport from being dependable: weak charging circuit, falling on it's face on hard acceleration, damp Carter, etc. Time to enjoy my Sea Body!

Good to be back, Captain Chrysler
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Old 02-02-2019, 12:01 PM
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Originally Posted by Iowan View Post
theres a name we haven't seen in awhile.
Always good to see the old farts....
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Old 02-02-2019, 01:05 PM
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Originally Posted by RacerHog View Post
Always good to see the old farts....
Greetings RacerHog!
Glad you're still here too!

Very interested in your thoughts fellas regarding just what rear gears I'm looking for. My go fast days are over but I would like to get my barge moving off the spot a little quicker.

For all the work involved, would 2.94 gears be a "noticeable" improvement over the stock 2.76 I have now? I'd go with the 3.23 gears provided the 383 isn't into valve float at 65MPH.

What donor car or van am I looking for?

Share the knowledge, Captain Chrysler
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Old 02-02-2019, 01:18 PM
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I think a person could be happy with 3.25s @ 70 pmh.
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Old 02-03-2019, 07:31 AM
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Nothing over a 3.55 for sure..
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Old 02-03-2019, 07:41 AM
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Originally Posted by Iowan View Post
I think a person could be happy with 3.25s @ 70 pmh.
Greetings Iowan.

So 3.23 is the way to go? I've been reading about Mopar differentials for information about the swap-out. Now I need to find the donor car. Not sure if it has to be a Road Runner or if a Coronet station wagon would have what I seek. Your thoughts?

Regards, Captain Chrysler
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Old 02-03-2019, 07:42 AM
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Originally Posted by RacerHog View Post
Nothing over a 3.55 for sure..
Yes Sir, I agree.
I'm not taking the car to Maple Grove Raceway! 🤗
Regards, Captain Chrysler
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