Gear choice decisions

So I have a 340/4 speed/dana setup in my 67 dart. Street/strip car but now its pretty much a street car. Even though it's not raced anymore (Maybe at nostalgia day) I still love steep gears and refuse to get rid of them. Old school ways I guess. My current ratio is 4.56 with a 27 inch tire. After a while of thinking , I'm contemplating putting 4.10s for a ratio. I have 2 questions. 1) will 4.10s make a noticeable difference as far as revving while cruising at 50 mph? ( I know its not going to be drastic but maybe a few hundred RPMs? ) I'm pretty confident that the 4.10s will still provide the low end punch I love. 2) can I fit a taller tire in a factory 1967 dart well? its currently a 255/60 R15. Thank you in advance everyone!!

Google rpm calculator, there are many, and enter your parameters for any scenario you want..

4mulas said:

Google rpm calculator, there are many, and enter your parameters for any scenario you want..

Click to expand...

Thanks!! just did that. it will save me about 350 RPM

67_Slimer said:

So I have a 340/4 speed/dana setup in my 67 dart.

Click to expand...

If your engine has good low-rpm torque, (do a compression test) then the A8330d is a good option so long as you treat it as a 3+1 and go gently into overdrive.
The .73od will turn your 4.56s into 3.33s and 65= 2700 with 27" tires.,
This is a Cheap and easy solution ................. altho, your starter gear will be another 16% deeper going from; 2.66 to 3.09, making it a real short first gear, but Second will totally be worth it. Your current gear selection, in Roadgears, is;
12.13-8.75-6.38-4.56 /65= 3700..............With the od box you will get;
14.09-7.62-4.56-3.33 /65= 2700 ........................ Obviously that 14.09 is extremely steep.
as a streeter, I know that 6.5ish is an awesome gear, and all that you could ever want; unless you had a 6.80, lol. So, what can we do to give up that 14.08 and get something in the mid 6s for second; and I get 3.91s, for roadgears of
12.08-6.53-3.91-2.85 and 65= 2300 ................ compared to the current at
12.13-8.75-6.38-4.56 Thus your first gears are the same, but you loose the 8.75 in-between gear, in favor of that awesome 6.something Second gear, and you trade away the 4.56 gear for two other gears, namely 3.91 and 2.85.
When I did this going from 4.30s, I was very pleased. Mind you, I had a very hi-torque 367, which hardly balked at the 1>2 split. Your 340 may want to rev a lil higher in first, before the 1>2 shift.
Unless your car has some form of traction aid, the Dana is overkill,. I imagine you could trade it for a complete 8.75 rear with at least a3.91SG, AND the overdrive with it's matching BH. Maybe you can even get the swapee to throw in something else.
So you might be out NO money. and Still have the valuable standard box left. and something else you could use, like an organic street disc.

IMO, this is not the best solution, but it should be affordable, and easy, and quick.
NOW:
I highly recommend that you fabricate an OD Lock-out, cuz you are used to blasting thru 4 gears, and if you forget to be nice to overdrive, that will be the end of it. and maybe the entire trans goes with it. I would be remiss if I didn't tell you that I broke three of those .lol. But back in the day, I was buying them as cheap as $50. cuz nobody wanted to drag them home after the Swapmeet.
Whatever,
Happy Hotrodding

with out writing a maifesto, ejnoy:


to more completely answer your question, based on the information above: the difference betwixt the 4.56's and 4.10's at an assumed 3000rpm (your cruise speed at 50 with the 4.56's) would be about 8mph, or 400rpm, give or take. note this does not take into account actual variances in tire height that is reported as spec vs in reality. so your mph and/or rpm may vary slightly.

i can't answer to the bigger tires specifically, but i know that there's limited space with factory rims and 255 seems to be about it width wise, but i'm fairly certain i've seen 28" tall tires out back without hacking anything up too much.

You could move the rearend back a bit (either spacers in front of the hangers, or redrilled super stock hangers. That should let you run a taller tire. Drag racers do it a lot. (Mine is an inch back in my 62, a 30" tire is no problem)

If 28s fit, that is an increase of 3.57%, which is a similar loss of cruise rpm.
My math says 50mph=2839rpm, with 4.56s and 27s.
thus 28s are 2737rpm.= 98rpm savings

AJ/FormS said:

If your engine has good low-rpm torque, (do a compression test) then the A8330d is a good option so long as you treat it as a 3+1 and go gently into overdrive.
The .73od will turn your 4.56s into 3.33s and 65= 2700 with 27" tires.,
This is a Cheap and easy solution ................. altho, your starter gear will be another 16% deeper going from; 2.66 to 3.09, making it a real short first gear, but Second will totally be worth it. Your current gear selection, in Roadgears, is;
12.13-8.75-6.38-4.56 /65= 3700..............With the od box you will get;
14.09-7.62-4.56-3.33 /65= 2700 ........................ Obviously that 14.09 is extremely steep.
as a streeter, I know that 6.5ish is an awesome gear, and all that you could ever want; unless you had a 6.80, lol. So, what can we do to give up that 14.08 and get something in the mid 6s for second; and I get 3.91s, for roadgears of
12.08-6.53-3.91-2.85 and 65= 2300 ................ compared to the current at
12.13-8.75-6.38-4.56 Thus your first gears are the same, but you loose the 8.75 in-between gear, in favor of that awesome 6.something Second gear, and you trade away the 4.56 gear for two other gears, namely 3.91 and 2.85.
When I did this going from 4.30s, I was very pleased. Mind you, I had a very hi-torque 367, which hardly balked at the 1>2 split. Your 340 may want to rev a lil higher in first, before the 1>2 shift.
Unless your car has some form of traction aid, the Dana is overkill,. I imagine you could trade it for a complete 8.75 rear with at least a3.91SG, AND the overdrive with it's matching BH. Maybe you can even get the swapee to throw in something else.
So you might be out NO money. and Still have the valuable standard box left. and something else you could use, like an organic street disc.

IMO, this is not the best solution, but it should be affordable, and easy, and quick.
NOW:
I highly recommend that you fabricate an OD Lock-out, cuz you are used to blasting thru 4 gears, and if you forget to be nice to overdrive, that will be the end of it. and maybe the entire trans goes with it. I would be remiss if I didn't tell you that I broke three of those .lol. But back in the day, I was buying them as cheap as $50. cuz nobody wanted to drag them home after the Swapmeet.
Whatever,
Happy Hotrodding

Click to expand...

Thank you for the input and research , seriously thats awesome and means a lot to me but I occasionally drag race the car and want the 4 speed. The dana , you can call it "overkill" but after 2 grenaded 8 3/4 rears (one with strange axles/spool) I call it , peace of mind lol. Very aggressive clutch on top of launching at around 5k takes it's toll lol. Thank you again.

I would leave the 4.56s and go with an A833 OD transmission. BOLT IN swap. There will be those that will argue the ratios suck in the OD. They're the fools that have never run anything lower than a 3.55. For a 3.91 and numerically higher, ESPECIALLY with a 4.56, you won't have any trouble.

AJ/FormS said:

If 28s fit, that is an increase of 3.57%, which is a similar loss of cruise rpm.
My math says 50mph=2839rpm, with 4.56s and 27s.
thus 28s are 2737rpm.= 98rpm savings

Click to expand...

So 30s would save roughly 300 rpm, about the same as a swap from 4.57 to 4.11.

30s on a 67 dart on the street?
Are we building a Hot Wheels Gasser-replica?
Have you thought that through?
I get your math but;
Here's what I am thinking;
How's that gonna handle?
so now, do I gotta buy de-arched springs, and new rear shocks, reset my pinion angle. lengthen my driveshaft, maybe I got no caster left so I dick with the T-bars and get the front to match,, and now I gotta fix the bumpsteer, but-um hey, I got this half-azzed Gasser-look going on, great!
and finally,
What if I already have nearly new 27s.
What if I hate that gasser look.
What if the cops don't like the gasser look either, and they hassle me about my rear bumper height.
The last time I jacked my back end up, every corner was an adventure.

But I get it, everybody has an opinion, and I don't really like that A833od box either, but, for me it was a super cheap means to an end, and I managed to like it enough to run it for about three summers. What are they worth today?

AJ/FormS said:

But I get it, everybody has an opinion, and I don't really like that A833od box either, but, for me it was a super cheap means to an end, and I managed to like it enough to run it for about three summers. What are they worth today?

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if i'm buying? 10 bux and a burrito
if i'm selling $700

all kidding aside i sold a really nice one three weeks ago for $475 with the shifter box + rods.

33IMP said:

You could move the rearend back a bit (either spacers in front of the hangers, or redrilled super stock hangers. That should let you run a taller tire. Drag racers do it a lot. (Mine is an inch back in my 62, a 30" tire is no problem)

Click to expand...

Did you have to lengthen the driveshaft?

toolmanmike said:

Did you have to lengthen the driveshaft?

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I did not. It appears that my Plymouth has a Dodge driveshaft in it, probably installed at the same time as the 65-67 8 3/4.

AJ/FormS said:

30s on a 67 dart on the street?
Are we building a Hot Wheels Gasser-replica?
Have you thought that through?
I get your math but;
Here's what I am thinking;
How's that gonna handle?
so now, do I gotta buy de-arched springs, and new rear shocks, reset my pinion angle. lengthen my driveshaft, maybe I got no caster left so I dick with the T-bars and get the front to match,, and now I gotta fix the bumpsteer, but-um hey, I got this half-azzed Gasser-look going on, great!
and finally,
What if I already have nearly new 27s.
What if I hate that gasser look.
What if the cops don't like the gasser look either, and they hassle me about my rear bumper height.
The last time I jacked my back end up, every corner was an adventure.

But I get it, everybody has an opinion, and I don't really like that A833od box either, but, for me it was a super cheap means to an end, and I managed to like it enough to run it for about three summers. What are they worth today?

Click to expand...

So , do they handle the same abuse as the 4 speed? Same exact dimensions?

Yes and no;
As for handling abuse;
the first three gears are pretty much bullet-proof, at least as far as I have experienced with my modest 367 power(maybe 400hp). However, as mentioned in an earlier comment, that overdrive gear, I always say, is fragile, mainly cuz I regularly blew them up. However that is probably not fair, cuz when I blew the overdrive gears up, it was every time cuz I failed to back out of the throttle on the 3>4 shift, or was late to back off. Driven normally, they all did well for months to years, even with my heavy factory flywheel...
and
several other guys here on FABO are running them and not a one has mentioned the same failure.

As for dimensions;
the boxes themselves are a direct fit.
However, this box has a couple of quirks;
1) is that the front bearing retainer is 5.125 versus 4.35 on the standard. Thus something has to be modified or swapped, to facilitate this. Parts are available, and usually cheap enough.
2) another is that the box has been factory modified in the area of the front cluster pin, in an effort to reduce so called rattle. They say, and I have not experienced it with my modest 367, that this front hole can, over time, become oval. The prevention is to just bush it back to cast-iron dimension.
3) the box is available in several flavors, and one of them is the LD mainshaft, that fits the A904 yoke. I have no experience with that item, cuz my first box had the 727 sized shaft which I carried into subsequent gearsets. One of the problems with the LD shaft, is that the associated A904 yoke carries the smaller 7260 U-joint, whereas the A727 carries the larger 7290 Ujoint. and you can get a 1350 U-joint slip-yoke for the larger shaft, if you think you need it.
4) I found a long-tail big-shaft version at the scrapyard, which I bought for parts. In the end I installed it, and used the rear shifter mount to move my shifter back between the buckets, and closer to my hip/thigh, and high enough to install the Top mounting bolt from inside the cab. Then I installed a short-stick shifter, and fabricated new rods using pipe-steel. With the shifter now falling to hand, I haven't missed a shift since 2004.
5) the main box is available in both C.I. and aluminum; and some/perhaps most overdrive gear sets can be installed in either box, with minor grinding sometimes required. . and man, that C.I. case is a porker compared to the alloy. Tails are available in aluminum as well, as are the side-covers. As to retainers IDK, mine were all iron.
6) lessee what else? I think that's it!

So when your ripping through the gears it looks like this?
I get why you'd be reluctant to swap.......


I think the American way is to spend a bunch of time and money swapping them out only to go back to what you had