1960 Valiant wagon
1963 Dart wagon

both have the p/b automatic, '60 has the smaller 904, I believe.

they really suck driving on the LA freeways in 75-80mph traffic, there's just no other way to put it. Especially when I'm going no faster than 60.

I so wish I had over-drive. that would make all the difference.

What have people come up with? I searched and found a bunch of discussions about rear-end gear ratios. Wondering how much of a difference that all makes.

There isn't a smaller 904. There are revisions to the 904, but none have a larger case.

Late A bodies had 2.76 gears standard with the automatic. It makes for more leisurely acceleration from a stop, but with the part-throttle kickdown (one of the revisions) they drive just fine. Going from 3.23 to 2.76 means the engine is spinning 85.4% as fast. If you're at 2600 RPM now you end up with 2222 RPM. If you have 2.93 gears it's 94.2% or 2600 to 2449.

If you want overdrive you can drop $3000+ on a Gear Vendors OD or cut up the floor and swap in an OD transmission. Lots of posts on this forum regarding both options.

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Joshua

If by "late A-bodies" you are referring to gear ratios that my 1974 Swinger had (225+904), that car was definitely better on the freeway than either the Dart or Valiant, but it still wasn't anything like a real 'cruiser'. Makes me fondly remember my '84 Buick Riviera coupe with OD. Now that thing cruised.

I'll search more on the forum and read in-depth discussions. I'm getting that there's not an inexpensive or uncomplicated way to make these vehicles more freeway-friendly. Really wonder why a 4th gear wasn't an option for these years. I know people drive much faster now, but it's not as if people then didn't make long hauls on the freeways or highways. I haven't calculated my RPMS at 60 mph since I don't have a tach, but they seem nice and high and make the whole experience sorta strained.

Explain your definition of "suck," how that definition applies to how your cars perform when going 60 MPH, tell us what your rear axle gear ratio is, and verify that you don't have any other problems with the engine (timing advance working, base timing set correctly, damper hasn't slipped thereby throwing off base timing, no vacuum leaks, etc…). Tell us why you think overdrive will help your situation.

What RPM is your engine turning when you are going 60?

Your 74 Swinger had the same gears in the 904 as your 60 and 63 cars. It might have had a different rear axle gear ratio though.

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Casually looking for a Clifford hyperpak intake for cheap.

"Suck on the Freeway"(vt). Origin: E.Atkinson

1. Something non-appropriate for the board
2. Driving a 60 Valiant or 63 Dart on the freeway with a 904 automatic transmission above 60mph where the experience feels strained and forced. When driving no longer feels like the engine can comfortably handle the speed at which you're requesting it spin.

I don't know what my rear axle gear ratio is on either car. As far as I know, it would be stock.

To my understanding, neither vehicle has problems with base timing or advance (yes, they're both working). 63 Dart has been advanced 3°, verified, no slip. Don't know on the Valiant.

Overdrive would help lower the RPM's leading to a smoother, quieter driving experience. I imagine by lowering the RPM's it would also mean better mileage (I don't stand by this: it's an assumption that may not be correct).

I stated before I don't know what my RPM's are at 60.

I was referring to my rear axle gear ratio re: my comment about the 74. Not the gearset in the trans.

Does it feel and sound like the engine is turning too many RPMs?

Can you crawl under the car and tell us the rear axle gear ratio? Hopefully the little metal tag with the ratio stamped in it will still be on one of the bolts on the rear axle cover.

My guess is that your engine is spinning a very high RPM and the motor exits its power band around 60 MPH. This suggests to me either the transmissions are't shifting into 3rd gear or you have a VERY low rear axle gear ratio, such as 3.9 or lower (numerically higher).

I haven't had a pushbutton shifted 904 or worked on one for about 20 years now, but I seem to recall that the shifter cable had to be adjusted properly or the transmission wouldn't shift right. Have you verified that your bands are adjusted properly and that you are shifting into 3rd?

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Casually looking for a Clifford hyperpak intake for cheap.

Nothing feels out of the ordinary about how it's running; everything sounds normal and everything shifts fine. It is shifting fine into 3rd gear. I have not checked the bands to be positive they are correctly adjusted, but you're right. The shift cable does have to be positioned just right, and so does the accelerator throttle linkage.

I'm saying though nothing is out of the ordinary and everything seems operationally fine, that doesn't mean the setup is good for freeway driving, especially at modern speeds. There may be nothing that can be really done about it. I recall when driving my 84 Riv that the car would be in 3rd gear, but dropping into overdrive at about 55mph created a large and noticeable drop in RPMs that made it seem like you could easily drive 80-100 with no problems. The Darts and Valiants act like mice on acid, in comparison. They're hyped up like crazy with RPM's somewhere in the 2,500 to 2,800 range at 60mph, I'll bet. It would be nicer at around 2,000.

I will look to see if I can find that metal tag you talk about. I have never noticed one.

What size are your tires? If you are still running 13's, going to a larger tire on a 14" rim will drop the ratio a bit as well... (the late cars also had those tall 195/75R14's...)

I have a nice set of 195/75/r14s on mopar rims with beauty rings just sitting here waiting for someone to use them! Hmmmmm.....

Running original 13's because I love the Dart stock full wheelcovers. I can't believe no one's found a good way to adapt these to 14" rims yet. Maybe other people don't like them as much. If I didn't care, they'd have been long gone in favor of 14's with disc brakes and the dog-dish centers.

Sounds like a great situation for someone who wants 14's. I wonder how much they help to reduce engine RPM's on the open fwy, compared to 13's.

If they are off your current car they are LBP or 5 on 4.5" bolt circle and will not bolt up to the A-body drum brake car (being they are SBP or 5 on 4' bolt circle...), if so he will have to update to the 1973-1976 A-body disc brake setup with rear axle to use them...


My current tranny calculator says that 185/75/13's are a 24" tire, and the 197/75/14 is a 25.5" tire...this change would lower your rpm to about 2500 at 60 mph in 3rd depending on tranny slippage and assuming you have a 2.94 rear, and is just a hair, but combined with a rear ratio change that could improve your situation a bit more (2356 rpm if they were 2.76's and 195/75/14)....

Going to OD would be either: manual transmission for a bolt in with min. mods, a gear vendors unit for a guy with deep pockets, an automatic OD for someone that has welding experience and is willing to cut the car up more than putting in the manual overdrive...

2 cents

I know of someone who took the J-type Laycock de Normanville from a Volvo and enabled it to be used on almost any rear drive vehicle - the same thing as the Gear Vendors ( which I think is the later P-type ). This solution did not use that type of adaptor, it was "divorced" - separated from the Volvo transmission. The Laycock o/d was mounted directly behind the regular driveshaft yoke and required a special cross member for the vehicle. The kit price including the overhauled Volvo O/D was less than half as much as the Gear Vendors, but was fundamentally the same thing. He was a machinist who fabricated the parts himself. I have some photos of this effort somewhere. Even as cheap as it was few, people ordered the o/d and he quit building the kit.

This vendor sells something similar for the J-type o/d, a special casting isn't needed, some appropriate sized pipe with end plates and bearing retainers. I think the shaft from the Volvo 240 transmission is used with a front yoke attached. I'm almost willing to try, I could use it for my '47 Dodge truck that is now geared for about 50 MPH.


http://www.maximum--overdrive.com/products.html

I think we get spoilt these days with modern cars and the very low NVH levels they have.... I love my 1970 Valiant but when I was using it for mainly highway duty to and from work it became very fatiguing and basically just plain took away the enjoyment of driving an older car. I had a 2.92 rear ratio and a 265 Hemi engine,just to keep up with the traffic at the speed limit of 110 KPH (66 mph) was a chore....driving at 70 to 80 Mph in a slant? That speed for any length of time would be pretty unpleasant in my book... I rebuilt the drivetrain in my Valiant using a smallblock and a 4 speed auto with a 3.23 rear....massive difference. 120 Kph now has the engine virtually idling at 2100 rpm,quieter and less fatiguing,it also has the legs to sit at much higher speeds for a long period of time without stressing the engine or deafening the driver...aerodynamics,or lack of, is the limiting factor !The problem with the push button autos is from what I have read there is no option to retrofit a 4 speed auto and retain the push button shifter. The gear vendor or the laycock overdrive would be the obvious options,but the gearvendors option would require a custom adapter because they do not make an adaptor for the early 904 trans with the rear pump..or possibly switch to a T5 if you want to go manual. There are some that use over drives behind slants with success,but make sure you are packing the torque in the lower rpm ranges to make it work,I realise the slant is known for its torque,but it is a relatively small engine and would need to be a good setup to make it work well with overdrive. As long as the vehicle isn't going to be a true restoration back to factory original, I would happily fit over drives into any street driven project. I am going to end up in the same situation as you eventually, I have a 1962 Wagon with a push button auto that I am going to rebuild/restore and want an overdrive so will be interested in any options that come up.

Thanks for the responses gentleman. If I get under my car shortly enough, I'll tell you what that metal tag says so we can ID what setup I have.

Nothing I've read so far indicates there is a good aftermarket solution to this concern, without making major mods to the floor of the vehicle, rendering the pushbuttons obsolute/useless, etc. Basically, it would be hard to keep a stock-looking/operating vehicle but with overdrive.

Oh well. I will keep looking but doesn't sound promising.