I am finding out here how deeply my wife feels about cars with stick shifts. They simply are not cars in her mind. If she cannot drive them they take on a lowered status. So I am finding out she is REALLY behind putting an auto back in. It is as if she is slightly envious of this secret relationship I have with the Dart. She wants in, and I am willing to let her in. It would be simple to just pull the T-5 and rebuild it, and I suppose the status quo would be maintained with that choice.

So I am not wavering TOO much on the decision to go auto here, but am on what type to install. I have as an option a recently rebuilt "lock up 904" out of an '87 truck. The seller does not know for sure if it is an a-500 when asked about that. He just knows he took it out from behind a slant when he put a v-8 in the truck.

Then there is the option of the 200-r4. This will be much more work than simply putting the Mopar trans back in. I am looking for strong arguments for doing this. I think this is essentially the trans that is behind the slant in my MBW 328, which is pretty nice. It shifts smoothly, and seems fairly efficient, and has all the modern features of overdrive and lock up TQ. But installing one would involve a bunch of engineering challenges. In my mind I have already worked out much of that, but then there is the task of getting things from the mind into the physical. BTW, Pat at Wilcap gave rave reviews to the 200-r4 available from Extreme Automatic as is being installed now by Andy.

The Wilcap adapter kits are only available in lots of 5 or more, and I would need to spear head another group-buy or find a current purchaser who wishes to sell theirs. I have talked to both Wilcap and Lou about that, and they are on board with me coordinating that effort.

So there are four questions.:

1. Why go to the effort of moving forward with the GM tranny? What makes it worthwhile?

2. Anybody wish to sell their Wilcap adapter kit?

3. How many folks wish to place on order for a Wilcap adapter? Is there enough interest here to get that going? Pat says he has been forwarding Lou's phone number to inquiries about this, but Lou says his land line is disconnected, and he is too far away right now to handle it. So it seems maybe those leads might have withered. I will call Pat again today about that, and get him my information. If there is enough interest out there, that solves one problem, and gives me a definite nudge in the direction of the 200-r4.

4. What are the drawbacks to the Mopar truck tranny? Is it really that bad? Is it a HP drain? Are there serious parasitic losses associated with it. I am not racing, but slants kind of need all the help we can give them. If the 200-r4 is more efficient that is one strike against the Mopar trans.

Sam

Thanks for your thoughts on this.

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Sam,

No A500s behind slants, ever. It's likely a lockup 904. To take advantage of the overdrive in the 200-4R you'll want at least 3.21/3.23 rear gears and probably 3.55. With a numerically low rear axle I'd just throw in a A904 with or without lockup and enjoy the ride.

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Joshua

I agree fully with what Josh said. Also, be aware that an 87 transmission MIGHT have a computer controlled lockup. I have seen repots that some 87 slant 904s had the lockup torque converter controlled by the lean burn computer. I am skeptical as to the truth of these reports, but they have come form a broad enough range of sources (different people on different boards posted at different times) to make it worthwhile to verify that the 87 transmission has no wires coming out of it except the neutral start switch.

I think the later lockup 904s really have an undeserved bad reputation. Sure the first couple years had lockup issues, but those were fixed fairly quickly. Yes the wide ratio gearset does have a larger RPM drop between gears, but if you are just using it as a daily driver you should be fine. I like the 80s era truck and van slant 904Ts. They will have the four planetary gear wide ratio gearset and the same (or more) clutches than the 70s era v8 904s. I think a warmed up slant with a 3.2 or even 3.5 rear axle ratio and a lockup wide ratio 904 would still get decent MPGs.

Be sure that whatever trans you choose has part throttle kickdown. It was supposed to be standard after the early 70s, but I have torn apart too many 70s and 80s era 904s that did not have the PTK assembly on the valve body to ever assume that a late 904 will automatically have the PTK.

Are you sure that the real reason for your wife's aversion to stick shifts isn't the fear of learning to drive one?

I bought a brand new 02 Camaro SS with a 6-speed manual and it was only in October that my wife finally learned to drive it. In September, we toured Route 66 and California and I did all of the driving (over 10,600 km!). I think she may have felt a bit guilty for not being able to help out with the driving. Once she got comfortable with it, she had no problems.

If your wife really "wants in" with your Dart, I think it would be better if she could enjoy the car as it is like you do.

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

Sam,
Monitarily this is a no brainer. The truck tranny will bolt in and it has lock up. So, with whatever gearing you would like on the highway you would be done. Of course you may need to put some money into the truck transmission too. But the overdrive conversion is big bucks anyway you look at it.
If you were concerned about acceleration and maybe racing with us, the overdrive would be nice. You could drop in a 3.73 or 3.91 rear gear and still cruise all day long. But I don't think you are interested in that.
Good luck!

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

After 47 years of marriage I can tell you, "That aint going to happen"! We have tried her and stick shifts several times in the early years. I confess, I am in the mood to stop shifting also. But, I have to respect her urges here, as it was she who talked me into keeping the car about 3 years ago when I was getting ready to sell it. We had a client all lined up, and she kind of talked me out of it.

I'm still looking for someone to make the big hard sell on the 200-4r. What are the compelling reasons to do this? I think the rear in my car is 2.71. But I cannot remember for sure. I'll go look to see if a tag is still on it.
Sam

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How do you even use OD now with that low of a rear?

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

With a 2.71 rear axle gear ratio I strongly recommend against an overdrive. Your final drive ratio in overdrive would render the car undriveable in all but perfectly flat conditions, with a tailwind. If you are going to keep the 2.71 rear gears then just go with the 87 904 transmission. You won't need an overdrive with a gear ratio that numerically low.

Car runs nicely at 65 on the highway @ 2200 rpm. Its sweet as can be. I just checked the rear and it is a 271 8 3/4".
Sam

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You know, even with the 904 you might actually pick up a few MPGs in town by switching to a 3.2 gear ratio.

There aren't any 2.71 gears for the 8 3/4. 0271 is probably a 10,000 day calendar date code. If you give me your tire size and 5th gear ratio I can work back from your cruise RPM to find the axle ratio.

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Joshua

While t wasn't on a Mopar, I have very recent experience with switching from a thre speed automatic to a four speed automatic in a vehcile. This might give you something to think about in your decision to install either a 904 or GM overdrive transmission.


My 89 Ford van has a 351. I have run a C6 (three speed) and an AOD (four speed overdrive) behind it. My rear axle gear ratio is 3.55. With those rear gears the C6 actually seems to have been a better choice. When the overdrive on the AOD engages on the highway, my engine RPMs drop insanely low- like 1700 RPM at 60 MPH. This might be fine if I lived someplace flat, but my engine's power band is in the 2300 RPM range. It feels like the motor lugs on even a slight hill if the overdrive is engaged. I also have noticed that with the overdrive my acceleration and top speed have decreased. With the C6 I could get up to over 80 fairly quickly and easily. With the AOD it takes MUCH longer.

A few weeks back I took a weekend road trip in my van. It was about 500 miles round trip. I started by driving with the overdrive engaged but by the end of the trip I was shifting into third as soon as there was any kind of incline. The overdrive was fine downhill or on the flats, but the motor lugged going uphill.

I am considering swapping the 3.55 gears out for a higher (numeric) ratio gearset. Which shouldn't be hard since I am running a Ford nine inch rear axle.

Again, this is in my big heavy (6000+ pound) Ford conversion van hauling four adults and luggage, but the same principles apply to your Dart. Too much gear can be a bad thing.

Sorry, It is 8 1/4". I'm sure that changes things. This car runs nicely in 5th grear at 65 and will pull easily up any hill on the interstate at that speed. In contrast, my brother's Mustang v-6 wants to be downshifted at the same speeds on the same hills.

Fifth gear on this t-5 .794. Tires are 205-60-15 and measure 24.5 across or 24 tall from ground to top of tire. I just went and test drove it. At 1600 rpm it is travelling at exactly 40 mph in 4th gear. This is an electronic speedometer which has been calibrated. According to my calculations a 2.71 rear would have the car going 45 at that rpm in 4th. I would actually like to make a few more test runs and get an average. I would also like to use the rpm readout on the laptop. Tell me what rear you calculate this to be. Please consider my earlier speed and rpm readings to be casual guesstimates. Probably not far off, but not scientific either. Thanks.

Sam

PS. Ater driving it I am feeling maybe a bit crazy to think about changing anything.

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8 1/4 did have some different ratios available.

http://www.corral.net/index.php/tech/ca ... calculator

I get 2.94 gears with your numbers and that is a valid 8 1/4 ratio.

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Joshua

The 904 lockup will be much easier and cheaper, and will get similar hwy mileage under part throttle cruise. You can use a somewhat higher stall converter than stock for better takeoff.

You definitely would want to put in a higher rear gear if you go to the 200-4R. 3.23 would be right, knowing you, Sam.

I like the OD auto for better accel and mileage around town as well as low hwy cruising RPM and higher hwy MPG. It will feel much snappier than a 3spd auto, esp if you use a stock stall converter on the 3spd.

Lou

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