Overdrive transmission swap questions....need some input
- Thread starter greasemonkeyman
- Start date
commando1
Old Man with a Hat
greasemonkeyman
Well-Known Member
Finding an engine/trans adaptor is probably going to be the biggest cost.Chances are I can get a tranny for less than $200,PATC solenoid/vacuum kits for $85,shortened driveshaft $100,and fabricated trans mount $100-150, labor done by myself(except for welding and driveshaft).What some people are not calculating is that the cost of gas also keeps increasing as time goes on,so they're only looking at current gas prices(when has gas ever decreased more than a few months?) and the fact that engine longevity will be longer due to lower rpm during highway usage.Where I live,I spend lots of time on the highway driving from show to show (150-200 miles each way) and would like to do a few cross country trips once in a while.
greasemonkeyman
Well-Known Member
Figuring an approximate value of what it will cost me,I'd say somewhere around $550-$600 plus the cost of the transmission adaptor.I'm not counting anything for my own labor because I'm doing it for myself.So if the maximum outlay is around $1000-1200 that isn't too bad for adding an overdrive transmission? The estimates about how much fuel used vs. the cost of the swap is calculated getting optimum mileage conditions during everyday use.When was the last time anyone ever got optimum gas mileage,every day for ten years of driving?
This link while for a 70 GTX should answer most of you questions. http://www.hotrod.com/howto/43323_mopar_overdrive_transmission_swap/
You should look to change the rear-end gear ratio.To make it worth while and not have the car falling on it's face on the highway. You good get just the same effect by swapping to some highway gears. My 66 Charger turns about 2500 RPM around 65 mph. Which i have figured out is probably a 2.94 (based on http://www.coastdriveline.com/htmlfolder/calculator2.html). Much easier and probably cheaper.
You should look to change the rear-end gear ratio.To make it worth while and not have the car falling on it's face on the highway. You good get just the same effect by swapping to some highway gears. My 66 Charger turns about 2500 RPM around 65 mph. Which i have figured out is probably a 2.94 (based on http://www.coastdriveline.com/htmlfolder/calculator2.html). Much easier and probably cheaper.
70bigblockdodge
Old Man with a Hat
I say do it document it for the rest of us thanks in advance. Adaptor kit is marginal at best and will cost 450, jw ultrabell is in the 300 range route I would go. You have to do the math on the highway rpm has to be above 2000 at the speed you would like to cruise at.
bajajoaquin
Senior Member
bajajoaquin
Senior Member
I built a spreadsheet to do this and tried to attach it, but we can't attach Excel files. But here's a chart from those calculations:
| mph | final drive ratio | Top Trans gear ratio | Revolutions per minute |
| 75 | 3.55 | 1 | 3626 |
| 75 | 3.23 | 1 | 3299 |
| 75 | 2.94 | 1 | 3003 |
| 75 | 3.55 | .69+lockup | 2252 |
| 75 | 3.23 | .69+lockup | 2049 |
| 75 | 2.94 | .69+lockup | 1865 |
| 65 | 3.55 | 1 | 3142 |
| 65 | 3.23 | 1 | 2859 |
| 65 | 2.94 | 1 | 2602 |
| 65 | 3.55 | .69+lockup | 1951 |
| 65 | 3.23 | .69+lockup | 1775 |
| 65 | 2.94 | .69+lockup | 1616 |
To calculate it, I figured that tires would squish by 5% from their unloaded height, and that a torque converter slipped 10%. If those aren't true, my numbers will be off.
If you want the spreadsheet, PM me your email address, and I'll send it to you.
greasemonkeyman
Well-Known Member
Does anyone know of any companies producing an engine to transmission adaptor plate to link the 440 RB to an LA small block pattern of the A-518 transmission? I've considered the JW Ultrabell,but am not sure about cutting off the bellhousing off a 518.just afraid that it will weaken the overall structure of the transmission casing and be prone to cracking under the stress/torque of the 440 engine.To me,an adaptor plate would be a better setup without having to modify anything on the transmission itself.I'm not afraid to cut off/grind a bellhousing,just wondering about the integrity of the transmission casing.
commando1
Old Man with a Hat
Give this guy an offline PM:
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=8013560&an=0&page=0#Post8013560
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=8013560&an=0&page=0#Post8013560
70bigblockdodge
Old Man with a Hat
The jw ultra bell is accepted sfi piece for racing so you don't need a shield around the bell housing so I don't think there is a issue SMR transmissions in Canada had adapters, the problem with adaptors is converter mounting and registering.
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bajajoaquin
Senior Member
I was thinking about this on my way to work this morning. You're totally right. The geography and traffic in your area makes this a crazy idea. Here in Southern California, however, I'm either around town or on a freeway. In morning traffic, low gears might actually be nice. For the rest of the freeway time, 75 mph is the normal, middle-of-the-road speed. 80 is not really speeding.
Modern cars routinely pull really tall gears. I know our cars don't have the same flexibility as a modern computer-controlled unit, but a 2012 Camaro I drove turned under 2000 RPM on the freeway (my calculator says 1885 at 75 mph). Sure, you needed to downshift to do much, but not a big deal.
My understanding is that the way the trans swap works is that it goes into lock-up at a given speed, and OD at a different speed. When vacuum drops to a certain point, it will downshift out of OD to 3rd. You can also wire in a switch to manually override OD if you have reason to want to keep revs up (towing, hills, traffic, whatever).
I think these cars would just plain ol' drive better with a four speed transmission. Since we have accepted the change to radials (even if some of us don't use them), dual exhaust, new carbs, or performance mods in order to make the cars drive better, I don't understand why there is so much angst over the idea of adding an extra gear.
70bigblockdodge
Old Man with a Hat
I didn't say don't do it just anything taller than 3.55 it just won't pull with a .69 od. I put a 440 in a 69 barracuda it had a perfectly good /6 did it because I wanted to go faster not cause it made sense or cents.
bajajoaquin
Senior Member
I totally agree: you never said don't do it. Sorry if I implied otherwise. I was just thinking about the geography of Western PA (where I last drove in about 2001), and your comment about how some combinations just wouldn't work. And looking at my freeways, which are totally different, I totally got your point.
I then changed direction in my post, and it may have seemed I was singling out your comments. I wasn't.
greasemonkeyman
Well-Known Member
Been doing a little research about doing the swap.Talked to the guys over at JVX Inc.(Memphis,Tenn),the guys who made the engine to transmission adaptor plate for the car in the old Hot Rod article years ago.They sell everything to bolt the engine/trans together(440 to A-518,price of kit is $675).There is some minor modification needed for starter clearance to get them to work together.As far as what I have come across in regards to the crossmember/mount,it seems the transmission mount for the A-518 sits 1-3/4" further rearward of the 727 mounting location and approximately an inch lower(this may vary according to how much room there is in the tunnel of the C-Body and if it can be massaged to fit better).The driveshaft needs to be shortened 3-1/2" and uses the same yoke that is already on the car now,this is due to the added length of the transmission and 1/2" thickness for the adaptor plate.If you have a column shift car,the shift linkage will work fine.Not sure yet about the downshift setup(whether you can still use the rod setup or may have to go to cable setup?).To get it to shift correctly PATC sells a vacuum controlled kit that contains two pressure switches,a vacuum switch and instructions to wire it all together(a pretty simple setup for only $85) and you can add a simple toggle switch if you don't want it to shift into overdrive(Example:towing).I'll have to see what is involved in modifying the existing crossmember once the transmission is in place.If I decide to go this route,I'll be sure to document everything with photos of the swap and what parts,suppliers and modifications need to be done to turn our C-Bodies into overdrive cruisers.
greasemonkeyman
Well-Known Member
I know alot of people here suggested using the JW Ultrabell and have talked to a few transmission guys about it.They weren't too keen with cutting/grinding off the stock bellhousing/casing off the A-518 and bolting the Ultrabell in it's place.This was a couple of the responses I got....1) cutting the case weakens the overall integrity of the unit and makes it prone to cracking. 2) The Ultrabell is bolted to the front pump cover and all the bolts from the front pump must take up all the torque and forces that keep the engine bolted to the trans. 3) It cannot be clocked correctly by being bolted to an engine this way. These are just statements that I'm passing on from experienced transmission guys that have been doing this for years.I'm sure everyone's got their own methods for what will work,I'm just trying to figure out which method will be the most cost effective,be reliable,look clean(as if it was factory installed),and could possibly be reversed if you'd like to go back to the old 727 in the future.
carsucharda
New Member
Just my .02 here but in theory couldnt you buy a modern 5.9L pickup or van (donor engine, trans, wiring) with an electronically controled trans & EFI, mod it to outperform the 440 and still get reasonable mileage in your price range and have the everyday driveablility so you would actually have the capacity to see some diminishing return? The GM guys do modern swaps all the time. In fact my neighbor has a 48 ford with an LTI and a 700R4 in it he drives to shows across the country. If nothing else i would like to see someone here do that to a C body.
carsucharda
New Member
True enough. It would still be cool though. Also not having a GM car means that people come up to you and go "cool car... what is it?" That is almost worth the lack of parts support... almost... well maybe not.
bajajoaquin
Senior Member
Yep. Totally true. That's one of the reasons I'm bullish on the 518 swap. It seems like several people have figured out the big issues. If you want to swap it into a truck or a B-Body, there are several people with direct experience. C-Bodies have been done, but not much documentation.
It's kind of about standardization: If a number of people settle on one solution, there is a buildup in the body of knowledge. It uses Mopar parts, a few custom/modded pieces make it work similarly to factory, and major components are available in junk yards. It's not perfect by any stretch, but it seems like the best option if you think 4 gears are a worthy upgrade.
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