stepdown tranny conversion FEASIBILITY, GN 200-4R

Unknown

On my last trip, less that 10 mpg; know the engine needs a rebuild
and that will help!! The Borg Warner, DG200 (2-spd) causes the
engine to run too fast on the highway? A GM, Buick Grand National
200-4R OD tranny (stock) will hold 330 ft-#s for torque, so I know it's
plenty strong enough; it will have it beffed and rebuilt before
installation as a precautionary move. With no rear support for the
tranny, it seems that the tranny must be fully supported between the
back of the engine and the front of the tranny (6 bolts) by a plate
designed to connect to the eng; simplifying, then the prepped flywheel goes on,
then the tranny w/TC is bolted to the assembly and the adaptor plate is
connected to the rear engine supports (motor/tranny rubber MOUNTS).
Next, the driveshaft must be altered & bal.; linkage etc.

Anyone know who has done this SUCCESSFULLY on a stepdown?

If so what are the major problems and/or suggestions associated
with this change?

Unknown

Just a thought, before you go to all the trouble of changing transmissions. Are you sure that the rearend has the correct gearing for your car? And that somewhere along the line, someone hasn't transplanted a differential with the wrong gearing? I was given to understand that the automatic-transmission-equipped Hudsons had rearends with a very good ratio for highway driving. I had never before heard anyone say the engine ran too fast at highway speeds (unless you're crusing at 90!). In fact some people salvage those for use on earlier Hudsons, so that they do can cruise at highway speeds. I'm not a StepDown era specialist, however, so could be wrong.

Unknown

Why not go find a dual range hydramatic. Hudson used this one in 52 and 53. It's a good 4 speed automatic.
As the man says, check out your rear end ratio.

Unknown

Some '54s had the Dual Range HydraMatic which was a much stronger box than the Borg Warner. My '54 has HydraMatic and I think it's a wonderful transmission. They came with a standard 3:07 rear axle. Before you make any changes in your car, first check the axle ratio. Connecting a late model transmission to the original Hudson engine would seem to be more work than it is worth.

Unknown

That will be our next move to determine the ratio of the differential.

Does anyone know the output ratio for 4th gear of a hydra-matic, dual range 4-spd tranny?

Park_W

The fifties vintage Hydramatics are direct drive in 4th gear. Thus the use of a nice (numerically) low rear end ratio such as the 3.07.

Unknown

OK, Park, and what about the Borg Warner 3-band DG-200 w/lockup convertor?
I wonder what ratio it is?

EssexAdv

Well, if the lock up converter is working on the BW the final drive is 1-1. Actually a BW transmission equipped car, if working properly, will get better fuel mileage than a Hydro equipped on due to the lock up converter. The torque converter in a Hudro has some slip even when it is fully "engaged". The BW does not. You called you trans a 2 speed, does the lock-up actuate? A good 308 motor with the BW gets about 16 - 18 mpg in a Hornet body. I, unlike a lot of other Hudson guys prefer the BW trans. It is a more modern type trans. The shift pattern, at reasonable acceleration, is more suitable for the Hudson motor and is quieter, due to lower motor rpm, at highway speeds.

It has developed a bad reputation for 2 reasons.
1, as they aged, they tended to leak. The pumps and governor are out side the case. When they leak pressure drops and the bands do not fully function causing slippage. This does not happen in a hydro.

2, when Hudson first put them in the car they were recalled due to premature wear. As it turns out there was not enough fluid in the pan based on the original Hudson dip stick. Hudson replaced the dip stick as part of the recall and the problems related to overheating the trans fluid. If you don’t have the later dipstick, all you have to do is run it ¼ past the full mark. I have an original recall dipstick and paperwork should anyone be interested in more information
(not for sale)

Unknown

Well, the 3-band I have does apparently lock up; it also has the leaks
which I hate and don't want to invest any more money into it. It also
has a klunk when it locks up, sometimes! I bought a new seal for the
rear. I will put it up for sale soon, I feel safe to say, as the conversion
seems the most reliable and practical alternative at this point. The car
is being torn apart for paint and upholstery and the engine will be rebuilt.
That's the time to make the upgrade. In case you know of someone
who needs one, please email (jgw2@bellsouth.net) me. THANKS

[Deleted User]

Why not check with Randy Maas. He already makes adapters for the turbo 350/400 series as well as the 700r4?
Just a thought. He is in the roster

Unknown

My '48 had a 4.11 (or something close), and on the highway, 65 was making the motor scream! If you're wanting to keep things simple, I'd take the advice from the people that said check, and possibly change the rear gears. If you want to change to a 700R-4, e-mail me at wkitchen@midsouth.rr.com and I'll send you pictures of what I did. Had to drop the crossmember 2and 1/2 in to get clearance for the pan, made a tranny support for the tail for the transmission, and still looking for someone that can take the original speedometer and convert it over so it will work with the 700R-4.(if that is even possible). It sometimes has a "domino" effect. Changing one thing, makes you have to change another thing, which makes you have to change something else. If you're the type that gets frustrated with these types of problems, I'd keep it simple!

Unknown

We are checking w/Randy; anyone know the number of revolutions the 54 Hudson speedometer
head turns per mile??????

Here are some sites that will help you to calibrate your
speedometer when you convert to a TH700-R4 or TH200-4R.

http://www.transmissioncenter.net/200-4r.htm

http://www.bgsoflex.com/speedo1.html

Unknown

I decided to rebuild the "3 band" tranny and keep her original; perhaps change to more economical
differential gears later on if the mileage doesn't get above 20 after break-in.

Unknown

I have converted my car to a 1956 DeSoto Hemi with a 700r4. the driveshaft was the correct length, just needed a different yoke on it. I am running 2125/75-15 tires on my hudson with the 3.07 dana 44 style rearend. I get 20mpg cruising at 75mph on the freeway, and I bet your hudson if swapped to a 700r4 could do even better. The low first gear in the 700 makes for good pick up away from a stoplight or stopsign. Good luck with your swap.

Unknown

The output ratio on the GM TH700-R4 is 0.70; on the TH200-4R the ratio is 0.67, providing even
better gas mileage, plus the gearing ratios are more evenly spaced in gears 1-4. Maybe I'll do it yet, later on

Unknown

hello all, I just registered and am the above anonymous poster 2 posts up. You are correct that the 700 has the largest ratio spread of modern day 4 speed autos. I would try and contact Randy Mass and see if his adapter would work for the 200. That lower overdrive would be beneficial to your mpg.