Technical Powerglide to 200-4R Swap

Hi all,
its been a couple of years since I've been on here or touched my project cars, but lately I've made some significant moves with my 1964 Impala sport sedan. It was originally a 283/PG car but spun a rod bearing about 2 years ago and I just pulled the drive train out recently. After doing research elsewhere, I've came to the conclusion that swapping the powerglide to a 200-4R, as well as changing out the 283 for either a 327 or 350 would solve a lot of the driveability issues of the car (lack luster acceleration/poor highway performance & high rpm) while also minimizing fabrication or custom work required. It's no secret, I'm not super adept at making custom brackets or bodging things together to make them work, but I like to think of myself as mechanically inclined. Anyway, I was hoping some of you could give me some insight on any issues I might run into with the swap. Already I'm wondering how the shift linkage will work and if the tiny drive shaft and rear will stand up to anything with mild power. If this sort of thing isn't allowed on here, more than welcome to delete. Thanks for looking an have a good one!

 

Someone else will have to chime in on the 200r4 trans fit; but we put a TH350 in a '62 with no hassle other than the driveshaft yoke and front shaft length. Used the stock shifter and "lost" the low position which was no big deal.
Car has no problem cruising on the freeway. On the other hand it is sometimes hard to go 70 in an 85 mph world.
The rear end is considered weak by modern standards; but long ago my friend had 300/327 with a 4spd that he banged on really really hard and had no trouble with the driveline; he later swapped in a 360/396 and that caused trouble with the hanger bearing; but never the rear axle.
Built more than a few hot rods with '55-'64 axles and would again if I had one at the time.

 

Thanks for the input. My reasoning to go 200-4R instead of the th350 is simply the overdrive. I'd love to be able to take long trip in it eventually and I think that would really help it work well in as you said, an 85mph world. Losing "low" seems like a bit of a bummer, for the occasional peel out haha. One last thing, have you ever heard of any issues with the two piece draft shaft? I've had my car for years but never really took it apart like this before and I've only been familiar with more common one piece styles. Thanks again

 

Oh, and you said you had an issue with the front shaft length. From what I've read the PG, Th350 and 200-4r are all the same overall length, no? what caused the issue in your case?

 

Here's a link to the swap in another GM car of similar vintage. If you have, or can find, the August 2000 Hot Rod magazine, it's a very informative article.
https://www.teambuick.com/reference/library/articles/over-under-hr.php

 

Maybe because the '62 was an iron glide while your '64 is aluminum; you may also have a fine spline yoke as compared to the coarse spline we had.

 

I did a engine trans swap in a 63 Chevy. Had no issues. Used V8 mounts.

 

The references you cite about the PG, TH350 & 2004R may or may not have given the whole story. Measuring your current Aluminum PG would be a good start in figuring out what you are going to be dealing with. Aluminum PG & TH350 both came in varying lengths of output shaft/tail housing. 6”, 9” & 12” as I recall. The 2004R is a one piece case and only came in one length.

There are diagrams that have been posted on the HAMB with trans shapes and dimensions and may be found with a search. I should have that in my photo files. If I can find it I will edit this and post it here.

As for your rear axle, no, not the strongest around but adequate for what you describe you want to do. That axle was used through ‘64, even with the 409…..though THAT was probably dicey.

Ray

EDIT:

 

Thanks for the article, I just read it and I'll keep it saved. Good reference!

 

Th2004R is the same bellhousing to tailshaft length as a TH350 short tailshaft(6").
Th2004R transmission mount is only ~1/8" different from a Th400 mount.
Your 'biggest' physical problem with a Th2004R install is the pan. It runs the length of the transmission. On an X frame car I don't know if there will be interference issues.
NOTE:
There are a few popular charts out there with erroneous information on Th2004R length and dimensions. Most transmissions are dual bolt pattern BOP and C, I've read of single BP Th2004Rs, but ht only ones I've ever seen had ears hacked off.

GM transmissions tend to always start off in 1st, even when selecting 2nd. Even with 2nd( 1.74) gear it's about the same as 1st(1.76) in a PG.
Yoke is 26 spline, same as a Th350.
Those rearends although considered 'weak' lived behind 409 4speed cars. Probably pushing the limits but they worked. A mild 350/Th2004R should not kill it.

If this is a mild streetable/driveable/highway cruiser, I would opt for a Q-Jet and the factory GM Th2004R TV cable bracket that bolts on top of the two rear bolt ears of a Q-Jet.
This T.V. bracket can be found on most GM B/D/G body vehicles of the 81-90 era. Pretty sure it is the same as the TH200 TV cable bracket which would be found in V6/V8 models as well. Aftermarket wants ~$40, can be found in most yardes for $5 and is not flimsy. Maintains the factory geometry and TV cable.

 

1964 Chevrolets came with a 425 horsepower 409 cubic inch motor and a two piece driveshaft.

 

hi, I will try to explain. first you need a FOUR speed front driveshaft or shorten yours. you have a 62-64 alum glide with a short tail. a 3 speed std. is the same. your PG is coarse spline, so you need a newer yoke. you will have to cut out the existing crossmember brackets and make a new one. we used 1/4 " plate bolted to the bottom of the frame .for the t-400 we did. also need to play with E/B linkage. watch the t/v cable close to the floor. good luck,Pete.

 

200r4 is a natural swap for a th 350 if you have a tall rear gear. 327 or 350 engine is perfect for the motor IMO. Unless you can get your hands on a 409

 

Ah, so there is going to be an issue with the front drive shaft as it sits. The ones that are the correct length for this swap are from 4 speed cars?

 

That’s a great idea, I’m just not a fan of any vacuum secondaries. There’s just so much fun feeling the switch between the primaries and secondaries with the pedal!

 

I did a 2004R swap with a power glide in a different car, so I don’t know your particulars. But it’s a great swap. The gear ratios are good, the rear ratio will probably be ok as is, and the “seat of the pants” feels like another 100 hp. Dropping one in behind a 350 will probably make you think you’ve got a 409, unless you’ve driven a real one.

Choice of carbs is up to you, but Mike’s comments about the factory cable set up are correct. I’ve done it both ways, and setting up a Lokar or other cable takes some time, and you need to follow the instructions, period. You’ll also want a transmission with the right parts, etc. Like many others, just because they look the same on the outside doesn’t mean they’re the same inside.

 

As alluded to, check your rear end ratio and tyre height. Last thing you want is an OD with mismatched rear axle gears. My rule of thumb with an OD, engine RPM is between 1,800 & 2,100. A 700R OD is .7 whilst a 200R OD is 0.67.
RPM in my 35 Chevy with 3.54:1 & 235:75:15 tyres is approximately 2K rpm. Also make sure that TV cable is adjusted correctly @ WOT, correct bracket geometry is essential.

 

When shopping for a 200-4R, are there any particulars to look out for? Are some better than others?

 

Just want to post this here as a big thank you to everyone that's commented so far. I know I haven't responded to everyone but I really appreciate the feedback and support. It goes a long way! Like I said I haven't really used the HAMB in a while but I might just have to do some more posts on here as I progress with my project Impala

 

Well, there are some that are BOP pattern (Buick-Olds-Pontiac, '64 up Cadillac) bellhousing pattern, only. You for sure don't want one, unless you also want to buy and adapter.

The other cases are one-case-fits-all, and have both BOP and Chevy patterns on them.

Chevy left, BOP right:


One case-fits-all:


If you cannot find the last one, there is an adapter. Despite the patterns looking different, Chevy and BOP patterns have the lower pair of bolts, and the locating dowels in the same place.

Adapter designs vary, but they are cheap: https://www.speedwaymotors.com/Spee...dramatic-Transmission-Adapter-Plate,3281.html

This one is a whopping $40.99!

 

The dee-lux version is $78.95. https://www.speedwaymotors.com/TCI-230000-Chevy-Engine-BOP-Trans-Adapter,333969.html

 

200R(L), 700R (R)

 

The illustration with color coded bolt holes is incorrect! On the vertical ‘stack’ of bolts, the top bolt, immediately above the dowel hole is Chevy only. The next bolt, angled inboard, is BOPC only. The color codes shown are incorrect (reversed) on those two positions.

Ray

 

swapped one into rod years ago...great swap ..really enjoyed that shift into overdrive hearing the rpms drop...

 

If the transmission is still factory stock or rebuilt factory there are differences in shifting feel and components.
Look at the tag on the side of the tail, it will have 'Hydramatic' on it as well as a two or three letter code. Early Caddy 'A' models shift soft/buttery, later performance 'Z' models will shift harder.
https://web.archive.org/web/20050204104518/http://members.aol.com/powerrslid/thm2004r.html

This will give you an idea of where the transmission originated. If the trans has been rebuilt or upgraded then the information may not be totally applicable.
Ideally you would start with a a later model V8 core.
Avoid the 'A'(caddy) models as they shift like mush, a 'Z' code would be ideal but don't expect to find one for cheap. I would easily find a CR/CR-F or K*-F code models, these made good cores for stock or mild builds. Later models added the 'F' denotes the later 86-90 models.

Some running changes from over the years.
https://web.archive.org/web/20050529085225/https://www.drwtransmission.com/thm_200-4r.htm

 

Love the 200R4. I put one behind a 235 straight 6 and one behind a 305 Chevy V8 in a '59 El Camino. Both fit great.

Two pieces of advice;
1) get a BowTie OD tranny throttle cable lever adaptor. That problem solved.

2) get one or two governors to play with shift points. The only proper way to raise shift points on these trannys is modify centrifugal weights and spring load on the governor. shop around the internet and you will find governors are really inexpensive. I got some for about $12 each.

I cut off weight and removed a spring as shown below. Got our Elky shifting just right. All the mods raise the shift points which is desirable on performance oriented cars.
Braze in a nail stub to corral the spring that is left in. Reports ofit jumping out.


Weight trimmed on left one, trim locations marked on stock weight on right one.


Another view of trimming


Remove this one spring for higher shift points.

 

Try to find a 2004R that came out of a Monte Carlo SS.

 

A "dumb" question....
is a 4L-60 (91 S-10.... 4.3engine) the same as a 200R4 ?!
Thx
6sally6

 

No. the 4L60 is the "new" name for the 700R4, but it's not the same as the 200-4R.