[AZ64GP]

Hello,

I want to apologize in advance, as this is a repost of a previous thread I started by me in the "Pontiac - Street" section. I only received two replies and both were from the same member, so I wanted to see if my question could attract any other members with more information, as my questions were not answered.

I am still about 6 months away from doing the automatic transmission swap with my '64 Grand Prix (good ol' Slim Jim has to go), but questions have been swirling in my head for a while now and I wanted to reach out for some answers. I'm trying to decide whether to pursue a swap with a TH400 or go with the 700R4 in my '64 Grand Prix. They both have advantages and disadvantages, but I'm leaning toward using the 700R4 if I can. I know the 700R4 is going to take more to beef up to handle the 389 V8 in my '64 GP and possibly need a swap for the rear end gear (I believe I have a 3.08 final driver ratio in my 9.3 rear end), but I like the lower first gear, having overdrive to keep the revs down on the freeway, and the smaller dimensions of the 700R4 so it should fit in the small-ish transmission tunnel. I don't plan on racing the GP, but I want a transmission that will handle the HP and torque of the 389 and be reliable. The difficulty and cost of the 700R4 vs. the TH400 for my '64 GP will likely dictate which transmission ends up in my car though. Fortunately my '64 389 was predrilled for a block-mounted starter, so I should be good there and can use a '65 and later starter.

I have been fortunate enough to receive some tips on how to install the TH400 in my car (I have read many of the previous posts in this forum on the TH400 conversion subject), but has anyone on this forum installed a 700R4 to a 389? If you have experience installing a 700R4 in a '63 to '64 darksider car, that would be even better. I know that the 700R4 was only made to attach to a Chevrolet engine, but there are brackets that can adapt that trans to BOP applications. Does the adapter bracket cause any problems with aligning the transmission and the engine, or in the fitting of the transmission and engine in the car? Is there a spacer commercially available so the difference between the adapter bracket can be made up at the flywheel of the engine?

Besides the 700R4 transmission, the adapter bracket, and the kickdown cable bracket at the carb, is there anything else that I will need to adapt a 700R4 to my 389? For example, I assume I would still need a Pontiac flexplate since the 700R4 (though a Chevrolet transmission) is still bolting to a Pontiac engine? What about any shifter linkage modifications (my '64 GP has a floor-mounted shifter) so my original shifter can work with the 700R4? If it won't, what are my options for using a replacement shifter and/or aftermarket linkage? As more a general 700R4 question, would the kickdown cable for the 700R4 and the carb bracket (available from B&M ,etc.) shift the 700R4 correctly or would I need to mess with any other kickdown switches or linkages?

Lastly, if anyone has installed a 700R4 in a fullsize '63 or '64 Pontiac, what did you have to do to get it to fit. I know for the TH400 there is some hammering to do on the transmission tunnel since the tailshaft bolts are in the way and the '63-'64 Catalina/GP bodies have smaller transmission tunnels, but is there much trans tunnel work needed to fit the 700R4? How difficult was it to match the 700R4 with the existing crossmember and transmission mount? If the existing crossmember won't work, what is another crossmember that is available which would work?

Sorry for all the questions, but thank you in advance to all of you for your help.

[61 389-348]

Originally Posted by AZ64GP

Hello,

I want to apologize in advance, as this is a repost of a previous thread I started by me in the "Pontiac - Street" section. I only received two replies and both were from the same member, so I wanted to see if my question could attract any other members with more information, as my questions were not answered.

I am still about 6 months away from doing the automatic transmission swap with my '64 Grand Prix (good ol' Slim Jim has to go), but questions have been swirling in my head for a while now and I wanted to reach out for some answers. I'm trying to decide whether to pursue a swap with a TH400 or go with the 700R4 in my '64 Grand Prix. They both have advantages and disadvantages, but I'm leaning toward using the 700R4 if I can. I know the 700R4 is going to take more to beef up to handle the 389 V8 in my '64 GP and possibly need a swap for the rear end gear (I believe I have a 3.08 final driver ratio in my 9.3 rear end), but I like the lower first gear, having overdrive to keep the revs down on the freeway, and the smaller dimensions of the 700R4 so it should fit in the small-ish transmission tunnel. I don't plan on racing the GP, but I want a transmission that will handle the HP and torque of the 389 and be reliable. The difficulty and cost of the 700R4 vs. the TH400 for my '64 GP will likely dictate which transmission ends up in my car though. Fortunately my '64 389 was predrilled for a block-mounted starter, so I should be good there and can use a '65 and later starter.

I have been fortunate enough to receive some tips on how to install the TH400 in my car (I have read many of the previous posts in this forum on the TH400 conversion subject), but has anyone on this forum installed a 700R4 to a 389? If you have experience installing a 700R4 in a '63 to '64 darksider car, that would be even better. I know that the 700R4 was only made to attach to a Chevrolet engine, but there are brackets that can adapt that trans to BOP applications. Does the adapter bracket cause any problems with aligning the transmission and the engine, or in the fitting of the transmission and engine in the car? Is there a spacer commercially available so the difference between the adapter bracket can be made up at the flywheel of the engine?

Besides the 700R4 transmission, the adapter bracket, and the kickdown cable bracket at the carb, is there anything else that I will need to adapt a 700R4 to my 389? For example, I assume I would still need a Pontiac flexplate since the 700R4 (though a Chevrolet transmission) is still bolting to a Pontiac engine? What about any shifter linkage modifications (my '64 GP has a floor-mounted shifter) so my original shifter can work with the 700R4? If it won't, what are my options for using a replacement shifter and/or aftermarket linkage? As more a general 700R4 question, would the kickdown cable for the 700R4 and the carb bracket (available from B&M ,etc.) shift the 700R4 correctly or would I need to mess with any other kickdown switches or linkages?

Lastly, if anyone has installed a 700R4 in a fullsize '63 or '64 Pontiac, what did you have to do to get it to fit. I know for the TH400 there is some hammering to do on the transmission tunnel since the tailshaft bolts are in the way and the '63-'64 Catalina/GP bodies have smaller transmission tunnels, but is there much trans tunnel work needed to fit the 700R4? How difficult was it to match the 700R4 with the existing crossmember and transmission mount? If the existing crossmember won't work, what is another crossmember that is available which would work?

Sorry for all the questions, but thank you in advance to all of you for your help.

I did this in my 63 Grand Prix. The former owner made the conversion to the TH400 and then I took it on to a Bowtie Overdrives 700R 13 years ago. We did have to fabricate a new cross member and driveshaft. Tunnel modifications were very minor, but different from what was required for the TH400. Nothing shows in the interior though. I used a B&M Quicksilver shifter. As suspected with a 700R, I snapped in input shaft within a few months on a WOT 3-1 downshift. The second tranny was a bit more modified and is still in the car 12 years later.

I do drag race on occasion and get on it on the street more than I should admit. I have a manually switched lockup torque converter. I got a huge gain in steady state highway cruise MPG due to the .70 to 1 fourth gear, which I waste by driving about 20 mph faster. Still though, I get 18-19 mpg going from Columbus to Detroit for Dream Cruise, and I'm cruising at a damn good rate of speed going up there. Very few folks pass me .... even on I-75 in Michigan.

I have a 3.23 rear so in lockup 4th it's a 2.26, but the stock 389 has enough torque that it's fine with it. At WOT on top end it won't shift into 4th until you let up on the throttle as you can see below so that might limit top end a little. I've wound it as tight as 5,700 and still no upshift.

http://youtu.be/8wH7F0oCAes

This is an old video of me out for a drive in around my area in West LA and SOviet Monica. I'm pretty aggressive with it, and although the shift quality might not be quite what the TH400 was, this isn't bad. The belt squeal is now fixed.

And another time when I did get it out on the freeway a bit

http://youtu.be/Xg8nMFz99d0

So overall, I think I'd do it again over the TH400

http://youtu.be/mXNB42BsdUA

[61 389-348]

When the time comes, I can put you in touch with the shop that did mine. It's been a long time ago for him, but I think he's done a few since, but all GTOs as best I recall.

[AZ64GP]

Thank you for the info, 61 389-348! Those are some awesome videos by the way. My '64 is a long way from being able to be driven, but those videos motivate me! I have a couple questions for you. When you swapped the stock shifter for the B&M, did you have to make any changes to the transmission tunnel or the console to get the shifter to fit? Did you have any problems getting the B&M shifter to work with the 700R4 in the car or was it pretty straight forward with getting the linkages (?) hooked up between the transmission and shifter? I'm all the way out in AZ, but if your mechanic wouldn't mind, I'd like to contact him in the future and pick his brain on how he did the swap. Thanks again!

[61 389-348]

Originally Posted by AZ64GP

Thank you for the info, 61 389-348! Those are some awesome videos by the way. My '64 is a long way from being able to be driven, but those videos motivate me! I have a couple questions for you. When you swapped the stock shifter for the B&M, did you have to make any changes to the transmission tunnel or the console to get the shifter to fit? Did you have any problems getting the B&M shifter to work with the 700R4 in the car or was it pretty straight forward with getting the linkages (?) hooked up between the transmission and shifter? I'm all the way out in AZ, but if your mechanic wouldn't mind, I'd like to contact him in the future and pick his brain on how he did the swap. Thanks again!

Thanks!

There are so few full sized Pontiacs in SoCal that he probably doesn't remember. I'm sure he's done several GTOs since my GP, but that doesn't help much.

Memory for pain is pretty short term so I don't recall it being a huge headache, but it was probably worse than I remember. The B&M shifter wasn't bad and I don't think we had to do anything to the tunnel to get it in, but had to do some mods to the console. The only undercarriage 'dent' we made was to clear the modulator.

When you get closer it might be worth you driving to West LA to have Ronnie do yours. I know he had some of out of towners come in from time to time.

[61 389-348]

Since these cars aren't worth all that much I took the liberty of doing some other little mods to make it look like I would have wanted when the car was new. These pics were shot over a period of several years, but doesn't include any since I've been back here in Ohio.

http://youtu.be/xm28FU7Fnzs

It was a bunch of effort and a lot of time and money, but I ended up with a very roadable, almost tossable, fun to drive car, and as you can see in the vids, I don't hesitate to make it scoot along from time to time.

[AZ64GP]

This is slightly off topic, 61 389-348, but what did you do to make your 389 run on today's gas? Did you rebuild the engine? I'll probably be doing the engine rebuild when I work on the trans later this year, and I'm thinking I'm going to have to do some head/piston work to lower the compression and harden the valve seats so the 389 4 bbl can run on today's unleaded, lower octane gas. The engine runs great (to my knowledge), and I'd hate to have to do rebuild just so it can be driven on 91 Octane gas, but I don't want detonation or other problems either.

[61 389-348]

Originally Posted by AZ64GP

This is slightly off topic, 61 389-348, but what did you do to make your 389 run on today's gas? Did you rebuild the engine? I'll probably be doing the engine rebuild when I work on the trans later this year, and I'm thinking I'm going to have to do some head/piston work to lower the compression and harden the valve seats so the 389 4 bbl can run on today's unleaded, lower octane gas. The engine runs great (to my knowledge), and I'd hate to have to do rebuild just so it can be driven on 91 Octane gas, but I don't want detonation or other problems either.

The owner before me rebuilt the engine. I don't remember much, but other than hardened valve seats, it's stock including compression ratio. I had it out for the first time at Carlsbad at the time of Wangers 75th birthday party. It still had the TH400 and ran in the 14.70s to 14.80s and it's very smooth, revs easily plus close to 18-20" of vacuum at idle so I left it alone other than timing chain, water pump, oil pump, etc., when we pulled the engine during the restoration. Depending on D/A that day, it runs anywhere from 14.70 to 15.40s with the 700R and 3.23 rear so I'm not messing with it.

Given that it's stock CR, it doesn't like pump gas very well so I add a bit of VP Racing fuels C12 to maybe a 10% mix and that takes care of the detonation. When I lived in sOviet monica the closest station to my house was a Union 76, which sold their 100 octane race gas. I had to run a little higher mix of it given that Cali is 91 octane instead of the 93 here.

[JessBo]

I'm in the process of this swap and my Pontiac starter throw is too short now with the new adapter plate.. what starter did you use? 64 Bonneville with 389 to 700r4. Ready to start it and go but I hit this snag, help please

[AZ64GP]

Hey JessBo - It's been years but I still haven't installed a trans in my '64 GP. I've spent the years working on body work, suspension, engine, steering, etc. It's been a slow go.

Anyway, if your car is a '64, you may already have the holes drilled in your block for a block mounted starter. They may or may not be tapped, but the holes could be there. My car was built in CA in December of '63 and it has the starter holes. My plan is to buy a TH400, get it rebuilt and install it with the engine. I abandoned the 700R4 idea when I realized how much more difficult it would be to get the adapter plate to work and how much I would need to upgrade a 700R4 to live behind my 389 engine. I figured that using that OD trans instead of the TH400 would cost me at least another $1500-$1800. For as little as I'll drive the car (i.e. only to car shows and cruise), it wasn't worth the money or the extra effort.

[MUSLCAH]

I would love to be rid of this slim Jim......and wake this car up ! So Iam following....

[pfilean]

This subject doesn't seem to come up very often anymore But I'll jump in just to get on he list. I probably should have done a change years ago when I might have been able to do it myself. Now to pay someone else I would likely have to lay out 10% of the value of the car. But O'l Jim still works like he should so until he dies I'll probably just keep cruising.

But one question I have had for those who have made this swap. How is the clearance of the engine to bell housing bolts heads for the various styles of adaptor The bolt head will have to move closer to the firewall so is it possible to get the bolts in and tight without pulling the engine to bolt it to the transmission? As I have a 61 block I might have to use the thicker of the available adaptors so I can mount a starter. And from what I remember from when I pulled the engine with O'l Jim still in the car that clearance to the firewall might get to close to slip the bolts in with the engine in the car.

[webfoot]

Look for an 87 and up 700r4, as the transmission was fully upgraded by then as GM customers R&D's this transmission for them. You'll get a 30 spline input shaft and several internal upgrades.

(a bit of research indicates the "MD8" case is a choice unit)