After battling with my original trans for several years. Leaks, Shifter getting locked up internally, Torus Seals, More leaks, and finally a professional rebuild that lasted about 3000 trouble free miles before MORE leaks and erratic downshifts/lack of downshifts... I've had it. Gonna do a TH400 swap (Because I have access to them on the cheap). I'll use the Wilcap adapter kit because everything I've ever used from them has been great quality and very "complete". My questions for you guys are:
1: Pros and Cons between the long and short tailshaft housing TH400s as I have access to either.
2: Can I swap in the gear shift indicator from the dash of a '64 SDV so that my indicator will match the gear that the TH400 is in?
You have the wrong crankshaft in your engine to be using a Turbo trans
Your crankshaft end that encounters the trans is smaller for the Hydromatic than the Turbo
A Hydromatic replacement is your only option with the engines crankshaft in your 390 now
This is not a reasonable option due to the above issues
Braking the flywheel is the result of attempting this trans change over
I’m in the process of this project now. I used the the long shaft and wished I’d used the short shaft. The long shaft gets close to the driveshaft tunnel. It’s doable but would have been a bit less crowded. Even the 6” tail would give more room. We went ahead and fabricated a new cross member. (Pics below) Also I used the adapter from Speed Gems with no issues. I should have mine on the road next weekend. I figured I would address minor issues like gearshift indicator and reverse lights after I’ve enjoyed the ride for a few weeks.
Thanks for the input & the pics. Have you shortened the driveshaft yet? I'm hoping you stayed with the 2 piece style and could maybe provide info on that as well. Did you keep the carrier bearing in it's stock location? Or move it aft? I've seen some go with 1 piece but that seems like asking for vibration.
The front driveshaft is at the shop currently and is being shortened. I stayed with the 2 piece with the carrier bearing in the stock location. Once I get the shaft in and driving I’ll report back as to if there were any adjustments to the carrier bearing location and further modifications. Should be on the road next weekend.
I’m replacing the fuel tank while we wait for the shaft to be returned. Now can’t find a replacement filler neck which might postpone the road test.
If the two of you gentlemen do not address the crankshaft issue I explained I do not understand how you think this swap will work for any length of time—- before you are braking a flywheel after all the time and expense of changing and making the other parts and alterations you are now in the process of doing
im not sure why you think we haven’t address the issue, we mentioned two different complete adapter kits for this project. One from Wildcat and one from Speed Gems
Speed Gems has a complete adapter kit that addresses the different diameter and flex plate issues.
I did miss the part about the trans adapters and very glad that is what you are doing
Glad we are on the same page regarding having to address that issue
Always trying to keep the people on this site out of trouble —-if I can
Do enjoy your new turbo trans in your 63
I would love to know how you feel about any change you might experience in the way the car drives having had the two different different type trans in the same car
The Turbo trans behind my 64 429 is what makes that ride so very special and a keeper for me
The Turbo is pretty much a bullet proof trans needing very little attention on this site since 2006
Enjoy Your pride and joy
#1 I can't help you with. I have probably 15 1964 Turbo Hydra-Matics and not familiar with how it compares with other long or short tailshafts.
#2 I can help you .... if you are installing an 1964 THM transmission. The metal shift indicator is the same plate for the 1963/64 HydraMatic (PND1D2LR) and the 1964 Turbo HydraMatic (PRNDL), with the lettering being the only difference. I probably have a dozen or so of the 1964 THM plates with the PRNDL lettering and can pick out a very nice one for $20. What I don't have is the 1965 and as the internal hydraulic circuitry was modified to provide a dual drive range as seen in the 1965 Cadillac Shift Quadrant below.
It sounds like you guys have covered the transmission to engine bolt pattern and THM flexplate to HM crank mounting issues (3" vs 3 1/16") with the adaptor kit, so I assume you have thought through and cover other mods that will be needed, but just in case here are a couple of comments.
First. The HydraMatic used a single shift relay rod setup from steering column shift rod to transmission lever; however the Turbo HydraMatic used a more complex setup that included a long relay rod from the steering column shift rod, down to a relay bracket that mounted to the LH frame rail via 3 hex bolts, and then a short rod down to the transmission lever.
Below are pictures of the Hydramatic Shift linkage, then the Turbo Hydramatic Shift Linkage assembly. There are many ways to skin this cat, but if you want to go factory and need the 1964 THM setup I have them with new Cadmium plating as seen in the 2nd picture for $75. You will need to drill some holes and use the hardened self tapping bolts to attached the bracket to LH frame rail and I can provide pictures of the mount up location and of course the bolts come with the linkage assembly. I know at least 3 occasions in the last 10 years or so where customers went to hook up the HM shift linkage to their THM transmission and realized that's not gonna work... but I am sure you have thought thru this.
For reference here are the pictures.
1963-64 HydraMatic Shift Rod Assembly
1964 Turbo Hydramatric Shift Relay Rod and Bracket Assembly
Second, and this is just a mention as I am sure you have it covered. But the 1963 and 1964 Cadillacs had different transmission crossmembers since in 1964 they had to provide for mounting both the HM & THM transmission, and of course the mounts between the HM and THM are different. While I don't have the mounts with nice rubber (maybe OK in a pinch) I have the 64 THM Yaw Mounts for cores to be revulcanized.
Good information for sure. We have already fabricated the required linkage and cross member. I bet Rick will really appreciate the availability of the 64 linkage if it can be adapted to the TH400.
Additional thoughts on the trans swap :
The turbo trans shifts off a vacuum from the back of the carb on the turbo trans ( not a tv rod like the hydro )
So a carb change and stock vacuum adapters off the back of the carb —will be needed
I would go with an Edelbrock carb ( of your choice ) if a new carb is needed and the carb spacer and gaskets from a 64 429 that has had the turbo trans behind it
The speedo gear needs to be addressed —for you rear end ratio— so the speedo records your correct speed
The car can no longer be considered a stock drive train for its year that can effect the sale of the car when that time comes ( a altered vehicle )
You will be needing a replacement Neutral Safety Switch - one for the turbo
The drive shafts ( especially the rear part ) of our drive shafts are getting harder to be locating in any kind of condition these days
This does get a bit complicated due to the number of items that need to be addressed and the time and expense to get that done —- but where there is a will there is a way — I have been told
Hope all the above have been considered in your trans replacement plans— or will be from this point forward
All good information as well. We have addressed vacuum and speedo gear. To be honest the speedo gear was the easiest part of this project. The driveshaft is at the shop being shortened currently. New fuel tank is shipping Monday. If the shaft and tank get here this week we should be on the road by the end of next weekend.
The neutral safety switch will need to be addressed although it won’t have to be bypassed to start but will also allow a start in reverse. I believe I can figure something for reverse lights. Jason said in another post that the only way to install a 64 neutral safety switch is to swap steering column as well. That is not going to happen anytime soon.
I’m not concerned with the stock drivetrain but am concerned about reliability. Personally I would have paid more for the same car with the switch already been made.
You are correct there is a lot to this project but I feel it’s worth it.