Looks like I have to change the Trans in my 66 Dynamic conv since problems with the Trans become worse. First it started slipping when the oil became warm/hot, but now it is slipping even when it is cold. I added some oil to max but no change. It now feels also that it will not shift in 3thrd geer.

Therefore I think about replacement. Looks like I could get a rebuild in Germany easily but almost from different cars like 70 or 76 cars. I would like to know if a TH400 equals an TH400, no matter from which car. Are there any additional specs I have to take care of?

 

Be aware that your 66 speedometer is driven from the front wheel instead of from a speedometer cable in the rear of the trans case.

If you get a transmission later than 1969, you will have to remove the speedometer cable provision, and plug it with a freeze plug.

Also, there are differences in tail shaft length. Yours would be a 9 inch tail shaft with the letter D on the rear housing.


The letter C housing is shorter by 3 inches, and will not be a direct replacement.
They also had a 12" version for trucks that would be too big for your car.

Another issue is the engine bolt pattern. Only a buick, olds or pontiac trans would bolt up to an oldsmobile engine.

The chevy transmissions are a different shape and pattern.
Here's a link to a picture of the letter. You need D not C

http://www.lextreme.com/TH400/yoke%20001.jpg

 

That helps a lot! I noticed there are also 4x4 th400 Trans here on German epay

 

Also note too that the 65, 66, 67 Oldsmobiles used a switch pitch turbo 400. If you use a newer trans the torque converter needs to match.

 

The switch-pitch also had switches on the inside to actuate the converter.
If you've never had occasion to use it, just get the converter that comes with the trans.
As far as the speedo - if they left the old gear and adapter in there, just leave it - won't leak!
Lastly, Cadillac will also bolt-up, but don't know about the tailshaft length.
Also, if it was me, I'd use the trans. flush in the spray can - for the radiator cooling and lines - don't want any old parts or pieces going through the 'new' trans!

 

I had to replace a TH350 in a 4X4 a few years ago. A car transmission would not work in a 4X4 because of reinforcements to the bellhousing. That made the 4X4 version harder to come by and more expensive then a car version.

 

I've never noticed any differences in the cases between 2 and 4wd TH-350's.. Chevy used a long rod that went from the bellhousing bolts down to the transfer case to help stiffen things up. However, the output shafts are much shorter on a 4wd due to the use of an adapter between the trans and t-case. the 205 case even used a sleeve to couple the 2 together.

 

My wallet and I are so happy to hear that.


It was a 1979 GMC Jimmy and about 10 years ago. I seem to recall something about extra mounting bosses for external bracing that were not on a car version. I don't really know because I hired the job out and the guy that did the R&R got a rebuilt unit from a rebuilder.

It's all water under the bridge now. The main point now is SachesDD sees a tranny on E-bay. Will it work for him and will the cost be inflated because it's for a 4X4.

 

If the trans he found is for a 4X4, it will not fit his application without tearing the trans down and swapping the output shaft for the longer passenger car version. If that job is within his mechanical abilities, he might just as well rebuild the trans he has.

 

Ok, that's a Lot of Input for me so far. Now next step will be checking out if there is someone around in Dresden who may have a closer look on the tranny first. I found an offer to get mine rebuild which will cost about € 1.100, but this would mean send it to south germany. Not so easy to find someone here in east germany who can take care about US cars. Easier to find spare parts for Tatra, Skoda and Trabant....
Keep you updated!
Thanx a lot!

 

Here are the TH400 transmissions that will bolt to your Olds block:
65-66 Buicks without Nailhead 425. Has to have 300 or 340 Buick V8.
67 Buicks -all with V8.

Oldsmobile 65-67 all with V8.

Pontiac 65-up v8, but will not have switch pitch converter.

Cadillac 1968 up with v8, but again no switch pitch.

1965-67 Cadillacs did not have BOP pattern.

 

You'll need a Buick,Olds,Pontiac bell housing,which fits your car.
The full size vehicles also use a long tail transmission.
You'll need to get the correct length,as you need to dis assemble the transmission to change the input shaft.
This drawing may help.

 

TH400s were also fitted to Jaguar and Rolls Royce cars and I dare say other European cars too, they might have their own unique bolt pattern.
If you have your own transmission rebuilt you know it will fit, and you will know you have a good box with a warranty from whoever built it if it is done by a reputable shop.

Roger.

 

Well, finally decision was taken by someone Else but me. On friday I arranged a Meeting with an ealderly guy who used to rebuild Trannys for a test-drive. About 40km from home. Weather was great so I started the Trip top open. About 10km bevore arrival some dark clouds came up and I decided to close the top. Unfortunately the generator did not work! 5min.later we had a bad weatherstorm with heavy rain and ice coming down. I did Not manage to find a roof or even a bridge to hide.
All this took about 5min and the Sun came back, 2cm of water left in the car. But back to subjekt..... the Olds did not drive any longer due to extremly slipping tranny. Only back-gear did work Fine. Since there was only 1km left to the guys garage I went there.

First he pulled the oil-control stick (?) smiled and said "burned Oil! No problem, I can fix it easily!". So decision was taken! I left the car in his garage to get the tranny rebuild, all with a good feeling because he already made some TH350 & 400. Rebuild to start on monday....

Thanx a lot for your help and advises, I appreciate it! Keep you updated!

 

Final Update!
It took finally about 4 weeks but since last week the Olds is back.
Trans-rebuild was done since 1st gear was "gone"... Now it drives perfectly, next step will be to check the kick-down function.
Costs were at € 850,00 for the work, incl. Tans in/out, and € 180,00 for the parts.

Thanx for all your help an suggestions.

 

Sounds like a fair price to me, lets hope you can spend the summer enjoying yuor car.

Roger.