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Lee Martin
07-07-2008, 08:49 AM
I should know the answer to this, but will a modern TH400 bolt to a '66 425? Or is an adaptor kit required?

Schurkey
07-07-2008, 10:06 AM
What do you mean by "modern"?

You need a TH 400/Super Turbine 400 that has the nailhead "round-top" bellhousing. And (I think) those were all done in '66.

No doubt there is an adapter kit that will allow you to bolt a BOP- or Chevy-style bellhousing to the Nailhead bolt pattern--but--I don't know where to get one.

GM built transmissions for a bunch of cars you wouldn't ordinarily expect--Jaguars, Ferrari, Rolls-Royce/Bentley, etc. Might be that one of those cases is the same as a nailhead, but I wouldn't hold my breath.

I know where there's a '64 TH 400 for Buick; and there's certainly other, newer, round-case 400s in the same salvage yard. Shipping is a bugger; and this yard isn't cheap.

DanStokes
07-07-2008, 10:56 AM
Google for Bredtsen's (I think he also uses the name "Transmission Adaptors" or something like that). They make adaptors for pretty much everything Buick.

Dan


I should know the answer to this, but will a modern TH400 bolt to a '66 425? Or is an adaptor kit required?

nailheadnut
07-07-2008, 12:35 PM
The transmission in the '64 is a ST400, but it DOES NOT have the switch pitch feature. Only the 65 -66 ST400 for nailheads, and the '67 with the BOP bellhousing are the s/p designs. If you can find a '66 LeSebre 340 engine with the ST400, it will have the s/p feature. However, most '66 LeSebres came with the ST300. The easiest way to tell is to pull the electric wire going to the terminal on the driver's side of the transmission: two terminal ends - switch pitch :grin: , one terminal end, just the kickdown for the passing gear :( .

Ed

Lee Martin
07-07-2008, 01:28 PM
Thanks guys. I'm familiar with Bendsten's and will give him a call. What I'm trying to do is mate a Chevy pattern TCI TH400 to a '66 425. Sounds like I need the adaptor kit.

nekkidhillbilly
07-07-2008, 02:18 PM
eelco has adapters and there about 300 bucks cheaper than benstends

if you plan to go that route i would go all out and mount a od auto to it though

Lee Martin
07-07-2008, 02:36 PM
eelco has adapters and there about 300 bucks cheaper than benstends

if you plan to go that route i would go all out and mount a od auto to it though

Thanks, but I'll stick with Bendsten's. I've dealt with EELCO before and wasn't that impressed. In fact, the manual adaptor kit they sold me for my other nailhead had the ring gear on the wrong side of the flywheel.

As for an overdrive, the 425 is going into a '55 gasser.....for nostalgia sake, I want to use 1:1 for high gear.

nailheadnut
07-07-2008, 02:43 PM
Thanks, but I'll stick with Bendsten's. I've dealt with EELCO before and wasn't that impressed..

Google Marty Lackner, owner of Eelco, and see what pops up.

Lee Martin
07-07-2008, 02:47 PM
Google Marty Lackner, owner of Eelco, and see what pops up.

I know what pops up. That's why I'm going to go with Bendsten's.

Thanks,
-Lee

nekkidhillbilly
07-07-2008, 05:10 PM
I know what pops up. That's why I'm going to go with Bendsten's.

Thanks,
-Lee

i bought from him no issues but to each there own

but question what is the nostalgia reason for going to a 1:1 drive ratio? i dont see what would be different other than better mpg?

lapham3@aol.com
07-07-2008, 08:06 PM
Funny/strange , but both of these adapter guys have certain 'issues'. I might be missing something, but why not just bolt up a '65-6 ST400? -they're strong, cheap and available-shipping could be bad. I have some-I think Ed does-pick up in Mpls or Kansas City-where be you?

nekkidhillbilly
07-07-2008, 08:34 PM
Funny/strange , but both of these adapter guys have certain 'issues'. I might be missing something, but why not just bolt up a '65-6 ST400? -they're strong, cheap and available-shipping could be bad. I have some-I think Ed does-pick up in Mpls or Kansas City-where be you?

i agree unless you want a od trans

yacster
07-07-2008, 09:41 PM
a Variable Pitch TH400 is an awsome tranny- it's like having 2 trans in 1. Hi stall for when you want to kick butt low stall for when you want to cruise.:TU: Both of my cars will be getting them. The Riv will be real soon!

Lee Martin
07-08-2008, 09:15 AM
Thanks guys. I agree the ST400 is a nice unit. The thing is I have a line on a new TCI TH400 (GM pattern). The '55 is pretty much going to be a drag car, so I'm not worried about OD and mpg.

DaWildcat
07-08-2008, 09:17 AM
The '55 is pretty much going to be a drag car, so I'm not worried about OD and mpg.

You'll want a well-built fixed pitch converter for consistency, then.

Devon

Mr62Buick
07-13-2008, 09:54 AM
I have 2 1965 turbo 400's and one 1966 variable pitch trans. One of each is rebuilt and ready for install. These are the round bellhousing style that require no adapters at all to fit the nailhead as these are from nailheads.

nailheadnut
07-13-2008, 04:00 PM
If the two '65 ST400 are indeed what you say, then you have three variable pitch transmissions. Only the '64 was the non-varible pitch ST400 that came with a round (nailhead) bellhousing. Look at the terminals on the driver's side; if there are two, it is a variable pitch. If not, look at the tag on the passenger's side and look for the year and trans model - BT, BS, etc. - for proper identification.

Ed