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401 hook up to 2004R tranny


ghaskett
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I was going to recommend Bendtsens Adapters in Minnesota however their web site says PERMANENTLY CLOSED! Appears it might have been bought out and now called SPEED GEMS transmission adapters located in Wisconsin. Worth investigating. Bendtsens had an excellent product and reputation! I am running one behind a 66 Buick 425 hooked to a 700R4.

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Such a conversion seems to be a bit popular with the Riviera enthusiasts.  Might pose your question on their forum on here.    Or look for threads mentioning such via "Search", although it's been several years since I noticed such over there.

 

Seems like TCI (or similar) has some stronger guts for the THM200-4R automatic, so that it'll hold lots of torque it was not originally desinged for?  Have to get the kickdown linkage worked out, as that trans has no vac modulator and such, just hard linkage.  BUT it also takes less power to run it, too!

 

Just some thoughts,

NTX5467

Edited by NTX5467 (see edit history)
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My original question was basically, "Has anyone hooked up a 401 to 2004-R"  If you have, I have a few questions. If you haven't..no need to answer this.
Currently have a 401  SP400 in my '56.  I have a 700R4 going in next week, but toying with switching to the 2004-R. Just curious if anyone has gone the 2004 route. 

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Although I have not done such a conversion, I am quite familiar with the THM200 family of transmissions. 

 

That THM200-4R will be moving a lot of weight...!

 

This design is not as strong as the THM400 (& Related units). However, installing a "Shift Kit" will improve both durability and driveability.  This modification should be done even if your 200-4R has been rebuilt and it doesn't require opening up the unit.  My 1984 Toronado with the THM 325-4L (same internal power flow) was vastly improved with a Transgo ShiftKit. It provided firmer but still "comfortable" shifts at all throttle positions. This greatly extended the life of the friction elements.  The first rebuild was needed @ 77,000 miles due to a worn out intermediate band (1-2 shift). The shift kit was installed at that time. At 160,000 miles, a second rebuild was needed. However, the friction elements were still fine...

 

https://transgo.com/products/thm2004r/

 

As mentioned, the transmission "throttle valve" linkage must be set up and adjusted correctly.  Like a vacuum modulator, this linkage controls the shift points (in part) and the apply pressures of the band servo & disk clutches. If misadjusted, the friction elements will burn up in short order. 

 

There are beefed up hard parts for the THM 200.  Unless you are going to really drive the car hard or race it, these parts aren't necessary (IMHO).  

 

A auxiliary transmission cooler can't hurt.

 

Paul

 

Edited by pfloro (see edit history)
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12 hours ago, ghaskett said:

My original question was basically, "Has anyone hooked up a 401 to 2004-R"  If you have, I have a few questions. If you haven't..no need to answer this.
Currently have a 401  SP400 in my '56.  I have a 700R4 going in next week, but toying with switching to the 2004-R. Just curious if anyone has gone the 2004 route. 

I have the same setup in my 56 as you do. After you do the 700R4 conversion, would you mind sharing with me how the conversion went and improvements you see in how the 56 operates. I am contemplating doing the same thing and just would like to talk to someone that has already converted to the 700R4.

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