1965 vs. 1966 BS TH400 Trans

[Guest ejc65]

Hey guys quick question for you I just pulled my trans on my 1965 GS however it says BS-66 could this be a warranty replacment? If not I'm not a purist, but are the 1965 and the 1966 BS transmission virtually same with reguards to shift points. Or is a 1966 BS equivallent to a 1965 BN transmission. Any info would help thank you

[tim63riv]

ejc65,

Not likely that your transmission is a warranty replacement as most issues with an automatic back in the day were repairable at the dealership. It is likely a used transmission or one from a rebuilder that matched the car. Not sure about the BS to BN shift points, but all that can be modified by a good transmission tech anyway. Kind of curious, why did you pull the trans?

Tim

[Guest ejc65]

It's currently undergoing a frame off restoration.

[RivNut]

Dear ???

I pasted and copied this from the Buicks.net site. It doesn't tell you about the shift points, etc. that Tim made reference to, but it will give you an idea of the original application.

It appears that one of the differences would be the speedometer gear in the trans that would relate to the rear end ratio.

According to this chart, your '65 GS Riviera should have had a BS code transmission, just like the Gran Sport and Riv for 1966.

Ed

YEAR APPLICATION CODE

1964 300 V8 LeSabre BU

401 V8 column shift BJ

401 V8 console shift BK

425 V8 column shift BL

425 V8 one carb console shift BN

425 V8 two carb column shift BP

425 V8 two carb console shift BQ

1965 300 V8 LeSabre BU

401 V8 3.07 axle BJ

401 V8 Riviera (3.23 axle) BR

425 V8 4bbl. carb 3.07 axle BN

425 V8 3.23 axle BT

425 V8 two carb 3.07 axle BO

425 V8 two carb Riviera (3.42 axle) BS

1966 340 V8 LeSabre BU

401 V8 BR

425 V8 Grand Sport & Riviera BS

425 V8 all others BT

[1965rivgs]

Hi EJ,

The BS coded `66 trans is essentially the same as the `65 unit including the speedo gear. Both these transmissions were installed in GS models with 3:42 diff gear.

Tom Mooney

[Patrick91914]

Does that mean that a '66 Wildcat GS would have a BS transmission? Regardless of single carb or dual carb set-up?

[RivNut]

You have to remember that in '66, in the beginning of the production year, most 2x4 set ups were installed at the dealership. I believe it was in March of '66 that the MZ engine came from the factory with the 2x4 set up. In this scenario, the BS transmission would have been used in all Rivieras. The way it's coded, it seems that the BS transmission was the transmission for all Rivieras in '66.

Ed

[Patrick91914]

Were these dealer installed 2x4 set-ups installed on MW coded motors. That is, are you saying that MZ blocks weren't introduced until later in the year?

Patrick

[1965rivgs]

Hi Pat,

My research indicates some `66 Wildcat GS cars were built with the BS coded trans and some were not. I have used original build sheets and protecto plates to form the basis of my research. Unlike the Riviera, the Wcat models were built in more than one assembly plant. So, even though it appears Buick intended the BS trans to be installed in both Wcat GS and Riv GS models, there may have been a shortage of BS transmissions in certain plants to properly build the Wcat GS cars....dont ask which plants!

It would seem logical if the dealer installed the Super Wcat option on a customer`s car it would do so on a 425, not a 401. On the Riviera, this is impossible with the exception being an export model built with a low compression 401, but Buick only built between 2 and 3 hundred of those. The 401 was the standard engine for the Wcat so conceivably, a dealer could have done it.

General consensus is the MZ coded factory built Super Wcat cars were available as of March 1, `66. Hope this helps,

Tom Mooney

[Guest Riviera66]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RivNut</div><div class="ubbcode-body">You have to remember that in '66, in the beginning of the production year, most 2x4 set ups were installed at the dealership. I believe it was in March of '66 that the MZ engine came from the factory with the 2x4 set up. In this scenario, the BS transmission would have been used in all Rivieras. The way it's coded, it seems that the BS transmission was the transmission for all Rivieras in '66.

Ed </div></div>

The data source you cited is in error. I have about 6 or 7 production order forms (build sheets) from '66 Rivieras. They confirm what has been otherwise reported... that the Riviera GS got a different transmission from the 'regular' Rivieras. The 'regular' was a BT, the GS's got BS coded transmissions for 1966.

Darwin Falk

1966-70 ROA Technical Advisor

[RivNut]

Darwin,

I took that info from the Buicks.net site. Are you registered on that site? If not, I'm going to forward what you've posted here to them.

Thanks,

Ed

[Patrick91914]

My WCat GS was delivered yesterday, I'll crawl under it this weekend to see what's there.