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Swapping 904 w/ lockup 727
https://slantsix.org/forum/viewtopic.php?t=25081		 Page 1 of 2
Author:  Jopapa [ Mon Sep 24, 2007 10:22 pm ]
Post subject:  Swapping 904 w/ lockup 727
Given that the two trannies are very close to each other, I'm putting a lot of consideration into keeping a 3-spd auto and installing a Gear Vendors unit (later on down the road of course), would it be a simple swap to install a later model lockup 727? I'd like to get a junker, rebuild it with a full manual valve body and the GV unit, and pop it right into the car.

Thoughts? Yes I know it'll be expensive, but I think once I get up to the point of doing it, it'll be worth it (to me).
Author:  rock [ Tue Sep 25, 2007 7:27 pm ]
Post subject:  Hey jopapa, here is some new data from my swap to think on
Hi Jopapa,

I thought I was gonna have to get a GV unit as I studied putting in my 727. I decided to wait at $2500 bor the GV, and put the 727 in to see what RPMs would be. With a 3.91, 28 inch tires, at 65 mph I get 3200 rpm, at 70 I get about 3500. I was afraid it would be about 4,000...well at 3200 to 3500, I don't need the GV in my opinon. Now the 833OD I just took out did 2400 at 70! If reducing rpm is your objective in the GV, it just wasn't worth the price to me drop abpit 800 rpm, but I realize it could be to others.

rock
'64d100
Author:  Jopapa [ Tue Sep 25, 2007 7:39 pm ]
Post subject:  Re: Hey jopapa, here is some new data from my swap to think
Quote:
Hi Jopapa,

I thought I was gonna have to get a GV unit as I studied putting in my 727. I decided to wait at $2500 bor the GV, and put the 727 in to see what RPMs would be. With a 3.91, 28 inch tires, at 65 mph I get 3200 rpm, at 70 I get about 3500. I was afraid it would be about 4,000...well at 3200 to 3500, I don't need the GV in my opinon. Now the 833OD I just took out did 2400 at 70! If reducing rpm is your objective in the GV, it just wasn't worth the price to me drop abpit 800 rpm, but I realize it could be to others.

rock
'64d100
Originally, the OD aspect was all I wanted, but when I started reading about the GV unit, I really dug the "gear splitting" capability of it and thought it'd be great fun for when I want to put a ricer in his place with my "old POS".

Was your truck originally 4-spd equipped?
Author:  rock [ Wed Sep 26, 2007 5:05 am ]
Post subject:  Jopapa, no, originally 3 speed
Hi Jopapa,

No originally a 3 speed with worn out shift rods, so of course the solution was to completely rebuild engine and truck and put in a 4 speed! I know several folks locally who have GV units and LOVE them. BUt they put the unit in '50s cars like big Buicks. THey like the splitting because they also tow trailers and such. I am sure the GV is great, I would like to try one, I just can't go that much money for my needs. If you don't like yours, please lemme make you an offer on it used!
rock
'64d100
Author:  Walter Lee Jackson [ Fri Sep 28, 2007 12:47 am ]
Post subject:  Swapping 904 w/ lockup 727
If you're determined to get a Gear Vendors unit, why use a 727?

GV does make a version that bolts up to the linkage type 904.

One other small problem with the GV is that it may interfere with the emergency brake cable. You'll need to reroute the cable.

--Walt Jackson
1963 Dodge Dart GT convertible
A904 with GV unit.

(not yet on the road, alas.)
Author:  Jopapa [ Fri Sep 28, 2007 5:46 pm ]
Post subject:  Re: Swapping 904 w/ lockup 727
Quote:
If you're determined to get a Gear Vendors unit, why use a 727?

GV does make a version that bolts up to the linkage type 904.

One other small problem with the GV is that it may interfere with the emergency brake cable. You'll need to reroute the cable.

--Walt Jackson
1963 Dodge Dart GT convertible
A904 with GV unit.

(not yet on the road, alas.)
I really just want the 727 because I know it can take a beating. Granted I don't plan on building up a strip car, but I still like to know that I can beat the crap outta the tranny (that just sounded weird) and not have to worry about it at all.
Author:  Reed [ Fri Sep 28, 2007 7:24 pm ]
Post subject: 
Jopapa-

if you want to make a trip over to Tacoma, I have a purportedly rebuilt but non-functioning 1974 slant six 727 you can have for free. Just come get it out of my garage.
Author:  slantzilla [ Fri Sep 28, 2007 7:30 pm ]
Post subject:  Re: Swapping 904 w/ lockup 727
Quote:
I really just want the 727 because I know it can take a beating. Granted I don't plan on building up a strip car, but I still like to know that I can beat the crap outta the tranny (that just sounded weird) and not have to worry about it at all.
Put the V-8 guts in a 904 and you'll never have an issue.

The 727 will eat about 10 horsepower in frictional losses that a 904 won't too. :?
Author:  Jopapa [ Sat Sep 29, 2007 2:01 pm ]
Post subject: 
Quote:
Jopapa-

if you want to make a trip over to Tacoma, I have a purportedly rebuilt but non-functioning 1974 slant six 727 you can have for free. Just come get it out of my garage.
I'm actually planning on being over on the west side on the weekend of the 20th. What's keeping it from working though?

Slantzilla, how would the 727 eat up more HP than the 904? I would've thought you'd lose less HP since the later 727s had a lockup torque converter. Can you even get a 904 with a lockup TC?
Author:  slantzilla [ Sat Sep 29, 2007 9:46 pm ]
Post subject: 
The parts inside are bigger and heavier. It takes HP to turn weight. :?
Author:  DusterIdiot [ Sun Sep 30, 2007 8:56 am ]
Post subject:  Late model...
Quote:
Can you even get a 904 with a lockup TC?
Yes, mechanical lockup 904's began somewhere in the late 70's in 904's (about 78-79-ish)...

-D.Idiot
Author:  Jopapa [ Sun Sep 30, 2007 10:27 am ]
Post subject:  Re: Late model...
Quote:
Quote:
Can you even get a 904 with a lockup TC?
Yes, mechanical lockup 904's began somewhere in the late 70's in 904's (about 78-79-ish)...

-D.Idiot
Ooohh very nice. I didn't realize that. That and the point about the heavier parts in the 727 have me leaning back towards getting a built up, late model 904 instead of a 727.

Now for another question: are the late model 904 housings the same as the earlier ones? IE: would it be a direct swap to replace my 904 with a later model unit?
Author:  slantzilla [ Sun Sep 30, 2007 11:20 am ]
Post subject:  Re: Late model...
Quote:



Now for another question: are the late model 904 housings the same as the earlier ones? IE: would it be a direct swap to replace my 904 with a later model unit?
Should bolt right in. :D
Author:  Jopapa [ Sun Sep 30, 2007 1:53 pm ]
Post subject:  Re: Late model...
Quote:
Quote:



Now for another question: are the late model 904 housings the same as the earlier ones? IE: would it be a direct swap to replace my 904 with a later model unit?
Should bolt right in. :D
Sweetness. Now to find a junker, a rebuild kit, and a good shift kit to install...
Author:  slantzilla [ Sun Sep 30, 2007 2:10 pm ]
Post subject: 
To check if you have a lock-up, remove the converter and look at the end of the input. A lock-up will have a pilot on it like a 4 speed trans. :D
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