Updating 3 speed auto TH400 to 4 speed w OD 1977 Mini

[Froggy1936]

Well I have located a doner veh for the Transmission 4L80E with all the electronics BONUS It also has throttle body fuel injection + many other parts Serpintine drive belt w rotory A/C compressor Power steering pump with remote reservoir Square headlights tinted door glass etc etc.  The veh is a 1995 Chev G30 ext Van. w 240000 mi in the odometer Let the butchering commence  Frank

[TommyM]

Are you swapping the engine too, then?  Or adapting your existing engine to TBI?

I swapped a 4L80E from a 1991 V2500 4x4 Suburban into my 1990 V2500 4x4 Suburban.  It required a swap of the trans and all its mounting components (crossmember, front & rear driveshafts. . . ), and the ecm and complete wiring harness, because the ecm controls both the engine and trans.  Fortunately, almost everything on the engine just plugged into the new harness.

The reason for the swap was the 1990 3/4 ton was the last year that got the TH-400 trans, and the 1991 was the first year of the 4L80E.  I honestly don't think I've seen any improvement in fuel mileage, but even so, I like having the overdrive and lockup torque converter.

Anyway, I like doing this kind of stuff, and have a little experience, so if I can help in any way, don't hesitate to ask!

Tommy

[Froggy1936]

HI Tommy I plan on doing the Tranny first with all the wireing and controls . Then later the intake with the TBI . this eng has 300,000 mi and mine has 100,000 w good compression and it does not use any oil and has new crank brgs & oil pump  I keep you in mind when the s--- hits the fan Ha Ha   Frank

[TommyM]

Hmm.  Something you'll need to think through, then, is how the engine & trans controls in the computer work together.  I've never heard of anyone using the transmission & ecm without running the TBI system. 

I do know the trans control portion of the ECM relies on the TPS (throttle position sensor), and am guessing it uses the MAP (manifold absolute pressure) sensor, too.  So somehow you will need to devise some way to provide those signals.  A map sensor is easy enough -- it just needs a manifold vacuum source.  And I'd bet you can find a TPS to attach to your Quadrajet carb somehow. 

Without all the rest of the engine sensors and outputs connected, you can be sure to live with a check-engine signal, and it might go permanently into "limp home" mode.  I don't know if that will affect the trans control, though.

There may be more I'm not thinking of, and maybe you're already ahead of me on this stuff, but I thought I'd toss it on there, just in case it's helpful!

Tommy

[Froggy1936]

Hi Tom. I am just starting to learn these syestems, And i see i need a 95 Chev manual (as all my 77 stuff does not apply) I am beginning to realize that i will have to do both mods as they are interconnected so much I also see my Shifter is another problem (B&M Floor) I think i will have to change the steering columns to get the 6 position shifter (wich luckily is a cable hookup) This veh does not have cruise so i will also have to update wiper T/S control Since i will have to overhaul the 4L80E (due to hi miles and replace convertor) I think i will just strip this veh. for now and wait till later to transfer. As the winnie is in fine operating condition now!! and its Traveling season  Frank

[Froggy1936]

There is one other option An  Aftermarket transmission control setup with wireing and computor it is a bit pricey but probably resaleable when done with it  . Frank

[Froggy1936]

Well Transmission is on the floor . This stuff is not as easy as it was 50 yrs ago!! 

[Froggy1936]

Intake TBI is on the bench along with serpintine belt parts im not shure 1977 cylinder heads have all the neccessary bolt holes for mounting these parts ? The cylinder block is ready to remove also.  And im going to pull the differential (wich is a posi ) not shure it is the same either but once the hull goes to the wrecker its gone. Frank

[TommyM]

You're off to a good start!  This may be a little late, but take lots of photos as you go.  They'll help you when you're ready to reassemble.  If you work like me, that may be months from now, and memories get fuzzy. . .

Tommy

[Froggy1936]

Thanks Tommy, I am taking a lot of pics and i see that this has become a monster with mant tenacles all the way to to the speedometer assy and main wireing harness / steering column / fuel lines etc. 1 Question I have duel exaust w headers where should i install OXY sensor L/S -R/S or both   The original was near the tranny after the ex pipes came together into 1 pipe info i have seen says it should be within 12 in of ex port ?

[TommyM]

The best answer is to put the O2 sensor where it will read "both" sides, but since you have dual exhaust and a system with one O2 sensor, just pick the one where you can get the best location in terms of accessibility, wiring etc.  And closer to the engine is better than farther away because that is not a heated sensor, and the sensor needs to be hot to work.

Tommy

[jkilbert]

one other item to remember is that the water pump for a serpentine belt motor is reverse rotation. you can't interchange them with the older motors eventhough it will bolt right up

[Froggy1936]

jkibert There are water pumps for both directions C/W & CC/W you only have to make shure you use the correct rotation The cooling syestem does not care as long as pump moves the coolant A C/W pump turning CC/W will not move any coolant The 1995 pump will work with the serpintine belt but the 1977 will not  Frank

[DaveVA78Chieftain]

Thanks to Franks post on Kevin's Quadrajet thread, I saw this book that might be helpful for this conversion.

http://www.cartechbooks.com/gm-automatic-overdrive-transmission-builder-s-and-swapper-s-guide.html

Dave

[Froggy1936]

Thanks But I already have it.  But now i am useing a 4L80E  instead of a 700R4   Took it apart today and first look at parts inside Most of them look like the day they were manufactured . There was a very minimal amt of shavings on the magnet in the pan I have seen way more wear on trannys with 60,000 mi on them   i may even gamble on the torque convertor !!  Frank

[Froggy1936]

I get the feeling that this tranny was just rebuilt recently (the veh sat for 3 yrs)  All the lined clutch plates (5 sets) I can still read the Raybestos name and part no on them The steel plates do not yet show wear patterns across full surface . Both bands are like new The only possible problem is the rear planetary drum where the reverse band rides shows some wear (less than .002) The frt pump shows no wear. I may get away with just gaskets and seals   Fantastic -  Frank

[Froggy1936]

After rechecking needed parts (a complete rebuild set is $1700.00)  Looks like gasket,seals,bushings,Thrust washers , fluid, assembly lube,wider frt band & a new spacer plate for the valve body will be about $400.00 Frank

[ClydesdaleKevin]

400 is better than 1700!  Keep up with the awesome posts and pictures!  Complicated things, transmissions!...looks like when I took apart a grandfather clock once when I was a kid.  My folks weren't too happy about it...

Kev

[Froggy1936]

After a visit to the local Transmission shop (for a second opinion)  i was able to cut the parts down to $250.00 So i also ordered a 6 ton press from Summit (New) $110.00 This will be a big help in replacing bushings instead of useing a hammer.   Valve body and frt pump good . Brazed a fitting into the pan for the temp gauge sender. Painted case. Waiting for parts !!!  Frank

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[TommyM]

Lookin' good!

Can I send you a couple of transmissions I need rebuilt?  Ha!

Tommy

[ClydesdaleKevin]

If I was anywhere near you, Frank, I'd be over at your house volunteering every day to help you...so I could learn a little bit about rebuilding transmissions!  The most complicated things I've rebuilt are old VW aircooled motors, and they are WAY less complicated than that there transmission you are rebuilding.  Awesome job!

Kev

[Froggy1936]

Rebuild Rear planetary This is low & reverse. New press removed old pins with ease. Frank

[Froggy1936]

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[Froggy1936]

The pinion free play (.009-.024) Allowable I had .030 on 239783 mi unit This planetary is 1st & reverse gears New are very expensive and used are unknown wear. The rebuild kit from Sonnon was $35.00 The hardest part was staking the new pins they are very hard steel. By the third one i had a good syestem. after rebuild the avg end play was .015  Started reassembling units  Still waiting for an updated 34 element sprag to replace a 16 element (second gear)  Frank


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[ClydesdaleKevin]

Holy crap!  That looks even MORE complicated than the grandfather clock I took apart when I was a kid...which, after a butt whooping from my Dad and the threat of being grounded for life, I did manage to put back together in working order.

That's just fascinating, Frank!  I do love gears and the way they work...looks like it would be a lot of fun to rebuild one if I had the tools and a garage to work in.  AWESOME!

Kev