Retrofitting 4l80e, couple questions.

[kape]

Hello

My c30 crewcab dually uses two-piece driveshaft. And now i changed Motor(old was 454) and transmission (old was th400)
to 6.5Diesel/4L80e.
Couple of unsolved issues coming up.

Old transmission have yoke with the bolt to the output shaft, it is non slipping model i think, because slipping
happend end of the first drive shaft after the chassic bearing
and 4l80e have slipping yoke.

So i tried to swap the yokes, but old th400 yoke go too far away inside to 4l80e, sealing get bad.
There is somekind rubber after normal oilseal.

So do you have some solution to get this problem solved.

and of course i have to make first driveshaft shorter, but is it not a problem.
i'd like to stay two-piece driveshaft combination.

Many thanks.

[meatwagon83]

buy a slip-on yoke, the 400 and 4l80e have the same spline count

[hatzie]

It sounds like the short transmission to carrier bearing shaft is a little too long.
Any decent driveshaft shop can shorten and re-balance it for you.

[kape]

Hello

I try to explain my proplem via photo. it's made by ms paint , but try to figure it out.



So what happend to carrier bearing if yoke end of the transsmission can slip in and out like normal one piece driveshaft can. It is getting broken?

And second problems is Gear selector leveller, Old does not fit to 4L80e. and does not reach to leveller.
is there any kind of parts to make that working correctly?

Many thanks

[GRADYS Performance]

You will have to use a 4L80E that has an output shaft that takes a bolt on yoke. The slip yoke transmission will not work with a 2 piece drive shaft. The Bolt on yoke transmission will have a threaded bolt hole in the end of the output shaft just like your original TH400. You can change the output shaft in the 4L80E but the transmission will have to be taken apart to do it. The shifter linkage will have to be moved on the frame and the shifter rod from the steering column will have to be lengthened about 2". Here is a picture of the frame mount from my 4L80E conversion. Move the bracket back putting the front bracket hole in the rear frame hole. I spaced mine down about 1/4" at the same time. Could not move it down more because of exhaust clearance.

[hatzie]

No need to spend the money or time to put a fixed yoke on the transmission.
The shaft has one universal joint at the transmission with U-bolts over one set of bearing caps just like the axle end of the shaft.

Get a new universal joint and a TH400/4L80E slip yoke for the transmission end of the first shaft section. If it's too long, after you assemble it, get a driveshaft shop to shorten that section and re-balance the whole shaft.

My 73 & 78 with Saginaw 3 speeds had a slip yoke and carrier bearing 2 piece shaft arrangement. The first shaft is in a fixed position between the transmission and carrier bearing. SO. The slip yoke will just ride at the same place on the output shaft all the time.

[kape]

Thank you for the reply.
Now i think i get it. Carrier bearing can hold the yoke to fixed position.
I install old th-400 yoke, without bolt and get shortened first driveshaft,just a correct lenght
, like that rubber seal after normal oilseal no get bad.(hope you understand).
Do gradys performance have a photo for the connection between transmission leveller and shifter linkage? I will put some extra steel on shifter linkage to get it right position .
Many thanks, awesome forum!

Little update what is going on project...

Last weekend i get Motor and transmision with rear support brakets installed.
Only modifications i have made was motor support braket realigmnet and four holes drilled to trans support and frame. And exthaust pipes looks like a only the joint between exthaust manifold and pipes have to be changed. I will get the old exthaust join on the g-30 VAN where i get a engine and transmission .

[hatzie]

Make sure the fixed yoke slides far enough onto the splines.

This is a slip yoke.
http://www.dennysdriveshaft.com/p69_...pline_wth.html

[kape]

Originally Posted by hatzie

Make sure the fixed yoke slides far enough onto the splines.

i will check that, or maybe i can use original 4l80e yoke.
i take some pictures and add them here, maybe there is the little help on others who's want to change transsmission to 4l80e.

[kape]

Here's my shifter linkage mod, i do that just like Gradys performace told. Some pics also.


On the start it was like that


Just welded 10mm bolt to linkrod and when exthaust pipe coming down i have cut that rod littlebit

[kape]

Hello again!
now my truck is running. It's take a while, because we have long winter here in north of finland., and my garage is so small that my C30 does not fit in. So have to wait when all snow has gone.

I find out some problems when i trying drove it first time..

Trans only have 2 gears. 2nd and reverse.
i find out i have to connect drac module to get speed signal to PCM.
So my engine and trans come out from 1994 chevy g-van. and i locate drac module just near on handbrake pedal on the left.
but where i can find pinout's of that drac module?

I Think those two wires from speed sensor comes to Drac module and one wire go back to PCM. but those Drac module has so many pin's so somehow have to find out those pinout's.

There is some pictures to fender jobs what i do today.
Some how the fender what i ordered from US to Finland is about 2 inch sort of lenght. But i lengthened it via glass fiber to correct lenght. and also i have colission damage at rear of the truck.

[bilfman]

Tci makes a stand alone controller for the 4l80e for about 600 dollars. Well worth the investment in a swap like this. Fully programmable and easy to install.

[bilfman]

Here is a link to my swap.

http://67-72chevytrucks.com/vboard/s...d.php?t=537481

[kape]

Hello.
Thanks for advise, i know those TCI modules, but before i buy that i give a try for original PCM.


After all i get all gears working.
I "ping" the wires from DRAC to wiring harness. and instument cluster.
So i use G-van : PCM, wiring harness and DRAC module.

Now i have speedometer problem, but i think i use G-van speedo meter.
Included to my original instrument cluster. I put some pictures when i get that modification done.

[kape]

Now the speedo problem is solved, only thing have to do is, mount the G-van speedo to pick-up instument cluster.

[mrolds88]

A 90 to 91 squarebody (suburban or crew cab) will have an electric speedometer and should bolt into your dash.