Cascade Crew

[Kage87Z]

Maybe my search skilz suck, but I can't find much on a 700R4 to Turbo 400 swap.

I'm detuning the 69 (want it to be more of a cruiser) and strengthening the drivetrain in the 87 (It's going to be race only) so I'm looking at doing a swap.

Step one is to get the T400 into the 87.

Anyone round here done this swap? if so, could you PM me so i could pick your brain?

Much appreciated.

[Twilightoptics]

Unbolt 7004r. Remove dipstick tube. Remove TV cable. ETC.

Install th400.

Buy this : On sale: gives you crossmember, better torque arm, safety loop.

http://www.spohn.net/shop/1982-1992-GM-F-Body/Suspension/Torque-Arms/Standard-Duty-Crossmember-Mounted-Torque-Arms/Tubular-Adjustable-Torque-Arm-TH400-Transmission.html


Install vacuum line for the TH400 to manifold Vacuum.

Buy B&M megashifter and install.

You'll need a custom driveline with the larger th400 32 spline yoke.

[aaron_sK]

Also gotta figure out the electronic kickdown in the 400, right?

[Twilightoptics]

It's vacuum pod related. Not electric. Unless there's some later th400 that I don't know of.

[Kage87Z]

I knew someone around here would have the info... thanks, TW!

[chevymad]

Part throttle shifts are controlled by the vacuum modulator. Aaron is right the kickdown is an electric switch. Older cars had it carb mounted, but most of the newer ones were on the gas pedal assembly.

If its too hard to rig something, just shift it down manually. Won't hurt anything. I've also heard about people using a toggle switch.. especially when using a th400 in a autocross. That way you flip the switch and it goes down a gear.. flip it back and it upshifts.. Almost a poor mans paddle shifter.

All th400s had the electric kickdown, some early ones actually had a 2 speed stall convertor(switch pitch) that was electric as well. There may be some 70s era transmissions with tcs(transmission controlled spark) plug ins on them too. It basically cut out the vac advance for all but high gear.

Myself.. i'd just forget the kickdown.

[Twilightoptics]

I thought I remembered the TH400 in my old 67 pickup kicked down and it definitely didn't have an electric anything.

Bad memory I guess, might not have downshifted....

[chevymad]

On your 67 the kickdown switch would have been actually mounted on the carberator at the factory.
http://67-72chevytrucks.com/vboard/attachment.php?attachmentid=509097&stc=1&d=1256891013

[aaron_sK]

[chevymad]

I think olds had switch pitch too.
My 74 firebird has the pedal mounted kickdown. The switch itself is junk. Never know whether it will actually work or not.
On a 3d gen swap i"d just ignore the kickdown switch. Easy enough to ratchet down a gear when you pass.. if you even need to.

[chevymad]

Gotta say.. I think this is the first mistake i've caught Paul on in a long time. Think he may be up to Master P status, and not just Hardcore. (it's probably just cause we're dealing with antiques here)

[Twilightoptics]

At least I can admit I don't fully remember. I just remember that Qjet had no wiring. I had it off a few times!

[chevymad]

There's so much i've forgotten people dont believe me when I tell them. Oh well. I can always just look it up or figure it out again. Makes every day new. LOL

Entirely possible after 40 years that the wiring would disappear. Was that the original Q .. I know you put a motor in the truck.. Some reason I was thinking it was a 6banger originally.

[Twilightoptics]

When I got it, it was 3 on the tree, 283 with a flat cam, TH400 with a Qjet. God knows who did what. Ended up having the carb rebuilt and put my '85 camaro 305 in it.