Automatic gearbox guru's, t400 behind 6.2 chev

[Tiny]

finally got the 73 in a drivable state with the auto in an having some issues

T400 behind a 6.2 chev, quicksilver shifter

goes into park reverse neutral and drive\1st fine, has excelent drive, no slip but when you throttle up it goes to change to second and wont engage second properly.

Oil is good, first time the auto has been in the this car and driven, auto was bought second hand as a reco box.

The box is not set up with vac for kickdown but my understanding is that this shouldnt be an issue, ie it should change up and down gears fine but wont kick down early when you give it a boot full. This is not an isue to me, I am happy to use it as semi auto if needed anyway.

I have ben told the likley reason is the bands need to be tightened, can anyone tell me i this sounds right and point me in the right direction please. If all it need is to be tightened up I will get it into an auto mob tis week

Cheers

Tiiny

[6.5 rangie]

don't 400's shift with vacuum???

[Tiny]

don't 400's shift with vacuum???

my understanding is that the vac was only for kickdown ie give it a boot full, loses vac, kicks down earlier......if that is not the case I am assumeing i need https://www.americanautos.com.au/cgi-bi ... tion=20219 in which case will this fix everything or is it likly the bads are loose as well?

Also how hard in the manual kit to install, can it be done with the box in the car?

[pongo]

from the t400 i had years ago not hooking up the vacuum kickdown is a good thing esp if you have have the HP to pull it. PITA when a healthy CHev kicks back a gear as soon as it hits a hill when you know full well it will pull it top gear easy peasy.

Cant help ya with the 2nd change, maybe it has a shift kit and is thumping hard into 2nd. A shop service prob not a bad thing anyway, pretty cheap out of memory

[Guy]

Tiny . I am no auto expert, but look up TV cable .. used when there is low manifold vacuum (which is a definite for a diesel)

[Gwagensteve]

TV cable also raises line pressure AFAIK - also important.

Steve.

[Tiny]

any links on TV cable? google brings up nothing relevent

[chimpboy]

Try "throttle valve cable"?

http://www.classicoldsmobile.com/forums ... lator.html

http://www.chevyhiperformance.com/techa ... index.html

http://www.tciauto.com/Products/Instruc ... adjust.htm

The thing is I thought the TH400 didn't have a TV cable! So... dunno.

[Tiny]

Try "throttle valve cable"?

http://www.classicoldsmobile.com/forums ... lator.html

http://www.chevyhiperformance.com/techa ... index.html

http://www.tciauto.com/Products/Instruc ... adjust.htm

The thing is I thought the TH400 didn't have a TV cable! So... dunno.

mine certainly doesnt

[6.5 rangie]

they don't, got a vacuum modulater or something like that, that controls shift (pressure)? i think

[Tiny]

they don't, got a vacuum modulater or something like that, that controls shift (pressure)? i think

yeah, there is a canister with an outlet line poking out of it attached to the side of the box

[6.5 rangie]

yeah vacuum goes to that

[Tiny]

so I asked the same Q on a chev oiler forum and they use a mechenical replacement http://www.transmissionpartsusa.com/TH4 ... 00040m.htm seems easuy to set up with a fabed bracket for the cable and use a cable from a 82 blazer iirk, would need to find someone to drop into a parts store over there to get the cable or see if somone like amereican autos \ rare spares can source one

also stumbled on wholesale autoes who have a manual kit for $800 or a vac pump and valve set up for $1200 and found a guy who could actually help who will supply and install a manual kit for $400 but wants the box out as he would want to do other stuf to make sure its 100% (builds drag boxes and wont let anything out sub par in his words)

I am in a quandry as it seems the $170 B@M kit can be done fro mthe sump and does the same thing as the $800 wholesale autos kit

The bloke who will do everything knows his shit and will get a good job but dont have the time, space or patience to get the box out AGAIN

the other auto places dont seem to want to do anything that isnt a supply and install a exchange reco box

The B&M kit sounds good but would prefer someone else to install just in case as I dont want any more hold ups and they can check the band tensions while they are in there

The mech modulator kit sounds good but still wondereing if manualized will be better for me but the mech kit apart from a wait for the parts and tring to find the cable can be done easily

what to do

hopefully this thread may help anyone attempting to run a t400 on an oiler in the future

out of interest to others, if you are say putting a t400 in say a TD42 where there is a vac pump on and available to plumb into, you can set up vac simply to the modulator with a valve on the throttle to mimic throtle position and thus allow the box to function properly or just getthe manual kit if thats what you are after before putting it all together

Also this is relevent to anyone looking to say turbo a petty engine with a t400 as you lose vac thus requiring you to manualise, mechanise or mimic vac

Cheers

Tiny

[6.5 rangie]

so you don't have a vac pump on yours?

[chimpboy]

a TD42 where there is a vac pump on and available to plumb into, you can set up vac simply to the modulator with a valve on the throttle to mimic throtle position and thus allow the box to function properly

If you do this you don't need to pull the transmission out do you?

[Tiny]

a TD42 where there is a vac pump on and available to plumb into, you can set up vac simply to the modulator with a valve on the throttle to mimic throtle position and thus allow the box to function properly

If you do this you don't need to pull the transmission out do you?

apparently I can install the manual kit through the sump and the mech modulator can be done with the box I , only box out option is the guy in girraween and that is due to him not having room at his workshop and possibly wanting to do other stuff like clutches

[chimpboy]

For what it's worth I think the manual kit would kind of suck. I'd rather have the auto working properly as an auto. If that's also the cheaper and easier option then all the better.

[Tiny]

For what it's worth I think the manual kit would kind of suck. I'd rather have the auto working properly as an auto. If that's also the cheaper and easier option then all the better.

I agree that I road car it would be but I am in two mind due to it been used mostly as a trailer queen

[Tiny]

Well it's booked in Wednesday for a full standard pattern manual kit $500 drive in drive out with high flow filter and oils will post what it drives like when I get it back

[Tiny]

picked the car up on thursday, the manual shift is awsome, great positve drive and hold back, basically it is torque lock in all gears, changes are quick and to the point but not harsh (unlike the owner ) would definanatly recoment to anyone looking to change to auto to manualize it