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What is this on my th400? Kick down ? And how...

82detroit diesel

82detroit diesel

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So I’ve been driving my 82 k5 around for a while, and everything seemed normal then when I took apart my dash and the fire wall to do my headers I noticed this cable which I assume is the kick down cable was just cut since I owned it, it never worked. I bought a winters shifter and am going to shift it manually now and eventually do a manual valve body. My question is, what is the right way to get rid of/delete the cable from the transmission? Is there a delete plate I can buy? Is it not that simple. Any help is much appreciated
 
Thats a cable operated modulator setup from back in the day .

Almost all of us use the stock style vacuum modulator setup .
 
Thanks,Ok so it’s just an older way of doing the kick down? And what’s the right way of getting rid of it?
 
Ive never seen a cable type on a 400. Might as well go full manual right now!
 
The kickdown was electric solenoid on the drivers side of trans and a switch usually on the throttle pedal.
The modulator controls shift points based on engine load.
 
NOT kick down . He controls fine adjustment of up shifts .

Kick down should be switch on gas/fuel pedal under dash . 1 wire to fuse box for 12volt . Threw swich . To driverside of trans near back just above pan a single wire orange in to trans . It fires off a solenoid to open the kickdown .
 
Ok know that I know what it’s called I found this th400 modulator block off on jegs for cheap79DEA01A-9540-438E-BD8B-BEEF460250B0.png
 
And if I’m shifting manual I do not need the kick down or modulator setup right? Thanks for the help guys
 
The only applications I've ever seen a stock GM vehicle with a Th400 use a cable operated modulator is on some of the trucks equipped with a diesel...mostly P series delivery vans or military CUCV trucks..

Some vehicles with a blower also used them ,as the vacuum signal on an engine with a blower is not suitable to operate a modulator correctly..
The modulator can and does also make "part throttle downshifts",and regulates the line pressure,which controls the speed the transmission will upshift at,and how firmly the clutches apply..
It can be "deleted" for drag applications..usually doing so just keeps the line pressure at maximum and a manual valve body is used to select gears and when the transmission upshifts..
 
You will need to modify the governor circuit and valve body to achieve full manual operation, a modulator plug by itself will not get the job done. Diesel4me's description of the modulator is accurate.
 
Ok thanks, So say I delete the modulator and kick down and when I drive, with no manual valve body yet. I manually shift from 1 to 2 . It will stay in 1st and 2nd with the shifter but when I shift it into 3rd and slow down it will go back to 2nd or 1st right? Will this be hurting the transmission?
 
But stock you can manually already shift and hold it in 1st and 2nd then shift it to 3rd/drive and in drive it will obviously go in all the gears.What I’m asking is if I drive it where I manually hold it in 1st then manually shift it to 2nd then put it in drive, is that messing the transmission up? So stock my 1st and 2nd would be the same as a manual valve body, it just wouldn’t stay in the 3rd gear when you slow down
 
TH400's will upshift into second gear automatically,when the engine reaches approximately 5200 rpms,even when you pull the shifter down into "manual low"..
To eliminate that requires valve body modifications..or a manual valve body..

A late friend of mine rebuilt a TH400 for his '67 C-10 pickup and he installed a manual valve body and did some mods to the pressure passages diameter in the spacer plate to gain more line pressure.

I recall he had it set up so you HAD to put it in "low" to take off,otherwise it would "drive" in whatever gear the shifter was in--you could put it in second and the truck would take off in second,by passing first gear,or even third gear ,if it was put in "drive"..this was handy in low traction conditions with a strong BBC ,like if you needed to take off gently on a road that had sand or ice on it..starting off in second reduces the amount of torque that would otherwise spin the tires too easily..
 
Ahhhh ok huh , I’ve reved the crap out of my th400 but it does not automatically come out of 1st or 2nd. Weird !!
 
Thanks for the help, Another question guys if I have a gated winters shifter that locks the gears in, and it’s locked in first and say I rev it past 5200 rpm what happens when the transmission wants to shift it to 2nd ?? Do I grenade the tranny or does it just stay in 1st
 
It'll usually go into second firm and hard enough to chirp the tires..

Remember some engines either cant rev to 5200+ rpms (or stay together very long if they do !)...my 6.2 diesel redlines at 3600 rpms,the governor in the injector pump shuts off the fuel so it cant go past that..
So my TH400 will never "self upshift" with that engine in front of it..

A friend had an '84 Cutlass he put several different small blocks in ,and he put a TH400 from a P-30 step van in it,that had the heavier duty case and clutches ,and a bolt on yoke instead of a slip yoke..

(He simply took the yoke off and used the slip yoke on his original driveshaft)...the last engine he had in it was a 307 that he assembled with many parts off other engines he blew up in it,like the cam from a 350 that was "hot" compared to stock,305 heads to boost the compression,and a 4 bbl intake & carb..
That engine having a short stroke would buzz like a chain saw well past 6000 rpms..and he liked to wind it up in "manual low" and make it self shift into second and chirp the tires..car had highway gears like 3:08's so it was going about 45 mph before it would shift into second..
 
Ok so I’m good, I’m to scared to rev it over 5k any ways, thanks for all the feed back guys
 
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