BW8 auto trans kickdown

the BW8 auto in my 420G does not “kickdown” from 3-2 upon WOT, except under one condition

It will do this if the trans lever is placed in Low, THEN WOT, it will change down as it should.

No amount of cable adjustment will alter this, pressure gauge tests etc etc.

An E-type owner has been down this path, and found the same thing.

As the BW8 was fitted to some E-types, I inquired on that list and no-one was able to say they have a BW8 that kicks down “auto” style

So now I wish to inquire upon Saloon owners, the BW8 was fitted to (as far as I can tell,for auto);
420, 420G, late MK10, early S1 XJ6, S2 E-types.

I would be interested to hear from ANYONE whose BW8 will kickdown upon WOT, whilst in D2 or D1

mine will change down as it should upon slowing, change up at correct speeds, etc, but will not kickdown UNLESS engage L

The FSM, and owners manual clearly state that it should

The BW8 has only 2 things control shift, which is an external adjustable cable which directly links throttle arm to internal valve, and internal trans governor

there is no vacuum, or microswitch

I can`t speak directly to kickdown on a BW8 but on a 1955 FOM ( related to BW8 ) the kickdown works. It is set to operate AFTER the linkage to open the carb is at the end of its travel. In other words if your pedal is at the floor when the carbs are full open, it needs to travel further to activate the transmission valve to downshift to second. Pete

The BW8 is almost identical to Ford FMX (and BW12)… EXCEPT, NO vacuum

The Valve body is identical to a '51 Ford-o-matic !

the kickdown valve is depressed to the absolute max, but no auto kickdown UNTIL Low is engaged (and throttle depressed)

unless advised otherwise to me by at least ONE owner, I am going to take it the printed instructions
are NOT correct.

BW8 was also fitted to Studebakers, International, and at least one other make

Tony. OK, the FOM does not have a vacuum modulator or any electric connections. It does have TWO levers on the side of the transmission case. One is the gear selector the other is the transmission throttle valve lever. To get a downshift the governor sends a ( speed ) signal to the valve body ( increased oil pressure ) AND the transmission valve lever has to be moved…It is moved by wide open throttle. With engine off check the throttle valve lever at wide open throttle. I hope that makes sense. Pete

Hi Tony

My BW8 will not kickdown either. I am sure that it has this function and there is a lever and mechanism connected to the the throttle shaft at the firewall end. This obviously connects to the tranny valve Pete mentions.
I was going to play with this at sometime and see if I could get it adjusted correctly so it would kick down. Having said this I might leave things alone as I don’t need it and my box also acts a bit strange under gentle acceleration in D2, if I accelerate gently (not WOT no where near) it kicksdown to D1 for a second and then back to D2 but not always, can’t figure it out. The other thing is the marker on the steering column does not line up correctly with the L,D1, D2, etc that could be just the column parts are not aligned properly they look a bit scew.

I can’t afford to open up a can of worms right now so am reluctant to jump in.

I competely dismantled one, and partly dismantled mine, and examined the function of every part using the FSM as my guide to understanding the hydraulic functions

There ARE two cables, one is the gear change cable, the other the kickdown cable, nothing else.

At WOT, my kickdown cable is FULLY depressed. This cable connects inside the trans to a rod that is directly linked to the kickdown valv inside the trans. I have verified with the pan off, that the valve is fully depressed when the cable is all in.

I dismantled the valve bodies and examined all springs and pistons.

There is no fault I can determine

The govenor pressure is supposed to work with kickdown and 3-2 pressures to perform the auto function

When the trans shifter cable is moved, that moves a valve with lands that block or allow pressure flow.
When L is engaged, the system work as described in the FSM.

As I already mentioned the system will auto CHANGE down, with slowing speeds.

So unless my (and others) governor is faulty, there is no obvious explanation

apart from one, and that is the trans is DESIGNED to require manual change to L
but for some reason this is not been printed in the instructions for use
(remember mine still requires throttle depression AFTER engage L to kickdown)

I have enquired on several forums over the years and NEVER had an affirmative reply

come on all you auto MKX/420G/420 guys?

re the pointer not lining up…here is the fix;

remove the upper nacelle that covers the steering column, exposing the trans position pointer
.
you will see a small nut facing you, which tightens a slot that allows the pointer to be slightly adjusted.

To work, the adjustment needs to be made with the engine running.

Line it up so that it is inline with R when Reverse engages, tighten and verify.
Test drive and verify that the column shift will engage every position and the pointer lines up.

The biggest issue is it must engage P and L at each end.

If it wont do that, adjustment can be made at the 15/16" twin lock-nuts, in the middle of the cable, up under the front parcel shelf. The parcel shelf must be removed to do this adjustment.

take GREAT care that the trans will engage PARK if you adjust the locknuts, guess how I know that!

Tony Thanks for that, I will have a go at getting the indicator to line up when I get back home in October, we are camping right now dodging forest fires.

Sorry I can’t help with the other issue, I have no idea how auto boxes work only ever worked with manuals in the past. I will be watching this thread though because if anyone can find a solution it will be you!

I bookmarked these when I was working on my BW12.
Here is a website with some info on Fordomatics which are similar to the BW8.
http://www.charlietranny.com/Fordomatic.htm
Here is another website.

According to the Mark X parts book, on the valve body you have a “control rod operating kickdown cam”.
This is how the kickdown happens.
The next question is what operates that control rod, if you don’t have a modulator like the BW12 has?

There were hundreds of thousands of Ford O Matics, Borg Warner Type 8, and type 35 made over a 15 year period. They all had a kick down feature that was caused by a throttle control valve IN THE TRANSMISSION VALVE BODY. This was connected to the throttle linkage ( gas pedal ). There was NO VACUUM MODULATOR or any electronics. They all worked. If they did not it was because the linkage was not properly adjusted or an internal fault of that INDIVIDUAL TRANSMISSION ( 3-2 shift valve or the governor ).
Check out Wikipidia Borg Warner type 35 transmission for a more detailed explanation. Pete

here is some pics

the kickdown cable connects to the rod, which operates a cam, depressing the kickdown valve.

Simple… have verified that the adjustment causes the valve to be fully depressed with the pan off, so that cannot be the issue. No amount of additional external adjustment makes any difference (to kickdown, but does mess with trans pressures at low rpm)

the lower pic hows the valve body, with kickdown cam, and manual selector valve removed.
When this valve is manually selected to Low, everything work as it should

There is a VERY detailed description of the auto trans operation in the MKX FSM

I would like to hear even just ONE person say that it does work that way!

In the MKX Parts manual, its shows the BW8 Valve body changed 3 times

The mode of hydraulic kickdown described is complex, involving governor pressure overcoming spring pressure in 2 kickdown valves. None of these parts appeared in any way defective, and I would expect springs to weaken with time, not stiffen.

I suspect the lands of the selector valve block fluid unless Low is selected…otherwise how / why would it work as described in that situation only?

Hi Tony,

I’ve been following this thread with interest, and I’m responding to your query for at least one person whose BW8 kicks down into Low by flooring the throttle. My saloon does not have a BW8, but my '67 E-Type 2+2 does, and it would definitely drop down into low gear when I floored the throttle. That car is presently in storage, but I have fond memories of the burst of acceleration from the E-Type, even with the BW8 “slush box” as we called them. I never considered this kick-down abnormal, as the MoPar products that I drove from the same era would do the same thing with their Torque-Flight transmissions. I had the BW8 rebuilt, and it’s now in storage with the kick-down cable still attached to it, because I didn’t want to go to the trouble of disconnecting it from the transmission.

Hope this helps…
Jay