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V-8 Engine Tech

Lokar Kick-down cable adjustment

Mopar Big Block Talk

by AndrewP » Tue Mar 05, 2019 10:21 am

Gents,

Having just gone through an engine-in-frame rebuild and a what-I-can-replace gearbox seal replacement, I fitted a lokar kick-down cable.

Its much smoother in its operation and should be good when adjusted, but setup is causing a few headaches.

The original kick-down linkage has a slot, which only acts on the kick-down linkage during its last 1/3 (ish) of accelerator travel, which in turn activates the kick-down lever and the box kicks-down.

The issue with the cable is there is no such 'dead-band' in the cable. It starts to move the kickdown linkage as soon as the throttle moves as it is directly connected to the carb throttle linkage.
This means that if its adjusted as per the old linkage (WOT and adjust to full travel on linkage) then the gearbox is always in kick-down and it never selects 3rd gear as by the time you are at 50% throttle, the kickdown is at 50% at its travel (enough to stop it selecting 3rd).

If I adjust the cable to introduce some slack and 0 -> 50% accelerator so that it selects 3rd normally, then the kickdown lever does not go to 100% (on the kickdown arm) when WOT and doesnt really kick-down well.

There are a few posts on this on Mopar forums, and the general consensus is to go with a Bouchillon kick-down kit (https://www.bouchillonperformance.com/m ... -cable-kit) which appears to factor in this non-linear relationship between the two (i.e I need 100% of the kickdown lever travel in the last 25%-ish of accelerator travel).

Any advise or experience with either and/or tips for anyone having fitted the lokar kit?

Thanks
Andrew P
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by cannonball » Tue Mar 05, 2019 10:57 am

maybe you need to position the cable on a different part of the throttle linkage arm, ie closer to the centre spindle or further away which ever works the desird way, or the same at the bottom end find either a longer arm or redrill your existing arm again you are looking to improve the relationship of the travel arc versus cable travel,, you can sort it sir,,
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by AndrewP » Wed Mar 06, 2019 2:54 am

Thanks Duncan,

I`ll have a think over a beer and work out what I need to do.

Thoughts are to have the widest arc on the carb and the smallest arc on the kick-down lever?....So the carb end has to travel further to make the kick-down end move less?

I wish Id paid more attention at mechanical engineering 101 !!
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by AndrewP » Sat Mar 09, 2019 1:37 am

For those playing at home...

There is a good article Ive found here:- https://www.hotrod.com/articles/the-low ... n-linkage/ or none hyperlink "https://www.hotrod.com/articles/the-lowdown-on-stock-torqueflite-kick-down-linkage/"
that goes into the linkage(s) available when new, fitting and (more importantly for me) the setting up of a lokar kick-down setup on a 727.

Interestingly, they recommend a 1:1 ratio..that it the accelerator moves 20mm, then the kickdown moves 20mm.

More interestingly is that using the setup on my car:-

Carb end:
Lokar carb end.jpg
Lokar carb end.jpg (47.12 KiB) Viewed 1508 times


and gearbox end:
lokar gearbox end.jpg
lokar gearbox end.jpg (36.35 KiB) Viewed 1508 times


I have this 1:1 ratio (+/- 2 or 3mm)

BUT...I found that if I adjusted so that I have full kickdown travel @ WOT then it remains in 2nd and was reluctant to shift into 3rd under load (sometimes it dropped into 3rd when I lifted slightly)

So..some more playing to do I think....when the rain stops :(
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by AndrewP » Thu Mar 21, 2019 11:52 am

To update this post.

Ive had a few hours tonight to get the car up on the hoist and try some other options.

As you can see from the above pics, the arm on the gearbox has another hole in, closer to the centre, and so I`ve placed the fixing for the cable there and will see it that makes a difference.

I have to be perfectly honest, and say that Im not hopeful that this will give the desired result (only kickdown when you floor the throttle) but we will see.

Has anyone here heard of or used the Bouchillon kick-down kit as I linked to in my first post? Id rather not spend $130 USD on it, but if it fixes the issue and behaves more like the solid linkage without the weight and faff of the rods and pivots, then it may be an option if moving the fixing point does not work satisfactorily.

Cheers
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by cannonball » Thu Mar 21, 2019 12:29 pm

even with original rods sometimes adjustment is a very fine balance between getting full throttle kick down when you smash the throttle and nice even shifts on normal driving without thumps and bumps or flare type shifts,
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by AndrewP » Thu Mar 21, 2019 1:34 pm

Hi Duncan and thanks for the reply.

The more I read, the more I understand, but then the more questions!

Do you mind seeing if you can help with this question?...
Im 99% sure I have a full kick-down valve body.
From what I can see shifting is a hydraulic balance between governor pressure and throttle/kickdown pressure. If governor pressure is greater than throttle/kick-down then the shift valve moves and shifts down...if throttle/kickdown is greater than governor pressure then it shifts up
It seems to me Chrysler wanted there to be all or nothing (almost like an on/off switch) by designing the linkages to have the slider rod setup, so no kick-down pressure at all for 2/3 of the throttle, then all in on the last 1/3rd.
Yet... none of the cable setups (Lokar etc.) cater for this and its a linear relationship from the minute the throttle moves, the kickdown moves.

By setting the kick-down lever at full travel at WOT it seems that even when apparently set correct (1" of throttle movement = 1" of kickdown movement), as soon as the throttle moves, the kick-down lever moves and therefore applies pressure to the shift valve stopping it from shifting.
This makes some sense as Im only getting it shifting into 3rd when I back the throttle off, causing the pressure to rise enough for it to shift into 3rd.

So..bit of final advise...am I 'in the ballpark' here so all thats needed is a slight tweak on the cable adjusters 1/2 turn at a time or am I way off (and need to look at fixing the cable/pivot points) somewhere else?
Is it worth temporarily removing the kickdown cable, going for a drive an noting the shift speeds, then seeing if I can replicate these shift points when the kick-down is re-connected?
Then...seeing if it kicks down when i mash the accelerator?

Im paranoid that I`ll burn out clutches etc, as whilst its all a great deal smoother than before I stripped it all down, and new fluid etc. it doesnt shift as well and as smoothly as it used to.

Thanks for reading my ramblings. Hope it sort of makes sense and if you can add any advise then very much appreciated.

Cheers

Andrew
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by AndrewP » Fri Mar 29, 2019 2:10 am

So, after much head scratching and deliberation and way too much time under the car I've found a setup that works.

Moving the kickdown pivot to the middle hole and adjusting the cable tension a little bit each time has found a new sweet spot that allows the box to shift up when cruising along under low to moderate pedal, but when floored, makes the box kick down and off it goes.
A turn either way really makes a difference between an early kick down vs. a later and probably more 'factory' kick down
Anyway, thought I'd document for future reference if anyone else decides to go down this path.
On the downside..the flaming box still leaves a puddle of transmission fluid on the floor after sitting for a while.
The only seals now not changed are the dipstick seal and the governor/pump seals which require the box to be removed to get to.
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by cannonball » Fri Mar 29, 2019 7:40 am

Hello Andrew I only just saw this well done finding a result it can be a p[ain in the butt to strike a happy medium, and its different on all cars/transmissions so you done good, your oil leak will most probably be the dip stick o ring,, the selector shaft seal, the rear servo pivot pin, all can be done in the car but awkward well except the dip tube,,
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by AndrewP » Fri Mar 29, 2019 10:33 am

Hi Duncan,

You were right as its a delicate balance between too early kick-down (or not changing into 3rd at all) and no kick-down at all. Anyway, hope it may be useful into if anyone else wants to run a cable setup rather than the rod.

Unfortunately, I think it will be the dipstick seal as its the only one externally I havent replaced. The shift seal and the kick-down seals were done whilst I had the valve body out, the speedo seal and o-ring, pan and gasket are all new and were replaced at the same time too.
Annoying as it doesnt leak when sitting still...its only really once the engine is fired up and the car moved for the first time for a few days/week. I end up with a line of transmission fluid running out of my driveway onto the road, so you can see its the Jensen going out for a day. Doesnt leak at any other point in time..not even a drip on a bit of cardboard whilst its in the garage.
Most annoying..ah well..all 'character building' stuff if thats what its called.
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by cannonball » Fri Mar 29, 2019 12:04 pm

AndrewP wrote:Hi Duncan,

You were right as its a delicate balance between too early kick-down (or not changing into 3rd at all) and no kick-down at all. Anyway, hope it may be useful into if anyone else wants to run a cable setup rather than the rod.

Unfortunately, I think it will be the dipstick seal as its the only one externally I havent replaced. The shift seal and the kick-down seals were done whilst I had the valve body out, the speedo seal and o-ring, pan and gasket are all new and were replaced at the same time too.
Annoying as it doesnt leak when sitting still...its only really once the engine is fired up and the car moved for the first time for a few days/week. I end up with a line of transmission fluid running out of my driveway onto the road, so you can see its the Jensen going out for a day. Doesnt leak at any other point in time..not even a drip on a bit of cardboard whilst its in the garage.
Most annoying..ah well..all 'character building' stuff if thats what its called.


That does look to indicate either the front pump/converter seal,, or its blowing fluid out from the breather on fire up that is also located inside the bell housing, check you are not overfull engine running hot as it will get dip in neautral should be in between the two lines ,
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by Chris_R » Mon Apr 01, 2019 9:39 am

As Duncan suggests, do not rule out having overfilled it and the excess is coming out of the breather hole. As this is located inside the bell housing you can't see it happening so you need to get underneath and see where it looks like the fluid is coming from. After fitting a reconditioned box we filled it with the amount of fluid as written in the book and on startup it appeared to leak from the front inside the bell housing. Thinking we'd damaged the front seal on assembly to the engine we feared removing it again but all it turned out to be was excess fluid. We drained some off and the "leak" stopped, then added some back until the level was correct on the dipstick and no "leaks" since.
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