Type 65 kick down cable adjustment to cure the clonks. (I hope)

[Stag About Town]

I have been checking out likely causes for heavy clonks on engaging D and R. All is fine when cold and on choke revs but this gets worse as the car gets hotter. Looking at the Automatic Transmission Service Group pdf on BW65 and 66 which one member kindly posted a link to previously, the causes are probably either idle revs too high or kick down cable adjustment. I think I can exclude the revs as there is no problem when running fast on choke revs and it idles at about 700 when off choke, so I am looking at the kick down cable issue. It seems incorrect adjustment can affect the pressure in the gear box which can be adjusted by the cable. The A.T.S.G. pdf says the gap between the end of the threaded outer cable abutment and the crimped stop should be .010 and .020 when on the idle stops , almost touching. I don't have a crimped stop on my cable so I am wondering what affect that would have and why that should be? The kickdown seems to work ok and the gearbox is fine when driving, just the heavy clonks taking up D and R that are bugging me. The Haynes manual explains how to check the cam positions but that is a bit beyond my equipment and experience. This is a 77 car with a fairly low mileage. Any suggestions or advice will be much appreciated. John

[Lingen]

John.
Perhaps it isn't the box at all. Have you checked all four U/Js on the drive shafts, and their splines? It could also be backlash in the differential. All these can be checked by seeing how far the propshaft can be rotated each way by hand with the box not in Park. It should only be about 45 degrees at the most. If it is worse when hot, it could be because the thick diff oil has thinned out with warming, and is not damping the "Clunk" as well as it will when it is cold.
Mike

[mallardstag]

To eliminate the kick-down adjustment just disconnect the cable at the carbs and see if you still get the clonks.

[Stag About Town]

John.
Perhaps it isn't the box at all. Have you checked all four U/Js on the drive shafts, and their splines? It could also be backlash in the differential. All these can be checked by seeing how far the propshaft can be rotated each way by hand with the box not in Park. It should only be about 45 degrees at the most. If it is worse when hot, it could be because the thick diff oil has thinned out with warming, and is not damping the "Clunk" as well as it will when it is cold.
Mike

Thanks Mike. The drtive shaft UJs were changed last year (one re-con shaft due to the staked joints). I did try to check the prop shaft and diff for play but didn't know about the 45 degree max test. Will try that when I get back from holiday. John

[Stag About Town]

To eliminate the kick-down adjustment just disconnect the cable at the carbs and see if you still get the clonks.

That sounds worth a try along with Mike's suggestions. Do you know if the cam will be then at the idle position? Not sure what returns it. All a bit mysterious to me. Removing the sump cover to check as per the Haynes manual is probably easy enough if you have a pit or a lift but I don't.

[Jonat127]

I don't have a crimped stop on my cable either.
When you disconnect the cable it will/should take any tension off the cable so the mechanism inside the gearbox will pull the cable inner into its rest position. In this position the gearbox will be in its most 'relaxed' mode. You can then engage D and R to see if you get a clunk. There will a always be some clunk and small jolt.
if it feels better without the cable attached then the next thing to do is reconnect the cable without putting any tension on it. You want it to have no slack and no tension. Take it for a drive and see how it behaves.it should change up to top at about 30mph on a whisper of throttle with everything nicely warmed up. Then try accelerating on a small throttle. It should change down at the 30mph Mark. If it doesn't or needs a lot of throttle to change down the cable is too lose. Conversely if it won't change up as per above and holds on to 2nd the cable is too tight. The manuals give you all sorts of measures to make your adjustments to. Personally I found a bit of trial and adjustment works perfectly well and you can tune the change point to your personal preference.

[dickr]

worth adding that, if you release the cable tension, be careful not to push the inner further into the outer once it becomes slack you might push the nipple out of the cam at the throttle valve end and you will have to take off the sump to refit it. How do I know ....?

[Stag About Town]

worth adding that, if you release the cable tension, be careful not to push the inner further into the outer once it becomes slack you might push the nipple out of the cam at the throttle valve end and you will have to take off the sump to refit it. How do I know ....?

Ouch! Think I might have done that but not sure how to tell if the nipple is out or in place?

[dickr]

if the nipple is still engaged in the cam, you will feel a spring resistance when you pull the inner while holding the outer - it will want to draw itself back under spring tension, just as if it were connected to the throttle cable. Anyway, dropping the sump is not too difficult. Good luck!