BW66 Shift points
#1
BW66 Shift points
Now that I've been driving my XJ6, it's time to iron out the shift points. It's shifting out of 1st at about 5mph and out of 2nd at 10mph. If fact, with a rolling stop at a stop sign (nobody around, or a rolling right turn at a stop light), it never downshifts. I'm not a spirited driver. I know, I know, the Jaguar is meant to be driven, but since I'm the one who has to fix it, I don't want to break it. As much as I like working on it, I also like driving it. Anyway... any ideas as to how to get the shift points higher?
Thanks, Bill
Thanks, Bill
#2
Further info - I've changed the trans fluid with the recommended. And done it 5 times; filter change twice. But these low shift points were there before I changed the fluid. So I'm reasonably sure it's not fluid. The old fluid looked good. No gunk. Also, the up shifts and down shifts are smooth as silk. No clunking.
#6
The 66 is just a slightly beefed-up version of the 65. They're almost identical.
If you have a 65 (do you?) the shift points can be set higher by ever-so-sightly increasing the tension of the detent cable/shift valve cable. The procedure is the same for 65 and 66 transmissions, so a manual covering the 66 will do.
Technically speaking this adjustment requires a pressure gauge but if you don't go wild with the adjustment you'll be OK.
Cheers
DD
#7
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#8
#10
Yes ....and no
We're talking about the same cable, yes. But, technically, "downshift cable" isn't quite correct.
The nomenclature gets muddled when discussing transmission cables. Often the terms are used interchangeably.
Some transmissions have a cable specifically (and exclusively) for downshifts. "Downshift cable". "Kickdown cable". "Detent cable"
Others, such as the BW65/66 have a cable that actually controls both upshifts and downshifts. Jaguar (rather erroneously) calls it a downshift cable. Elsewhere it might be called a "throttle valve cable" or "TV cable" or "shift control cable" or similar. The cable actuates a valve in the valve body which alters internal pressure....which dictates when shifts take place.
Anyhow, yes, again, for the purposes of this discussion we're talking about the same cable. I'm just doing some Saturday morning blathering
Cheers
DD
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yachtmanbuttson (06-29-2019)
#11
#12
The way the parts are listed in my Series III catalog makes it hard to confirm if the 65 and 66 used the same dipstick. I suspect they are the same.
Cheers
DD
#13
yes
Judging from what I've said about my problem, what thoughts do you have as to whether I first adjust it tighter or looser?
Cheers
DD
#14
Upon closer inspection my lockdown cable adjustment threaded portion is broken, so I can't do any adjustment. Looks like my best bet is to replace that whole cable before continuing to troubleshoot. So... how complex is it to replace that cable? I've already had the trans pan off a while ago, so if that's part of the process, then no big deal.
#15
OOPS.
Seen that a few times.
Pan off for cable replacement, and inside the trans the inner simply rolls around a cam, very simple once you eyeball it.
The outer at the trans casing, FORGOT, really, it was so long ago, but will not be rocket science, as the same system was used on the BW35 trans.
Seen that a few times.
Pan off for cable replacement, and inside the trans the inner simply rolls around a cam, very simple once you eyeball it.
The outer at the trans casing, FORGOT, really, it was so long ago, but will not be rocket science, as the same system was used on the BW35 trans.
#16
#17
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Grant Francis (07-08-2019)
#18
To set up the TV cable or whatever you may want to call it.
Perform the following:
Throttle Wide open.
Pull the TV cable out as far as it would go.
Tighten adjusting nuts.
The idea being that the throttle cable and the TV cable must be able to work in unison with each other.
If at WOT you still have movement outwards on the TV cable, you have to adjust it to take up the slack.
WOT = TV cable out all the way. The proper geometry of the two cables already exist.
An incorrectly adjusted TV cable will cause considerable wear on the clutches and bands.
A loose TV cable will have the early shifts you are experiencing. Tightening the TV cable will change the shift points. Too tight and you would have a harsh shift.
Once you get it where the throttle cable and the TV cable are working in unison, you can then tweak it to get the shift points where you want it.
Perform the following:
Throttle Wide open.
Pull the TV cable out as far as it would go.
Tighten adjusting nuts.
The idea being that the throttle cable and the TV cable must be able to work in unison with each other.
If at WOT you still have movement outwards on the TV cable, you have to adjust it to take up the slack.
WOT = TV cable out all the way. The proper geometry of the two cables already exist.
An incorrectly adjusted TV cable will cause considerable wear on the clutches and bands.
A loose TV cable will have the early shifts you are experiencing. Tightening the TV cable will change the shift points. Too tight and you would have a harsh shift.
Once you get it where the throttle cable and the TV cable are working in unison, you can then tweak it to get the shift points where you want it.
#20
I don't believe it!! Replacing that cable was an easy job. Took me longer to jack up the car and put the four jack stands under it. Can't check adjustment yet until I get the alternator back down to 12v instead of the 18v. Will do that job while it's still up in the air. Have ordered a alternator rebuild kit.
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Grant Francis (07-12-2019)