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Another Overdrive question

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C

Coastalman

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Hi to all! I took my recently purchased 1966 BJ8 out for a shake down run of about 100 miles last week and had these questions about the use of the OD. The OD engages just fine when I flip the switch, but when I hit the gas hard at about 50 mph it drops out. It feels like hitting passing gear in an automatic drive car. As soon as I let the gas off a bit, the OD kicks back in. Is this normal?
Next, I have read on some of the older posts here that you should engage the OD while slowly accelerating. What is the proper proceedure to disengaging and can I leave the switch on while down shifting, even to 2nd gear?
Thanks,
Charlie
 
HI, your OD is doing just what it is suppose to do. At about a little past 20% of throttle it will kick down into the lower gear releasing the gas pedal it will engage again.--Fwiw--Keoke
 
Hi Charlie,
If it helps,
You can see the OD wiring schematic here:
https://www.britishcarforum.com/lore/attachment.php?id=13

In your case, if the OD dash switch is still in the "on" position, the OD relay will remain operated & it's C1-C2 contact closed. This bypasses the throttle position switch which should only be closed at nearly closed throttle positions & open at greater throttle settings. With the C1-C2 relay contact closed, as it should be, if the dash switch is "on", the OD should stay engaged regardless of throttle position.

You "should" only be able to disengage the OD/downshift if the dash switch is off, & there is a bit of throttle applied, or the gear box shifter is not in the 3rd or 4th gear positions.

If the OD is disengaging/down shifting when you open the throttle but the dash switch is still in the OD "on" position, - either the OD relay C1-C2 contact is not making contact or something is not wired correctly.

The OD should engage/upshift, any time that the dash switch is on & the transmission is in 3rd or 4th gear. If you leave the dash switch on & shift to second, the OD will automatically disengage & you will be in second direct. When you shift back to third or fourth, the OD will re-engage & you will be in 3rd over or 4th over.
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"Keoke - HI, your OD is doing just what it is suppose to do. At about a little past 20% of throttle it will kick down into the lower gear releasing the gas pedal it will engage again.--Fwiw--Keoke"
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It won't kick down into the lower gear (out of OD) unless the dash switch is turned off. It won't re-engage OD unless the dash switch is turned back on. Unless, of course, something is not working correctly.
D
 
All of mine do that but I am not going to worry about why.---Keoke
 
[ QUOTE ]

All of mine do that but I am not going to worry about why.---Keoke

[/ QUOTE ] thank goodness for those stoutly build laylock d-normaville units /ubbthreads/images/graemlins/grin.gif
 
I am going out for a long drive again tomorrow and will feel better about how I use the OD. I just did not want to hurt anything due to my lack of knowledge. It sounds like the unit is very sturdy and forgiving.
 
But it should not jump out of OD unless you have the switch off or are in 1st or 2nd.

NEVER EVER back up with it engaged.
 
Very good advice about not backing up with OD engaged! I may just tag the switch with that until I know it by heart.
 
Charlie, just so happens I am having the same problem.
I was also told by my Healey mechanic, 3 and 4 should not come out of overdrive on acceleration, unless I switch the toggle off.

We will be looking into it next week or week after. I will share the findings. And hopefully what was required for the fix.
Roger
 
Roger, your problem is not the same as Charlies problem, He doesn't have one at all. Me thinks you don't either.---Keoke
 
There is an oil pump in there which provides a very high pressure to an accumulator. When you engage overdrive the oil pressure causes a cone clutch to engage the stationary brake ring and bring the sun wheel to rest giving the overdrive ratio. I don't really know what I'm talking about here, I'm just quoting from the manual. I do know however if it can't get enough pressure (long drive on a hot day for me) or if the system is a bit knackered, it pops out of overdrive when it shouldn't.

Could this be your problem?
 
Yes Richard, that could be a problem. However, I would first try a heavier single viscosity racing oil. Then check the operating valve for dirt as well as the one way return valve. Make sure the mechanical linkages are also set up correctly. A pressure guage would be a big help in locating the problem as a worn pump might be the culprit.---Fwiw--Keoke
 
I took the car out yesterday for a nice run. It is about 70 degrees here so we put the top down and drove over to the sound. Any time I give my car a quick boost of acceleration in 3rd or 4th it does jump out of OD. I plan on spending some time on this problem in December since my car will be safely in the garage for the winter. If AUSMHLY gets his problem fixed hopefully we can hear what that fix is. Right now I am just enjoying a string of 70+ degree days by taking my car out every chance I get.
 
If the od is costantly coming in and out on aceleration and deceleration you will eventually wreck it
it wasn't designed to do that-it constantly throws you forward and backward in the seat and puts so much stress on the drive train
 
Hi Coastalman, does the OVD still feel like you are hitting a passing gear in an automatic drive car and then come back on when you let up on the gas or does it actually drop out of OVD ?--Keoke- /ubbthreads/images/graemlins/confused.gif
 
Hi MikeSpain, Excessive outs and ins on acceleration and deceleration are not desirable. However, this OVD purposely includes a smaller accumulator piston assembly which removes the shock on the Tranny. Normally, when it functions it feels just like an automatic drive car.Further, Rally cars have the actuator switch mounted on the gear lever and use an unmodified Accumulator to circumvent the lost motion effect.---Fwiw---Keoke
 
I think Coastalman and I are having the same thing happen.

I'm driving in either 3 or 4 and the OD is engaged. When I aggressively step on the gas to speed up, it comes out of OD and will stay out as long as I keeping giving it more gas, speeding up. Once I let up on the gas, it will return into OD.

Note when in 3 or 4, with OD on, if I increase speed slowly, it will stay in OD the entire time.
If I want out of OD entirely, I simply flick the toggle up and it comes out.

Maybe next week or week after, I will get together with my mechanic. I will share what we find out and the fix. Roger
 
It sounds OK to me Roger, but we will wait on the prognosis.---Keoke
 
My OD is acting exactly like Rodgers! The OD will stay engaged as long as I am driving at a steady or slightly accelerating speed. It only jumps out when I hit the gas and immediately goes back in as soon as I let off to a steady speed again. It is NOT jumping in and out at random. I drove it about 75 miles yesterday and it only jumped out once and that was in 3rd when I accelerated hard.
Charlie
 
[ QUOTE ]
Very good advice about not backing up with OD engaged! I may just tag the switch with that until I know it by heart.

[/ QUOTE ]

Coastal, There is a gearbox switch on the transmission housing that disengages the OD whenever the shift lever is out of the 3rd to 4th gear path (i.e. in 1st, 2nd or reverse) The OD will be disengaged when in reverse if this switch is working and the OD functioning correctly. Sit in the car and turn on the ignition switch (but don't start the motor .. you want things quiet). Move the gear lever left and right when it is in the middle of the gate. Everytime you move it to the right you should hear the solenoid actuate. Then press on the gas slowly, moving the gear shift lever back and forth until the throttle switch cut-off actuates and then you won't hear the solenoid making noise anymore. This is also a good way to check the adjustment of the throttle switch i.e. how far the pedal needs to be pushed down.

Cheers,
John
 
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