AH 3000 activating the overdrive

[Keith_M]

This discussion is interesting because I've never used the clutch to engage or disengage the overdrive. In fact, I kind of like the feeling of the overdrive kicking in at speed, and the clutchless downshift that you get when you briefly depress the the accelerator after flipping the switch to off. From what I've read so far, I think it's fair to say that either way is fine as long as your throttle switch is correctly adjusted (which is easy to get wrong).

And Bob, I feel really bad about you only getting 125K on your clutch! :highly_amused:

 

[RAC68]

Hi All,

I have been reading the discussion and am amazed at the thoughts presented. I have been driving my Healey since new and in all that time have raised RPM when exiting OD without touching the clutch. This has given me a smooth exit with no jarring or hammering of the drivetrain. Had I not increased RPMs on exit, the OD would remain engaged as though the switch was not thrown and would exit once I did raise the RPMs or the car was turned off.

Although many have drawn their own conclusions on how the OD should be activated and de-activated, the differences in approach seem to stem from how the throttle switch is adjusted and the units operational feel may be further acerbated by the type and viscosity of fluid used in the transmission. In any case, I would suggest going back to 30W non-detergent and readjusting (following manual procedures) the throttle switch and solenoid in order to regain an feeling of how the unit was intended to operate. With the feeling in mind, reinstalling a different transmission fluid will allow you to better interpret if the new fluid provides the operational feel you are looking for.

Just my thoughts,
Ray(64BJ8P1) since new

 

[John Turney]

Where did the idea of dipping the clutch come from? The throttle switch is there to take car of the issue.

I don't have the throttle switch, so I either rev the engine coming out of OD, or use the clutch.

 

[vette]

Ray, as with John Turney's situation, I can't adjust my throttle switch. And I have made sure that I will never have to adjust my throttle switch again, Because it's not there. By design. My own design, who needs it. One more piece to either fail or get out of adjustment. :wink-new:

 

[ozhealey]

Vette,

Interesting perspective, and while I agree over engineering can sometimes complicate what could be a simple operation,
I agree with Ray’s perspective and have no experience with failure of the throttle switch. I have helped a few people to adjust and setup or install a new one when they were doing a restoration. I’m sure they could fail as all electrical components can, however I am not sure it is prevalent enough to warrant removing the switch.

In 28 years of driving a BJ7, and over 100,000 miles I have never had my switch fail and it is the original switch from 1962. I set it up initially when I restored the car and have not touched it in over two decades.

I drive my car the same way Ray does in terms of the O/D operation and always have with no judder, jump, hammer or jerking when the O/D engages or disengages.

Just my experience and opinion.

Cheers

 

[DerekJ]

The throttle switch isn't there just to be an extra bit of kit that could fail, it's there to ensure that the driver has to open the throttle when de-activating the overdrive. I don't have a throttle switch either but I blip the throttle when coming out of overdrive. If the clutch was meant to be depressed then the overdrive manufacturers would have issued instructions to do this..

 

[shortsguy1]

Sorry if this is old news to all of you, but this is a nice explanation of the overdrive system (by Anderson, Moment, and Russell) for beginners like me:
www.healey6.com/Technical/Tech-OverdriveTroubleshooting.pdf

 

[vette]

My perspective about the Throttle switch is as Derek has just mentioned. I know that it is ( or was not ) intended to be "just a piece of Kit". It had/has a realistic purpose when considering the masses of intended drivers that the manufacturers (not just Healey) intended to sell the cars to. Since the throttle switch is part and parcel to the circuit that insures the most possible longevity for the OD it is installed for just that purpose. Many if not most of the people that would be buying and driving a Healey or an MGB or a Jag would have no sympathetic notion about what is going on mechanically when they drive their cars. A little switch on the dash or elsewhere could easily be flipped at anytime by accident or with no regard to resultant driveline aberations occurring. The throttle switch is a safeguard to ensure that IDIOTS don't destroy their cars prematurely where by creating too soon call backs to the Service Department and corresponding bad ilk for the manufacturer and dealers. But once you are ENLIGHTENED and realize that the throttle switch is just an early and vintage form of todays automated Nanny devices in modern cars. (such as, stability & traction control ) then with enlightenment turn the dang things off and drive the car like a man's sporty car is ment to be driven. As to why the clutch was never incorporated into the literal procedure to use the OD, probably because it would just complicate the matter for the same group of prospective buyers as mentioned above. You might note that about the time the Healeys were being introduced to the public the concept of ease of use of everything especially for female drivers was a paramount consideration in all merchandising. Most auto manufactures where trying their darnest to bring out Automatic Transmissions. To eliminate one more use of a clutch would be a merchandising boon. So in consideration of all the previous, the way to use your OD is to say to use it anyway you want that doesn't cause some kind of damage. I find the clutch to be convenient because I know that at any time I can engage or disengage the OD with no driveline drama and that it will engage and disengage when I want it to. Which is immediate.

 

[John Turney]

When I bought my Healey some years ago, it didn't have a throttle switch or a driver's manual, and I didn't know it was suppose to have one. I decided that it would be appropriate to blip the throttle and/or use the clutch like shifting any other gear. Subsequently, I became aware it was suppose to have one, but by then I was in the habit of blipping the throttle or using the clutch. Since I wasn't going for concours and I had developed an appropriate habit, I never installed one.

 

[Bob_Spidell]

Well, I have the switch and have always hit the clutch just a bit on disengagement, but I'll give 'clutchless' a try. When I adjusted the switch per the book, it seemed to take too much throttle pedal to disengage, so I adjusted it 'by ear'--on the assumption that if there was absolutely no jolt in the drivetrain on disengagement life was good--and it was much more to my liking. Note 'by the book' sets by throttle opening only, which doesn't account for slack in Rube Goldberg's throttle mechanism. FWIW, my OD has almost 200K miles with nary a glitch that wasn't due to electricals.

 

[vette]

Well Bob, after 200K miles you must be doing something right. But I also can tell you that just go down with the clutch, flip the switch and come back up off the clutch. It couldn't be simpler or smoother. Just like shifting another gear.
It is encouraging to hear of the durability and accuracy that people are having with the throttle switch. I suppose that some day, if I ever wanted to, that would play a large part in any decision to go back to a throttle switch. But for me I rather doubt that that would ever happen. Years ago when I was putting my car on the road for the 1st time, I took a look at the potential sloppiness between the accelerator pedal and the switch itself and said, 'yeh right, I don't need that kind of gimmicktry". But I want to readily admit that some would consider it a convenience.

 

[Keith_M]

Interesting discussion. I never knew there were so many people running without a throttle switch, or that many people use the clutch to engage and disengage the overdrive. I'm going to have to try using the clutch now, although I doubt that I'll ever disconnect my throttle switch.

 

[vette]

If your throttle switch is still hooked up into the circuit then I think the result you get from using the clutch may be a little different than in my situation w/o a throttle switch. When let up on my clutch pedal after turning the OD switch off, I am definately engaging the driveline in "Real Time" with my clutch pedal because the OD will have shifted out. If you use the clutch when you still have a throttle switch you must realize that your OD will not shift out until you give the accelerator part throttle. Now that can be or could be almost all the times you shift out of OD because most people will blip the throttle just before they downshift. But know that it will take the use of the throttle to make it come out of OD. I like it my way w/o the throttle switch because at times I may be coming to a stop at a stop sign or traffic light and I may be just putting in the clutch and using the brakes. Maybe just a gentle stop or one where I didn't have the distance to give the throttle one more blip before the stop. When there is no throttle switch you know that anytime you hit the dash switch that it is going to down shift. With the clutch in it is just like coming to a gentle stop in any gear. Of course with your throttle switch the OD will drop out as soon as you touch the gas pedal, IF IT IS ADJUSTED WELL!