Jump to content

Overdrive in 2nd gear and logic switching (moved from "miss-fire over 4000 rpm"))


Hamish
 Share

Recommended Posts

Moved from Greta's "Miss-fire over 4000 rpm" thread

https://sideways-technologies.co.uk/forums/index.php?/topic/8993-misfire-4000-rpm/&tab=comments#comment-130401

 

 

my 2nd gear OD has been used a lot but i suspect a different box and switch arrangement alloy switches are on the top.

its an early tr6 box

later tr6 boxed have switches on the side of the top case remote.

H

Link to comment
Share on other sites

Hi Hamish. I've got the 3 rail gearbox in the wee car which has a different switch arrangement to the TR/Saloon boxes.

The remote has an extension with a cam and a switch on a bracket out front. This is a pic of a GT6 box with the selector switch on the gearlever but basically the same. The reverse light switch is under the extension

724628511_Gearbox--Overdrive.jpg.1a593be83d513ad0db13f7fa96e97ab4.jpg

Edited by Escadrille Ecosse
Link to comment
Share on other sites

10 hours ago, Escadrille Ecosse said:

I am interested in the second gear OD option for the Spit. I would prefer to go the second inhibitor switch route if anyone had info on that?

Hopefully this is legible and doesn't upset anyone for copyright reasons... :whistling:

Courtesy of Dirk Devogeleer and Club Triumph:

DSC_8488.thumb.JPG.49630b836d81e84af76434cf2f43ea23.JPG

Close-up of the circuit diagrams - original at top, modified version beneath. 

DSC_8485.thumb.JPG.84704a283ea1f12b232be72bcfd6f855.JPG

Link to comment
Share on other sites

Thanks @PeteStuppsI was thinking of the second switch when I wrote my post but I might have a look at that. Just slightly concerned at having to remember not to use it in first :biggrin:

@mpbarrettI'm curious about your comment about dropping out between 3rd and 4th. How does that work with the selector switch on the column/gear lever?

@Gretamy apologies for hijacking your thread :ninja:

Edited by Escadrille Ecosse
Link to comment
Share on other sites

That looks sort of OK except the indicator lamp in series with relay 2 coil.  As drawn they would both have to be 6v items. Both relay2 coil and the lamp need to be in parallel to be 12v ones. 

(If it is a J type I would have taken the earth returns for relay 1 and the solenoid both through the interlock switch.  That way the OD is still inhibited in 'wrong' gears even if the relay sticks closed. )

 

 

 

Link to comment
Share on other sites

For those like me without electrickery understanding revington tr do them at a cost 

https://www.revingtontr.com/engine-transmission/gearbox/logic-overdrive-device

it’s what I use. They use the switches on the box.

going up the box is fine but on the way down it’s trickier eg 3rd od to 2nd is a big step. As you need to move the gear lever or flick the switch out by hand.

a momentary switch on the dash to engage up and a clutch switch to disengage would be good. Just dip the clutch and no gear stick waggling would work.

but you can’t have the clutch switch operating the od or every gear change would be trying to operate the od.

you see it’s beyond me already. 

Link to comment
Share on other sites

2 hours ago, andymcp said:

OLB.jpg

This is a neat solution, I like it. Mind if I copy it?!

57 minutes ago, Hamish said:

a momentary switch on the dash to engage up and a clutch switch to disengage would be good. Just dip the clutch and no gear stick waggling would work.

Hamish this is what andymcp's circuit does (in case it's not apparent!), the clutch only disengages. To get OD on 2nd as well you'd need to lose the 3rd/4th inhibitor - think it's slightly different on the TR box though. For my 3-rail Spitfire I would stick with OD enabled on all forward gears, with a changeover relay driven off the reverse-light switch to inhibit on reverse as it does now. The clutch would disengage OD if I ever accidentally left it on and dropped down into first. 

Here's my current messy circuit diagram, which relies on a warning lamp and good luck to avoid accidental OD in low gears. Ignition-switched power is sourced from green wire on left, which flows through changeover relay to the OD column switch unless the reverse switch operates. 12V from column switch then operates the OD relay to energise the solenoid. Lamp comes on as soon as the OD relay operates. It works as expected, lamp is a bit too bright for night driving but at least it's noticeable. 

_20210909_214928.thumb.JPG.c01a6db7dec3819f34b287af50e7d4ed.JPG

(Sincere apologies @Greta for the massive thread drift!)

Link to comment
Share on other sites

23 hours ago, Escadrille Ecosse said:

 

@mpbarrettI'm curious about your comment about dropping out between 3rd and 4th. How does that work with the selector switch on the column/gear lever

there are 2 switches on the gearbox one for third and fourth gear and the standard reverse and and momentary push switch to select OD. 
All the logic is done in software in a 8 pin Microchip embedded processor. It drive a relay to power the OD and another relay to turn the reverse lights on and turns on an LED when OD is engaged (the LED flashes when in reverse, why because I can).
Basically the logic is if in reverse OD is disabled, and can only be selected if in 3rd or fourth. Press switch to turn on and again to turn off.
I had planned to measure the car speed (sensor on prop UJ bolts)  and then turn OD on automatically above a certain speed....
Can give you more details if you want.

mike

Link to comment
Share on other sites

  • Nick Jones changed the title to Overdrive in 2nd gear and logic switching (moved from "miss-fire over 4000 rpm"))

Cheers Mike. That's really interesting and helpful and I understand what you've done there.

I am rather like Hamish in respect of the processor based logic control though. It's way beyond my comfort zone.

However a logic based control for the OD makes so much more sense than the very basic mechanical switch and interlock from the 1960s.

I am very tempted.

Link to comment
Share on other sites

could be done in a small (nano) Arduino. Cheap to play with, plenty of 12v power 5v activated relay boards on Amazon etc so easy to put something together.
Just need to be careful with the power supply design for the processor as I have found that the Ardunio do seem susceptible to noise on the power supply lines when used in car applications. Worth implementing the built in watchdog timer in the code just in case it crashes.....

Mike

Link to comment
Share on other sites

1 hour ago, mpbarrett said:

could be done in a small (nano) Arduino. Cheap to play with, plenty of 12v power 5v activated relay boards on Amazon etc so easy to put something together.
Just need to be careful with the power supply design for the processor as I have found that the Ardunio do seem susceptible to noise on the power supply lines when used in car applications. Worth implementing the built in watchdog timer in the code just in case it crashes.....

Mike

Mike you are great and very polite is assuming I properly understand even 50% of that. :biggrin:

I now need to go and look up Arduino, activated relay boards, automotive power line noise, watchdog timer and coding and I should be a bit more up to speed :thumbsup:

Sorry, not being cheeky it's just that I realise how far things have moved on since I was playing with electronics 40 odd years ago! 

Link to comment
Share on other sites

53 minutes ago, Escadrille Ecosse said:

Sorry, not being cheeky it's just that I realise how far things have moved on since I was playing with electronics 40 odd years ago! 

At the user level things have got infinitely more powerful and probably easier to use.  At the design level....... forget it!

Speeduino is a family (extensive family these days) of engine management ECUs based on the Arduino platform.  Offer a high features, low price alternative to Megasquirt. Chris has one controlling the Spitfire injection etc.  It was a fairly troublesome experience (mostly but not entirely resolved) and sensitively to noise has been one of the big bugbears with it.

Link to comment
Share on other sites

22 hours ago, Escadrille Ecosse said:

I am rather like Hamish in respect of the processor based logic control though. It's way beyond my comfort zone.

... and dare I say it , rather OTT in my opinion (but each to his own).  Perhaps it's because my electronics training came long before PICs were even dreamed of but I was always taught to keep things as simple as possible, commensurate with the function required.   

 Two relays is all you really need for the 'logic' as per Andy's circuit above. Even if you want to get complicated and have only one momentary switch to operate it on and off, the most you need is a couple of transistors in addition. Since this is a fixed-function device there is absolutely no need for programmability, and voltage glitches don't affect relays. 

Link to comment
Share on other sites

1 hour ago, DeTRacted said:

... and dare I say it , rather OTT in my opinion (but each to his own).  Perhaps it's because my electronics training came long before PICs were even dreamed of but I was always taught to keep things as simple as possible, commensurate with the function required.   

 Two relays is all you really need for the 'logic' as per Andy's circuit above. Even if you want to get complicated and have only one momentary switch to operate it on and off, the most you need is a couple of transistors in addition. Since this is a fixed-function device there is absolutely no need for programmability, and voltage glitches don't affect relays. 

So then, going back to this circuit from Andy

On 9/10/2021 at 11:37 AM, andymcp said:

OLB.jpg

Would it be possible to achieve the clutch dropout function by filing a slot at the neutral position of the 3rd/4th interlock cam?

 

Link to comment
Share on other sites

2 hours ago, Escadrille Ecosse said:

Would it be possible to achieve the clutch dropout function by filing a slot at the neutral position of the 3rd/4th interlock cam?

Hello All

             I haver done that on a single rail gearbox I made a new cam and it works on 2nd as well and fitted an extra switch

I have also done it on a 3 rail gearbox but just for 3rd and 4th (can not find photo will look later)

DSC08443.JPG

DSC08448.JPG

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...