Jump to content

Recommended Posts

My overdrive has stopped. There is no click from the solenoid. I have checked the terminals on the relay and there is power to all points except C2.

 

This must mean that the relay is dead or am I making another faulty diagnosis?

 

Thanks

 

Richard & H

Link to post
Share on other sites

The relay will only pull in if the gearbox interlock switches are closed, which earths the W2 terminal and hence pulls current through the relay coil. What voltage do you get on the yellow/green wire which should be on the W2 terminal? If its 12v the interlock switches are open and the relay is not getting powered.

Link to post
Share on other sites

Hi Richard,

in the working condition W1 will be 12V and w2 will be 0V. (W2 will be grounded by the OD switch)

This will pull the contacts together so you get 12V on both C1 and C2.

 

If C2 has 12V on it then the solenoid should energise.

 

To check to see if the solenoid is working simply put 12V on C2 - no need to select a gear or even have the engine turning.

 

http://www.advanceautowire.com/tr24a.pdf

 

Roger

Link to post
Share on other sites

Hi roger,

 

I tried 12v on C2 last night and the solenoid was jumping well. So this must suggest the relay is at fault.

 

What is the number of the relay so that I can look for old stock on the internet. 6RA does not look the same as my installed unit.

 

Thanks

 

Richard & H.

Link to post
Share on other sites

Have you really eliminated the od switch and interlock wiring? I'm not so sure. To follow up on RobH suggestion - with the ignition on and od not selected you should read +12v on one side of the switch and continuity to earth on the other side with the gear lever in an od position (2,3 or 4). Then with the switch operated you should see 0v on both terminals of the switch. If you don't see these conditions then you have a switch or transmission interlock fault. If you do see these conditions and the solenoid still doesn't work then the relay is suspect.

Edited by peejay4A
Link to post
Share on other sites

Richard (& H)

 

From your description of seeing 12V on W1 & W2, fault is more likely to be, in order of probability:

 

1) wiring disconnected somewhere between W2 on relay, & the isolator switches (goes via the manual O/D switch)

2) wiring from other side of isolator switches not going to ground.

3) failure of manual O/D switch

4) mal adjustment of the height of both isolator switches

5) failure of both isolator switches

 

Bob

Link to post
Share on other sites

Hi Richard,

OK the solenoid is working.

 

To test the relay -

Ignition on. This will give 12V to W1.

 

Connect a new wire to the W2 contact and the other end of the wire grounded.

 

The relay should now click along with the solenoid.

 

If the relay clicks but not the solenoid then the relay 'C' contacts are dicky.

If the relay does not click then the relay is dicky.

 

The isolator switches on the GB can go out of adjustment.

 

Roger

Link to post
Share on other sites

I found my switch was getting slow to operate and i thought it was on its way out so i ordered a new one. When i took the old one off i took it apart i found the only thing wrong with it was old lubricant had gumed up the flick part and after a clean up and new lubricant its good for another 50 years.

Link to post
Share on other sites

Hi Richard,

do you really want a Lucas 6RA - a new one will be dodgy from day one, A NOS will be expensive.

 

Why not use a modern quality equivalent -

http://www.vehicle-wiring-products.eu/product.php/642/12v-4-blade-relay

 

Type 'A'

 

You can also get a socket for it or a simple mounting tag.

 

Roger

Hi Roger,

 

I have cleaned off the connections for C2 and there is still no action. A direct 12v feed to C2 makes the solenoid jump. Connect W2 to earth and the relay clicks. So now I have given up

 

I have ordered the one you suggested but I need help with the connections which are not numbered as on my original relay. This may be a very old fitting because the terminals are screw on. I found a nos on ebay for £70.00 and decided to take your advice and start again with a modern relay. which should work first time.

 

I will try again in a couple of days when the new one is here.

 

thanks Richard & H.

Link to post
Share on other sites

There are a couple of combinations which will work equally well because you can connect the coil and contacts either way round, but this will do:

 

86= W1

85= W2

87= C1

30= C2

Link to post
Share on other sites

Hi Richard,

as explained by myself and other putting 12V on the C2 should and did make the solenoid function. That eliminates the solenoid.

Earthing W2 makes the relay click - this shows that the winding is good.

You now need to connect it all as standard - switch on Ignition, select 4th and select OD - if it doesn;t work then that puts suspicion on the oD switch, the inhibit switches and the wiring.

 

If you have a Ohmmeter (or light bulb) you could check the continuity of the wires and inhibit switches - break into the wiring leading to the top of the gearbox and with one meter lead and the other to earth - this should show a short circuit (this is good).

You could do the same to the two wires from the dash switch and check that for continuity - in the ON position there should be a short circuit.

 

Report back

 

Roger

Link to post
Share on other sites

Hi Richard,

 

I've been following this with interest, having had similar issues in the past. In post #11, you say you've given up, but don't despair! If you look back carefully at Roger's post #8, I do wonder whether you might actually have identified the problem.

 

When you ground W2 with the ignition switched on (i.e. 12v on C1), both the relay and the solenoid should click. If only the relay clicks (which is what your note says) then, as Roger pointed out in the earlier post, this almost certainly means that the relay contacts are faulty, most likely burnt. In this situation, I've had success by gently prising apart the 6RA casing and then using a points file to lightly dress the contacts. Once this has been done, they never seem to last as long again but you can just repeat the exercise if necessary.

 

Hope this helps - fingers crossed.

 

Regards

Mike

Link to post
Share on other sites

I don't have the Lucas 6RA. My relay is flat and the terminals are held on by a small screw. It has been working for over 20 years and I was always worried because one terminal points upwards and the other three are along the other side pointing downwards. the top one is very close to the heater and I have insulated it with a small tube covering the terminal. When this is over I will find out the number and open it up to see what is going on inside..

 

I am back on the car on Friday. I will report how the new relay works.

 

Thanks R&H

Link to post
Share on other sites

Fine sunny weather and free time to spend on the car. It must be my ideal summer week end.

 

I unscrewed the connections on my existing relay and temporarily connected the new relay. It has flat blades and my existing has screw on. I had some new flat blades but was hesitant about cutting off the ring terminals which would be difficult to find new and solder on if my existing relay was OK.

 

The new relay failed to click so I ran an earth to W2 and it worked instantly. This leads me to the switch and the gearbox switches. I have a flick switch and took out the three screws, which are very tiny, and made sure there were no lost parts by using a newspaper on the car floor. The switch falls in two parts and it was immediately clear that one terminal was not connected. It was a 30 second job to fit it and the relay instantly clicked.

 

I had the original circular terminals still on the relay wiring and cleaned up all contacts. A quick trip out to the garden machinery shop on a different mission, and the o/d worked fast and well.

 

I am very lucky because the next stop was to remove the gearbox tunnel and that is the one job that I am really fed up with.

 

While I was out in the garage I found a 6RA relay in the redundant parts shelf, but it seems to have only three terminals.,C1, C2 and a double. This would mean a different wiring layout to my new relay which has W1 & W2 making a circuit which pulls in the contact for C1 & C2.. How does this 6RA work?

 

Thanks very much for all the advice and help. It was a beautiful evening to drive back from my daughter's house on empty country roads with with the o/d working and my dog Harry beside me in the TR3.

 

Thanks

 

Richard & H.

Link to post
Share on other sites

Hi Richard,

 

Glad to hear that you've sorted your relay problem and the overdrive's now back in full working order.

 

Lucas seem to have made a number of variants of the 6RA relay - there's some useful information detailing some of these on the following link:

 

http://tvrna.tvrccna.org/lucas/lucas-relays-6ra.htm

 

In terms of the 3-terminal relay you've found, see the following links (sorry about the MGB one!):

 

http://etype.chrisvine.com/tag/6ra/

http://www.mgb-stuff.org.uk/relay.htm

 

Hope this helps

 

Regards

Mike

 

PS Roger, if you scroll down the MGB link, it explains how the 3-terminal set-up works

Link to post
Share on other sites

Hi Richard,

I believe your three terminal 6RA uses the body/case of the relay as the earth contact.

 

Roger

Not if it's a horn relay. 3 terminals only. Mike's links above show the internal connections.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.