"J" Type Overdrive stopped working

[zelger]

My "J" Type overdrive has worked fine for the year I have had my TR6 - it has always switched in and out reliably with no hesitation, then one day it just stopped working.

Having trawled forum posts for suggestions I tried the following:

   1. Topped up the gearbox oil
   2. Engaged 3rd with ignition on, switched in overdrive and heard solenoid click in and out as expected
   3. Cleaned up both spade terminals at the solenoid to make sure the connections are sound

Any suggestions what to check next?

[Richard B]

455 wrote:

   2. Engaged 3rd with ignition on, switched in overdrive and heard solenoid click in and out as expected
    

Sure that was the solenoid? J'types are very quiet. Could it have been the OD switch that clicked?

Jack it up and check you have 12volts getting to the solenoid when it's engaged?

[Clive]

Not with workshop manual, but maybe the o rings on the solenoid, easy enough to check. Not sure about filters,  think they are under the sump??
But def check the solenoid is moving properly first.
clive

[rotoflex]

Obligatory link to overdrive info on Canley Classic's site:
http://www.canleyclassics.com/infodatabase.asp?article=overdrivesjtype

This guy makes up diagnostic pressure gauges for the J-type overdrive (and also gauges for the A-type), & sells them on ebay US for $50.  If you want one, you could send him a message:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120370559827
(Item # 120370559827 )

[Bob Bowling]

Check the electrics. The clicking you heard may have been a relay installed in the circuit to ease the load on the switch (I did just that when I fitted mine, and with the ignition on, when you move the gear lever into 3rd & 4th position I hear the click of the relay)
Make sure you are getting a good supply to the overdrive, the terminals are quite exposed and it doesn't take much reduction in the current (12 volts at the terminals doesn't mean there is enough current to do the job) getting through to stop it the overdrive working.

[Doug Paterson]

When done with the electrics, if no joy, next things to do would be (in my view)

drain the oil completely and change it.  To get all the old stuff out you're best to remove the sump cover on bottom of the OD - so you'll want to order a new gasket first.

While in there, clean the low pressure filter and if you have a means of getting the plug out, clean the high pressure filter too.

blockages can contribute to preventing the OD behaving.

The pump and pressure relief valve are trickier (and surprisingly expensive) so if all else has failed a replacement unit might become worth considering.  Not as expensive as you might think - I replaced mine after months of tinkering in October and the difference is fantastic.

[monty69]

Clean or chance filters and replace the oil

If it where a MGB overdrive I would say broken (what is) washer! that falls out when you take the filter out, its either item 69 or 70 on the buckeyetriumph diag.

This interesting reading

http://www.buckeyetriumphs.org/technical/jod/JOD1/JOD1.htm

[zelger]

This has been a really useful thread in terms of troubleshooting J Type overdrive problems.  I also found the article by Steve Ash on "Overdrive Electrical Connections" in the November 2008 issue of Club Torque invaluable - in fact, it was that article that eventually helped me trace the fault.

I started off with the view that electrical faults were most likely, but since I thought I could hear the solenoid click in, I was all set to turn my attention to other things - the first being a gearbox oil change and good cleaning out of whatever filters I could access (and I was going to use Castrol XL20/50 rather than EP90, having researched suitable oils for gearbox/overdrive).

So the red herring was thinking that I could hear the solenoid click in, but with the bonnet up it was soon clear that it was the relay I could hear clicking, not the solenoid.  That is when Steve Ash's article came into good use. Having learned that there were two feeds from the fuse box to the relay (one to power the relay and the other to power the solenoid) and discovering that the one that powered the relay was good but the one that powered the solenoid had no power, it was easy to trace back and fix the problem with the wiring from the fuse box.

Thanks to all for their help.

[Tim Bancroft]

BTW that is a nice looking TR6.

[Greeks]

timbancroft61 wrote:

BTW that is a nice looking TR6.

... I agree, looks great. Nice to see a TR6 that isn't red.

And I like the wheels a lot, in fact they're the colour I want on mine.