help! overdrive weakness threatens TR's presence at cLM

[hpremote]

Morning chaps: After twenty-odd years of perfect operation, the 3's o/drive has been playing up over the past 6 weeks or so. No untoward reason I can think of, except perhaps less use than usual over the winter/spring months.

 

The symptom is: intermittent engaging of o/d in any gear when I switch in; more recently it has not engaged at all. I have listened for the familiar "click" on pulling the dashboard switch, and the click is there, but not so loud as when it's actually bringing o/d in. I've checked the relay, which is clicking as usual.

 

This morning I took the car for a rip down the A1 with the g/box tunnel off. I found that after pulling the o/d switch, overdrive would engage immediately and strongly - but only if I reached across and helped the plunger rise with the aid of a push from my finger. For obvious reasons I am reluctant to drive to LM with the tunnel off, and with my passenger manually operating my seven gears...

It may be too late for me to sort this by departure time for Le Mans, in which case I'll use the Tiv - but it's the TR I want to use.

Any ideas, please?

Cheers in advance,

Tim.

[david ferry]

Tim,

 

Check the rubber cover isn't restricting the solenoid plunger's movement.

 

This is a problem with the new solenoids, I suspect yours isn't new but one never knows!

 

When you and the TR get to Le Mans, make sure you pop over to Mark Hoble's paddock garage (plateau 2, car 3) where you'll find the whole of Team Hoble, the winning TR2 from 2 years ago, and some refreshing beers!

 

David

[Dave Larnder]

Morning chaps: After twenty-odd years of perfect operation, the 3's o/drive has been playing up over the past 6 weeks or so. No untoward reason I can think of, except perhaps less use than usual over the winter/spring months.

 

The symptom is: intermittent engaging of o/d in any gear when I switch in; more recently it has not engaged at all. I have listened for the familiar "click" on pulling the dashboard switch, and the click is there, but not so loud as when it's actually bringing o/d in. I've checked the relay, which is clicking as usual.

 

This morning I took the car for a rip down the A1 with the g/box tunnel off. I found that after pulling the o/d switch, overdrive would engage immediately and strongly - but only if I reached across and helped the plunger rise with the aid of a push from my finger. For obvious reasons I am reluctant to drive to LM with the tunnel off, and with my passenger manually operating my seven gears...

It may be too late for me to sort this by departure time for Le Mans, in which case I'll use the Tiv - but it's the TR I want to use.

Any ideas, please?

Cheers in advance,

Tim.

 

Hi Tim

 

May sound silly, but is the oil level in the gearbox/overdrive full?

Dave

[hpremote]

Thanks, David and Dave, for your quick responses.

First, Dave - yes the g/box level is fine. It's something I am always mindful of, and check after a long drive and at 3k services.

 

David - I don't think there's ever been a rubber cover at the bottom of my car's solenoid; the plunger (that part which is brought up electrically to operate the o/d)is exposed to the elements - but doesn't look gunged up. There is a rubber cover at the top of the solenoid unit - and of course there's a rubber gaiter (slightly holed in my case) halfway up the unit.

So I'm still scratching my head on this one.

And thank you so much for your invitation to come to the Team Hoble garage; I am already impatient to be there! I admired the Hoble 2 at cLM in 2008; it will be great to watch it once more.

 

No, the feeling I have from watching (and helping) the o/d engagement process, is that somehow there is a lack of the usual electrical force to bring the plunger up with sufficient impetus. I haven't yet gone into the reckoning of clearances with feeler gauge, etc., but may try researching this in the TR bible, later today or tomorrow.

 

Cheers again,

Tim.

[Tr4Tony]

Tim

 

I suggest you check the relay on the OD circuit and the earths that run to the top of the casing and the relay / solenoid. A bad connection or grubbed up relay would cause intermittant engegement of the OD as the current isnt passing through to hold the solenoid 'on' when engaged.

 

Also, worth checking the adjustment on the actuation lever on the OD unit (side opposite the solenoid), the various manuals show you how.

 

Regards

 

Tony

[Don Elliott]

I agree with Tony's last suggestion. There have been reports recently that you may need to add (or subtract) a bit to the adjustment of the drill in that hole for "proper" alignment so as to simulate more roation of the shaft that goes from the solenoid lever which you are pulling up manually.

 

In 2000, the overdrive solenoid on my 1958 TR3A failed just before I was to leave on a 7250 mile round trip from Montreal to Portland, Oregon so I removed the carpet, drilled a hole in the tunnel and jury-rigged a length of steel coat-hanger wire to go through that hole and hooked it around the lever that you were pulling up with your finger. On the top end I made a fully closed loop and hooked a stretch-elastic bungy cord about a foot long which I pulled up tightly to engage the overdrive and hooked the top end around the knob for the choke cable. It work fine for 3535 miles till I got to Portland where a new solenoid I had pre-ordered was waiting for me.

 

After installing the new solenoid, I made it home (by a shorter route) with no issues.

 

BTW, after I parked the TR on the showfield, I removed the hardware and re-installed the carpet. They awarded me the "Longest distance driven award to the event in a Triumph" as well as 2nd in the judged concours competition.

[ianc]

As your overdrive has been operating for many, many years, it is quite likely that there is bad contact on the INSIDE of the solenoid, such that the pull-in coil is not being energised - see my article on page D-49 of the Technicalities CD. Your description of the symptoms suggest that this could be the problem, because you had to pull it into engagement. A short-term answer could be to clean the contact faces, but this may not work for very long if they are badly pitted (quite likely after this length of time!).

I have seen the contact arm break away after many years of operation, and this would have the same effect.

A new solenoid can be the best fix - but don't forget to set it up as per the manual!

Ian Cornish

[hpremote]

Tony, Don and Ian: thank you for the extra comments and advice.

 

Tony: the relay does seem to be OK; I had already checked the contacts, and of course the relay "click" is audible on operation of the dash switch.

The actuation lever adjustment is the next port of call. I will check the alignment of the holes using the 3/16" twist drill. Will also check for the 0.150/5" clearance between the rubber stop and the plunger.

 

Don: I really appreciate the coat-hanger system you rigged up for your trip - that is just my style! It sounds from your story that the solution for you was the purchase of a new item due to the ultimate failure of the solenoid itself - as suggested by Ian.

 

Ian: very useful word to the wise on the mortality of the solenoid unit - I had always put blind faith in the notion that the 2nd law of thermodynamics doesn't apply to this component, since it has always been faultless (and I got the 3 back in 1975).

I will check D-49 on the CD. I had not thought to dismantling the guts of the solenoid, but I'm always game for a laugh. The other solution in my case re. this unit, is a place called Autodiesel on the Newcastle Quayside - a miracle worker for all things electrical.

The bu**er on this is that as I work in London 4 days a week, it is now less than likely that I'll have resolved the issue by set-off time on Weds. evening - so, much to my chagrin, it looks as if an alternative (and probably less reliable) set of wheels will be pressed into service.

Cheers, all,

Tim.

[Don Elliott]

Tim - Drive the TR. Just don't use the overdrive. You'll get more pleasure with the TR sans O/D than with your modern Euro-box.

 

I kept the solenoid that failed before my long long trip in 2000 and took it apart when I got home again. I had to re-solder a tiny wire back onto the entry lug. The Solenoid reads "Lucas 1954" and I kept it as a spare. About a year later the newly purchased solenoid failed so I have been running the 1954 solenoid for the last 9 summers with no solenoid issues for a total of 51 years now. I dismantled the "new" repro solenoid and found that the top was filled with RTV silicone and I found a round piece of white RTV silicone - the size of a green pea wedged between the contacts at the top inside the unit. I removed it.

 

There's another case of poor quality with repro items. I removed the "pea" and tested the solenoid. It works fine and I carry it in the boot as a spare - just in case.

 

To make the job easier in the future, I cut 3 holes, the larger one for access to the solenoid and the two higer up to permit a very long screwdriver to reach down to un-screw the straight slotted scrs retaining the solenoid to the casing. The large hole uses the same large rubber plug as for the floor jack.

Edited July 4, 2010 by Don Elliott

[hpremote]

Don: thanks for the exhortation!

However, while I would certainly rather be travelling to cLM in the TR (we'll be in convoy with a number of Northumbria TRs) the one upside of this is that at least I won't have to use a Eurobox to get there. I don't own one; I am left to choose between a slightly souped-up Morris Minor and a TVR Chimaera - and purely because of the initials (ahem) it is no contest: I'm taking the Chim.

Not as basic as my 3, with its aeroscreens, straight-through exhaust and lack of carpets - but enjoyable in its own way - so long as nothing breaks - always a fair possibility with a Trevor.

Because of the sustained high speeds at which the convoy will travel, I will not subject the TR engine to sans-overdrive torment. I know I just wouldn't be happy with four, rather than my usual seven gears!

 

Very useful pointers re. the dismantling and resuscitation of the solenoid, too; those pics are fantastic. I will get stuck into this task when I have a few days free, later in the month.

 

I'll post a follow-up when I have news.

Cheers,

Tim.