TR4a Overdrive conundrum - please help!

[AlanT]

Well I'd guess you are almost there.

 

No harm in rotating the shaft to get more valve lift.

If you really did over-do the lift then the accumulator will dump more rapidly and there will be more of a jump.

But you don't always get engagement so you are some way off this.

 

Loosen the clamp.

Power the solenoid so it goes right to the end.

Check the current falls back to holding value.

Position the lever so that the 3/16in pin is tight up against or a bit past the hole in the casing.

[Shuthonger]

Thanks for your reply Roger, apparently the file is too big. its only just over 2 meg but the limit 1.95.

 

I've just checked the movement on the lever and it moves only 1/4 of an inch or about 6mm where it is attached to the solenoid. I read somewhere (or maybe something on YouTube) that it should move 0.7 of an inch which is about 17mm.

Any ideas whats right?

 

Steve

[AlanT]

Can you get a 3/16 drill through the hole in the lever and mate the end into the main OD casing?

[Shuthonger]

I've just been for a test drive and it is just as before, fine when cold but failing to engage when hot, with the ammeter high on the scale, however, as I had the g/box cover off I could push on the lever on the other side to the solenoid and noticed a fair bit of resistance, like a tight spot, which when you went past, the solenoid did the rest and held it in. I did this many times with the electrics off hoping that it might free itself - but it didn't.

 

So I guess Roger was right, its gearbox out again (5th time) and back to the repairers.

 

I am losing faith in TR's to be honest. This isn't fun at all.

 

Steve

[Shuthonger]

Hi Alan, just saw your earlier post.

 

No, weirdly the holes line up when the OD is not activated and goes about 1/4 inch past the hole once the thing is on.

 

I know it doesn't make sense but there you are............. a mystery!

 

Steve

[Shuthonger]

Hi Mick R, just saw your earlier post too.

 

Sorry I don't know what oil is in the OD, its whatever was in there when is was re built a month or so ago. I didn't ask, but I will when I speak to him.

 

PS It definitely has oil in it!!

 

Steve

[Lebro]

This could be the problem, it should line up when O/D is enguaged.

Thes are the ST instructions for setting this up (from the TR2/3 service manual)

 

Remove the cover plate by unscrewing three cheese head bolts. Slacken off the clamping bolt on the solenoid lever.

Rotate the valve setting lever untill its 3/16" diameter hole lines up with the 3/16" diameter hole in the casting.

Insert a 3/16" diameter pin through the hole in the setting lever and into the casting thus locking the valve operating shaft.

Actuate the solenoid with a 12V battery and while the plunger is drawn into the solenoid, tighten the clamping bolt on the

solenoid lever and at the same time ensure that opposite end of the solenoid lever is against the head of the actuating bolt.

Repeat the first check and if satisfactory, refit the cover.

 

(the "actuating bolt" is the plunger in the solenoid)

 

Bob.

[RogerH]

Hi Steve,

the person that did the overhaul should have set the alignment correctly.

 

Do not give up - we are enjoying this.

 

Align the little lever with the hole in the casing and insert the 3/16 drill

On the solenoid side slacken the pinch bolt for the lever.

Lift the solenoid plunger and lever to the max up position and then tighten the pinch bolt.

 

This should get the lever in the factory set position

 

DO NOT give it a go.

 

It looks like when the OD was not energised it was half way there. And then when energised it was halfway passed the correct position.

 

get it aligned - it will work.

 

Get a workshop manual

 

Roger

 

PS - Bob beat me to it.

Edited August 27, 2014 by RogerH

[AlanT]

The operating valve, lever etc can come to bits with the gbox in situ.

 

I think there may be a bit missing in the assembly of the operating valve.

Ball-bearing, spring, washers, lots of little bit with this. All easy to drop and loose.

 

Or the shaft is upside down or some similar trivial mis-sassembly.

You must get the lever in the right place.

 

It's coming back to me now that maybe the operating valve can fall past the thing that lifts it.

You should try to remove the operating valve and get the shaft and lever in the right place and refit the valve.

 

http://vintagetriumphregister.org/maintain/TransRebuild/OverDriveA02.pdf

see Step 17

Edited August 27, 2014 by AlanT

[Shuthonger]

Thats it, Thats it, Thats It, thats it!!!!!

 

Full of despair I went out and thought, well if the gearbox is coming out again I may as well have a fiddle. I took apart the lever mechanism and reset it with the holes in line when engaged, instead of off! It took a couple of goes and hey presto it all works a treat. I've just been out for a long hard drive getting the car really hot and absolutely no problems. Brilliant!

 

Whats more I just know its right in my gut, so I am very confident its sorted.

 

I can't believe it was set up so far out, the shaft was passing the hole by a full quarter inch and as I mentioned before was almost in line with the holes when at rest. I guess it was nearly permanently engaged!

 

Although lining these holes up has been mentioned several times here, I just couldn't see how it would or could work if I brought it back so far. I guess from how it was set up the mechanism was jamming inside due to the excessive turn on the operating shaft causing things to come into contact which weren't supposed to. Bob and Roger H, thank you for your posts, they are what finally got me on the right track.

 

A lesson learned. if you want a job doing, do it yourself....... with some help from your mates on the forum of course!

 

To all of you, thank you very much. faith in TR's restored................. at least for now!!!

 

Cheers!

 

Steve

Edited August 27, 2014 by Shuthonger

[RogerH]

Hi Steve,

never lose faith in your 4A. It is old and delicate. It will break down.

Have a mobile and recovery insurance - go out and enjoy it.

 

The forum is here to help anybody that asks - was that a line from Harry Potter and Hogwarts.

 

Roger

[AlanT]

Lesson to learn are:

 

1. read a manual

 

2. read it again

 

3. if there is a mystery, mention it on here LOUDLY

 

4. post a picture, a shot of the lever in the wrong place would have solved this very quickly

 

Glad you are working.

Edited August 27, 2014 by AlanT

[Motorsport Mickey]

Given that the overdrive reworker has set up the operating lever so far out I should definitely confirm what oil it'd got inside.

 

Mick Richards

[AlanT]

I am wondering if the notoriously poor clamp worked its way around the shaft.

 

Can't believe it was set that way to start with.

 

I suspect it may slip around again.

[Shuthonger]

I was wondering about the activating lever and it's clamp as it does seem weak, the shaft is smooth and it could easily turn. Does anyone know if there is an uprated item available that I can fit while I'm at it?

 

Steve

[AlanT]

I've not seen any "up-rated" versions of this lever.

 

Clamps of this type wreck the clamping-bolt.

The edges of the folded metal cut into the thread and the shape of the thing makes the bolt go "banana-shape".

 

You may do better with a new hex-head cap-screw.

 

I reworked the central hole a bit to make sure it was round when done up to the right diameter.

You will realise that it goes out of round as you tighten it.

[littlejim]

I was wondering about the activating lever and it's clamp as it does seem weak, the shaft is smooth and it could easily turn. Does anyone know if there is an uprated item available that I can fit while I'm at it?

 

Steve

Steve it shouldn't be a worry gripwise, but you could simply cut/grind a bit out of the two bits the nut compresses, to get more 'gription'.

With all the advice that has flowed I'm not sure I should say anything further.

However my O/D was not engaging according to book when the thingo on the driver's side was lined up with its hole.

I put mine up on jack stands, with the hand brake on and kept adjusting it until the O/D cut in and stayed in. The 'line up' lever was noticeably above the 'hole' when I decided I was happy with its operation.

has worked perfectly ever since.

Won't mention adjusting the clutch, which again didn't follow the 'book' version, but has been good ever since.

[AlanT]

The best way to do this is with a depth-micrometer on the end of the operating valve.

 

You don't run the engine doing this and can click the solenoid o/off to check for repeatability.

 

These days depth mics are cheap:

http://www.ebay.co.uk/itm/Moore-Wright-Depth-Micrometer-/191305027088?pt=UK_Measuring_Tools_Levels&hash=item2c8aab0e10

[grimboh]

Hi Steve,

 

Sorry to wake up this thread after so long but I have exactly the same problem as you had. As the valve ball only has to move up 0.5-1.0mm only a small range of lever movement is needed to achieve that, and most of the initial movement is taking up the slack before the lever actually starts to push up on the valve.

 

Other than for the w/shop manual method of setting the solenoid 'accurately' I see no great relevance to where the lever actually is in relation to the hole lining up on engagement.

 

I also do not see how to set up the the actuation lever to be any different anyway, as it is determined by the crude 'cam' that pushes up the valve, along with the pin securing the position of the lever on the shaft - neither of which is adjustable as I see it.

 

So I am intrigued to understand what you actually did when you stated " I took apart the lever mechanism and reset it with the holes in line when engaged".

 

As I see it the real trick is the non-reliance on the lining up with a 3/16th drill bit and instead using a measuring dial gauge and if you do that then there is no relevance to whether the the holes line up when engaged.

 

I guess I must be missing something!

Thanks

Graham

Edited October 10, 2016 by grimboh

[dingle]

This part of the Buckeye articles really flogs the subject of adjusting the operating valve- http://www.buckeyetriumphs.org/technical/AOD/AOD4/AOD4.htm

The valve lift can be checked using a dial indicator, but is awkward with the gear box in the car. I think the bottom line is that the alignment hole should not be trusted. I set my lever for about .020" valve lift and it makes for very quick engagement. Also, I have found that when running the the trans/OD on a test stand, it takes much more effort to operate the valve lever by hand than a unit that isn't under power.

Berry

Edited October 10, 2016 by dingle

[Dic Doretti]

If you have to take the gearbox out again go to a specialist with a jig to enable the gearbox to be run using an electric motor. The overdrive can then be run up to its operating temperature and the solenoid operation and adjustment can be easily checked. Also they should have a gauge to check the oil pressure which activates the overdrive, this is produced by a piston operated pump which may marginal when cold and failing when the oil is hot and thin. I know Steve Craig, the Clyde Valley group leader can do this but there must be specialists down south which have this equipment.

 

Cheers Dic

[grimboh]

Thanks Berry and Dic,

 

As I didn't have a dial gauge and the GB is still in the car, just refurbed by Peter Cox, I didn't want to take it out again really.

 

So.... I looked at an alternative to measuring the valve ball lift. I used a 1/4" 6mm dia steel rod, about 6" long, and a metal ruler braced against a suitable part of the o/d case!

It worked a treat. The W/shop man says 1/32" rise on activation, about 0.8mm. That's enough to see on a good ruler. (Glasses needed in my case).

First I checked the rise with a 3/16th drill inserted per the manual, by taking it carefully in and out and checking the difference at the top of the rod as measured against the ruler. It seemed to actually be pretty close to spec.

So I then mounted a new solenoid and used the 3/16" drill method, activating the solenoid and tightening the solenoids' lever clamp.

 

I then retested using the rod and ruler. This is easier as the o/d lever switch is more accessible and quick to switch on and off, compared to my above description using the 3/16" drill bit.

So being able to switch quickly on/off allows easy repeated checking of the rod against the ruler. Looking for just short of a mm diff is perfectly possible.

 

Driver's seat back in, cardboard to protect from the prop shaft and off for a test drive. Worked perfectly and with lots of use!

Done a longer run again today - faultless, and with many many changes that one would not normally do in typical driving.

 

So this method works really well if the GB is in situ.

I agree the alignment hole should not be trusted, but to know how far off it is is very useful - and my case I was able to use that method and then my retesting after setting up showed that it was accurate. And then driving proved it in practice.

 

Cheers

Graham

[JPD]

I've had a few od problems recently and read this old thread with interest. My od has worked fine on 3/4th since I rebuilt the car (4A) 3 years ago. On 2nd the solenoid (new at rebuild) 'chatters' in and out. Sometimes the od will engage, but it soon drops out and the solenoid starts chattering again. The od has always reliably engaged and disengaged on 3/4th, until yesterday when the solenoid started chattering in those gears as well.

 

That's when I did a bit of research and came across this thread. I decided to remove the interior and check the lever and shaft position. It wasn't set up as per the WM - the setting lever was past the hole in the gb case by about 1mm, so I set it as per the WM, with the holes aligned when the solenoid was lifted. Went for a drive and the solenoid lifted with a good solid click, but no sign of the od engaging on any gear. I noticed that there was very little movement of the setting lever when the solenoid lifted. With the solenoid powered, I could manually push the lever well past hole, by about 4-5mm.

 

I then re-adjusted the setting lever so it went about 2mm past the hole in the gb case with the solenoid lifted. Went for a test drive and the od worked fine on 3/4th, but the solenoid chattered on 2nd. Back to how it was before.

 

So now I could refit the interior now and be happy with 3/4th working like I have for the last 3 years, or is it worth setting up the lever further past the hole to see if that gets 2nd working as well?

 

I don't know the operation of the system well enough to know why it won't work on 2nd but does on the others, or why it won't work with the lever set up as per the WM.

 

The gb has not been rebuilt and has Penrite GB40 in it. The level is good, in fact it was slightly over full when I checked it, so I allowed it to drain out of the refill plug.

 

Any suggestions welcomed.

 

Jeff

[peejay4A]

I can’t see how adjusting the solenoid would affect its operation in 2nd gear if it works OK in 3 and 4. I’d suspect the 2nd gear interlock switch. It might just need tightening down a touch.

[ChrisR-4A]

Jeff, check the spring and ball on the bottom of the gear-lever are still in position, if so then +1 for faulty switch on top of gearbox, try bypassing the switch just to test it but don't use reverse whilst doing this!