OVERDRIVE WOES

[John McCormack]

Reverse gear on my TR3 packed up (broken layshaft tooth) so I pulled the gearbox and removed the overdrive. I put the od away in the garage while I repaired and overhauled the gearbox. 

Yesterday a mate and I reattached the overdrive to the repaired gearbox. No issues, it went on with the normal adjustments of the mainshaft and overdrive.

Now it was all together we tested the gearbox and overdrive on his test bed. Gearbox works nicely but the overdrive doesn't engage. It worked perfectly before it was removed from the box and it was not touched during the gearbox work.

We have 20 thou lift on the ball valve, 400 psi oil pressure. The 8 springs are all the same length and weren't removed from the overdrive anyway.

Pushing the od lever manually there is a small change in noise a bit like the overdrive engaging, but it isn't engaging. This morning he tested it with an rpm gauge and the output flange is not changing speed.

The output and input rpm is the same so the od is not stuck on.

A member who is a gearbox and od professional suggested the clutch might be stuck so give the box a decent tap on the joint where the clutch is with a copper hammer. We tried this with no success. 

It is looking like we will have to remove the overdrive but as it was working fine before it was removed for the gearbox repairs we have no idea what we might be looking for.

Any pointers before we remove the od or inside the od if we have to get it off.

Edited November 15, 2023 by John McCormack

[John Morrison]

Hi John

clean the operating valve replace and then reseat the ball bearing 

Finally have more than one attempt at setting the operating lever

John

[John McCormack]

5 minutes ago, John Morrison said:

Hi John

clean the operating valve replace and then reseat the ball bearing 

Finally have more than one attempt at setting the operating lever

John

Thank you. Unfortunately done a number of times already.

[Trumpy3]

Hi, I'm the mate who is helping. Have built a number of both A and J ODs. With the oil press gauge connected and input rpm at 2500 and in top gear ( my tester drives from the gearbox input) I can actuate the solenoid or manually actuate the leaver and there is a very slight change in noise, no change in output speed. On activating the control valve there is a very slight flicker on the pressure valve, no where as large as all the other boxes I have tested.

The control valve has been removed, cleaned and reset a number of times. The ball lift is set to 0.020".

The box is nice and quiet.

Suggestions ?

.

[Drewmotty]

Maybe a stuck clutch. It might free with a bit of load on it. 
I’d strip the front end of the overdrive while it’s on the bench. 

[John McCormack]

19 minutes ago, Drewmotty said:

Maybe a stuck clutch. It might free with a bit of load on it. 
I’d strip the front end of the overdrive while it’s on the bench. 

Very much a possibility thanks. The tap on the casing with a copper hammer was intended to release it but this one may require a more direct approach. 

The next question is why it is stuck. It isn't uncommon on overdrives that have been left in storage for a long time, but this box was being used only 6 or so weeks ago. I didn't do anything to the overdrive while it was off the box, didn't even clean it as the oil I drained out was clean.

[Rob Salisbury]

Hi,                                                                                                                                                                                                                                                                                                     This maybe a minor point but I seem to remember the springs should be different lengths, 4 long 4 short and colour coded red and yellow (long springs on the outer ring).                 Cheers Rob

[Trumpy3]

Rob

This is an older unit and is fitted with 8 same length springs.

Tried "tapping" to free any stuck clutch. No success. Although assured by John that the oil level is correct, I will put more in today just in case. Would be embarrassing to pull it apart and find it only needed oil. I do not think that is the problem as we have oil pressure. This box does not have the fill level plug on the side and only relies on a dip stick to get correct level.

I think it will be OD off.

Brian

[BlueTR3A-5EKT]

12 minutes ago, Trumpy3 said:

Rob

This is an older unit and is fitted with 8 same length springs.

Tried "tapping" to free any stuck clutch. No success. Although assured by John that the oil level is correct, I will put more in today just in case. Would be embarrassing to pull it apart and find it only needed oil. I do not think that is the problem as we have oil pressure. This box does not have the fill level plug on the side and only relies on a dip stick to get correct level.

I think it will be OD off.

Brian

I have never come across all 8 springs being the same length on a TR ‘A’ type overdrive.

image from TR2 service manual.

 

[Trumpy3]

Peter

I seemed to remember I had read somewhere that the early ODs were all the same length, as these were. Have not been able to verify that but reading the Buckeye Triumph write up on the A type OD, it gave me a thought and possible cause of our problem.

When John removed the OD he did not disassemble it except a couple of clutch release springs fell out and he refitted them. When we fitted the OD we had removed all of the springs during the preparations and refitted them. As I thought they were all the same, and looked it, I did not take a close look. They all looked the same. When Buckeye did their rebuild the first time they had the same problem as we do. Turns out they had spring bind that prevented the clutch from activating.

Looks like OD of and some spring examining. Thanks for the note on springs Peter.

Brian

 

[John McCormack]

6 minutes ago, Trumpy3 said:

Peter

I seemed to remember I had read somewhere that the early ODs were all the same length, as these were. Have not been able to verify that but reading the Buckeye Triumph write up on the A type OD, it gave me a thought and possible cause of our problem.

When John removed the OD he did not disassemble it except a couple of clutch release springs fell out and he refitted them. When we fitted the OD we had removed all of the springs during the preparations and refitted them. As I thought they were all the same, and looked it, I did not take a close look. They all looked the same. When Buckeye did their rebuild the first time they had the same problem as we do. Turns out they had spring bind that prevented the clutch from activating.

Looks like OD of and some spring examining. Thanks for the note on springs Peter.

Brian

 

I didn't think we removed the springs from the overdrive. I hadn't taken them off the overdrive before so if we did remove them at your place that might explain it.

[BlueTR3A-5EKT]

8 hours ago, John McCormack said:

I didn't think we removed the springs from the overdrive. I hadn't taken them off the overdrive before so if we did remove them at your place that might explain it.

If the springs are fitted they all look the same length as they must sit level to the adaptor plate.   They are physically different lengths to compensate for the step that 4 of the springs sit on. 

[Dic Doretti]

I usually find the springs are counter intuitive, the short springs appear slightly longer when fitted.

Cheers

Richard

[Trumpy3]

Problem solved.

I had inadvertently interposed one inner and outer clutch springs. That meant one of the springs bound up and prevented the pistons from engaging the clutch.

Started to remove and examine the OD after breakfast and sent it home with the owner after testing just before lunch. Easy fix

Brian

[Lebro]

Well done (for finding it, not causing it !!)

Bob

[John McCormack]

Put the box back in today and all is good. A short drive without the tunnel to test it. Then reassembled the car fully and took a 30 km drive. Box is nice and quiet, changes nicely and the overdrive works nicely on 2nd, 3rd and top.

I'm back to having a choice of cars to drive.

Couldn't have done it without the help of Brian and other TR Register Australia members. And the people on this forum.

 

[TRier]

Great post everyone, thank you.