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Testing tranny/OD TR 3 A -PRESSURE TEST DONE!!!!!

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Tinkerman

Tinkerman

Darth Vader
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I'm all set to spin test the tranny/OD, using Randalls method of a 1/2 inch drill motor and a hose to connect them. If all sounds well in all the gears then I will put the pressure gauge on it. My question is what about electrical testing? Should I rig up a test for that, did any of you do that and if so, how did you do it?

As ever your thoughts greatly appreciated!

Cheers, Tinkerman
 
Re: Testing tranny/OD TR 3 A

Dick-

Others will likely have better thoughts, but if you pass the mechanical/pressure testing I'd just mount the trans and do final electrical testing after it is installed. Everything is easily accessible, and it will likely work immediately otherwise you may need to trace the entire circuit anyway.

Randy
 
Re: Testing tranny/OD TR 3 A

Just use a car battery or battery charger. I don't know offhand what the draw is on the solenoid, so if you use a battery charger, make sure it's large enough to handle the current. Some of those small trickle chargers won't be big enough. At least you'll see if the solenoid works.

Will the drill provide enough ummph to turn things when the OD is engaged?? Randall should know the answer to that.
 
Re: Testing tranny/OD TR 3 A

I would be inclined to (at most) bench test the solenoid to assure the pull-in and hold coils (and the internal cut-out) all work as they should. I suppose you could even bench test the relay. Beyond that, I too would just wait until it is in situ to do the final test and adjustment.
 
Re: Testing tranny/OD TR 3 A

The A-type solenoid takes a large amount of current to pull in (like 20 amps). Although I've not tried it with a battery charger, I wouldn't be surprised if a common 10 amp unit wouldn't supply enough oomph once the OD has built pressure. If that happens, be sure to either disconnect or give the solenoid a helping hand quickly, as the pull-in coil will overheat if the cutout doesn't open.

My 1/2" drill motor worked fine for me. The OD pump really takes very little power to turn (contrary to what some have said). Of course the drill only hits 800 rpm or so; it's not really a high speed test. But it's plenty for checking pressure and engagement. Be sure to have the gearbox secured, as it will try to jump around a bit when the OD is dis/engaged. You wouldn't want it to fall off the bench!

I would (did) also check the lockout switches on the bench. Put some load on them, not just an ohmmeter (I used a taillight bulb and the bench power supply) and check the voltage drop across the switch. If it's more than a tenth of a volt or so, replace the switch even if it appears to work otherwise.

Personally, I hate having to work under the dash, so I try to check as many things as possible beforehand.
 
Re: Testing tranny/OD TR 3 A

Well I did it, I ran the pressure test this afternoon. Started to look like a dismal failure because I got no pressure, did it several different times. Finally with my wife looking on, it built up pressure, fairly rapidly, did it several times, same results. Built up to about 360 pounds and held steady. If I'm correct from what I read it should be about 450. Anyone have any thoughts on that?

Nelson Reidel talks about shimming the accumulator pump piston. Again any thoughts?

Randall, the 1/2 inch drill worked like a champ.

Cheers, Tinkerman
 
Re: Testing tranny/OD TR 3 A

Tinkerman said:
Built up to about 360 pounds and held steady. If I'm correct from what I read it should be about 450. Anyone have any thoughts on that?
Click to expand...
The correct pressure depends both on the application and which particular variant of overdrive you have. As I recall, 360 psi is about right for an original TR3A OD with the larger accumulator piston and large operating pistons. 450 is for a TR6 with the small accumulator and the torquier 2.5L engine. And the Stag is higher yet. The TR2 OD with the smaller operating pistons also took more pressure.

Unless you are going racing or have done something to increase engine torque (like a blower), I'd leave it alone.
 
Re: Testing tranny/OD TR 3 A

Hmm, thot I had a copy of the TSB giving the A-type pressures, but I can only find the one for the J-type. However, Nelson says "... the pressure for the early large piston accumulator was 350 to 370 psi while the pressure for the later small accumulator models should be about 450 psi." and you presumably have the large accumulator.
 
Re: Testing tranny/OD TR 3 A

Thanks for the thoughts Randall. My question is what happens in an operating mode. If I understand it all correctly, if the pressure is too low the OD won't kick in? Do I have that right? Also what your saying is that under the right circumstances 360 might be just right? I feel that if I just mount the rascal and it doesn't work right I can "get out and get under" and probably fix it with the Reidel shim fix on the accumulator piston. As you might expect. I am more than ready to get these items done and out of the way so I can go on to more fun stuff.

Thanks for your input, Tinkerman
 
Re: Testing tranny/OD TR 3 A

Call Quantum mechanics and ask if you can't find the pressure listed anywhere and you'd like another expert opinion...
Given Nelsons response I'd mount it an go.
That's quite an accomplishment rebuilding an OD, great deal and I know you'll love it when it kicks into gear and the rpms drop 800 or so.
 
Re: Testing tranny/OD TR 3 A

At 360 psi it will definitely engage. If that isn't quite enough, it might have a tendency to slip when you make full-throttle shifts in 2nd gear.

It's not especially easy to get the accumulator spring out with the unit installed in the car. As I recall, you have to take the rear mount loose and jack the gearbox up to get enough room to work (also take the passenger seat out).

I found one other reference, the TR4 workshop manual gives 380-400 psi. So if you've installed the 86 or 87mm liners, I'd probably try to shim it up into that range. As Nelson notes, you can shim the spring some, but too much can lead to coil bind and disaster, so don't go too far.

But I tend to "drive it like I stole it", so if your driving style is more moderate, 360 will work just fine, IMO. I believe John at Quantum says you should never shift under full throttle, so make of that what you will.
 
Re: Testing tranny/OD TR 3 A

The pressure tested 320 psi on my 1958 TR3A and it shifts nicely. Except I don't go fron 2nd to 2nd O/D without lifting my foot on the gas pedal for about 1/2 a second and it shifts smoothly and without any slippage. Into the other two gears is not a problem.

I think that 350 psi will work fine.
 
Re: Testing tranny/OD TR 3 A

I have a reprint of an original Laycock OD manual. In the Troubleshooting section, it specifies the "correct" pressure for the unit as fitted to the Vanguard and Renown as 470-510 lbs.sq in. For the TR2, it's 420-445. Not sure if this helps or hinders, since I don't know what changes (if any) were made to subsequent models. Sorry, but this is the only reference I have.
 
Re: Testing tranny/OD TR 3 A

All very good thoughts, thanks all. Kind words, Thanks prb51. I think waiting until monday and getting some expert opinion will make sense. Pretty easy to add a shim wHile it's sitting on the bench. As I recall Randall, I do have the smaller accumulator piston so I suspect they are going to tell me that I need to get up to around 450, which is doable.

For me a very exciting time in this restoration!

Regards, Tinkerman
 
Re: Testing tranny/OD TR 3 A

Thanks Fergie, I tried copy and paste and got back the reply that there was something with the address. Would love to see it so if you could try it again and send it to me at tinkerman@charter.net we'll give it another go.

Thanks, Tinkerman
 
Re: Testing tranny/OD TR 3 A

I had no trouble with the link...

I sent you a copy.
 
Re: Testing tranny/OD TR 3 A

Thanks, Art. I have tried several times to post a proper link and all I get is [url blah, blah, blah url]. Can't post photos either. I have the Lucas operating system on my Mac, so that's probably what's wrong. :smile:
 
Re: Testing tranny/OD TR 3 A

The forum software doesn't always recognize links that are just pasted in; usually because the link itself doesn't follow the usual format (in this case, having 'obswww' instead of 'www'). The solution is to click on the "Switch to Full Reply Screen" button at the bottom, and then use the "Create a link to a webpage" button next to the smiley button at the top. Then you can paste your link into the dialog box and give it any name you wish.

Like This

BTW, I have a PDF file of the A OD manual that I ran through OCR, so it's both smaller and text-searchable. Let me know if you would like a copy. Someone did put it up on a web page, but I've forgotten who/where.

PS, the A-type OD manual is a very early document. Although it is quite useful, it only covers the TR2 version of the A-type and so lacks information on the TR3-TR6 versions (like a table of the various operating pressures).
 
Re: Testing tranny/OD TR 3 A

Thanks, Randall. I would <span style="font-style: italic">swear</span> I did this this before (several times), but couldn't make it work. I'm still blaming it on Joe Lucas.

Now I just need to figure out how to post pics. :smile:
 
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