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tdskip
02-25-2012, 02:28 PM
...than the solenoid wiring on the '66 TR4a. I rigged up a tie to the lever the solenoid operates and just took a drive. Lever down, everything is fine. Happy car, happy gearbox.

3rd or 4th gear at speed, pull up on the tie to operate the OD and RPMs jump like a badly slipping clutch. Uh oh.

It will disengage on its own in a second or so once I release pressure on the tie used to pull the lever up.

First checks is low oil level not allowing the unit to generate enough pressure, right? Not sure I want to hear about 2nd or 3rd things to check here - ha.

TR3driver
02-25-2012, 05:11 PM
Won't hurt to check, but I doubt low oil is the problem.

Taking a "second or two" to disengage sounds like a problem as well; perhaps not the same problem. I'd check the tiny drain hole in the side of the operating valve stem (shown somewhat larger than actual size).

https://i258.photobucket.com/albums/hh260/TR3driver/Misc%20parts/A-type%20OD/A-TYPEODOPERATINGVALVEANDDRAINHOLE.jpg

tdskip
02-25-2012, 05:25 PM
Thanks Randall. I topped up the gearbox oil and it still slips if I have the throttle one, but if I lift off it will hold the OD engagement. So, as you suspected, something else is up.

Is it worth cleaning the filter before pulling that valve stem?

TR4nut
02-25-2012, 05:36 PM
Tom-

Its probably been asked, but do you have a gauge for the od? It will help a lot to see what pump pressure you are getting.

Randy

tdskip
02-25-2012, 05:39 PM
Hi Randy - why instrument something when it can remain an unknown but critical variable?
















Ha.

TR3driver
02-25-2012, 05:54 PM
Same as before, it can't hurt to check, but I doubt that is the problem. IMO you're going to wind up doing just what you're trying to avoid : buy a gauge, check the pressure, then pull the unit apart to find out why it won't build/hold pressure.

The hole in the valve (shown above) only affects dis-engagement. It's basically the drain hole that lets the oil back out of the pistons when the valve is closed.

tdskip
02-25-2012, 06:36 PM
Yeah, sigh, kinda of expecting that it needs to be pulled apart. Wasn't really in the game plan. Oh well.

JerryVV
02-25-2012, 09:18 PM
Do you have any idea how long it's been since the OD worked? Has the car been driven much, oil warmed up, changed, etc? Cheking the valve that Randall suggested is pretty easy and does not require pulling the gearbox and disassembly. It does sound like you are bleeding pressure and that valve is the likely suspect. I'd refill with Redline MT 90. Expensive but best that I've found. Pull the plug at the bottom and clean the filter too if you have not done so already.

TR3driver
02-25-2012, 09:53 PM
I'd refill with Redline MT 90.

I wouldn't. I like MT-90, use it myself and it is great stuff.

But it's not cheap and it is not going to cure this problem IMO, so you would be just throwing your money away. I actually use cheap motor oil while troubleshooting; then once it all works right, drain & refill with MT-90.

tdskip
02-25-2012, 10:28 PM
Do you have any idea how long it's been since the OD worked? Has the car been driven much, oil warmed up, changed, etc? Cheking the valve that Randall suggested is pretty easy and does not require pulling the gearbox and disassembly. It does sound like you are bleeding pressure and that valve is the likely suspect. I'd refill with Redline MT 90. Expensive but best that I've found. Pull the plug at the bottom and clean the filter too if you have not done so already.

Hi Jerry - it has been years. She sat for 5+ years. At this point I have only topped off the oil. At this point I'm going to check the valve that Randall pointed out and then try (per your idea) taking her on a longer run and then changing the oil. Not expecting too much out of that, but occasionally Hail Mary pass plays work out.

tdskip
02-25-2012, 10:35 PM
I'd check the tiny drain hole in the side of the operating valve stem (shown somewhat larger than actual size).

https://i258.photobucket.com/albums/hh260/TR3driver/Misc%20parts/A-type%20OD/A-TYPEODOPERATINGVALVEANDDRAINHOLE.jpg

Randall (and guys) - is it normal for oil to come welling up when the top bolt for this assembly is loosened?

EDIT - Yes, normal. Especially if you ready the Buckey guide afterward and it says to actuate the lever several time before loosening the valve nut.

tdskip
02-25-2012, 10:56 PM
OK - pulled that assembly. The hole on the shaft is about 1/2 the size in the picture but having the location enlarged definitely helped find it. Oil did flow through it, but I cleaned it just in case.

What I did find, however, is that the oil seemed dirty on shaft. There was darker oil that was not sludge but heading that way. May not be my problem, but can't be helping anything.

JerryVV
02-26-2012, 07:50 AM
After 5 years that sludge will settle into all the wrong places. It may be as simple as that. Have you solved the solenoid issues? Maybe changing the oil before you go for a good run with some GL4 or even 30 weight. Get it cleaned out and then replace with Redline MT90. Using MT 90 as a quick cleaning oil gets expensive. be certain to clean the screen before you make the warm up run too.

TR4nut
02-26-2012, 08:36 AM
Apologies to Tom for slightly stealing this thread, but I have a closely related problem - I put in a spare gearbox/od in my TR4 - the overdrive bench tested ok but I find it frequently won't disengage in overdrive. Cleaning the operating valve, whacking the brake ring, jiggling the solenoid linkage etc eventually will free it up.

Like Tom, the od sat for several unknown years before use. Old gear oil was old. I'd like to flush it with something, it has been recommended to put in a little diesel fuel and try to dissolve some of the sludge. Horrible idea? I've already put in MT90 so that will be a loss but at this point I need to get it to work reliably - its taking me to the Mitty!

tdskip
02-26-2012, 08:58 AM
After 5 years that sludge will settle into all the wrong places. It may be as simple as that. Have you solved the solenoid issues?

Hi Jerry - thanks for the help.

I'll get the gearbox oil warm and then drain/change it today and see if it makes a difference.

I think I've narrowed my solenoid issues down to low power at the relay, but that troubleshooting is on hold until I get the OD to function.

tdskip
02-26-2012, 08:59 AM
Apologies to Tom for slightly stealing this thread

You are going to have to try harder than that to need to apologize Randy - especially since you question is directly related and you have been such a huge help over the years.

I'm curious to see what comes back on that question as well.

Guest
02-26-2012, 09:39 AM
What about ATF as a flush?

JerryVV
02-26-2012, 11:25 AM
Like Randall said, use an inexpensive motor oil as a flush. A 5W-xx might be good for a short period. I would not put a lot of stress on the gearbox using a thin oil. (slow starts, easy slow speed driving around town enough to get it warmed up) but I would change it before making the run so as to drain as much of the old stuff out as you can before trying to clean with a new fill.

Randy, hope to see you at the Mitty (Royal Blue 4A with Surrey top) I'l be mostly hanging with the FOT crowd in the pits. Hard to say what your problem might be. I'd do the light oil flush too and put fresh MT 90 back in. Be careful in reverse if it's sticking too as that will fix your problem in all of the wrong ways. A friend who rebuilds these has had good luck using MT 90 when freeing up a stuck clutch

KVH
02-26-2012, 12:04 PM
I'm still learning on my OD, and just tore it apart again due to bearing alignment issues, but it would seem to me that if the pistons are working when you manually operate the OD operating lever, that would mean that the clutch has disengaged the annulus head, thereby locking the sun gear and allowing the OD to operate, with the planet gears turning inside the planet assembly.

That being the case, high speed RPMs like a slipping clutch may indicate issues in the planet gear assembly or the roller clutch. Though, I suppose if the sliding clutch doesn't properly disengage from the annulus, and fully engage with the brake ring, the sun gear might not be locked properly, and that may be the problem. And, I guess, that's why a gauge may be necessary now. I suppose the problem could be the accumulator springs, the piston rings or the accumulator piston rings, or not enough washers between the piston the accumulator springs. Maybe not difficult fixes.

I could imagine another scenario where the clutch springs are shot and the OD sliding clutch is always slipping. I'm not sure what the symptoms there might be, but the symptoms might change depending upon the gear you're in and the speed you were going.

Someone with more experience please take over, but the issue is interesting.

I'll wait for a more insightful analysis.

TR3driver
02-26-2012, 01:09 PM
Maybe I'm not following your argument, KVH. The pistons do pull the clutch away from the annulus; but until the clutch locks against the brake ring, it will just spin uselessly and there will be no power transmitted through the gears. The sprag (roller) clutch inside the annulus normally covers this transition, since it keeps the input shaft from turning faster than the output shaft (so effectively the OD stays in direct drive until the OD clutch locks to the brake ring).

However, if the pressure in the pistons is too low, the clutch doesn't fully lock to the brake ring and can slip back to direct drive (through the sprag clutch) when extra torque is applied. I assume that's what tdskip is talking about when the "RPMs jump". Could be a mechanical problem, but most likely is low pressure IMO. I got some slippage at around 250 psi, but only at full throttle in 2nd gear.

Experiences will vary, but mine has been that for there to be a lot of sludge, the OD is coming apart internally and the sludge is actually very tiny bits of metal. I don't know why Jerry thinks it will accumulate in the wrong places, as it normally accumulates at the lowest point of the reservoir, which coincidentally gets removed every time you drain the oil. Or on the magnets, same story. The only tiny passage is that one in the valve stem, which is also easily cleaned.

Way I see it, if you pull it apart and it only needs gaskets, seals & thrust washers, then the job is cheap. But replacing hard parts gets expensive very quickly. Thus if you know it's coming apart, it's best to service it now rather than wait until later. Broken thrust washers let the gears start touching in bad ways, which will eventually tear them up even though the OD is still working. Somewhere, I've got a ruined annulus that came out of a "working" OD.

Randy, have you checked the hydraulic pressure? One cause for repeated clutch sticking can be too much pressure. And your DPO/M may have made the same mistake I did, by shimming up the pressure just a little bit too much, so it tests fine on the bench (at relatively low rpm), but the spring reaches coil bind before the relief port is fully uncovered (meaning that at higher rpm, the pressure rises until something breaks). Not the only possibility of course, but one of the first things I would check.

IMO, ATF would work fine as a flush. That's even what Herman van den Akker used when testing on his stand. But I would definitely avoid using full throttle in lower gears (or even doing a hard launch). The countershaft thrust washers in the main gearbox are the Achilles heel, and the lower gears are when the forces are highest on the countershaft. 4th gear should be fine, though, as it doesn't send power through the countershaft.

KVH
02-26-2012, 01:17 PM
Yes, Randall, I may have clarified my post in an edit that hit while you were responding. Did I say it correctly?

JerryVV
02-26-2012, 01:32 PM
I don't know why Jerry thinks it will accumulate in the wrong places, as it normally accumulates at the lowest point of the reservoir.

There is aways some oil that does not drain and just stays in pockets or passages. Those are the same places that don't need to get clogged with debris. That's my point. And if the gearbox sat for 5 years that debris can get hard. Think about the piston bores, does that oil fully drain? Oil around the rings or o-rings if dirty and allowed to harden up over 5 years, wouldn't that tend to gum things up some? I stand by my thoughts.

TR3driver
02-26-2012, 06:18 PM
No worries, Jerry, not trying to pick a fight. I just don't see it that way.

For example, the oil trapped in the pistons can only be in the space where the pistons never travel. Doesn't really matter if there is gunk in there, the space is not used.

And we're talking 400 psi here; which is pretty much going to blast through old gummy oil without much trouble.

As far as debris; I've already said that any significant amount of debris is, in my opinion, plenty of reason to tear down the unit and find where it came from. This isn't like a car engine, with various kinds of gunk constantly coming past the piston rings. A perfect example is the two units shown in the "Greasy Hands" articles on the VTR website. Both had lots of sludge in the filter, both had broken thrust washers and parts of the washers that were MIA. IMO the sludge was the ground-up bits of the MIA thrust washers (plus wear particles from where the gears had been rubbing on each other).

My OD was driven for about 5 years & 50,000 miles then sat for another 5 in the wrecked car with no attention at all. The oil came out a bit darker than it went in, but was still clearly oil and not gummy at all. I'm sure it would have gone on working just fine (except for a tendency to slip at full throttle in 2nd gear) if I hadn't decided to shim up the pressure.

tdskip
04-02-2012, 07:42 AM
Hi guys - hope everyone is doing well.

So before I left on a business trip I drained the transmission oil, the gearbox oil that came out was gear oil and it was pretty dark. I put new non-detergent 30 weight oil in and ran it. The OD was still slipping if there was any throttle pressure but it disengaged nice now. Small comfort, yes.

I drained the gearbox oil last night after and it was pretty dirty again after about 5 miles of driving. I am not getting anything that looks like metal, it just looks dirty.

The Brit mechanic (very experienced, trustworthy) I use as my backstop said it is fairly rare for a clutch cone to break up so he encouraged me to give it another couple of oil changes to see if that can avoid the cost/time of pulling the box and rebuilding it.

So at this point I am wondering if I just need to keep cycling new oil through until it gets whatever is making it dirty out, or it is the OD clutch cone breaking up that is making it dirty? Should I try flushing it with ATF for a quick gently drive?

So what do you think guys? Thanks.

TR3driver
04-02-2012, 08:52 AM
You could try continuing to flush it out. It's easy and cheap, compared to pulling the unit (especially if you are going to pay someone else to do the work). And it's not likely that it will make it any worse (though if it is a broken thrust washer, the surfaces will continue to rub and wear).

But I'm very doubtful that it will help. IMO the dirty oil is a symptom, not a cause.

tdskip
04-02-2012, 09:36 AM
IMO the dirty oil is a symptom, not a cause.

Lah lah lah lah - I can't hear you due to my fingers in my ears.

(agree this is one last hail Mary).

TR4nut
04-02-2012, 02:08 PM
ATF worked great for me, sort of - completely cured my problem if the od remaining engaged. Unfortunately, it wound up being a better flush than I really wanted, I developed leaks around the adapter flange. Bad ones. So I'm pulling it out and going with my original gearbox which is fixed now I think. Nothing wrong with the ATF, but if you are slightly worried about it you might want to stick with 30 wt.

Alec
04-02-2012, 03:28 PM
An Interesting thread here. I have similar symptoms of a slipping OD when nominal power applied. On the flat it will hold fine but as soon as a gradient appears ........

Stepping back in time, the PO had used some evil smelling gear oil which I did not realise for about 1500 kms. The gearshift was rattling and the box quite noisy. I drained and filled with MT90. This transformed the shifting and the rattling went away, but there was still OD slipping but not as bad - for this change I did not remove the large OD drain plug.

I drained again. The oil still showed contamination of the previous gear oil, probably because I did not remove the OD drain which I did this time and cleaned filters etc - another refresh with MT90. Ran it for 200 kms, some improvement but still slipping, so drained again. It was still dirty, so another change and again the OD a little better - but not right. This spring will be the third refresh/flush with MT90 so will see....

Based on this post I may try an ATF flush but likely not driven hard or far. Maybe even idle it in the garage. However, for now, the plan is another oil change with MT90 when the weather improves and assess what the drained oil looks like.
Will know in a month or so. I really want to avoid the rebuild scenario for awhile

TR3driver
04-02-2012, 04:18 PM
Low pressure would not necessarily require a rebuild. Del Border wrote a long time ago that sometimes the problem is as simple as a weak spring in the "non-return" valve; which should be accessible without removing the gearbox from the car (though you still have to remove the tunnel, disconnect the driveshaft and jack up the gearbox).

In my case though, when I got to that point, it was obvious that there were serious internal problems, so I didn't finish trying to change the little spring.

At that point, you can also replace (or add shims to ) the main accumulator spring to bring the pressure up a bit higher. Just don't do as I did before, and get too carried away with the shims!

Just for completeness (not trying to fan any old flames), I'll point out that 90 weight GL-4 gear oil WAS the factory-recommened OD lubricant from roughly 1960 through the end of the A-type in 1972. Contrary to what a certain well-known OD mechanic has posted on his web site, it works fine.

Alec
04-02-2012, 05:39 PM
Hi Randall,
In my case, I'm just not sure what OD problem is yet. It could be relay, oil pressure, level, or old age - still working through it and looking for a local expert. The nice thing is that one can still drive and enjoy.

I observe that the type of oil to use has been a debated for years and the only concensus is that there are two sides. Apparently even the manuals of Jaguar, MG, Triumph, Healey, Volvo differ on the oil question. Intuitively, since the GL4 and 20/50 oils are fairly close on the table, I am OK either way. However, the distinct improvement in the behaviour of the box, that I got with MT90 has my feet in that camp for now.

Also, having browsed most sites and forums I get the impression that fundamentally these Laycock units are very robust, so with only 95,000 Kms, one holds thumbs.
Alf

HerronScott
04-02-2012, 06:14 PM
IMO the dirty oil is a symptom, not a cause.

Lah lah lah lah - I can't hear you due to my fingers in my ears.

(agree this is one last hail Mary).


Thanks Tom for the laugh. :smile:

Scott

TR3driver
04-02-2012, 08:02 PM
In my case, I'm just not sure what OD problem is yet. It could be relay, oil pressure, level, or old age

Just my opinion (and I don't claim to be an expert), but if it engages and then slips, it's not likely to be a relay/electrical problem. The solenoid draws a huge surge of current when the relay contacts first close, and only stops drawing 20+ amps when the solenoid moves all the way. If it is jammed or not getting enough current through to move the solenoid all the way, then something is going to smoke! (After having gone through that myself, I opted to add an in-line fuse that will blow if it happens again.)

If the oil level were that low, then you've got a "fix it now" problem IMO. The gearbox is higher up than the OD and relies on splash lubrication. If the OD sump is empty, then so is the gearbox and it won't survive for long without lubrication.

That leaves old age, and it is marginally possible that the clutch is worn out. But in my limited experience (over 30 years now with a variety of units), the clutch never wears out unless you've been continuing to drive with it slipping constantly.

Low oil pressure is by far the most likely cause of slipping in overdrive, IMO.

Alec
04-02-2012, 08:40 PM
Thanks for the respnse Randall, though did not want to be the thread "high-Jacker" here, sorry. You have given me some homework, as now I have to do a search on how to correct low oil pressure in the OD. Unfortunately your photobucket pictures earlier in this thread have been deleted, so I need to check around.
The next oil change will be interesting to see if any more crud has collected at the screen filter. (At the last change probably 500 kms ago, it was cleaned thoroughly). Will also need to buy a pressure gauge.

TR3driver
04-02-2012, 09:06 PM
Unfortunately your photobucket pictures earlier in this thread have been deleted, so I need to check around.
Oops, sorry. Not deleted, just reorganized a bit. Here's a new link
https://i258.photobucket.com/albums/hh260/TR3driver/A-type%20OD/A-TYPEODOPERATINGVALVEANDDRAINHOLE.jpg

But that tiny hole (shown larger than actual size) is only important to the OD disengaging. It won't have anything to do with slipping while in overdrive.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Will also need to buy a pressure gauge. [/QUOTE]

Good idea! Here's one source: https://webspace.webring.com/people/tj/jholekamp/

tdskip
04-02-2012, 09:53 PM
Thanks for the response Randall, though did not want to be the thread "high-Jacker" here, sorry.

No apology needed - glad it helped. And don't let him give you that I'm not an expert stuff...and we're all very glad to have his help here.

So Randall, is this the non-return valve?

https://www.buckeyetriumphs.org/technical/AOD/AOD2/NRValveA.JPG

(not my hairy finger BTW)

TR3driver
04-02-2012, 11:19 PM
Ayup, that's it. And since it doesn't seem to be on the web any more, here's a copy of the article I was referring to:
https://docs.google.com/open?id=0B2H2NJt34OffcVp0TUJiU29Sa214cXVOQzJCTGJXU Q

tdskip
04-04-2012, 02:36 PM
Hmmm - I may be on to something here;

Shouldn't this OD filter be see through?

https://i207.photobucket.com/albums/bb73/tdskip_photos/1966%20TR4A%20Solid%20Axle/filter4-4-12.jpg

https://i207.photobucket.com/albums/bb73/tdskip_photos/1966%20TR4A%20Solid%20Axle/filter4-4-122.jpg

and not be filled with this?

https://i207.photobucket.com/albums/bb73/tdskip_photos/1966%20TR4A%20Solid%20Axle/filter4-4-12gunk.jpg

JerryVV
04-04-2012, 03:52 PM
Yes it should be cleaner than that and easily washed clean. Do you have any idea what the material is? Does it desolve with solvent? Rubbed between your fingers what does it look like? Any metalic particles?
You may want to buy a new screen if you cannot get this one clean. If I recall the OD sat for a long time is that correct? In the end it doesn't look good. Try cleaning or replacing the filter and another batch of clean oil. Run it and see if the cleaned screen begins to capture stuff again. If it does then a teardown is in order.
Mineral Spirits works good as a cleaning agent.

TR3driver
04-04-2012, 04:02 PM
:iagree:
Except I'm pretty sure there are fine metal particles in that goop, because of the way it is sticking to the magnet.

And I still think it's a symptom, not a cause.

tdskip
04-04-2012, 04:13 PM
Well got her back together, fresh oil and......
















She is still slipping. Time to pull it.

sd80mac7204
04-04-2012, 04:28 PM
Well that sucks. At least you tried your hardest to try to solve the problem before you pulled it.

tdskip
04-04-2012, 07:35 PM
Randall - hope you are sitting down;

https://i207.photobucket.com/albums/bb73/tdskip_photos/1966%20TR4A%20Solid%20Axle/removed4-4-12.jpg

TR3driver
04-04-2012, 09:53 PM
3 hours, 22 minutes = Not Bad!

I used to get that motivated, but these days I usually stop in the middle to take 5. And 5 usually turns into 30-40 ...

mrv8q
04-04-2012, 10:59 PM
Cue the <span style="text-decoration: line-through">applesauce</span> applause!