Looks like I have got bigger OD issues...

[KVH]

Yes, Randall, I may have clarified my post in an edit that hit while you were responding. Did I say it correctly?

 

[JerryVV]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.

Scott

 

[TR3driver]

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]

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]

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

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]

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?

(not my hairy finger BTW)

 

[TR3driver]

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=0B2H2NJt34OffcVp0TUJiU29Sa214cXVOQzJCTGJXUQ

 

[tdskip]

Hmmm - I may be on to something here;

Shouldn't this OD filter be see through?

and not be filled with this?

 

[JerryVV]

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]

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]

Well got her back together, fresh oil and......
















She is still slipping. Time to pull it.