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LT77 transmission oil pump

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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
A couple of years ago I replaced the oil pump in my transmission with metal gears. The original gears were missing a few teeth. Since my transmission was leaking from the front cover, I drained the fluid (Synchromesh) in preparation. The fluid was very metallic looking, so I stripped down the gearbox. This is what I found in the oil pump. I can't find anything else in the transmission that looks like it is wearing, so I think this is the culprit. Have others seen this with the metal gears? Are the original gears still available?



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1496697 by darrellwalker A couple of years ago I replaced the oil pump in my transmission with metal gears. The original gears were missing a few teeth. Since my transmission was leaking from the front cover, I drained the fluid (Synchromesh) in preparation. The fluid was very metallic looking, so I stripped down the gearbox. This is what I found in the oil pump. I can't find anything else in the transmission that looks like it is wearing, so I think this is the culprit. Have others seen this with the metal gears? Are the original gears still available?

Darrell:

A metallic sheen to the oil is considered to be normal. Nothing to worry about there.

Any swarf should be inspected carefully. Chips from gears are an indication that a teardown is needed, but fine powdered metal is typical wear and not a cause for concern, as long as the amount is small (a couple of grams, tops). If there is a lot of swarf, then there is excessive wear on a mainshaft or layshaft most likely. Possibly a bearing is letting go.

The original plastic gears are available from Rimmer Brothers.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Vance,

I believe there was much more sheen that should be expected for a few thousand miles. I don't see any wear or damage anyplace but the oil pump. It appears that the oil pump gears where eating each other and the housing.

I found the plastic gears from Rimmer, and ordered them. I also ordered a new oil pump housing from the Wedge Shop. There is still some scarring on the rear case, but not much I can do about that, other than make sure there are not any sharp edges I guess.

One other question, the pickup tube is flattened. That appears to be how it is supposed to be, but the opening is quite narrow, about 0.025". Does that sound right?

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1496742 by darrellwalker Hi Vance,

I believe there was much more sheen that should be expected for a few thousand miles. I don't see any wear or damage anyplace but the oil pump. It appears that the oil pump gears where eating each other and the housing.

I found the plastic gears from Rimmer, and ordered them. I also ordered a new oil pump housing from the Wedge Shop. There is still some scarring on the rear case, but not much I can do about that, other than make sure there are not any sharp edges I guess.

One other question, the pickup tube is flattened. That appears to be how it is supposed to be, but the opening is quite narrow, about 0.025". Does that sound right?

-Darrell

Interesting. I can't say how much is too much. I just know that my books on the matter say a brassy sheen is normal. When I drained my tranny there was only a little over a quart of fluid in it, and it had a very strong brassy sheen to it. If I had not read up on the topic I would have been worried. But get this, not so much as a whisper of swarf. Given that it had apparently been a long time since the fluid had been changed, if ever, I was impressed. It tells me that the transmission is way over designed - it was intended for Land Rovers, after all. Same thing for my rear end. The Parkerizing on the gears was virtually intact after 90,000 miles - so those gears are very stout for use in the TR8.

Pump gear wear. Perhaps the Triumph/Leyland engineers knew what they were doing when they specified plastic gears instead of steel? Still, the gears do not look worn to me as much as they look like they ingested some grit. The pump rotor teeth tips have what appear to be locations where the teeth were overloaded locally, and thus deformed plastically (e.g. like tiny craters). If they were wearing each other the faces of the teeth would show the wear, not the tips. The tips should never come in contact with anything but oil, since the teeth are tapered. The faces would wipe against one another with the tips never contacting the opposing gear. Strange.

Oil pickup. 0.025" or 0.250"? All I can suggest is that if it really is 0.025" that perhaps it is deliberate to avoid picking up a gear tooth, if one should fracture and land in the sump. Since the gears are also getting splash lubricated, that small an opening may be to keep the transmission from pumping too much oil and overloading the original plastic oil pump? <shrug>. In any event, I would not expect too much oil to be needed given the fact that the tranny is a wet sump design and oil would literally be flying all over the place anyway.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Vance,

In reply to # 1496789 by Darth V8R Interesting. I can't say how much is too much. I just know that my books on the matter say a brassy sheen is normal. When I drained my tranny there was only a little over a quart of fluid in it, and it had a very strong brassy sheen to it. If I had not read up on the topic I would have been worried. But get this, not so much as a whisper of swarf.

No swarf. But the dregs of the fluid looked like silver paint. Defiantly way more than I've seen on previous changes.

In reply to # 1496789 by Darth V8R Pump gear wear. Perhaps the Triumph/Leyland engineers knew what they were doing when they specified plastic gears instead of steel?

I've seen references that say the idea was that any swarf would embed in the plastic gears, rather than be ground up by metal gears.

In reply to # 1496789 by Darth V8R Still, the gears do not look worn to me as much as they look like they ingested some grit. The pump rotor teeth tips have what appear to be locations where the teeth were overloaded locally, and thus deformed plastically (e.g. like tiny craters). If they were wearing each other the faces of the teeth would show the wear, not the tips. The tips should never come in contact with anything but oil, since the teeth are tapered. The faces would wipe against one another with the tips never contacting the opposing gear. Strange.

I agree, but the only source of material to ingest that I can see (and the only change in the last few thousand miles vs the first 80K miles on the transmission) is the oil pump gears (and the damage they did to the housing).

In reply to # 1496789 by Darth V8R Oil pickup. 0.025" or 0.250"? All I can suggest is that if it really is 0.025" that perhaps it is deliberate to avoid picking up a gear tooth, if one should fracture and land in the sump.

0.025". The tube end has a slot, then flattened. So it should not be able to pick up anything above that size (assuming that is the reason). It also keeps the end of the pickup submerged even if the oil level is very low, but I would think you would have other problems if that was all you had. But I was also thinking that if the metal gears were starved of oil, that might have started the destruction. Plastic would have some self lubrication properties (depending on the type of plastic).

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Here is a picture of the pickup tube. The slots along the sides are 0.025", the corners where it is flattened are a bit bigger.

I used some 600 grit paper on the case to remove any raised edges from the scoring.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA


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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
So the Rimmer site shows plastic gears, and makes no mention of the material. I just got my shipping notice, and is is listed as:

Quote: OIL PUMP KIT (GEARS - METAL TYPE)

So we'll see what shows up. Was still less than at the Wedge Shop, even with the express shipping option.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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