[TR] Overdrive issues

Sun Jun 12 13:36:30 MDT 2016

Yes, even when shifting into OD, I need to ease up for it to engage.  Then if I aggressively accelerate, it will drop out of OD until I let up and it will then shift back in.

I think you are talking about the Sun gear with the lining on the inside and outside of that gear?  They showed me this, it's getting a bit over my head technically.  Anyway, if that is the lining you are talking about, they said the lining looked very good and thick, not worn at all, and all the rivets looked factory.  The lining wasn't shiny, but they did scuff it up a little before installation.
Rye

On Jun 11, 2016, at 06:18 AM, ptegler <ptegler at verizon.net> wrote:

when you say 'drops out' if you ease up, does it come back in?
If so it IS simply lower pressure and the annulus shoes are not holding against the ring. If these shoes have worn and are thin, simply put the annulus is not moving far enough to hold (just like maladjusted brake shoes)
ptegler

On 6/10/2016 9:23 PM, Rye Livingston wrote:
I'm very confident that they know what they're doing having worked on hundreds of transmissions and overdrives, and they've made the similar assessments that you have, that it's not that complex and they are stymied why they're not finding an obvious issue.  They've replace the o-rings on the pistons and checked every seal and journal hoping to find some scratch or something.  And yes, at moderate speed, 40 mph in 3rd or 4th, switching on the OD it shifts right in.  It's not until it's under load that it drops back out.  They've done test drives with the pressure gauge on it, and it doesn't sound like there's a time when there is too much pressure, but IDK for sure so I'll forward your email to them.

Rye

On Jun 10, 2016, at 05:22 PM, David Porter <frogeye at porterscustom.com> wrote:

What I am reading is that your car has a throttle switch installed. "when I'm accelerating and flip the switch for OD, it doesn't go into OD until I let up."
The switch on the dash activates only the solenoid which allows oil pressure to flow into the operating pistons and push the clutch assembly into the "OD" mode.  Period. Did I say Period.
So assuming you are going at least 40MPH, even 200PSI will engage (regardless of what the books say) All the A units are virtually identical. Now, having said that, Triumph did specify differences in the accumulator/lack of accumulator and accumulator spring.
So, you told me before that there is no throttle switch (kick down relay) installed, therefore it sounds to me that there is too much pressure at increased rpm and it is blowing the oil pressure past the currently installed o-rings and or piston rings. After you decrease engine (ergo pump speed) it re-engages. I would certainly replace the rings and rubber O-rings. There is no modern computer involved. This is a purely 'mechanical' issue. Your shop should have found the issue by now???
DaveP

On 6/10/2016 9:50 AM, Rye Livingston wrote:
Transmission update - for those reading about this for the first time, this is a 1960 TR3 with a TR4 OD transmission. Yesterday they said it's basically a TR250 transmission. The whole transmission and OD was rebuilt by a British car specialist of 40+ years.  His employee has also been working on British cars for years, and is a transmission specialist.  They've rebuilt literally 100s of transmissions and ODs.  They had 4 OD cores on their bench as they were showing me different parts of the system.

Symptom - when I'm accelerating and flip the switch for OD, it doesn't go into OD until I let up.  When in 2-3 or 4th gear, OD engaged, and punch it, it will downshift like an automatic transmission while I accelerate, then shift back into OD when I let up.

I'm not technical enough to know how to describe all what they told me, but I'll try.  First off, I forwarded the comments when I posted this issue a couple of weeks ago, and keep in mind it's not the easy/obvious things.  They've checked all the electrical, solenoids, ground, oil type, etc.  When in OD it's not slipping.  They've tested the PSI with a gauge attached while driving down the expressway, and jacked up with the wheels off the ground.  

The issue is that it's not getting high enough PSI.  It's over 400 PSI, but it needs to be 490 to over 500, I think they said 520.  They've taken the transmission back out, taken the OD all apart, and there's nothing obvious. They've changed the piston in the pump. Originally it had a pump that would shift softer because I've got a torquey engine and the other pump, which they called a competition pump, would be hard on the differential, but they've got that one in the car now.   They showed me a seal that goes around that piston and said the new seals are rubber and they got one like the original style that has some sort of metal reinforcement in it to hopefully make a better seal.  Not very clear I know, but hopefully that makes sense.  They've checked the seats where a small ball bearing must make a perfect seal, they all look perfect.  They said everything looks absolutely pristine.  No scoring down passageways that might not allow maximum PSI, etc.  They also showed me the lining on a Sun gear they had on the beach, and said mine looked good and the rivets looked original. They put it all back together, went for a test drive, and that didn't fix it.

They've spent literally 20+ hours on this transmission, plus several more hours doing internet research on the problem.  As they described everything and what they've checked, which seems like everything, I said I'd send out this email to the list.  Not that they haven't tried everything, but I'm hoping there may be one little nugget of info they haven't tried, or a test they can run, that will lead to the solution.

Thanks,

Rye Livingston
Triumph Travelers Sports Car Club
Activities Chairman
1960 TR3A
PH: 530-FIND-RYE

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