[TR] Overdrive issues

[David Porter]

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
>
>
> ** triumphs at autox.team.net **
>
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-- 
Dave Porter Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM 
87107 505-352-1378 Go HERE: my world www.porterbikes.com/
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