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TR4/4A I Removed My Overdrive--TR4A

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To add just a bit, when the A-type solenoid lifts the valve stem, it in turn lifts the ball bearing off of it's seat. This both blocks the exit passage through the center of the stem, and allows oil to flow around the ball and outside of the stem, through a passage in the side.

The J-type control circuit is quite a bit different. It has the pistons exposed to the pump outlet pressure all the time, and the solenoid only controls the pressure relief valve through a dashpot arrangement. In direct drive the dashpot is released and regulates the oil pressure to only 20 psi or so, which is overcome by the return springs. When the solenoid operates, it passes oil to the dashpot, which closes off the relief valve until the pressure rises to operating pressure around 450 psi.
 
About that brass thrust washer inside the planet gear assembly. Does the bevel part face inward? Surely, it must, but I just want to be sure when I seat it--and before driving a pin back in the shaft.

Thanks everyone.


(I'm still re-reading the articles so I understand this part of the drivetrain)
 
No, the bevel is outward, towards the planetary gears. That's why its beveled, to keep it from hitting the little gears.
 
HOLY MOLY, glad I asked. I assumed the bevel was to meet the area shown in my photo above.

Anyway, here's another question. Does the speedo gear really come out by prying behind the rib of the cable attachment head above the brass cylindrical bushing? That seems mighty primitive. Yank a bearing out by its head?

Can that really be so? My first try showed "zero" movement.

Thanks.
 
Be sure to remove the setscrew first; then it just pries out. Works best if you can pry on both sides at the same time. Or you can try getting a wrench on the flats to turn it back and forth.

It's best to have a cable (or just the sleeve from an old one) screwed on, so you don't mess up the threads if your pry bar slips.
 
TR3driver said:
It's best to have a cable (or just the sleeve from an old one) screwed on, so you don't mess up the threads if your pry bar slips.
Click to expand...

A very loud 'I agree' on that one - and don't ask me how I learned it - once those threads are messed up they are difficult to clean back up!
 
All of the above advise is good but the best advice is to read the Buckeye Triumphs articles on transmissions and ODs. Follow their directions closely. If you can get another mainshaft to help you align the splines it will be very helpful. Otherwise you will do a lot of trial and error attempts to mate the trans and OD together. That plus getting the pump roller onto the cam. Do not force anything. Try lowering the OD onto the mainshaft without the 8 springs to get the splines aligned. Once you have full engagement lift it enough to install the springs. Don't turn the output flange from this point onward. You can use a couple of deep sockets between the OD and the adapter plate for spacers, Once the springs are installed on the pins remove the sockets, lower the OD and beging to tighten the nuts on the long studs being careful to be sure the pump and cam engage. Setting the cam at it's lowest position helps too.

You need to do this with some gasket sealer on the large OD to adapter plate gasket. Last time I did this I used the Hylomar product from Moss and was very pleased with the results. I'm never going back to anything other than this Hylomar sealer. First time I used it. Very pleased with the product.

Hope all of this helps, been there and done that and learned some of these tricks from a friend who rebuilds OD's. Best wishes

JVV
 
That all makes sense, and also tells me how the PO chipped the roller on the end of the pump housing. I think it's OK, but I may file and repolish it. The chip is on the top outside edge, so I don't think it's critical--unless someone really, really conservative (Randall?) tells me I need to buy a new one for $250.00!

Also, are you saying that if I tinker with the adjustments endlessly, the gasket sealer will dry and I'll have to start all over?

Can anyone guess why the prior owner had washers set as spacers behind the springs? I'm not inclined to do that, but I question why it was done.


Thanks
 
Washers under the springs is a common remedy for old weakened springs -- though I've never heard it recommended for that location. I assume you're talking about the eight springs between the sliding clutch and the adapter plate. In this day and age, nearly everyone has a washer or two under the accumulator spring(s). One just has to be careful not to put enough washers in place to induce coil bind, before full travel can be accomplished.
 
can you not purchase repacement springs, IF you can why would you reuse old springs that cost 20 bucks and risk having to do it again and all that labor to get the tranny out

Hondo
 
The roller sounds like it should be fine, after all it's been working since installed, right?

Here is an article showing a different method of holding the pump plunger down while assembling. I ignored the rest of the article (which is written about a Healey gearbox anyway), but the "wire trick" might be marginally easier than trying to reach through the gap.
https://www.acmefluid.com.au/larry/finespanner.html

One of the nice things about Hylomar, it basically never dries hard. The solvent evaporates almost immediately, but the sealer is soft enough that you can remove and reinstall.

I agree with Moseso, especially since you mentioned that the springs don't seem to be different lengths. Your DPO was probably trying to shim them back to their original length.

But IMO the spring tension is a lot less important than not getting into coil bind, so I would remove the washers. The spring tension is used to hold the clutch in the direct drive position, but actually it is the sprag clutch in the annulus that takes most of the torque in direct drive. The only exceptions are while backing up (which hopefully you don't do at full throttle), and on overrun (where again, the torque is minimal). And since someone wrote recently that switching the springs was the cause of their OD slipping in OD (the inner springs were reaching coil bind and preventing full force being applied to the OD clutch), there doesn't seem to be a lot of extra travel in those springs.

Of course, I am a bit gun-shy, since I found a lot of damage caused by my shimming up the main accumulator spring until it hit coil bind with the relief port only partially uncovered.
 
hondo402000 said:
why would you reuse old springs that cost 20 bucks
Click to expand...

Where can you find them for 20 bucks???
 
TR3driver said:
T

Here is an article showing a different method of holding the pump plunger down while assembling. I ignored the rest of the article (which is written about a Healey gearbox anyway), but the "wire trick" might be marginally easier than trying to reach through the gap.
https://www.acmefluid.com.au/larry/finespanner.html
Click to expand...

That wire trick seems a lot more complicated that what I did - not sure if this came from the VTR or Buckey write ups, but I took a loop of thin wire and just snagged the roller, then took the loop out the front of the od box and looped it to the overdrive drain/sump piece. It held the roller down just fine. Then mated up the od to the gearbox - a pain no matter how you describe it. After I knew it was going to tighten up, I cut the wire and pulled out the loop before the gap between the box and the od closed completely. Hard to explain but easy to implement when you look at it.
 
Last time I bought a new set of springs I paid about $62.00 bucks. I've done the wire trick too and it works well. I'd polish the chip to eliminate any sharp edges making certain that the pump shaft is not bent or that the roller turns freely and nothing is binding as a result of the chipping. A few .030 washers under the large accumulator spring tends to bump the engagement pressure a bit. Follow the thoughts on the Buckeye site and you'll be OK. Don't overdo it on the washers. Never heard of washers under the 8 clutch springs. Don't recomend that.
You can do the trial fitting without any gasket or Hylomar to get the splines lined up, pull the OD all of the way off, install the gasket and Hylomar, trial it one more time and then use the sockets and install the springs. Just don't turn the output flange once the splines are lined up. I really can't emphasize that enough as the final assembly is the most frustrating part of this job and you don't know you are in trouble until you are about a half inch away from being tight. If any resistance at all STOP and start over before something breaks.
 
Washers under the 8 springs might be more of a sign that you need to get the cone clutch relined.
 
I'm getting ready for a rebuild on my od trans. Which folks can you recommemnd that does a good job on relining these days?
 
On this side, Quantum Mechanics might be a good start - my guess is TRF and Moss get them from Quantum Mechanics - or they go to England to Overdrive Repair Services. I just ordered a relined clutch from them about a week ago, hopefully it will come to me in good shape as expected.
 
I wouldn't assume that the clutches need relining, none of mine have even though I've covered a whole bunch of miles and frequently shift the OD under power.

John Esposito will reline your clutch; or I believe either Moss or TRF will sell you a new one for about the same price.
 
TR3driver said:
I wouldn't assume that the clutches need relining, none of mine have even though I've covered a whole bunch of miles and frequently shift the OD under power.
Click to expand...

Well that's certainly true, but there is a specification on how much play should exist between engagement/disengagement. Don't spot it now in the TR3 manual, but a friend showed me it. When I compared it to a couple of cone clutches I had, one was out of tolerance, the other ok.
 
I think the clutches deteriorate more often than wear out causing a need for replacement. Clean oil and usage is good for them. If working properly there is very little slippage and or wear. Of course if one experiences a lot of slippage and heat due to dirty or low oil then the clutch will fail. My guess is that they get replaced more often than they need to be replaced.
 
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