Not best, but optimum Transmission?

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toolmanmike said:
The original flexplates will last 40 or 50 years of abuse. You could put a performance one in but it probably isn't necessary.
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If that's the case, why would this one be cracked? Not doubting what you say, but if mine (which looks OEM) is cracked, I would like to know the root cause and address it.
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toolmanmike said:
Also something to do while it's on the lift, service the transmission. (Fluid, filter, and gasket)
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Whilst I whole-heartedly agree, it got nearly 2 services in a row right at 5k miles ago. I changed the fluid, filter and adjusted the bands. And then dealt with more leakage than I could tolerate afterwards. Went back again and I changed the old leaky pan, pan gasket, and of course the fluid somewhat soon thereafter. The trans worked good before, and better after the band adjustments. Previous to this maintenance, when easing up to speed, the 2-3 shift would sometimes start to happen, then it would "decide" not to, and repeat like that a couple times sometimes. But since the adjustment, it shifts crisp 2-3 under light throttle. Medium to WOT it always shifted well and still does. And when I check the fluid level now, it's such a pretty red color, it makes me smile that such an old transmission runs so well and clean. Should I do it again anyway?
 
7milesout said:
If that's the case, why would this one be cracked? Not doubting what you say, but if mine (which looks OEM) is cracked, I would like to know the root cause and address it.
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Whilst I whole-heartedly agree, it got nearly 2 services in a row right at 5k miles ago. I changed the fluid, filter and adjusted the bands. And then dealt with more leakage than I could tolerate afterwards. Went back again and I changed the old leaky pan, pan gasket, and of course the fluid somewhat soon thereafter. The trans worked good before, and better after the band adjustments. Previous to this maintenance, when easing up to speed, the 2-3 shift would sometimes start to happen, then it would "decide" not to, and repeat like that a couple times sometimes. But since the adjustment, it shifts crisp 2-3 under light throttle. Medium to WOT it always shifted well and still does. And when I check the fluid level now, it's such a pretty red color, it makes me smile that such an old transmission runs so well and clean. Should I do it again anyway?
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If it was just done then you don't need to do it. Many don't know how important a clean filter and new fluid is and how many issues can be fixed by a simple trans. service.
 
7milesout said:
If that's the case, why would this one be cracked? Not doubting what you say, but if mine (which looks OEM) is cracked, I would like to know the root cause and address it.​
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Well my point was is that your original flexplate failed after almost 50 years. That's good service life. If you don't constantly abuse or drag race your car, a stock replacement will probably last another 50 years. Install what ever you want.
 
toolmanmike said:

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Well my point was is that your original flexplate failed after almost 50 years. That's good service life. If you don't constantly abuse or drag race your car, a stock replacement will probably last another 50 years. Install what ever you want.
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Yeah, duuuhhh. I missed that point. You're right. It has been nearly 50 years. How much hp is an original flexplate good for? The most I would imagine I will ever have is … ummmmm, maybe 450-500 at the crank. Right now it is probably at ~325 hp at the crank (270 at the tires).
 
Without looking part numbers up, the heavy hitters (440 6 pack and Hemi) had the same design flexplate as your car. I don't know if they were somehow made stronger with thicker material but the design was the same. Most of the HP aftermarket ones are a full disc shape. Price may be a factor as well. Something you will need to decide.
 
Hmmmmm … while the transmission is out, is it worth considering to replace the torque converter? If you remember back in the beginning of this thread, I mentioned that I'm not auto transmission expert. So, I'm allowed to be ignorant and ask dumb questions! :D I have read and believe that the 727 is the best 3 speed auto available. But is the torque converter it comes with the best?

For example … if a had a lockup torque converter, that would lower my rpm while doing interstate cruising. However, I believe I read that torque converters cannot interchange between a non-lockup and lockup converter because the transmission input shaft and valve body used for lock-up application are different. But how big of an expense or is it even possible to change the input shaft and valve body on a 727? I would imagine the input shaft is not an easy thing to change. Aside from that, are there other torque converters that may be more efficient? And/or robust? Neglect the cost of said converters for this argument. I won't be spending an arm and a leg, but I prefer to know the costs even if they're on up there. Because I might consider spending just an arm … or a couple fingers at least.

I'm going to try to google some torque converter info and learn myself. Feel free to school me on TC 101. Thanks.


7milesout
 
7milesout said:
Hmmmmm … while the transmission is out, is it worth considering to replace the torque converter? If you remember back in the beginning of this thread, I mentioned that I'm not auto transmission expert. So, I'm allowed to be ignorant and ask dumb questions! :D I have read and believe that the 727 is the best 3 speed auto available. But is the torque converter it comes with the best?

For example … if a had a lockup torque converter, that would lower my rpm while doing interstate cruising. However, I believe I read that torque converters cannot interchange between a non-lockup and lockup converter because the transmission input shaft and valve body used for lock-up application are different. But how big of an expense or is it even possible to change the input shaft and valve body on a 727? I would imagine the input shaft is not an easy thing to change. Aside from that, are there other torque converters that may be more efficient? And/or robust? Neglect the cost of said converters for this argument. I won't be spending an arm and a leg, but I prefer to know the costs even if they're on up there. Because I might consider spending just an arm … or a couple fingers at least.

I'm going to try to google some torque converter info and learn myself. Feel free to school me on TC 101. Thanks.


7milesout
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You can't add a lock up converter to a non-lock up transmission. You need to quit thinking. A converter seal is a good idea. A converter is not necessary unless you need a different one. (like you changed the camshaft)
 
Guys - I believe the LA 360 to be an externally balanced engine. Heck, I put a harmonic balancer on it when I got it from the p.o. because he said the one on it at the time had slipped. Added timing tape to the one I put on. Went through the whole process of zeroing out the location of the timing tape, yada yada yada.

Correct me if I'm wrong, when looking at the B&M flexplates, I should be buying the one with the pacman mouth cut-out, no?

upload_2020-6-12_13-51-26.png

This one, right?


7milesout
 
Looking for and appreciating anyone's feedback. This is another area on which I am yet but a rookie.

Thanks.
 
Guys - I bought the flexplate as shown above. I had a transmission shop do the install, as I do not have the time, space or tools to do it myself. The shop just called and said it was done, but now there's a vibration.

I haven't gone over to check it out myself yet. I literally just hung up the phone. But WTF? I'm sitting here pi$$ed off. The chosen flex plate was for an externally balanced engine. What could have gone wrong? Did I screw it up by choosing the wrong flex plate? They said it only installs one way … and they said they replaced the front seal and that the torque converter had a (balance) weight on it.

I have little to no knowledge of auto transmissions and torque converters.
 
I do not believe you are supposed to have a weighted torque converter and a weighted flex plate. Where did the t/c come from? Aftermarket ones might have a tiny weight on them, but that is just to balance the converter itself. They don't normally make the t/c weighted to match up to a specific external balance engine. Of course I did use the word "normally", and as we know, with Mopars that's rare.
 
I don't know the history of the t/c. It was on the car when I got it.

I haven't put my hands on the original (or at least the) flexplate that was (cracked) on the car. But it would look either symmetrical (balanced) or not symmetrical, right?
 
Right, if there is a big weight on the t/c then it was made for the 360 motor, and you do not need the pac-man shaped flex plate. I believe B&M sells those to put on a 360 , to go with their neutral-balanced toque converters.
 
OK, I believe I'm following that. And I'm not laying the blame at anyone's feet here. At least not yet.

But this place is an automatic transmission specialists. I'm just a dude. I provided them with the flexplate that was made for an LA 360 externally balanced engine. If they open things up, and see a big weight on the torque converter, shouldn't they know the flexplate and the weight on the torque converter are not a match? Or that the flexplate being removed is symmetrical and the one going on is not? I would think they are the experts and would recognize an issue.

However, that aside, WHAT IS MY NEXT MOST LOGICAL MOVE HERE? REPLACE THE FLEXPLATE? OR HAVE THE WEIGHT PULLED OFF? OR OTHER?

Obviously the new flexplate is throwing off the balance. I'm not sure if it can return it to Summit Racing for a refund or not. Which leads me to think to pull off the weight on the TC (that's free sans the labor maybe). However, it also seems the TC with the weight on it is balanced. If the weight is now pulled off and the pacman flexplate is used, I don't know that it is guaranteed to be balanced. Seems like balance is more guaranteed if I exchange flexplates (if the one removed is symmetrical). I'm frustrated now, and appreciate your help guys!
 
1st, see what the original flex plate looks like. If its an OEM-type neutral balance (symmetrical style) I think your best bet is to get one just like it and, unfortunately, replace it. I'd be concerned as to the outcome of attempting to remove the weight(s) from the torque converter.
 
69_340_GTS: Yeah, that's my thinking. At this moment, that's the route I'm going to take. I appreciate your input!


7milesout
 
Hey guys, I got the car back yesterday and it is good to go. I had the flexplate replaced with the solid version (no pacman) for internally balanced engines. The weight remains in place on the torque convertor. The moral of that story is: If you want it done right, just do the opposite of what a hack tells ya!

I have hesitated to mention the following because I don't know the truth of it. The previous owner told me that the engine was built by Herb McCandless. It wasn't built to be some super monster, but built strong and well. Most of you guys will know who Herb McCandless is so I won't go into that. But evidently when the engine was built, it was internally balanced. This is evidenced by having to switch to a flexplate built for an internally balanced engine, and everything coming back good.

This got me started thinking ... and now begs a question. The engine has never been perfectly smooth. Or even all that smooth. But I've just always shrugged it off to, that's how it's supposed to be. But since discovering that this engine is internally balanced, something occurred to me.

When I was given the car, the p.o. told me that the harmonic balancer weight had slipped. But he said that he had bought another harmonic balancer, gave it to me new in the box, and said, just install this before you drive it out on the road. Which I did. And went through the whole timing tape positioning etc. Here's my question:

Since this engine was built balanced, should it just be running a pulley on the front instead of a harmonic balancer? Maybe if I just put a pulley on the front, it would be even smoother...
 
No, ur engine is not internally balanced. That’s why u have a weight or 2 on the converter. Also the harmonic balancer has to be weighted. U can’t omit the balancer. Kim
 
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