Questions about Fitzall TeckPack A74741Q -hard 1-2 shift fix

Questions about Fitzall TeckPack A74741Q -hard 1-2 shift fix

Postby gman [OP] » March 8th 2020, 10:38am

tl;dr a lot of this is intro fluff, and please skip to the next bold question if you don't want to read it (that's my real question).

Hello everyone.New 1999 Astro owner here.
As a GM guy, I gotta say that I really love this van and owning it makes me very happy.
Especially because the 4.3 is essentially the same block as a 350 (iconic GM pushrod) with 2 cylinders lopped off.

I have some questions about this fix.

I had the P1870 code, and while doing some research on the forums , I was lucky to be under the conditions of just a worn valve body (no burning fluid, no problems in any other gears, and only a hard 1-2 shift after heating up the transmission after going 65 on the highway).
So I went ahead and bought this:
https://www.teckpak.com/spgm.cfm?id=A74741Q

And installed it using this video:
https://www.youtube.com/watch?v=YK46XJbAJqg

Oh, by the way, I have heard a lot of complaints about peoles pliers being too thick or having to angle grind them to get it to work.
I bougt these very thin needle noses, and they actually worked like they were made fro this job, so for future reference, people should use something like these or similar to make it as
straightforward as possible:
https://www.amazon.com/gp/product/B0001 ... UTF8&psc=1

For doing it without a valve body, they should include "Need 3 hands" in the description.
Although it was actually extremely straightforward and very easy to install folllowing the video, if I didn't have experience with doing weird things in weird positions with cars, I would probably still be on the side of the road.

I was greeted with nice red transmission fluid (slighly brown due to age), and NO metal shavings in the pan (thankfully).
And my problem was fixed! Took it for a long drive at speed, and was greeted with no torque converter slippage at 55mph+ (nice smooth ride), and no more hard 1-2 bang shifts after a long highway drive. The code also stopped popping up (after about 25-30 minutes at 65mph, it would give a pending P1870 trans slipping code).
My 1-2 shifts are also noticeably smoother and you really have to listen to hear it shift.
Got pretty lucky on that one, I was hoping that it wasn't burnt 3-4 clutches or a torque converter issue.

Anyways, none of this is news, but I really wanted to ask.. I didn't feel so comfortable with putting that clip in upside down while just leaving it hanging there.
Although the video is probably right (it will rotate instead of moving downwards when it vibrates), I was able to yank it out with a little force and that kinda scares me.

So, my real question is:
If it falls out, what's the worst that can happen?
I'm hoping that it won't catastrophically destroy my transmission if that clip falls out.
My guess is that it will just start slipping like crazy, but since the transmission itself isn't bad, it will still engage, but just fail to lock up in a lot of situations.
The problem the transmission had comes from too much fluid passing through that valve, so I'm assuming that if A LOT of fluid passes through that valve, It will just be the above problems magnified.
I am hoping htat I will still be able to limp to some spot and put a new clip in (I bought an extra one just in case). Obviously won't drive it like that for a while as it would probably eat my torque converter in short order, but knowing that I can limp it to a safe spot (or tow it to a DIY garage) wiould be nice.

My biggest fear is a total catastrophic transmission failure, where something doesn't read right, and the transmission essentially rips itself apart because of some sort of inconsistency in pressure.

Does anyone here know what will happen if that clip falls out?

I want to replace the upper and lower valve body gaskets anyways, so I will eventually drop the pan again (and the entire valve body) at some point, and do those gaskets and then put the clip in in the right direction.

Anyone know what will happen if the clip just falls out?
Please let me know thanks.
1999 Chevy Astro Van
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gman
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Re: Questions about Fitzall TeckPack A74741Q -hard 1-2 shift

Postby AstroWill » March 9th 2020, 2:54pm

gman wrote:So, my real question is:
If it falls out, what's the worst that can happen?


I would think that a complete loss of line pressure would be the worst case.

Also, quoting my reply from https://www.astrosafari.com/viewtopic.p ... 0#p1540982
AstroWill wrote:I do like that install video thinking a little bit outside the box but getting it done without dropping the VB.

I think the cheapest would be inserting a $0.50 spring from your local transmission shop that would do the exact same thing. They know which one it is.

It does do away with the PWM for the TCC and makes it on-off only, giving full line pressure to the TCC which will definitely be harder on certain parts and probably cost elsewhere like fuel economy. But if it gets you some more life out of the transmission before needing to be completely rebuilt then it's a freaking awesome cheap and easy fix. Sonnax has a lot of good info on it's site as well.

Good work!

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Re: Questions about Fitzall TeckPack A74741Q -hard 1-2 shift

Postby gman [OP] » March 9th 2020, 4:25pm

AstroWill wrote:
gman wrote:So, my real question is:
If it falls out, what's the worst that can happen?


I would think that a complete loss of line pressure would be the worst case.


So would I just have extreme transmission slip with no lockup?
Would I be able to limp to a parking spot somewhere?
I can also tow it.
Would it completely destroy my transmission, or would I just need to put the clip back in? lol.
Little new to these things.

Again, I'm probably just being a little too careful here, as I don't see any conditions in the transmission that "grab" the clip like my fingers did and pull on it as hard as I had to to pull it out (but it was a lot less force than I expected), but I would like to be prepared for the worst case scenario just in case.
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Re: Questions about Fitzall TeckPack A74741Q -hard 1-2 shift

Postby AstroWill » March 9th 2020, 10:10pm

Well basically the entire transmission requires hydraulic pressure to function. I have no idea what "exactly" would happen, and I hope that neither you nor I find out ;) That is a longer 1-piece section so I don't think that it could fall out completely and end up in the pan, but it doesn't have to be ejected all the way to cause all kinds of problems and a loss of pressure.

Even a little loss of pressure causes some problems, but a complete loss of pressure and the transmission would stop functioning. That is actually what was happening because of that bore on the VB being worn out, it was loosing pressure to the TCC, causing the computer to see slippage, thus ramping up the pressure to stop the slippage causing the harsh shift because of the higher pressure.

With hydraulic systems the pump creates flow, imagine a pump siting in fluid without anything attached to the outlet of the pump. It's going to move the fluid but really won't create any pressure(for practical purposes). Then you have all of the rest of the parts that are added on that add restriction to that flow thus building pressure. The biggest one usually being the pressure regulator that determines the system pressure. Anyway, without enough restrictions the pump would continue to flow but wouldn't build up the pressure that is needed to do work.

Kinda like when you loose engine oil pressure, the pump is still pumping away creating flow, but the loss of restriction causes a loss of pressure meaning that you can't get oil to everywhere it needs to go.

Same with the fuel system, your fuel pump creates the flow and the regulator holds back that flow creating the pressure needed to force the proper amount of fuel through all of the injectors when they open.

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Re: Questions about Fitzall TeckPack A74741Q -hard 1-2 shift

Postby gman [OP] » March 9th 2020, 11:02pm

AstroWill wrote:Well basically the entire transmission requires hydraulic pressure to function. I have no idea what "exactly" would happen, and I hope that neither you nor I find out ;) That is a longer 1-piece section so I don't think that it could fall out completely and end up in the pan, but it doesn't have to be ejected all the way to cause all kinds of problems and a loss of pressure.

Even a little loss of pressure causes some problems, but a complete loss of pressure and the transmission would stop functioning. That is actually what was happening because of that bore on the VB being worn out, it was loosing pressure to the TCC, causing the computer to see slippage, thus ramping up the pressure to stop the slippage causing the harsh shift because of the higher pressure.

With hydraulic systems the pump creates flow, imagine a pump siting in fluid without anything attached to the outlet of the pump. It's going to move the fluid but really won't create any pressure(for practical purposes). Then you have all of the rest of the parts that are added on that add restriction to that flow thus building pressure. The biggest one usually being the pressure regulator that determines the system pressure. Anyway, without enough restrictions the pump would continue to flow but wouldn't build up the pressure that is needed to do work.

Kinda like when you loose engine oil pressure, the pump is still pumping away creating flow, but the loss of restriction causes a loss of pressure meaning that you can't get oil to everywhere it needs to go.

Same with the fuel system, your fuel pump creates the flow and the regulator holds back that flow creating the pressure needed to force the proper amount of fuel through all of the injectors when they open.


Thanks for the reply.
Yeah, I basically figured that it would just stop functioning, but again, I can just tow it to a random spot and put my back up clip in really quick (much faster this time, and much faster than if I had to replace the entire valve again).
As soon as I notice anything extremely funny, I would immediately pull over, get towed to a safe spot if I have to, drop the pan, and get it done in an hour or so.
Again, I don't see any reason why it would happen, but the clip being upside down just kind of bothers me lol.

I was mostly afraid of the clip coming out, the valve being pushed out and into the pan (or worse, through the pan), and the transmission just eating itself apart.
But, like you said, it would just be like a pump that is not pumping anything, meaning all the spinny stuff in the transmission would, well, just stop spinning instead of "breaking", and I would just pop the valve back in and replace the clip.

Also, is this your site?
https://sites.google.com/site/astrosafa ... or-disease

If it is, you're missing the affiliate links. I would gladly use an affilliate link on the site to buy a distributor drive gear or an aluminium distributor to fix my pancake problem if I have it.
Apparently, a lot of Astros out there just have that problem and the motor keeps continuing to run forever so they never get it fixed lol.
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Re: Questions about Fitzall TeckPack A74741Q -hard 1-2 shift

Postby AstroWill » March 10th 2020, 12:27am

gman wrote:Also, is this your site?
https://sites.google.com/site/astrosafa ... or-disease

If it is, you're missing the affiliate links. I would gladly use an affilliate link on the site to buy a distributor drive gear or an aluminium distributor to fix my pancake problem if I have it.
Apparently, a lot of Astros out there just have that problem and the motor keeps continuing to run forever so they never get it fixed lol.


It is, started out just as a place to put my various links that I could no longer fit in my signature.

I have some affiliate links, and I am definitely missing some. Not that I need the extra $5-6 a month or anything, but i did just use it to purchase another manual to help people out.

I like that the affiliate links don't add any cost to the buyer and it's like throwing a tip in the tip jar without having to actually part with any extra cash. I appreciate you mentioning it, and I will take a look later and see if I can add one there. :thumbup:

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