What does the stock VB boost valve do? (+ how to yank a stuck end plug)

[saxon]

What does the stock VB boost valve do? (+ how to yank a stuck one)

Background: rebuilding valve body out of 1991 4WD A4LD. Obvious things found thus far: OD band adjusted 2.0 turns for single wrap, should have been 3.5 turns for double wrap. Also, TCC solenoid was defective.

New issue: The stock boost valve is the only bore in the VB that I have not been able to pull out. Since I bought the Sonnax boost valve update I can ruin the stock valve. I'm planning to drill a small hole in the stock boost valve, stick a screw in it, and yank it out that way (the same way that Glacier991 removed the stock boost valve from his oval boost valve bore; http://www.explorerforum.com/forums/showpost.php?p=1269705&postcount=52). Wonder if my boost valve bore is oval, too...? Is that common?

btw, what does the boost valve do anyway? I haven't seen that info. anywhere.

 

[BrooklynBay]

That part controls the amount of boost pressure. The pump makes the pressure, but it is not regulated. The pump's pressure varies in relation to the engine's RPM, and fluid gets distributed to various areas, like the clutches, pistons, torque converter, etc.

 

[saxon]

Cool, thanks Brooklyn Bay.

My boost valve bore did not seem to be oval. The Sonnax upgrade slid in and out cleanly (prior to installing the o-rings).

I'm just going to install the rebuilt VB now.

Wish me luck.

I think that the VB upgrades will fix what they are supposed to fix but unless there was a HUGE VB gasket leak, I don't think the VB rebuild will fix my 'always in a forward gear' problem. Maybe the manual valve was way out of alignment, maybe the 2.0 turns out on the double wrap OD band was enough 'wrong', and maybe the possibly bad TCC solenoid caused that problem,.... but I doubt it.

Now that I know that my OD band is a double wrap, I am going to correct that band adjustment before test driving. Bummer is that if the 'always in forward' problem goes away, I will not know which fix corrected the problem. However, if the band adjustment is wrong I don't want to drive it.

I will know in a few hours and I will keep the list posted.

 

[saxon]

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[BrooklynBay]

70 in. lbs.

 

[saxon]

That's what I had guessed but didn't want to leave it at that.

Thanks!

 

[BrooklynBay]

I just wanted to be a little more specific on the exact numbers, so I looked it up in the ATSG manual (page 61) of the 4R44E/4R55E manual. It says that the 3 separating plate to main control screws are torqued 8-11 N-M (71-97 lb-in).

 

[saxon]

Sorry about sticking this at the end of a boost valve thread. I thought that I had sent a query about the torque value for the separator plate screws directly to BrooklynBay and instead added it to this thread.

For more on the torque values, see: http://www.explorerforum.com/forums/showthread.php?t=157515

 

[BrooklynBay]

I did get that email. I just wanted to say that my 5R55E ATSG manual (page 119) states a 53-71 lb. in. torque recommendation. It is a little lower than what was written in the 4R manual, so just torque those 3 separator plate torx screws to 70 in. lbs.