..

 

It will still shift under boost it will be fine.

 

X2 It will work fine.

 

I had issues with my shifting under boost.

I rigged up a check valve to vent boost.


manifold--> small orriface --> T --> modulator
l
l
V
check valve plumbed to let air out

hope this makes sense

 

.

 

I've always used a MVB but have heard of folks using the Checkvalve method as described above with a std valve body. I would think shift kit used may also come into play.

 

X3 I just hooked it up to manifold vacuum, like stock and it works fine.

 

The moderator is a diaphragm with a spring in it, the vacuum sucks on the diaphragm witch pulls on the spring and when there is no vacuum the spring pushes against the valve so when boost comes in it will help the spring I was just wondering why you would need the bleed off are you just trying to protect the diaphram from boost?

 

Mine wouldn't shift out of 1st gear after about 15 PSI of boost IIRC. I installed the check valve vent and now it shifts fine.

 

X2

 

This is odd!

 

..

 

Careful running the car without the turbo charge pipes hooked up. They can overspin and grenade.

 

Transgo # VBP-VAC


Heres one on Ebay . they get way to much money for what it is . Its a tee with a check ball in it . It also has a restrictor on the side that goes to manifold for some reason . :noidea: Anyone know why that would be ????? Maybe if the hole is too large the check ball could not relieve pressure fast enough .

http://cgi.ebay.com/ebaymotors/TRAN...r_Truck_Parts_Accessories?hash=item3c913210cc

#ad

 

Blown - That piece will work for the 400 as well?

 

Yes , it worked on my TH400 before I went to a full manual .

 

I did some checking on this it will not shift under because the boost pressure over rides the line pressure and the modulator valve will not move,that area ratio thing plays a part in this!

 

OK I'm buying it.

 

I just used an old holley needle and seat assembly installed inside a section of vacuum line so that the needle would close once any boost was seen, this stops the boost from effecting the line pressure. A pin hole was added to the hose between the needle and seat and the mod valve to allow a bleed port in case a tiny bit of pressure gets past. I've been running like this for over 4 years.

Brad J.

 

Gonna bump this up as I'm close to getting mine going.

Could you also use a cheap manual boost tee to do the same thing as the transgo check valve?