Need some input on this. I just finished my TH350 swap. Trans was fresh but sat for a couple years not installed in anything. So here are stats.... '95 formula, LT1 of course, LT's, ect, Yank 3600, Transgo 350-3 FMVB, Hurst Quarter Stick 2, MSD shift light, Autometer Ultralight Trans temp guage (sensor in pan), BMR crossmember w/torque arm mount, B&M 70264 trans cooler.

So now to the issue. I drained what fluid that had been in the trans, not alot in there, cleaned everything out with brake cleaner to be safe and also blew out valve body as I went. Installed Transgo kit and so on. Now on first driving it, around block or short distance, all is good. I drive about 20 miles to work and about halfway I notice third is not engaging right away. Stop and go driving about 3/4 of the way. It will take maybe a 5 one thousand count at times. It will engage sooner if you back off the throttle a bit it seems. This does not seem as noticeable at first. Further playing with it on my drive home this morning I notice that once I do get third that I can go from 3-2-3-2-3 and so on and I have imediate engagement. No problem at all. I do have the vacuum modulator hooked up. In park from under the hood at the point I T'ed into seemed to have good vacuum. My trans temp at highest showed me 180. Norm is 160. I have not ripped into the throttle yet. I am at about 90 miles on the set up so far and am still waiting my 150 mark on the yank conv. I played with the shifter easing it back and forth to see if possible adjustment issue, no luck.

So I need some input. Please!

 

Make sure that the modulator valve moves freely and also that the governor is clean and free. These are the first two things I would check. Vince

 

Im not a tranny expert by any means, but he said the trans has a FMVB.. Isn't the vac mod & gov not used once a manual valve body is installed?

 

He said he hooked up the vacuum modulator. It can be used or an aluminum plug can be put in it's place, I'd use a plug. The governor should be modified in some way. I forgot how transgo does it with a th350, I know they have you put a clip in it for a manual 700.

 

The TransGo -3 kit for the TH350 uses a clip on the governor like the 700.
It retains use of the modulator to control line pressure. If you want fixed line pressure just unplug the modulator. Installing a plug in it's place will result in excessive line pressure in reverse.

Could possibly be a worn governor or bore.

 

Transgo claims extended trans life with use of the modulator. If I remember correct I think the instructions even said by 10x. True or not? I dont know. But yes governor uses clips to hold it open.

So what is the best way to check worn governor or bore? Just replace gov? I will pull the valve and gov an make sure all looks well and clean it back out to be sure on that part. This trans did appear to have an adjustable modulator and I wasnt sure if anything on that will have an effect on it. Also anyone else running a fwd manual vb and not using the vacuum modulator?

Thanks for your responses. I need all the help I can get with my luck.

 

You can check governor and governor bore wear by taking the cover off and moving it up and down. I guess you need to do a few to know what good and bad feels like.

You can also take the governor out and run your pinky finger in and out of the bore to feel for ridges. Also measure the governor with a micrometer, it should be .800 or bigger.

If all thats good take the transgo clip out of it and see if it shifts ok, if it does you have internal leaks.

 

Ok so I pulled vac modulator, cleaned it out, checked it to see for leaks, all good. I checked the governor, its almost dead on .8. the lower part towards the gear is just maybe a thousanth or two under. I also guaged the bore. It was .801 . The gov itself is seated very well in the hole. No wiggle what so ever. Also I have noticed that it will not always engage reverse right away. If i go from reverse to N or to a gear and return to R it will engage fine. Other wise sometimes it only acts half in. So I sat down and scratched my head and looked over the transgo instructions again. I remembered something I came across while installing the kit. On the the pressure valve I had a piece that kept hanging up sideways when I was installing it. It kept shifting every time and did not want to seat smoothly. So here is what it is. The reverse and modulator boost valve. So what is my chances this is whats causing both my delayed 3rd gear and intermittent R issue? Anyone have this issue? Here is also a pic. Best I could include. Oh I also adjusted the shifter cable, no change. Seemed dead on. Only other thing is I am using a rubber vac line. I know they used metal factory. So I had my fiancée run it up to 4k in N with me having my thumb on it, seemed to pull pressure still. Wasn't sure if it was maybe collapsing.

 

All of the symptoms point to a leak in the low circuit.