th400 transpak after install issues

[Liltroy]

Hey guys, I recently installed a b&m transpack kit in my th400 trans and I'm having some issues and also have a few questions.
This is the first time Ive installed the transpak. I usually just install the lower priced shift improver kit and have never had any issues and am usually rewarded with really hard shifts. This time however, the shifts seem quick, but not really hard like they usually are with just the shift kit.
Since installing the transpak, I am having an issue with first gear. if I take off at full throttle, everything is good. But if I try to drive easy, the transmission immediately shifts to 2nd gear, even with my shifter in 1st. downshifting to first gear does nothing. the only thing that will force a 1st gear downshift is the detent solenoid kicking it down if I give it full throttle. I currently I have the transmission on an engine stand and I've already checked the governor for proper operation. I will also be pulling the valvebody to make sure the 1-2 shift valve isnt sticking because I didnt have this issue until I installed the transpak.
Now for issue number 2. I noticed when installing the transpak that the instructions only told me to drill one hole in the seperator plate where as with the regular shift kit I always had to drill two holes. the other difference is that the shift kit tells you to remove the 2-3 accumulator spring and the transpak does not. Im wondering if the reason for these modifications missing is because of the stiffer pressure regulator spring with the transpak and the higher line pressure caused by this? Since I have to pull the valve body to check on the 1-2 shift valve anyway, I am wanting to remove the accumulator spring and drill the other hole in the seperator plate while I have it apart again but am worried about what size to drill the holes since I now have increased line pressure due to the new regulator spring. Any input would be greatly appreciated. I've got a couple days before it all goes back together because I'm waiting on the new VB gaskets to get here. Help me out guys!

 

[Irishman999]

There could be something weird going on with the 1-2 shift valve since you put the B&M kit in there but my turbo 400 was doing the same thing after its rebuild, I adjusted the shift vacuum modulator and it was fine.

I highly recommend the Transgo shift improver kit, especially since you have the transmission out. It changes fluid pressures by about 3 times to give you better clamping force. The kit is top notch as far as quality and instructions, it even includes the valves to eleminate the 1-2 shift valve in case you have some serious power and dont want it up shifting on its own.

http://www.summitracing.com/parts/trg-400-1-2/overview/

Hotrod could add alot more here, between him and a really good book I got I ended up rebuilding my trans with a Reybestos kit I got on ebay for 109 bucks. I got the one with waffle clutches for heavy duty applications, installed the transgo kit and its a beast. Transgo kit offers different levels just like the B&M kit but I did not even drill any holes in the separator plate, its plenty right out of the box. Just the other day I was going up a hill at half throttle and when it hit second it barked the tires!

 

[Liltroy]

I definately wish I would have went with transgo from the start. I'm on a position now where I dont want to spend any more money. Thats why I'm asking about working with what I have already. I'm planning an LS/4l80 swap next year so I only want to do whats necessary to get it running till then. Unfortunately I was forced to pull the transmission due to a bad front seal which in turn was due to a chewed up torque converter snout and pump bushing. I was just going to do what I could to get her running for the winter. I'm gonna try adjusting the modulator once its back in but i didnt touch that when i put the transpak in so idk.

 

[Irishman999]

I definately wish I would have went with transgo from the start. I'm on a position now where I dont want to spend any more money. Thats why I'm asking about working with what I have already. I'm planning an LS/4l80 swap next year so I only want to do whats necessary to get it running till then. Unfortunately I was forced to pull the transmission due to a bad front seal which in turn was due to a chewed up torque converter snout and pump bushing. I was just going to do what I could to get her running for the winter. I'm gonna try adjusting the modulator once its back in but i didnt touch that when i put the transpak in so idk.

Sounds like the center gear thingy in the pump got put in backwards, if thats the case your pump might be damaged. Check the clearance in the pump gears before you put it back together or it might not have pressure now.

If its an OEM modulator its not adjustable. I have an extra B&M modulator, if you pm me your address I will mail it to you.

 

[Liltroy]

pump was taken to trans shop today to get checked and have bushings replaced. my modulator is adjustable(must have been replaced at some point) but i really appreciate the offer. talked to transmission guy and he said if i overtightened the valve body bolts it may be causing the 1-2 shift valve to bind. he recommended loosening them slighty and then retorqueing to spec so im gonna give that a shot.

 

[Irishman999]

pump was taken to trans shop today to get checked and have bushings replaced. my modulator is adjustable(must have been replaced at some point) but i really appreciate the offer. talked to transmission guy and he said if i overtightened the valve body bolts it may be causing the 1-2 shift valve to bind. he recommended loosening them slighty and then retorqueing to spec so im gonna give that a shot.

Sounds like you got it under control, I have alot of useful **** sitting around so I mail it to people meet on here that could use it instead of throwing it away or letting it sit in a box.

Im not a transmission expert by any means, I just bought a book on the internet and dug in. With that said, a turbo 400's valve body is a healthy chunk of well machined cast iron. Im not gonna say those guys are full of **** but its hard to imagine that you could torque those little bolts into an aluminum case enough to warp that valve body and cause the shift valves to stick in the bores. They are tight tolerances, maybe they are right.

If you have that adjustable valve modulator already in it I suspect the B&M shift kit changed some shift parameters.

This is just a suggestion and I give really questionable advice but if I was in your position I would just tear down the transmission and freshen it up for a few hundred bucks. You are doing the modern LS swap but you can still sell it when your done and not worry about problems between your swaps, huge benefit is having a general understanding of how transmissions work and thats like the missing link to me as far back yard shade tree 'WRENCHIN.

http://www.amazon.com/Rebuild-Modify-Transmissions-Design-Workbench/dp/1934709204

Thats the book I got and its pretty much step by step. Only specialty tool you actually need is a clutch pack spring compressor and I got mine through Jegs for 30 bucks. I also got some Snap-on ring pliers but I look for any excuse to buy more tools. I got the case cleaned for 30 bucks at my local machine shop and the rebuild kit was around 100 bucks on Ebay.

 

[Liltroy]

I was actually thinking about going that route but I really dont drive this thing but maybe once a week when its running and thats just to haul off the trash or just cause I like cruising in it,lol. as an example, I only put about 500 miles on it all last year. I'm having another issue now though. I got my pump back from trans guy today and everything checked out ok, front bushing was just shot( it is a 74 model,lol). my new problem is that one of the detent solenoid bolts broke off!!! I torqued it to spec but the second bolt I tryed to torque down snapped off the head. I think these are NOT the original bolts. they look like some cheap crap someone probably bought to replace the hardened ones after they lost them Im guessing. Anyway I bought an easy out and drilled the bolt, then the damn easy out snapped off in the hole I just drilled!!!!! Im wondering if I can get away with just one bolt in this solenoid as I have absolutely no idea how Im gonna get this thing out now. murphys law. get s me everytime.