p.s. .150 band clearance is 98% going to be your issue.
Get it closer to .060

 

Op, here are a few pictures of a pin that I used on a previous build. You can see where it is welded, then just grind down to the necessary spec with the tip of the pin having a slight dome/ roundness.

 

Thanks guy. Pictures very helpful. Not many mechanics my age know how to weld (not a skill they teach in the trade anymore unless your a fabricator or work in an exhaust shop) so I'll be getting one of the older boys to help me and showing them a picture makes this 100x easier lol

My original transmission that lost 2nd had easy over an inch of free play so even though it was over spec I thought I could get away with it. I should know better 🙄

 

Get the clearance down to a minimum, is the first place to start. Too much clearance keeps the oil pushing the band off (when it is already off) instead of going to the 3-4 clutches. Once this is done, let me know what happens.

 

Ok I had to extend pin 3mm to get servo travel to .060

Flare seems better at light throttle. Maybe only 100rpm but when you give it more the flare gets worse. Just been coasting it on the 2-3 shift to save any damage happening

​​​Should I test line pressure next? Can anyone provide specs I should use for testing. Or should I try something else?Cheers guys

 

so when adjusting travel....stick to the lower end of the clearance ....check !

 

You want 235 to 240 psi. at WOT in 1st or 2nd gear above 3,000 rpm.

 

I installed the trans go hd 2 in my 4l60e. The one thing the instructions didn’t explain unless I missed it is how to adjust the band clearance. A couple of guys on here helped me through it. My transmission was flaring on the 2-3 until I went with the recommended hole sizes in the separator plate and a very tight band clearance right around .060”. The 2-3 shift was fine after that. Also, the hole sizes that transgo recommends for the band release and third apply didn’t work for me.

 

This is because the HD2 kit is a shift kit and most people are going to install it in a running transmission. Those who are installing it during a rebuild need to get their instructions for rebuilding transmissions from another source (other than a shift kit manufacturer)

Edit: you did miss it. It shows how to make sure it's within a range of not to tight and not too loose. Which it should already be if it was running.

 

Don't be afraid to take it back apart and check everything. Say you put a pressure gauge on it, if it's got good pressure, then what? If it's got low pressure, then what? You've got to take it apart no matter what the pressure reads. Guess it's good info to have though.

What kind of assembly lube did you use on this and how many miles have been put on it?

If everything is done as you said it shouldn't have a problem, seems something's been overlooked or done wrong.

I usually block the check ball hole when I block the 3-2 valve inboard.
I usually don't slot the steel servo back cover (3rd accumulator) on the HD2 kit. I do with the SK kit.
I usually don't use the transgo hi rev 3-4 release springs WITH the stock release springs.
Seems like you've created a few things to make 3rd apply slower. It might be very very slightly slower, to the point where no one thinks it's going to be a problem, but ironically there is now a problem. The people that say none of this will be a problem, where are these people now?
No one jumped on here with a definitive answer to what is going on or even possibly going on.

You had one reply. Check the line pressure, see my comment on that above.

If you go WOT for 1-2 is it firm? If it is theres probably nothing wrong with the line pressure. What about driving in fourth, give it some gas but not enough to downshift, do the rpm's slide up? If they do then you have a big problem.

Look at this at the :26 mark, it's in 4th locked up and with a little throttle it slips. I do continue on in the video and go WOT and theres still no 2-3 flare. This video was my diagnosis. The 3-4 clutches were worn down to paper thin. The fix was to build another transmission. I could have connected a pressure gauge, it would have said the pressure is fine, need to continue on and tear it down to find the problem.

 

I'm not afraid to pull it back out, just need time. I even have the original box with burnt band I can put back in. I half enough left over parts from the donor box that I only really need to buy a seperator plate, couple gaskets and a oil filter and that one is up and running again.

I posted what size I made the feed holes. Maybe I should make a couple of adjustment and try again before pulling box out

I'm happy to block the check ball for 3-2 valve. How do you usually go about doing it and I'll do it at same time.

Still waiting for a pressure gauge to arrive but all other shifts feel nice and firm even the 3-2 which I never used to be able to even feel. Haven't got speed up enough to test 4th for slip but 1-2 is good
​​

 

Ok so I got gauge hooked up but obviously a little hard to read while trying to drive (currently cable ties to wipers) so this is what I got

Edited after going for drive with mate

At idle
60psi in park/neutral
75psi in 1,2,3,D
100psi in R

With just a light constant throttle going up around 3000rpm range when I can get flare to happen it's holding around 90psi in 2nd and jumps to 120psi in 3rd

With full throttle gauge is 200-220psi

Holds pressures pretty constant I only noticed for a very split second on the 2-3 upshift it dropped to 150psi and immediately back over 200. I had to record it and watch it to notice.

 

The pressures are low. It seems from your description, that pressure rise is not very responsive at lighter throttle openings. I would adjust the EPC solenoid to get another 15 - 20 pounds more pressure. The pressure at idle should be 75 - 80 maximum. Adding 15 - 20 psi. more would give you 235 - 240 at WOT. Go on line and see how much you have to move the set screw to get the additional 15 - 20 psi. needed here. This might fix the flare too.

 

Really?

 

Maybe everyone is just sick of of my thread lol. I hope atleast it's a good troubleshooting guide for someone else

I might actually swap the EPC out of my original gearbox into this one and see if pressure is better. The donor box had a lot of clutch material in it from burnt forward clutches and was of unknown distance travelled.

I'm even tempted to close the band release feed in the separator plate since pan will be off but if problem goes away I'll never know which of the two possible remedies it was 🤹

 

There is no harm in making small adjustments to the electronic pressure control solenoid for testing purposes...

I do not find it to be good practice to use the adjustment as a band-aid/ repair though... as there are multiple other methods available to achieve the same result.

 

Are you still mad at me for being realistic? Like when I said this:
I'm still here, where are the other guys? Hmm.

I'd swap the EPC with anything and recheck the pressures. If they are different maybe it's the EPC solenoid. If the pressures are the same it might be something inside that you'd find.

Here are two easy fixes that were assembly mistakes. At the time I found them I thought they were the reason for burned 3-4 (which is what would happen if you just kept driving (I know you know this)

 

I agree though... wide open throttle line pressure should ideally be close to 250 Psi.

In a THM700-R4 , I even prefer pressures to be at about 300 Psi.

 

LMAO! that solid teflon ring!

Jay has a very, very good point.

I have seen countless transmissions brought to me inoperable after a DIY rebuild...

Those two photos are examples of build errors that can take place at dozens of different locations with in the transmission.

Double and triple check the work!

 

When you have got the servo apply pin clearance close to where you want it...

You can install the 4th piston backwards to tighten-up clearance slightly as a test for correcting shift timing.