My 4l80e/Transgo HD-2 shiftkit with .096 holes in the seperator plate for firm shifts. My 1-2 and 2-3 shifts are fast and firm WOT shifting @ 5600rpms, but my 3-4 is less than stellar under the same condition( and yes I am haulin *** at this point ), what can I do to improve this correctly?

 

From what I have learned and seen, you really don't what to mess with OD part the 4L80E. The only thing I could think of to do is check the springs in the fourth clutch assembly you could have some weak springs. The last time I overhauled an 80E, I could remove the snap ring holding the spring assembly in by hand without using a spring compressor. One last thing, check the clearance in the fourth clutch assembly, GM specs are 0.040-0.100 inches, try to get it close to 0.040 this will reduce any slippage.

 

exactly how fast are you going when it shifts? i think i could go close to 160mph in 3rd.

i can't help with yor question but if you locked up the converter mid 3rd gear at wot you will gain some mph without having to get into 4th.

i was told not to let it shift into 4th at wot.

 

I was told the same thing about WOT shift to 4th, but that doesn't stop me, although I try to be somewhat mindful of it.
there's this Quadzilla 4l80 they are claiming WOT 3-4 shifts are Ok
http://www.transmissioncenter.net/4L80E.htm

I was hoping there might be something basic I could do

 

thanks cbrich, I'll look into those suggestions

 

I did one on a cammed 6.0 HD. It goes into 4th at about 132mph. Done it a few times, shift really firm yet. It has a Superior shift kit and a tune that it for the trans. The cam is a 220-224 572-577. It lats rubber into 2nd like there is no tommarow and 3rd gets loose in the rain at WOT 90mph.

 

anyone else have any thoughts on this?

 

The 4L80-E can do WOT shifts. On my truck the WOT 3-4 takes place at about 99mph, so I have frequent opportunities to do it.
My trans was rebuilt with a Level 10 PTS kit before I installed it. At the time there were no 3-4 clutches available with high performance friction material. I'm just running stock replacements on it. I made the fourth orifice larger to make up the difference. This worked well. Another guy that rebuilt his own 4L80-E did the same thing based on my experiences and got good results also.
There are now Blue Plate Special performance clutches available for Fourth and its overrun packs. This goes for about $75. The next time my trans is apart it will be getting a set of these.

 

your talking about the seperator plate right? mine are all drilled @ 096. What did you drill yours out to if you don't mind saying?

 

I used 0.086" for Second (C) and Third (B), and used the 0.096" drill bit for Fourth (A).

You might consider drilling hole (A) out to 0.120".