I just went through over 15 pages and years of information on 700r4 transmissions not going into 3rd at WOT and I couldn't find anything conclusive on this issue. I remember my old built 700R4 wouldn't shift into 3rd at WOT, that trans was junk through and through, and I swapped it for a Th350. Now I have a stock 87 up unit (with auxillary valve body) that for some reason quit hitting 3rd at full throttle unless you let up on it. I went ahead and swapped the governor, .480 boost valve, and vette servo into the trans because these are some of the reasons I'de read for the lack of shift, and now the problem's worse! The trans will hit 2nd and chirp the tires, manually shifting at 1/2 throttle it will hit 2nd nice, then will rev a bit and hit 3rd just fine. The problem occurs when I go WOT, the 1 to 2 is great at around 4800rpm, then it won't engage 3rd, it just zings right up past 5500, even if I let off the gas and let it coast down it won't go into 3rd until it's down to about 3000rpm. What should I be looking for here? I have a Superior shift kit but I don't want to mess with it unless this is something a shift kit can fix. From what I can tell these trans have been having this same problem for years now, has no one identified for sure what's going on with them?

 

The changes you have made sound good, but it might already be to late. The TransGo Performance Shift kit will normally fix this, but the 3-4 clutches "must" be in good shape. I do not like the Superior valve body kit, as it does not address the WOT 2-3 shift, and other problems.

 

So the problem is a design flaw in the valve body?

 

ttt

 

never had that problem in my 87. upgrades in my sig

 

Well I searched and searched on this and found someone who said "try seafoam". I put seafoam in it and drove it for a while then on a whim I hammered it and there is third! It's been hitting third good and crisp for a while now, it did mess up once again but the fluid was a quart low so I assume that caused it. I also had a crazy issue with my distributor that may have had something to do with it but I'm not sure how it could. Anyways I'm pretty happy about it I now have a functional trans that shifts very nice.