ok so even with the modded tranny (syclone valve body corvette servos od downshift delay thingee) OD is only really good for cruising. I mean it will accelerate but only slowly because if I give it a good amount of gas it will kick outta OD.

If i was running a low boost turbo setup at like 5 psi, could one concievably add more boost and fuel in OD via like a two stage boost controller and tuning to increase airflow at 1/2 throttle in OD? Like my old turbo k car, its head flowed like **** so 14 psi on pump gas without an intercooler happened. From that i know that its cylinder pressure, not measured boost pressure that matters when it comes to safety.

even though thr. blade angle would be at 1/2, wouldnt additional boost (say 3-4 psi) make it feel more like the car was at wide open throttle without having to approach the dangerous OD kickdown point?

im not trying to turbo this thing yet, im just wondering if this would be a solution to something that bugs me even now.

 

I've tried this in my car several times and it always kicks down before I can get much acceleration at 120 mph. At some point I cannot put enough pedal to make any boost or it will kick down, regardless of what rpm it will be when it gets to third. The fix is a modified valve that goes in the valve body:

http://www.bmracing.com/PRODUCTS/Tra...t-GM-TH-700-R4

Or, contact Dana at Pro-Built Automatics, as he has a cheaper fix!

 

got one of those, it still kicks down, just not at 1/2 throttle anymore. u can dip in a little harder, but not much

 

Talk to Dana then, he said his mod will prevent kickdown above a certain mph (you have to manually downshift to 3 to get it above that mph).

 

cheaper and works better? +1 for that guy, checking it out

what do u mean by manually downshift?

 

I had Dana set it up as ZZ3Astro described except I told him I didn't want it to ever downshift out on my street/strip 700r4.

Shifter in OD position acts like normal all upshifts occur. If you put your foot into the throttle in OD it will never downshift out of OD into 3rd AKA "Passing Gear". This allowed me to get full WOT Upshifts into OD and not have to ever worry about it downshifting out. If I want to change from OD to 3rd with throttle I need to put the shifter into 3rd. I use a pro-ratchet and the weights are set to shift around 3500 RPMs anyways so I know when I bump the shifter it's going to shift.

Slow down and it will shift back into 3rd on it's own. So there it still works like a normal automatic at that point.

I vote +1 for Dana. Always nice and you can get ahold of him by phone or online forums.

 

This is not a good idea. The 700R4 and the 4L60E trans can't handle the torque/hp in OD. I have rebuilt my 3-4 clutch a few times because I tried to accomplish exactly what you are trying to do. I don't care what these guys say about building a 700/60E to handle 700+ HP it won't handle it in OD. 1st through 3rd no problem but OD it just doesnt hold it. I have tried every 3-4 clutch package out there and they all fail. The longest I got one to hold up was a little over a year. This one had 9 high energy clutches and kolene steels with the transgo upgrades springs and all. I am switching to the 4L80E this winter.
There is a reason the factory wouldn't allow WOT upshifts into OD, they had reliability issues behind stock engines.

 

I know I won't be planning on full throttle upshifts myself.. I might do a few seconds of boosted OD acceleration, but mainly it would be for passing without downshifting when I'm on the interstate (not very often in the Iroc!)

 

Just be careful...pulling transmissions sucks.

 

yeah. and mine only has 5k on it and I like it otherwise. very neat though, i just have a stock 220 hp gm truck replacement 350 in a 273 geared RS, i like to cruise just over 3k in OD which puts me at about 120 and when i hit big rolling hills it will sometimes downshift