Autom8r

Gents,

I have a TH700-R4 (old version of the 4L-60E) in a '78 'Vette. When I floor it at 100 MPH (or any other speed for that matter) it will downshift into 3rd and scream it's guts out.mANyone have any idea what's causing this????

Thanks,

Dave

performabuilt

iTrader: (25)

The 700r4 cannot be in overdrive at full throttle it will downshift from 4-3 at around 3/4 throttle at any speed , If you want full throttle 4th you can get a throttle sleeve from sonax and I beleave superior thats easily installed that will allow this
But the stock one will not .

Autom8r

NO BULL!!!! You mean they are built like that?????

This was the first time I had her up to any big speed in the 2 years I have had that tranny in it. I didn't trust the old cracked and dryrotted tires that were on it and I was trying out my shiny new Firestone Firehawk Indy 500 tires when I noticed it.

How can I find Sonax? When I Googled them up all I could find was a Sonax car care supply outfit in Germany.

Thanks for the tip!

Dave

Gilbert@Ace Racing

http://www.sonnax.com/ That's their home page.
g

performabuilt

iTrader: (25)

yes thats the way they were made and heres the link

http://www.sonnax.com/

PBA

Most 700R4's were like that, some Corvettes held 4th gear at WOT. You can modify the TV plunger sleeve with 2 Allen screws. Plug the 4-3 downshift passages with the two Allen screws, make sure that they do not interfere with the plunger and then take a dremel to grind them flush so they will clear the valve body. $.34 for both. You do not even have to drop the valve body to do this, just remove the two bolts that hold the bell crank mechanism, then remove the pin, pull out the plunger with the sleeve, do the mods, reinstall (90-95 in lbs. on the two bolts). Check TV cable adjustment when you do this, and reset if necessary. This will allow the 3-4 WOT shift to occur, and now it will hold 4th gear at anything above 65-75 mph, sometimes slightly later if you have numerically low gears (2.73's for example).

performabuilt

iTrader: (25)

I did fail to mention in either way o acheiving this you may lose part throotle kick down from 4th to 3rd like when climbing small grade and hill ect which can also be a little anoying FYI

Autom8r

Actually, that might be a good thing. Mine kicks down with only a slight amount of throttle tip-in. With 3.55 gears, there is plenty of grunt in top cog.

Where does the throttle sleeve fit in or where does it go?????

Dave

performabuilt

iTrader: (25)

it slides in the valve body you do not have to remove body but you do have to remove the pan its very easy