4T60-E dropping out from 4th when hot issue (code p0740)

[johnd89]

Hello,

I'm new here. My car, '95 riv s/c 160k miles (4T60-E) has the dropping out from 4th when hot issue (code p0740).
I was thinking to install an aux tranny cooler hoping it will temporary fix the issue.
Any recommandation on what brand(B&M, Tru Cool) and GVW rating would be appreciated. Also, does the position counts? I've seen with the in/out fittings facing down, as well as on one side.

If not, maybe a new sonnax TCC apply valve. If I understand correctly, upon disassembly should be able to know if I need the regular replacement one, or the oversize one. I would think that in both cases I need to get the valvebody out.
Do I need to drop the tranny for this, or just the side cover? Upon reading the manual, should be doable without dropping the tranny...
One last question: when on the highway, downshifts al the time from OD -if let's say I lift a little, then go on again very easy on gas- Is there a fix for this?
Appreciate really any input.
Thanks!

[JMH1950]

I had the same problem about a year ago. The cooler won't help much that valve has to be replaced. I had a trans shop do it for $500 cause I don't trust myself to mess with the innards of a transmission. They just lowered the driver's side enough to access the cover and did the deed through there. Besides the TCC apply valve, they increased line pressure with another sonex mod (forget the name). 15 months and about 25,000 km and trans is still strong. (knocking on wood here)

[johnd89]

Thanks for the reply!
Do you know if they machined the valve body to install an oversize valve, or just drop-in replacement?
Thanks

[JMH1950]

Mine was just a replacement as far as I know.

[johnd89]

Thanks a million!
That for sure simplifies things. No special tool ($$$) needed then. pheeew...
I'll get brave one day then;-)