i have a 91 z and would like a bit more top end speed, and my tranny ( 700r4) wont lock into 4th at high speed, ( obviously) , any way to do something about this????

 

B&M shift improver kit stage 2, 49.95 at kragens, less everywhere else but they usually have it in stock, bypasses the mandatory 2/3 throttle downshift in fourth gear for later model 700 r4's. dont try putting it in yourself unless your familiar with auto trans valve bodies. hope it helps

 

I have experienced the same thing you are having problems with and you can not change it,yes b&m makes what they call a kickdown kit but it is the same thing the 700r4 has in it factory.All camaro,firebird and corvettes all will down shift at 3/4 throttle and no one has been able to change it,that part made by b&m was for other 700r4's such as monte carlo,etc that down shifts at 1/2 pedal or so.Call summit tech line at 330-630-0240 and they will tell you if you figure out how to get the 700r4 to go full throttle we can go 160mph all day long,and who ever figures out how to do it will be a rich man.I almost bought the part before the summit tech explained it and I also called sevaral gm dealers.If someone says you can and tells you how to do it be cautious.

 

GM make a kit that allows the tranny to shift at WOT. the part# is 8673948 and it was fitted to the corvette.

Hope that helps.

Rob

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter
I like to think of her as Arnold Schwartzeneger in a dinner suit

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat. K&Ns, AFPR and Air foil.

Future mods:
Cam change
New torque converter
New heads (maybe corvette L98)
Strut brace
Sub frame connectors
Ram Air

Current G-Tech times
0-60mph 6.26 seconds
1/4 14.74@100.2mph