I have a nice firm shift in my 86 iroc. It isn't a hard shift, just firm. I was told by my tranny guy that iroc's came w/ factory shift kit. I have not heard this anywhere else. Can anybody verify this info?

 

Never heard that before. It is probably something that the guy at the trans shop heard once and he just absorbed it not his memory.

 

Is it possible that the person that had it before you put a shift kit into it? If other mods were done, maybe the past owner put a shift kit or corvette servo in there. The servo would be my guess seeing as that it isn't a "hard" shift, just firm.

 

I was told a corvette servo would allow me to kick it down in 4th w/o it going into 3rd. It goes into 3rd when I kick it down. I'm not sure of this is the case or not.. Maybe someone before me did modify it.
There were no other mods made that I can see..

 

Would a shift kit cause a hard shift, or a firm shift?

 

Depends on the kit and the install. The B&M shift kits are like being smacked by a brick wall. My Pro Built Trans Go is near stock at low throttle and progressively quicker shifting with more throttle. I do have the Corvette servo in there. But the Pro Built kit comes with way more stuff besides that. The stock Trans Go instructions will give a pretty hard shift. The Pro Built Trans Go came with custom instructions that were all over the place. Arrows here. Things crossed out there. Do this, Don't do that. The transmission shop said I shouldn't install the Trans Go because it would be too hard of a shift. But once they installed following the custom instructions and road tested it, they were really impressed.

I've ridden in Corvettes with the 700R4. They're a bit snappier. But not what I'd call "hard." Maybe precise would be a better word to use.

Could be something that's been done in your transmission. Could simply be the throttle cable is adjusted wrong. Stock IROC 700R4's will be firmer shifting than say a Cavalier with an automatic.

I had an 88 IROC that would shift hard all the time. And it would make the 3-4 WOT shift. But it got annoying pretty quick having the shift that was that hard. The only other non stock thing in that car was that it had a 3.45 axle. So I'm guessing it was originally a 2.77 axle and somebody did something to the transmission before hand.

The servo won't change your ability to make the WOT 3-4 shift or keep your car in 4th at full throttle above 85 mph. There is a sleeve in there that has holes drilled in it. If you fill those holes or get the sleeve without holes on it, you should be able to do the above functions. As for why GM made transmissions always downshift to 3rd while under full throttle? I'm guessing it was for towing purposes.

 

GM did put different trannies in V8 F-bodies and Corvettes that had higher line pressure than a non-performance (truck, caprice, etc.)version. They can be identified by pulling the pan and looking at the detent mechanism (the "rooster"). If its gold its a hi-po unit, silver is standard. GM continued this practice in the LT1 cars too.

 

I need to pull he pan and see. My 92 RS doesn't seem to have a shifty kit (L03), but I know the tranny had some improvements made in 87 which among other things, gave it a smoother shift. Are you saying that all f bodies w/v8's came w/this performance addition?

 

By the way, my 92 rs will get a scratch in second at times. Maybe it does have a gold rooster in it. I never knock the way the L03 performs, and the way my iroc performs. I dropped a 3.42 rear end in the iroc z and it made a world of difference. the taller gears seem to be less stressful on the tranny also.

 

Not all V8's. The TPI cars were the only ones that did. I had a GM crate tranny that had it too and it would spin the tires shifting to second and sometimes chirp them shifting into third. That was on a 110K mile stock L98 1LE.

 

Not all V8's. The TPI cars were the only ones that did. I had a GM crate tranny that had it too and it would spin the tires shifting to second and sometimes chirp them shifting into third. That was on a 110K mile stock L98 1LE.

 

I am now convinced (short of dropping the pan) that someone must have installed a shift kit. Funny thing is, the rest of the car (86 IROC lg4) is bone stock. I do have to run at least mid grade to prevent it from pinging.. I don't think I should have to do this. It does seem quick though.

 

My dads 84Z shifted hard as hell in 1-2 and it is completely stock! My car has (had lol) a built 4l60e and it shifted smooth, my other buddy had a modified transgo on his built 4l and i find it annoying it shifts very very hard.

I better get use to it bc i have a manual vb th400 going in lol

Jay

 

was you dad's 84 z a HO 305?