Last friday I went to the local 1/4mi track in my 86IROC , about 95mi's away, and couldn't get the trans to shift when I need it to. I shifted to third at about 5000rpm and the thing stayed in second till about 5300rpm, right at the lights. Needless to say it slowed me down. With a bad 60ft time of 2.552, wheel spin was a major problem too. I wasn't able to get the kind of burnout I wanted so it never hooked at the line. My best run was a 15.984, I know it's capable of better times, how much better, I don't know, I just know it could be better. The car is vertually stock with the exception of some free mods and has, I think, a 2.73 peg leg rear end. I was using my hoosier road race tires that I normaly auto-x with. If I can get the left rear tire to spin in the water then the right rear to spin as I power brake it, it hooks pretty good off the line, but I could not get it just right friday nite. Oh well, Just help me get it to shift when I want it to and I'll get it to hook on the line. Should I go heavier or lighter on the govener weights?

Thanks for any help anyone can give.

[This message has been edited by steve8586iroc (edited September 03, 2001).]

 

Sorry I can't help you. I gave up the 700R4 for a TH350 for drag racing. The 700R4 doesn't have a good gear ratio for the track. First gear is too loaw and the range between 1-2 is too far apart.

This might be a better question to ask the driveline forum so I'm moving it over there.

 

the rear is killing you.
I had the same problem with a friends 90 Formula. 2.77 rear, TPI 350. At the track it was just shifting into third at the traps, and it was at about 5-5200 RPM.
The car did a 14.43 @ 94 MPH, with a 2.1 60ft. This car would easily be at 14.1 - 14.2 with a better gear ratio in the rear.

My 87 IROC 350 TPI with a 3.27 rear is well into third when I hit the traps and it does 14.46 @ 93 MPH with a 2.01 60ft

Firt thing, is your TV cable adjusted properly? Check that.
Next I would look for a posi rear with at least 3.23 or better gears.. that will make a big difference in how you hook up and where the car shifts along the track. That 2.5+ 60ft is really slowing your times down.

------------------
Member of The Connecticut F Body Association
1987 IROC 5.7 - 14.46 @ 93
1988 Formula

[This message has been edited by Jay (edited September 04, 2001).]

 

The 700R seems to have a slight delay when moving the lever and it actually shifiting on the 2-3 shift. Check to see what rpm in D it shifts from 2-3. If it shifts on it's own at 5300rpm then it won't shift earlier if you manually shift it before that rpm. You can only shift later then the governor wants it to when in D.

With the governor recalibration kit from B&M they say:

Suggested to start by using a weight/spring combo similar to your stock setup, but at least one step in the direction, heavier or lighter as desried. Heavier weights produce earlier shifts, lighter weights produce later shifts. Stiffer springs tend to produce earlier closely stacked shifts, weaker springs tend to raise and spread shift points.

As a general rule, the weight selection tends to bring the shift points into the general desried range. The springs then adjust the shift points more precisely to match your vehicle's performance to your driving preference. Always make changes one step at a time, first to the weights and then to the springs.


Also, if your car is basically stock and you're running stock type radials, you probably don't need to go through the burnout box at all. Go around it, maybe do a dry hop to clear rocks and stuff off the tires. Try a slightly lower tire pressure, that may help you out too.



[This message has been edited by ryn28 (edited September 04, 2001).]

 

ryn, thanks for the tips. I am using hoosier road race tires that I normally autocross with, these are far better than street tires but not as good as drag radials. If I can heat up both tires then it hooks as if I had a posi if not then it just spins the rr tire. I'll be looking into some heavier weights to bring the shif point down a tad.

Steve