Ok, track opens in a few weeks and i've got a couple concerns. I made a couple runs with my accelerameter and some of the numbers got me a little worried. Now I know these things arent the most accurate things out there, but I dont think it should be this far off. I never managed to trap over 86.5mph. I just switched from a 2.73 open w/ bald (bald = see chords) to 3.27 posi and new tires. I trapped a consistant 88-89mph at the track last year with the 2.73. Correct me if i'm wrong but shouldnt my MPH go up with the lower ratio?

Now here's my real question, because if i'm right about this, then none of this other stuff matters. How does the car know when its hit the 108mph required to shut off the gas? I havent changed my speedo gear out yet (cant for the life of me figure out what i need to switch too). Now i know the value for the governor is in the prom, but how does it know its going 108mph? Is there a seperate sensor somewhere or does it use that same speedo gear? I pulled the speedo gear for now, just waiting on a new brake line before i take it out again. If that speedo gear is out will the governor not kick in b/c it will always think the car is going 0mph?

-chillen

 

The computer looks at teh mph (from the VSS input) to determine when its going over the limit for the governor. All thats in the trans is either a mechanical drive or a pickup for the VSS Pull the VSS connector and there will be no governor. VSS error code and some other issues, but no speed limiter.

Also, your mph probably wont change much unless teh motor was way out of its powerband with the old gears. Remember, the gears only transmit the power.

 

im happy i have my speed limiter removed... i did the 2.73- 3.23 rear swap and now 100mph on the gague is actually about 82mph... so my limiter would kick in at about 90ish.. lol... how lame would that be? the gears to fix it are cheap though... 3 bucks a peice @ gmpartsdirect.com, the tricky part is finding the right ones that best match your setup... you have to factor in rear gear ratio, tire size... and even then, its hard to get 100% accurate

 

which ones did you use? and which did you take out? Ive asked about this but get many different answers, and the GM dealers out here have no clue. If anyone has a TPI 350 z28 from 1987, those only came with the rear axel i just swapped in so if you could check which gears you have that'd be great.

Where is the VSS? is that cable that goes from the trans to the speedo what the VSS gets its readings from? I'm really not worried about going over 108mph, its just that if my governor is kicking in before 1/4 miles that aint good.

-chillen

 

bump

 

Go to the dealer and tell them you want replacement speedo gears for your '87 350 TPI Z28 that came stock with a 3.27 rear gear. They'll be able to look that car up in the computer and give you the right gears.

 

he looks it up and it comes back with like 8 different gear sets. I tried it, ticked me off. I think for some reason it just shows up all the gears that came w/ the 700r4.

-chillen

*does disconnecting that speedo cable disable the governor?

 

Yes.

 

thanks

 

I was under the impression that the speed limiter was in the PROM chip. Was this wrong?

 

The limitor is in the chip. But with speedo cable disconnected the ecm has no idea what speed the car is travel. You will only be able to judge speed by rpm, gear, and tire size though.

 

yeah there used to be info on disabling it, I hit the wall racing a 98 integra type r on the freeway... i think you have to switch the brown wire that goes into the ecu, but there may be more than one. You cant just putt the plug cause there will be shifting issues down low, but a switch to throw in 4th gear at 100 when theres no shifting to be done... that works great. just dont get on it at 125, the 7004r likes to downshift, and thats bad news.

no speed limiter+3/4 throttle so it wont kick into 3rd+125hp NOS= big grins and 130 mph with 2.73 gears

 

Come on guys, it isn't THAT hard to search with google.
Searched for 700r4 speedo gears and the first find was what you need.
http://www.transmissioncenter.net/sp...n_______va.htm
It's all in the chart. When I went from 2.73 (or 3.08) to the 3.73's I had to change the drive gear which required removing the tailshaft housing.