Black 91 Z28

I was doing some searching today on the boards about the location of the stock shift points. From what I read the shift points on the stock Z28s with a 700R4 should be around 5200 for the 1-2 and 2-3 shifts. Is this correct? After I read this I drove around and under WOT my 1-2 shift was at 4400 and my 2-3 shift was at 4200. I know the trans was rebuilt before I got it, did they swap governors on it and change the shift points? Or is my info wrong?

David

PS I have a L98 91 Z28.

D Stroy H8

My guess is it is running a very conservative weight/spring combo in the govenor. The shift points are vacuum controlled and the govenor can be modified to shift at a later predetermined rpm.

If it is this, and not the TV cable (not informed on those), then you can call up summit and ask for a "B&M govenor recalibration kit" for 700R4s. It's about 25 bucks. A transmission shop shouldn't charge more than 75 bucks to set the points for you, really. All they need to do is trial and error different combos to get the shift points you want.

Black 91 Z28

Hmm well that sucks! Thanks for the info though. Is it hard to install the kit at home?

D Stroy H8

Not really if you are handy at all. You just need to set aside a day in case you have trouble getting the right combo. Basically, you remove the govenor housing, and take out the govenor and you have to clip off a little piece of metal, to access the springs and weights. Adjust combo, replace govenor and about a cup of ATF and test it out.

Thing is, when you realize you don't have the points you wanted, you have to let the transmission cool down before attempting a new combo. So if you get it wrong a few times you're looking at a couple hours at least! Thats why I would just use a shop for this.

Pro Built Automatics

First, make sure that the TV cable is tight at WOT, before you do any governor modifications. Second, if the governor needs to be modified call me (800 7753288, 11-6 PST) when you get ready to do this, and I can save you some time on this.

JMatlock88

I'm gonna highjack your thread because I'm in the same boat

Here is the governor out of my pro-built trans that is shifting very early. I noted two triangle markings that appear on the weights and then the J and diamond that appear on the "cap". For each side 1 and 2 I noted the spring color and weight letter that are currently in the governor. I'll also attach the chart and instructions that came with the weight kit.

JMatlock88

As you can see in the chart, supposedly the factory trans had a "narrow tab" weight and red and dark blue springs. My kit comes with A-F weights and green, red, orange, black, purple, and light blue springs.

My question is... what weights and springs should I start with in this trans if I want it to shift at ~6300rpm? Once you have two springs and two weights picked out for me, where do I put them (position 1 or position 2 as shown in the diagram)? Thank You!!!

Pro Built Automatics

JMatlock88, take another picture with the gear towards me, so that I can see the inner weights. What rpm does it shift at now at WOT?, and at what rpm do you want it to shift at?

JMatlock88

I want 6200 rpm optimally... Right now it shifts at 4200ish the way it came. Picture coming! Thanks!

D Stroy H8

This is why I shift it manually

JMatlock88

I was having trouble getting a good picture of the weights, so I just went ahead and took it apart. As you can see, C weights are on each side. One side has a heavier spring than the other. Thanks!

JMatlock88

Ya, well some of us like to have it right for bracket racing.

Pro Built Automatics

Go to the weights that have the point on them, and see where this puts you. Then if this is not enough, use the weight that is completely flat with no point and rework it so that it has a smaller point than the one you started with, this will make the shifts at WOT later yet. You will have to experiment. The springs help fine tune it, but is mostly for part throttle. I hope this helps.

JMatlock88

Thanks for the help. What springs do you think will be best? I wouldn't mind the 1-2 shift being firmer...would a particular spring help the firmness?

Captain C

Depending on the year car and the engine with which it was equipped. 4500 from the factory is correct. The 85 305 TPI cars shifted at 5K, all the 350 cars and the later 305's shifted at 4500. You could adjust the TV cable to make it shift later, but there is a limit before you cause other problems (Too much pressure will fry things or so a Trans shop told me).

I changed the spring combo on my governor and it solved a lot of shifting problems with my trans, but while is was way better, it wasn't where I wanted it. I like the information that Pro-Built is giving!!!!! I wish I had more of that kind of info!!!!!!!