Change Gov Spring to Change Shift RPM?

[A. G. Olphart]

At what RPM will a high performance transmission shift if the soft spring (small plain) from the heavy weight on a low perf Gov is substituted for the standard single blue high perf spring?

Has anyone tried it?

The small weight is flimsy enough that I'd rather not be drilling it... a spring change is more aesthetically appealing.

[BigTurbo6]

And where would one get a replacement stock one or slightly stronger one (rpms are high).

[A. G. Olphart]

BT6, I beleive that both PTS extreme and TCI have stock replacement springs.

Depending on how many RPM you need to drop, your problem could possibly be cured by just pinning the spring in place. Here's info I've culled/copied/paraphrased from earlier posts...

"If there is already a hole through the lighter governor weight just run a 6/32 tap through it and use a 6/32 set screw. I use one 3/8" long and it lowers my shift point about 300 rpm--a 1/4" is long enough.
If there is just a dimple in the weight use a 7/64 drill to make the dimple a hole and then follow above steps. Be sure to use locktite, I use red--the 271".

Me again- If 300 RPM isn't enough, you might try drilling and tapping for an 8-32 screw. Bigger daimeter screw = more weight. (You need to make sure that the head will clear the case/housing; filing or grinding may be necessary).

.

[BigTurbo6]

Thanks, I have yet to check it all out. Waiting for the warmer weather. Got the PTS shift kit to install too.

[77 cruiser]

I did it on an OG & it raise the 1-2 shift about 1000 rpm but it didn't have much affect on the 2-3. I went to drilling the weight.

Jim

[A. G. Olphart]

Thanks Jim-- Interesting results, if not what I would have predicted.

Wait a minute... OG-- It has 2 springs; what did you actually do?

The OZ was the high perf Olds (with one blue spring on the light weight, just like the BRF)

[77 cruiser]

Yea it had 2. Just took the soft spring from the heavy wt. & put it on the light wt. & didn't use a sring on the heavy wt.

Since that didn't work too well I put the normal spring on the light wt. & started drilling & ended up with 5500 on 1-2 & 5000 on 2-3.

Still have some more tuning to do.

Jim

[A. G. Olphart]

Well Jim, you're getting closer!

When I get everything together (including a rev limiter) I may try the spring swap described in my original post.

[chris718]

the spring change only will usually net a 200 rpm difference.weight arrangement and there distance from the center of centrifical force will more precisely interact with more drastic or gradual changes in shift rpm at all driveshaft speeds and therefore governor rpms.although the oz had a high performance valve body that is basically identical to a gn or mcss it did use a governor with more secondary weight and a numerically higher final drive ratio .however if you use it (the oz or kz valve body)with a gn or mcss governor it is in my opinion the 2 best valve bodies for high performance usage and with proper cable adjustments it will net 5600 rpm wot upshiftsfrom 1/2 and 2/3

[A. G. Olphart]

Thanks Chris- I actually do have a dead OZ to play with. Sounds like drilling or grinding the primary weight to come close to a GN's might be a good idea during the rebuild.