1989porsche928

Has anyone tried this Upgraded Vacuum Modulator?

ROG100

If you order the 86 to 95 modulator 126 270 92 79 you get the green version - so I guess it works as I have sold plenty of them. The black version seems to be 126 270 91 79 and looks the same apart from color.

Jchiodi

I was having a big issue with harsh shifting. So much that the car was really not that much fun to drive unless I just mashed the go pedal, and let er rip. Gets old to do that all the time.

Really couldn't get to the modulator unless I dropped the entire welded exhaust.
When I finally got to test it, the modulator would not hold any vacuum.

Got the version from 928srus and it scared me that it did not come with the plunger rod. But I reused the old one. Put it in with no adjustment. I didn't want to run engine with just the headers on.

After it's all together shifts are damn near a brand new car! Very smooth, low speed shifts, with just a little more firmness under harder acceleration. Low cost, fairly easy job.

Just love my car a little more,lol....

SMTCapeCod

Interesting, I was having no luck finding professional help calibrating a new modulator, didn't want to install without that.

I posted a chart indicating the various housing colors/722 versions baseline operating pressures etc to a separate trans info thread, OP
G8TRB8.

granprixweiss928

Would a failing modulator cause rough shifts into reverse?

All other gears engage and then up shift and down shift fine.

but when putting into reverse, I get a delay and a jolt. Worse when hot and kinda normal when cold.

I dont know much about Roger-boxes....

Schocki

The vacuum modulator would not cause this problem. I assume you are talking about your 81 with a 3-speed Rogerbox. According to the A22 manual this indicates a defective one way clutch at the rear planet gear set.

If you're talking about your S4, the symptoms would be different.