Xvetteowner

My car, an 84 Euro S has the vacuum line running down the passage side ( Under the car) but it looks like its hook up to the Air pump divertor valve. But that's not hooked up to anything. The vacuum charts show direct vacuum ( Like what goes to the fuel pressure regs) going to the transmission. Should I just correct the error from the PO or its the cable that controls the shifting and leave it alone? What does the vacuum to the transmission tell it to do? Thanks in advance

MainePorsche

I take it your car is an auto ?

Xvetteowner

see above

WallyP

The vacuum line to the transmission operates the vacuum modulator, which affects the speed at which the clutch actuators work, which affects the softness/firmness of the shifts. The line should hook to manifold vacuum, with no vacuum boosters, venturis, check valves, reservoirs, etc., involved.

MainePorsche

?

Anyway, exactly what Wally says. I would change to a single contiguous line from the manifold 'T' to the modulator. There are two unions out of the factory, and you could lose vacuum there. I used the # 3 line in the link below. Can do by just having car up.

https://www.pegasusautoracing.com/pr...p?Product=3260

Xvetteowner

I'll hook it up

MainePorsche

If you didn't have vacuum to the modulator, you will notice much better shifting once you're done.

jpitman2

On the spider type inlets (up to 84?) the vacuum supply for the trans comes off the very front of the spider doesnt it ? On mine it does anyway - banjo bolt, hard steel line down RHS of engine , then a rubber joiner somewhere to another steel line down the TT, then another rubber joiner onto the tranny connection. My rearmost rubber tube was shot when I got it, fixing made changes much better.
jp 83 Euro S AT 55k

MainePorsche

My error.
What I wanted to convey about the line is that it should be as singular as possible, limiting unions and re-unions.