Transgo 4L60E Vacuum Pressure Control

This looks like a very nice setup for beefing up the 4L60E. In combination with a shift kit, etc., I bet the shifting is awesome.

However, a camshaft that provides adequate vacuum at idle must be used. What cam spec number, or combination thereof, gives an indication about cam vacuum at idle? Understanding there probably isn't a hard-and-fast answer, I'm just looking for a rule of thumb to follow.

In addition to replacing the EPC solenoid, where/how does the vacuum line attach at the engine side. Somewhere near the TB, on the intake manifold...?

Does it require a tranny drop?

I'm guessing this install is best left to a Professional Mechanic.

Yup, you're correct in needing good low speed vac for it... otherwise it makes shifting that "slams" and that's bad. I'd venture to say... -7 to -15° overlap, basically stuff that idles pretty well. Like a 214/218 on a 114LSA has -12°.

You need to drill a hole in the case and tap the hole. Then run a tube to the motor somehow. I'm not sure where peeps hook it up at, but a place with a GOOD vac source is a must. Maybe run somesort of stainless line up there to minimize rubber lines.

Hope that helps.

Yeah it helps alot Hit Man, I appreciate it. This mod will probably have to wait until my truck is out of warranty, I just like to make sure my facts are straight. Long term planning you know.

Just to clarify, the tapped hole would be needed in the tranny case? For the vacuum source, aren't there access holes (for lack of a better term) in the LS1 truck intake manifold? I gotta think you could pull enough vacuum there.

It looks like the kit contains a metal line, not sure if it is stainless. I'm thinking about calling Transgo directly and drilling them about this kit, just not sure if they will talk me.

I'll post my findings if I can get some good 411 from Transgo.

why the vaccumn mod on the tranny. from what i hear from top buil;ders they so no to it.

Quote:

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Originally posted by 02Denali@May 4 2005, 05:08 AM
why the vaccumn mod on the tranny. from what i hear from top buil;ders they so no to it.

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And that's good information also. My questions about vac modulated shifting are more along the lines of research, rather than something I'm planning to definately do. The more this kind of stuff makes it the forum, the more we all can learn. :hshake:

Yup the hole goes in the case around the EPC solenoid location.

Ya probably could tap into a vac line under there currently for the vac supply.



I too hear mixed stuff on the vac mod setup, I'm not sure exactly why. My guess is you have to build the motor around it? Maybe?

T in the brake booster vac line