I am about to order my FLT Level 5 4L65-E and I am wondering if you think it would be a good idea to upgrade to the Trans-Go Vacuum Modulation kit? I have heard good and bad things about it...What are your opinions/comments/experiences?

Thanks ahead of time guys!

-James

 

What are the bad things you heard about it?

 

I heard something about if there is an engine backfire, it is possible for transmission fluid to get into the engine, usually noticed by white smoke. I beleive it is due to the actual vacuum line malfunctioning..? Sorry if I am not describing it in detail...I am not very knowledgable about transmissions...

Any More Input?

 

FLT? ACE? Performabuilt? Do you guys have any advice?

 

I will not build a High performance 4L60E without using a Vacuum Modulator. It's that simple. I have seen too many Tuning mistakes take out these units. The 4L60E lives and dies by its Line Pressure rise.

If you were to log the Line Pressure during a pass when using an EPC, then draw it out on a graph... you would find that the line is not linear at all. In fact it makes very sharp swings. This is not healthy for a High Performance unit.

If however you were to do the same test with a Vac. Mod. you would see a very linear sweep.

PCM's use many different inputs to determine Line Pressure. Vac Mods use only one.

And as far as the backfire issue... When was the last time your engine backfired? I am around many, many LSx powertrains and I cannot remember the last time I saw one backfire. I have installed many, many 46Mod kits and have had only 1 problem with a hose. And that was last week. We had one come back with a hose in the pan split for no apparent reason. It is to be expected IMHO. When it happens... fix it and move on.

You mentioned that you have "heard" good and bad things... what has your research proven? Are you going to go with a "popular" vote and just go ahead and do what the most people say to do? Just curious....

Good Luck... either way, if indeed you buy on of Vince's units, you'll be fine if you don't abuse it.

g

 

Thanks for the info! I appreciate the honesty. I am beginning to think that the pros outweigh the cons. It seems like ti is more failsafe to go with vacuum modulation then not. I would still appreciate more input though...

 

It is about that someone else "agrees" with me on vacuum modulation (besides Vince at FLT). I have done the pressure test on these units both ways, (that you did) and came to the same conclusion. Has you ever wondered why the 700R4 never broke the forward aluminum piston, but when the 4L60E came out this became a somewhat common problem, hence the introduction of the heavier molded rubber pistons. This is because of "spikes" in oil pressure that can happen because of the instability of the electronics. I talked to Ed Wright at fastchip.com about this quite awhile back, and he stated the same thing about the electronics. He preferred the vacuum modulator to the EPC solenoid, and used it on his 1996 high 9 second Firebird for quite awhile. He has since changed the motor/transmission setup to something else completely different. He is an expert on the OBD1/OBD2 and found that the vacuum modulator to be more "stable" than the EPC solenoid. Is it preferred in all cases? No, but the vast majority of cases, it can help. As for the vacuum hose cracking in the pan, I have found that sometimes customers using a poor quality oil (it sometimes has more "seal swell" in it) and that is what can cause this.

 

Not sure what that's suppose to mean unless you mean being stupid with one of my units. Obviously they are built to be abused! I guess there are different levels of abuse.

Back on topic. As far as the modulator is concerned I really like what I see on the dyno with these units over a EPC unit. I will build them both ways and have found a good balance for the epc units to greatly reduce the fluctuation of what I see in the gauges on the dyno. As mentioned above a tuner or vehicle can kill one of these units if not done or working properly. I myself if I was going to do my own, it would be vacuum modulated but that is just me. I do however like most things I do, have modified this kit to make it better. We are currently working on a solution for the hose in these units as well for reasons mentioned above. Either way that you decide to go I will build it and look forward to hearing from you. Vince

 

The stock setup for trans line pressure control is an
involved mess and some of the settings are stupid
especially if you move into performance converters and
hop up the motor. There is all kind of opportunity for
adding tuning error as well as what GM gave you. The
vac mod is simple and simple is usually good.

The down side is, you have a pretty straight trade
between line pressure and comfort (shift harshness
at lower pedal) and you hope the modulator takes
it easy when easy is OK, but gets it all in before the
motor can overpower any frictions. Since it's only
vacuum based, this has to be a bit iffy (trans does
not know that your punched out 427 is in front of
it, and torque per vacuum level is not too much like
the profile of a stock 346). So you'd have to count
on the trans builder's tech support if there is any
selection to be done. You might be able to get an
adjustable vac modulator (?) but then there is again
the possibility of "tuner error" in between got it in,
and got it right.

Not much attention seems to be paid to trans tuning
and many people who do it, do it without the benefit of
any clue about line pressure profile (actual) or its
deviations. A vacuum modulator, if performance is the
thing that matters, is set-and-forget. You just don't
get to play fussily with comfort and economy. I have to
believe the whole EPC (force motor) deal is CAFE, CAFE,
CAFE. Why else would you design in an expensive solenoid
valve, wiring and programming to replace a $5 biscuit
(not retail, but how much can a generic biscuit cost GM
to outsource?).

 

Any more input on this??

 

vac mod for sure....my 80 has one...Mightymouses 80e has one...its simple..reliable and if it fails, you get full line pressure which just makes your shifts harder....not burn up like a faulty pcm controlled tranny could

 

tHE 80E DOES SHE BLOW YOUR SKIRT UP ? i WAS THINKING OF THE UPGRADE.