And that would be the first time i've read that on this site, out of all the people here that have been running it

 

I use the vacuum modulator on the vast majority of my 4L60E's performance rebuilds, and with little or no problems. The majority of performance transmission builders, do not know how to build the 4L60E correctly, as you can see from the responses of customers who have had them rebuilt over the years with 4L60E problems. The case of "local builders" has been a major problem when it comes to these units. When someone says that it does not work, ask why, and how using it, destroys or ruins the transmission. I for one would like to know?

 

Hmmmm, interesting ..... over on cz28.com, vacuum modulation has always been a real no-no!

..... I'm no tranny builder, I don't know the "facts" or "theories" one way or another. All I know is that vac. mod has been credited for burning up lots of "built" 4L60E's? But this feedback has come from one of the most reputable builders on that board (while I'm a new member on here, I've been a "lifer" over there, but I'd say the builder I'm referring to on cz28.com has just as solid a reputation as Rock-on does ).

..... I'm now confused again as to which is the best configuration to setup a 4L60E ... the explanations both ways seem equally convincing!!

 

I would not own a built 4L60E without it. IMO, get the computer out of the line pressure business. plain & simple.

Many builders have alot of experience, but how much of it's specifically related to the 4L60E family of transmission?

BTW, been around numerous amounts of cars with this mod and I've never heard of one sucking tranny fluid into the motor. Thinking about how my vacuum modulator is setup, it would take a pretty major failure or someone installing it wrong to cause that.

 

vacuum modulators belong in the same category as dual point distributors, poly glas tires, double hump heads, etc. they're antiquated and will never be capable of controlling the pressure in a 4L60E the way an EPC will.

Remember the fact that TH350's and TH400's came from the factory with vacuum modulators. When most enthusiasts added a big cam, or forced induction, what did they do next??? They went to a manual valve body! Why? Simple...Because vacuum modulators couldn't control the transmissions accurately any longer. Now you guys are thinking about replacing a state of the art piece with something that didn't even work 20 years ago?

Yes, I've used vacuum modulators in 4L60E's. We did until we found out they just don't work. To this day, we still remove many vacuum modulators from transmissions built by our competitors...So we can build the customer a transmission that will last.

If anyone has a problem burning up 3-4 clutches in their 4L60E's, don't blame the EPC solenoid. Maybe they should analyze the rest of their building techniques and parts. I know enough now to never install another vacuum modulator in a '60E...and...no, we don't have any clutch failure problems.

Frank
CPT

 

I've been building transmissions, professionally, for over 17 years. Our shop specializes in racing 700/4L60E's. I worked at a shop for 7 years that was an R&D shop for the racing industriry. I helped develop a few of the parts that are now availible for these transmissions. The shop owner I worked for is now part of Sonnax Industries. I've tried every part and technique availible for the 4L60E, so I think it's fair to say I have "experience" with this particular transmission.

Frank
CPT

 

Like I've said before also................I've talked to "MANY" experienced tranny builders in the last year or so on this issue.Each of them had 20 + years of experience in building trannys(including the 60E).One even builds tranny's for a racing team.Each one of them almost laughed in my face when I brought up vacumn modulation.Like the guy in the post above said, why would you want to go 20 years backwards in technology when it wasn't even good enough back then.I just am so confused on this issue.I know everyone has a different oppinion on this but who has the better one?!Traver

 

I have over 29 years at this..... Guess how many TH400's & TH350's I have built using Trans-Go Performance Shift kits, all using vacuum modulators, except one. They number in the hundreds over the years, from low 9 second vehicles, on up. The vacuum modulation works very well even with a large duration cams (you have to know which vacuum modulator to use with the large duration camshafts). If you do a research on this, (as far as quality performance transmission builders) you will find that there are quite a few who have used vacuum modulation with much success. "Like the guy in the post above said, why would you want to go 20 years backwards in technology when it wasn't even good enough back then" Are you kidding, these units (TH400) were the most successful in terms of reliability in GM's history. Just look at this for an example, "you change the camshaft" to a larger duration..., more lift...., closer or further lobe separation..., the vacuum modulator "sees the vacuum changes" right now, and will compensate immediately, as far as load (torque input), and line pressure changes, where is the downside??? there isn't any "think about this"....

 

I have been following this thread from day one. We do build these units both ways due to the facts that many are scared of the old school tech! One thing that I have noticed on the dyno, keep in mind I've been doing this for almost 17 years, is the steadiness of the cooler and line pressure gauges. Most EPC units that I have tested with oversized boost valves it has been my experience that the gauges seem to flutter due to the pulsing epc/pwm that the new school units use. This new school tech was designed for shift comfort. People in non-HP applications would complain clutch apply being harsh or comfortable. This is why they designed epc/pwm. The constant flutter on these gauges I'm thinking has to be wearing out valvebodies and pumps. Also you hear about pumps that keep breaking even when tc depth is correct. I have been thinking that the flutter in these gauges has to really effect how the pump works along with it's life span. I do know for fact because I have converted units over right on the dyno to the vac-mod. Guess what no more flutter! My question to all the trans builders is how many of you are checking cooler flow and line pressure readings? I do however adjust epc's and vac-mods to keep the pressures down to what I believe is a happy medium. By doing this and playing with different boost valves, pressure regulator springs, feed hole sizes and exhaust hole sizes it comes down to how much do you want to tune the hydraulic's of this unit. I do believe that Chuck and myself have found a good setup for both EPC and vac-mod. I do know that my findings are not pump related issues do to the fact that we have installed oversized pressure regulator valves, machined pumps, brand new ac delco pump kits and many other setups. I do believe if the gauges are fluttering more than a few psi there is a problem. With the vac-mod kit alot of this goes away with very little effort. At FLT we have a electric dyno which you can really hear the little noises that all trannies make. Most of you would **** if you ever were able to hear the noise that pumps make when the balance of the unit is incorrect. I believe this is what the cause of many pump failures and worn out valve bodies comes from. I'm not going to get into the old internet pissing match because it really comes down to RND and test equipment. Most never test as some of us do. And it also doen't come over night! Good luck to all of you! Vince.

 

Thank you Chuck & Vince, as this I can well attest.

 

^ ^ Vince ... I liked your post . It seems you're not pushing one method over another, just stating real experience with both setups.

All I can make out of this is that it's critical to go to a shop who REALLY KNOWS what's going on with these 4L60E's. And regardless of whether running vacuum modulation or not, it seems that whatever the shop specializes in, that's probably the best route to go with for THEM? If the guys at Rock-On, FLT or PBA build WITH vac. mod., then stick with that. Frank @ CPT doesn't run it, then go with that!

What we need are HONEST reports of failures from all the big builders, and see what the failures are attributed to? Is there REALLY a "better" way of building the 4L60E, or is it just hit & miss regardless?

 

i have a rock on tranny with the vac modulator and i have a huge cam and over 600ftlbs of torque and drive it daily and i would not have one without it

 

I support the vac mod.

I have 2 4l60 trans with them in. Shifts on the 150 shot. With no modulator installed hits the rev every shift. I know this because last fall we had a problem with vaccum line in the case colapsing before the vaccum modulator, so right before I took it to the 1/4 we swapped it out for the computer controlled modulator and it bounced of the rev every shift on the bottle. This year it shifts once we found and fixed the colapsed line. Have vids of me on the track hitting the rev in every gear last year and I can go out right now take a vid and spray 150 and it will shift in each gear holding 550 hp to the wheels. Cam specs are in sig.

Now that is real world results



But what do I know I'm just the driver.........

 

I have the vacuum mod on my H/C LT1. I just installed my 3000 fuddle stall, adjusted the pin, and now when the car is pretty hot it has a very soft 2-3 shift. Yes I have a trans cooler. I think my car has some valve float issues. Can valve float have an affect on the vacuum mod?

 

If the pin is to short, you will lose maximum line pressure. Now this will soften the 2-3 WOT shift. Run the longest pin length when using small diameter torque converter. If the throttle body is too small, and you are using a larger duration camshaft, it will create more vacuum at WOT openings. This will lower the line pressure at WOT, which will soften the shifts. To check this, disconnect the vacuum line and do a drive test to see if the shifts firm up. If they do then the throttle body is too small, and is creating vacuum at WOT, this will lower the main line pressure. I have seen this several times, and going to a larger (cfm) throttle body will solve this. As for valve float... if this happens the power drops off at an incredible rate, which would give the appearance of a soft shift.

 

As someone who has in their learning experience (which never ends BTW) experimented with vacuum modulators. I have come to a few conclusions.
At the VERY LEAST
they are a
* Un Necessary Mod
and at the WORST
* A complete mistake


Every transmission that i seen using a vacuum modlator ends up a burned up pile of garbage. My real world testing and others i know has shown that a EPC can control and regulate line pressure rise instananeously. With No lag. I have heard the reasoning fron Ed wright.

Take a computer and type in a command .. does the computer respond to the command instantly or does it take a second for the screen to come up.


That dosent apply on our LT1 LS1 PCM's and what WE are doing expecting out of the force motor. The force motor is NOT a super complicated piece of equipment.They respond instantly.

Some builders say yeah well i want to rule out any possibility of a bad sensor causing problems. Sure ok it covers YOUR buts and sticks your customers with an inferior product with antiquated technology.

When i was taking classes when going through GM training in college, we had a hydramatic engineer stop by. One of the questions asked was Why dont 700s have a vacuum moculator?Why do they have this finickey trouble prone TV setup. His answer was that they determined that Vacuum modulators were pieces of crap and they Hydramatic felt that the TV setup was superior to the POS modulator and that the 700 wasent even designed with it in mind PERIOD.

Im not here to bash any builder. As i am a student of life. However i have seen with my own eyes too many good 4l60e's that ended up as burned up piles of trash and some of them were built by some well known well respected builders. Not to say they never burnup. But when a supposidely 600+ hp trans burns up in 3k miles after a year of weekend driving or when a guy i know has to go through 4 transmissions to get one that works half *** (built by a poster in this thread)i start looking at whats done diffrently than what i KNOW works.

And i KNOW the EPC works. As far as the modulator.... im still heavily leaning to the side of more harm than good.Just by seeing what ive seen. Big name transmissions burned up when everything looks good. GOod builds just burned up because of the modulator. Sucking atf into the motor,Hell ive seen one LT1 at the track BEND A ROD because of the vacuum mod on his firebird due to hydrolock , number 6 got full of atf and yippie bent rod.

You make the call.From what i know i wouldent be calling frank so stupid.
FWIW shane@ the other CPT
Edit non-sponsor company

 

so basicly were back at..

the 4l60e sux...

 

This thread is starting to worry me...good information yes, but I have a vacuum modded 4L60E that I paid a good chunk of money for to last me a long time as my car evolves and the power increases. I was assured that there is nothing to worry about.

 

You have one of the best units on the market. I have worked very hard to modify both the vac-mod kit that you have along with the hd-2 kit that is in your trans. If you have any questions please feel free to give me a call at any point and time.Vince

 

I had a Pro-Built vacuum modded 4L60E hold up to about 10k miles at 550rwhp and about 650rwtq. Shifted perfectly until I pulled it out because I toasted a motor. Everyone is entitled to their opinion on the vacuum modulators but I'm starting to get sick of seeing a certain Northern shop step over the lines a little bit and question other shops owners and builders and take cheap shots (both on cz28 and here).

Without PROOF that vacuum modulators destroy trannies I think the claim that they are antiquated pieces of garbage should be let be.