vaccum mod. 4l60e
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From: SPRINGFIELD MISSOURI
vaccum mod. 4l60e Is this worth the extra $250.00 the tranny shop to put in my tranny. With my mods and running 10.51 on a 100 shot. And what does this actually do? THANKS also I keep breaking the front seal on the tranny when a race it at the track and us the nitrous thanks guys
Personally I dont use them but some people swear by them ,But in either case wether the PCS or a vacume modulator is doing it , Its simply presure control ,
The pcs is pulsed on and off by the pcm according to demand lowering of increasing
presure
A vaccume modulator does according to engine vacume , the lower the vacume the higher the presure ,
The pcs is pulsed on and off by the pcm according to demand lowering of increasing
presure
A vaccume modulator does according to engine vacume , the lower the vacume the higher the presure ,
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From: SPRINGFIELD MISSOURI
I was having trouble shifting from 2nd to 3rd at the track when I stalled the car up. Do you think it is worth the money and trouble then installing this?
Originally Posted by dnkynrbk
I was having trouble shifting from 2nd to 3rd at the track when I stalled the car up. Do you think it is worth the money and trouble then installing this?
As I said personally i dont use them , Some people like them some dont .I think of it as going backwards , GM like any company will use the most cost effective yet functional method , Modulators are cheap enough , So in my opinion if GM thought they would be as good or better they would have used them and saved the money they spent on the ecm and pcs solinoid ,
Just my opinion ,each to his own
Just my opinion ,each to his own
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Check the WOT transmission oil pressure on the 2-3 shift, it should be minimum of 225 lbs. (hot), and a maximum of of 240 lbs. (hot). The vacuum modulator will give you this quite easy, and I use them in all of my high HP setups, and with very good success. Remember to leave the shifter in "OD" (when racing), not in "D", that way the overrun clutch will not take away 3-4 clutch apply oil. The 2-3 WOT shift needs all of the apply oil that it can get.
Last edited by PBA; Oct 16, 2006 at 03:05 AM.
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PBA I think that is exactly what has been happening with my built 4l60e. I was doing a search the other day to figure out why my tranny on every build eventually starts hitting the rev limiter on the 2-3 shift and came accross someone saying the same thing. I reciently had the tranny built for the 4th time and after 2 passes it started hitting the rev limiter on the 2-3 again racing in "D". I took it back to the tranny shop and they found noting wrong with the clutches, bands, etc.. I talked to the tech about the overrun gears and a possible pressure drop and he said the pressure will deffenately drop when they are applied. So I guess the next time out I will run in "OD" and see if that takes care of the problem. Thanks for the insite on this problem.
Yes there is a presure drop on the 2-3 shift in the drive position due to the application of the overun clutch , However the pump is more than capable of keeping up so we are working on a way to aleviate this issue ,
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If youn use the vac mod your preasure will be totally vacume contolled , Though it would solve that issue at a cost of pcm contol which personally I beleave is better.The issue can also be addressed in tuning ,
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Originally Posted by performabuilt
If youn use the vac mod your preasure will be totally vacume contolled , Though it would solve that issue at a cost of pcm contol which personally I beleave is better.The issue can also be addressed in tuning ,
Does anyone have an HPTuners file for a tranny that was hitting the limiter and a file that fixes it. I am curious as to what it is. My tuner messed with shift extensions and mph, but still hits limiter. Put in billet servos, helped on motor, but is just as bad on the bottle. Needless to say, I have ordered all parts to build tranny and it is still functioning. Fix it before it's completely broken.