Manual VB 727 line pressure

Posted By: turbobitt

Manual VB 727 line pressure - 03/15/09 02:28 AM

Is there a prefered line pressure for a full manual non-transbrake VB ? I would like to set the pressure a little more accurate than the measurment method described in the kit. Just looking for a ballpark figure. The TV linkage is set for max pressure full time.
Thanks,
Allan G.

Posted By: DusterW2

Re: Manual VB 727 line pressure - 03/15/09 03:39 AM

It really depends on HP/torque of the engine. The Turbo Action VBs are around 105 psi, Griner Engineering 140-220 psi. Of course the more pressure, the more load on the pump. If you have a high torque engine, I would set it to around 175 psi, especially with the 904 with small surface area clutches. Lower torque engines, use 105-140 psi.

Posted By: 440Jim

Re: Manual VB 727 line pressure - 03/15/09 01:07 PM

For what it is worth, I have my Griner set at 165 psi. I have 5 front clutches in my 727, and a 511 CID engine.

Posted By: turbobitt

Re: Manual VB 727 line pressure - 03/15/09 01:16 PM

Thanks for the replies. This transmission is going behind a roller cam, 572" Hemi. I will check it today and if it is around 150 than maybe I'll leave it alone.

Allan G.

Posted By: dOc !

Re: Manual VB 727 line pressure - 03/15/09 03:05 PM

I have never actually experimented with this ... but with the car I am working on now I will.

I say it depends on what your race-car-combo is. Some might need to run 165 psi

... but with a car that does not weigh much, has better aero than a big-car and does not have a ton of horsepower ..... I think you can run A LOT less.

PLUS ... running not-more-than-you-need line-pressure is EZier on the metal and rubber seals AND it would take less power to run way higher than necessary PSI.

My combo will be a front-motored dragster ... that all I hope it will do is be a mid-9 second "fun car" .....zero maintenence .... "change the oil once a year".

I am going to set my trans at 80 psi or so.

Posted By: turbobitt

Re: Manual VB 727 line pressure - 03/15/09 04:48 PM

I check the line pressure this morning and it was around 95 PSI. I dropped the pan and removed the VB and shimmed the spring with about .200" worth of washers. The was some adjustment left but not much. The spring looks flimsy so I didn't expect much results. After reinstalling the pressure only cam up to 110 psi.
I should also add that it didn't matter how much RPM, or frst, second, or third gear, pressure stayed steady.
Car weight is at 4000 pounds. Engine should be good for 700HP.
Allan G.

Posted By: Anonymous

Post deleted by Defbob - 03/15/09 05:04 PM

Posted By: turbobitt

Re: Manual VB 727 line pressure - 03/15/09 06:11 PM

I've been looking for pressure regulator springs and can't find any. May need to call around tomarrow.

Posted By: moper

Re: Manual VB 727 line pressure - 03/15/09 07:28 PM

I'm confused... Why did you need to shim? It's a screw to preload the pressure relief spring... Or is this some other valve body design?

Posted By: turbobitt

Re: Manual VB 727 line pressure - 03/15/09 09:18 PM

Quote:

I'm confused... Why did you need to shim? It's a screw to preload the pressure relief spring... Or is this some other valve body design?

I shimmed because it was already adjusted almost 3/4 down to the end. The shims gave me more preload than going completely to the end of the adjustment.
Allan G.

Posted By: dOc !

Re: Manual VB 727 line pressure - 03/15/09 09:24 PM

Quote:

Car weight is at 4000 pounds. Engine should be good for 700HP.
Allan G.

If yours is OK with 700 hp and pulling 4,000 lbs ....I should be good-to-go with 50-60 psi.

Posted By: 440Jim

Re: Manual VB 727 line pressure - 03/16/09 12:05 AM

Quote:

Thanks for the replies. This transmission is going behind a roller cam, 572" Hemi.

There is more to it than just line pressure, the entire trans build and valve body comes into play. For that big motor and heavy vehicle, I would want a valve body designed for at least 120 psi, and prefer 5 clutches in the front drum. Just my opinion. I don't know what valve body you have, but it sounds like a modified stock one. Call John at CRT and order one of his valve bodies.

If you really want to experiment, he might sell you one of his regulator springs.

http://coperacingtrans.com/

Posted By: moper

Re: Manual VB 727 line pressure - 03/16/09 12:39 AM

turbo, are you sure the pump is good and the bushings/sealing rings are working properly? Seems like a ton of preload to get it to work.

Posted By: turbobitt

Re: Manual VB 727 line pressure - 03/16/09 01:23 AM

Quote:

turbo, are you sure the pump is good and the bushings/sealing rings are working properly? Seems like a ton of preload to get it to work.

Pump is good. New babbit converter bushing installed. Teflon sealing rings also. Pressure is consistant in all forward gears and rock steady.

Quote:

There is more to it than just line pressure, the entire trans build and valve body comes into play. For that big motor and heavy vehicle, I would want a valve body designed for at least 120 psi, and prefer 5 clutches in the front drum. Just my opinion. I don't know what valve body you have, but it sounds like a modified stock one. Call John at CRT and order one of his valve bodies.

The transmission is built up with good components. It has a 5 disk direct with Alto red eagle clutches. 4.2 lever with solid red eagle wide band. Completly rollerized including thrust, tail support and output yoke. Bolt in super sprag as well. The VB is a modified stock unit built by a reputable vender that I won't name. It looks like a modified TF-3 kit when I inspected it but without the blue PR spring. I have built a lot of these for myself over the years but never actually measured the pressure with a gage. I always trusted the adjustment method given by the instructions. In this case, it was preset by the vendor who sold this to me.
Allan G.

Posted By: CRIKEY

Re: Manual VB 727 line pressure - 03/16/09 10:33 AM

Interesting how alot of you guys use GRINER Vb's & always state your transmissions run flawlessly yet you tell this guy to buy someone eles product??

Do yourself a favour & contact 727 specialist on this board & he will hook you up with a GRINER VB

Posted By: moper

Re: Manual VB 727 line pressure - 03/16/09 04:06 PM

I'm getting out of my league admittedly at this point. But it seems like if you can't get past 110 psi, steady or not, with 3/4" of air behind the preload plate, plus .220 of shim, it seems you have leakage somewhere in the system. Maybe John Kunkel or Cope can chime in on that.