th400... mechanical modulator???

[gndoug]

Im planning on putting in a 400. Ive heard that because its going into a turbo car, i need to get a mechanical modulator for the tranny so it doesnt wear the pump out??? Any ideas anyone?

 

[blackplague]

you don't really need it.

a one way check valve in the vaccum line will do the trick.










c

 

[CTX-SLPR]

a one way check valve in the vaccum line will do the trick.
c

I don't think so... you'll hold vacuum in the modulator when the check valve closes rapidly and it pretty much eliminated the fuction of the modulator from the shifting equation which I wouldn't think would be a goodthing. Raptor has it called a Cable Operated Modulator,

its about 1/3 down the very baddly organized page but I've called them and they have it on the shelf. Appearantly it was a stock part off of deisels using a TH400. I'd honestly like to see Chris or Bruce chime in as to what would be needed to run a TH400 with an automatic valvebody behind the turbo motors.

 

[chevyII]

I think most running 400's go manual valvebody/transbrake. NHRA or some saftey rule to have a auto valve with a brake.

 

[CTX-SLPR]

I think most running 400's go manual valvebody/transbrake. NHRA or some saftey rule to have a auto valve with a brake.

I'm not sure if its possible to have an automatic VB with a transbrake. Anyway, I don't want a transbrake either so not as much of a worry for me as controlling the transmission.

Thanks,

 

[blackplague]

I don't think so... you'll hold vacuum in the modulator when the check valve closes rapidly and it pretty much eliminated the fuction of the modulator from the shifting equation which I wouldn't think would be a goodthing.

Ok than. How much vaccum will an engine have when you start getting into boost??? My vote is for 0 :biggrin: .

 

[MeanBuicks]

its about 1/3 down the very baddly organized page ...

LOL! That site has been a perpetual train wreck for years but I guess it works for them.

 

[INEEDAGN]

I don't think so... you'll hold vacuum in the modulator when the check valve closes rapidly and it pretty much eliminated the fuction of the modulator from the shifting equation which I wouldn't think would be a goodthing.

Ok than. How much vaccum will an engine have when you start getting into boost??? My vote is for 0 :biggrin: .

Of course it will be 0. The problem is that if it had a check valve in it, the modulator will still see vacuum when under part throttle or full boost. More vac at the modulator is less pressure in the trans. The modulator needs to have 0 or near 0 vacuum when under load to raise pressure high enough to keep it from slipping and burning up.

 

[blackplague]

The modulator needs to have 0 or near 0 vacuum when under load to raise pressure high enough to keep it from slipping and burning up.

You are forgetting about the modulator spring setting {adjustable modulator} or the fixed setting {non adjustable } that opposes vaccum.

 

[blackplague]

Instead of using the mechanical modulator

at $105. You could use this:http://www.blowerdriveservice.com/categorynarrow.php?category_id=3457&company_id=101011
At $68.00 and save a little$$$. just T it off of the Vaccum block.

 

[Zoliaster]

I ran a 350 with a check valve and a tee with a real small hole in it to relieve the vacuum. It worked good. I ordered the mech. modulator from CK because it seemed like the thing to do. I hated not having overdrive so I pulled the tranny before I ever put the modulator in.
HTH