Syncro vacuum system replacement?

[Druck1]

I have a 4WD Syncro drive train that I am planning to build into a buggy application. It has a rear locking diff and I plan to add a decoupler. Rather than locate/install the vacuum system I am considering using levers/cables or hydraulic master/slave cylinders.
Any issue with this? Is there something special in the transmission that requires use of vacuum actuation?
Thanks
Druck

[Howesight]

There is no reason that a vacuum system has to be used. A lever and cable system will work.

Having said that, I think that part of the reason that Steyer Puch and VW went with vacuum actuation is that is can be kept functioning despite mud, ice, etc. which can foul a lever system if the system is not weather-proof and mud-resistant.

You should also be aware that the diff lock often requires time to engage and disengage and the vacuum system keeps up the force to lock-unlock while you pay attention to the trail. With a lever system, you will be doing two or three things at once.

If you decide to use a vacuum system, you are not stuck with just the Vanagon parts. Many Audi quattro cars use vacuum-operated diff locks and the vacuum valves and vacuum reservoirs are available on E-bay for far less than the Syncro parts.

Have a look here:
https://forums.quattroworld.com/s4s6/msgs/170940.phtml
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'86 Syncro Westy SVX

[danfromsyr]

the vacuum system is far simpler than the alternatives.
likely similar costs if not cheaper..
there's no voodoo in a vacuum system. and Ford used coffee cans for vac reservoirs in the 80s. it's not alot of negative pressure.
and with a running engine the power is always available. that's one reason 'most' cars have a vacuum power booster for the brakes.

[MarkWard]

Somewhere here, there is a thread documenting what you are asking about. Sorry I don’t have it book marked.
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[Druck1]

Thanks for 5he replies here
Looks like many possibilities and more investigation needed
Good to know I am able to use other vacuum systems.

[Druck1]

Thanks for 5he replies here
Looks like many possibilities and more investigation needed
Good to know I am able to use other vacuum systems.

[MarkWard]

To help you think about it. The vacuum servos use vacuum to engage the locker/decoupler and vacuum to disengage the lockers.

The switch, swaps the vacuum to either side of the servo depending on if it's engaging or disengaging. Vacuum is always applied to the disengaged side of the servo.

The vacuum system is easy to route vs cables, electric motors etc. Plus the transaxle is already setup for that method.
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