[Joel]

i know the thomas vacuum pumps (easily found on ebay) are pretty popular here, but i want to push the envelope for low cost factor.
i've read that old GM ICE cars had supplemental brake assist motors and other EVers have found these motors in scrap yards for real cheap.
however, the ones i'm talking about are becomming quite rare because of their age (typically from 1982 model cars), (GM part number 22034995)

i checked 3 scrap yards in my town and none of them had the cars listed on this page (that are reported to have the pump in question)

but in my research, i found some newer vehicles that use a supplemental brake assist vacuum pump
Chevrolet
03 tahoe
03 silverado
03 Avalanche
all are 1500 with 5.3L engines

the GM part number seems to be 22034995, and i've found it on gm part supplier websites for under $130, but since these trucks are within the last decade, i'm sure i can find the part in a scrap yard for much less.

but before i spend another 2 days walking for hours in the burning sun looking for these trucks, i want to hear if any other EVers out there have used something similar with success? or would you guys recommend i stick to what works and just get a thomas pump?

[Twilly]

I read something somewhere about someone mounting a 12 volt air pressure pump inside a 4 inch pvc pipe, with the outlet connected to the outside of the tube... So the pressure pump drew a vacuum on the inside of the tube which also acted as a holding tank..

Could be done on the real cheap...

[Joel]

thats a good idea, but we still want it to be reliable right? this is the brakes we are talking about.
an automotive vacuum pump would be preferable because it is built for extreme tempuratures and can take a beating.
plus it already has an auto shut off switch that turns itself off at a set vacuum level. a regular off the shelf air pump wont have that.

[John]

Originally Posted by Twilly

I read something somewhere about someone mounting a 12 volt air pressure pump inside a 4 inch pvc pipe, with the outlet connected to the outside of the tube... So the pressure pump drew a vacuum on the inside of the tube which also acted as a holding tank..

Originally Posted by Twilly

Could be done on the real cheap...

One problem with that idea is how to cool the pump. Most are air cooled. There won’t be much air circulation inside a vacuum reservoir. It would have the same overall effect as piping the intake into the vacuum reservoir apart from the noise. If its not designed to act as a vacuum pump it might strugle to achieve much pressure drop.

[kittydog42]

The only vacuum pump that is going to have an auto shut-off is the one that GM used on it's cars in the 80's, as outlined on this web site:

http://www.gmcmotorhome.com/tech/vacuum_pump/index.html

These pumps are not truly large enough to handle the duty cycle of all of the vacuum braking requirement; they were designed to be small and provide supplemental vacuum for the engine. Therefore, they are not recommended, though many have used them with mostly positive results. The use of a large PVC or ABS chamber does not really alleviate the duty cycle concerns, since it just concentrates the run time to charge the chamber rather than reduce it.

Any aftermarket Thomas, Gast, SSBC or other brand vacuum pump that you may buy will require the additional purchase of a switch. Many of these pumps, as long as they are about 1/6 HP or greater, would be excellent choices. If the switch is not properly HP rated, you will also need a properly rated relay to switch the load. You want a vacuum switch that can be set to 18"Hg, which is the typical automotive setting. You can either set it with a removable vacuum gauge, or permanently mount one if you so choose.

[piotrsko]

the ford superduty series from 2000 and on diesels have the system intact with a self regulator pre set. runs the A/c and the 4wd drive hubs and sometimes the vacuum booster, can be had as little as $20 USD in a junk yard.

[Joel]

Originally Posted by piotrsko

the ford superduty series from 2000 and on diesels have the system intact with a self regulator pre set. runs the A/c and the 4wd drive hubs and sometimes the vacuum booster, can be had as little as $20 USD in a junk yard.

is there any way we could see a picture of this?, or description on where in the vehicle it usually can be found?

i'm going to go back to the scrap yard soon to look at some of the chevy trucks to try and find one of their pumps, but i don't know what it looks like, or where to look other than following the hoses that come out of the master cylinder

[joseph3354]

found a list of gm vehicles with supplemental pumps here:
http://www.gmcmotorhome.com/tech/vacuum_pump/index.html

priced the one for a skylark at partsamerica.com $140.

[Joel]

Originally Posted by joseph3354

found a list of gm vehicles with supplemental pumps here:
http://www.gmcmotorhome.com/tech/vacuum_pump/index.html

priced the one for a skylark at partsamerica.com $140.

i linked to that page in my first post of this thread, those pumps are extremely hard to find these days (in scrap yards), this thread is asking for the new ones that are found in 2003 chevy 1500s

[joseph3354]

sorry i must have missed that,still the pumps listed at parts america are new or rebuilt.not too bad of a price. what about a cruise control vacuum pump? do they have the capabilty needed?