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Tech Area => General Buick Tech => Topic started by: gnonyx on January 16 2020, 07:14:48 PM

Title: Vacuum Brake Conversion on my 87'
Post by: gnonyx on January 16 2020, 07:14:48 PM
My question is how do you remove the brake pedal bolt for it's location?
What bolt and nut size?
I'm in the process of going to vacuum system from the Powermaster system
Removed the powermaster from the firewall, but I'm having a hard time trying to get to the bolt to remove the powermaster pedal.
Also what is the nut size that holds the steering up against the bracket?
Thanks
Title: Re: Vacuum Brake Conversion on my 87'
Post by: Steve Wood on January 16 2020, 11:20:51 PM
I don't recall.  I just laid in the floor and tried wrenches til I found the right size :)  I do recall one car had a damned tinnerman on the bolt that drove me crazy until I cut it off.  The nuts on the column bracket are a standard size...pretty sure they were SAE and not metric
Title: Re: Vacuum Brake Conversion on my 87'
Post by: 1KWIKSIX on January 17 2020, 07:00:52 AM
it's an awkward / cramped job to do, that's for sure.
I've found it easiest to simply unbolt the drivers seat and remove it.
Gives you a lot more room to work (albeit still uncomfortably), but laying on your back is upside down sure is easier!  :045:
Title: Re: Vacuum Brake Conversion on my 87'
Post by: Steve Wood on January 17 2020, 09:33:30 AM
This has some sizes    http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html (http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html)
Title: Re: Vacuum Brake Conversion on my 87'
Post by: gnonyx on January 17 2020, 09:56:54 AM
Thank you all for the info, and Steve thanks for the site, I'm going to try to lay the driver seat down first before removing the driver seat.
Title: Re: Vacuum Brake Conversion on my 87'
Post by: TexasT on January 17 2020, 11:47:48 AM
Seat comes out pretty easily. But we did ours laying under there. Did you get a vac pedal to swap? I would have a replacement cotter pin as I ended up cutting off the stock one to get the eye off the pedal.
I'm pretty sure we used a ratchet and deep 15mm (could have been 13mm been a while since we did it) on firewall nuts. And you will need a helper to hold the vac unit on the firewall while you are under the dash reinstalling the pedal.
Title: Re: Vacuum Brake Conversion on my 87'
Post by: gnonyx on January 17 2020, 06:14:52 PM
Seat comes out pretty easily. But we did ours laying under there. Did you get a vac pedal to swap? I would have a replacement cotter pin as I ended up cutting off the stock one to get the eye off the pedal.
I'm pretty sure we used a ratchet and deep 15mm (could have been 13mm been a while since we did it) on firewall nuts. And you will need a helper to hold the vac unit on the firewall while you are under the dash reinstalling the pedal.


Yes I have the vacuum pedal, and I'm also replacing the gm disc/drum brake brass proportioning valve pv2 universal ACDelco, all of the brake rubber hose with ACDelco type with new Banjo bolts and Banjo bolt washers. I already replaced all of the brake pads, drum brakes and springs.
I'm in the process of building my own one man bleeding system, similar to the one Amazon has on their site:
Motive Products 105 Brake System Power Bleeder
https://www.amazon.com/Motive-Products-105-System-Bleeder/dp/B00CJ5DY16/ref=pd_sbs_263_6/136-2495268-9658918?_encoding=UTF8&pd_rd_i=B00CJ5DY16&pd_rd_r=22dfc183-3aa6-4505-abeb-6f7750d8d3d6&pd_rd_w=maxK7&pd_rd_wg=71s4X&pf_rd_p=bdd201df-734f-454e-883c-73b0d8ccd4c3&pf_rd_r=BQ0N91G4VPVBV9WHRSPE&psc=1&refRID=BQ0N91G4VPVBV9WHRSPE (https://www.amazon.com/Motive-Products-105-System-Bleeder/dp/B00CJ5DY16/ref=pd_sbs_263_6/136-2495268-9658918?_encoding=UTF8&pd_rd_i=B00CJ5DY16&pd_rd_r=22dfc183-3aa6-4505-abeb-6f7750d8d3d6&pd_rd_w=maxK7&pd_rd_wg=71s4X&pf_rd_p=bdd201df-734f-454e-883c-73b0d8ccd4c3&pf_rd_r=BQ0N91G4VPVBV9WHRSPE&psc=1&refRID=BQ0N91G4VPVBV9WHRSPE)
Once I finalize I will display on site what I did.

Title: Re: Vacuum Brake Conversion on my 87'
Post by: TexasT on January 17 2020, 06:59:56 PM
I like going old school with a block of 2x4  under the pedal so my helper  doesnt over stroke it. I usually get one of the kids to help. But a wife, drinking buddy or neighbor who can follow directions can work. Clean fluid, clear mayo jar and a hose that fits through the 5/16" deep socket and I turn that by hand while bleeding. I did do a gravity bleed on the rears when I did the hydroboost on mine but it had been sitting so I had to pull both bleeders out several times to clean them out. It had some nasty stuff in there. Then bled em until it came out clean. 
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