[John V.]

'73 TA

Trying to rebuild the master and power booster.

How do I access the nuts to remove the booster from the firewall?

Also, any tricks to removing the main brake outlet line connected to the fender side of the Combination Valve?

I was able to disconnect all the other lines but that one has me stumped.

I disconnected all the other lines and disconnected the Combi Valve from the Bracket hoping to get more access. But still won't budge.

I need to remove the Booster anyway, so I'm hoping by removing it, I'll gain some more room.

But so far I can only just see the (2) nuts on the RH side of the Booster at the firewall.

Can't spot what I assume are (2) more on the LH side and even if I could spot them, not sure how I will be able to get a wrench on any of them.

There is a plastic box mounted to the firewall behind the Booster limiting any access. I don't know what that box or module is for and can't see how it can be removed without removing the Booster. There are a bunch of wires stuffed behind the Booster, some that I know aren't factory (there have been a bunch of mods made to this car that I am trying to correct). But the wires aren't really the problem as far as I can tell.

So right now I'm stuck.

Any and all advice appreciated. Thanks.

[njsteve]

That little black plastic box is a snap-on cover to keep water out of the horn relay. It should just pop off.

There might be some bolts going from the firewall side into the firewall that are accessible by laying on your back and reaching under the dashbard to get to the nuts. Also, you have to unbolt the link that operates the booster, from the pedal swing arm of the brake pedal under the dash.

[Dens71TA]

A swivel end GearWrench works well for removing the brake booster to firewall nuts.

[John V.]

1-1/2 hrs later I have the RH nuts off. 5 lbs. of sweat in my shirt. I love Fla weather most of the time....

njsteve, I pulled back that cover just enough to see a Delco Remy marked part inside of it, so good to know it is the horn relay. At least now I know it belongs there, I kept wondering if it was for an aftermarket alarm or some such. No bolts to turn inside, they must be studs, else I couldn't have gotten the nuts off.

I knew enough to pull the clip off to get the rod disconnected from the pedal. But you say unbolt a link? Is there something I need to unbolt from the actuating rod?

Noticed that the brake lights were lit after I disconnected the rod so I tied the pedal up to turn the pedal switch off

Dens71TA, kept thinking that was the type wrench I needed. Was no fun at all turning my 9/16" combination wrench about an 1/8 turn at a time.

But worse that that, to get both of them started I had to whack the wrench with a hammer, all the while fearing I'd mess up the nut if it slipped. Luckily they broke free but had to wrench them all the way to the end, wouldn't/couldn't turn them by hand.

I've now spotted the upper LH nut, even got the wrench on it but no way to get any leverage on it to turn it.

I'll go get the Gearwrench tomorrow and hope for the best.

If anybody else has a better idea, I'm all ears. I keep wondering how I'm going to be able to reassemble this.

[njsteve]

Yup, you gotta have a gearwrench 9/16" otherwise you will be there forever. As for the link to the pedal, if you got that clip undone and the linkage rod is no longer attached to the pedal arm, it can come out with the booster.


P.S. it's 115 with the heat index here in Jersey right now. I used to live in Lakeland, Florida and the humidity here in August is worse.

[RamAirPwr]

I was in the process of switching out my hood hinges so with the hood off, it's all about line of sight and leverage. I was able to get the bolts off in about 20 minutes with a whole lot of WD-40.

[SMW]

I removed the fender well and the wiper motor. Easy access to everything.

[John V.]

Well I finally got the left side nuts off this morning.

Took 3-1/2 hrs. to remove the hood and then remove the 2 left side nuts. Nothing was easy about this job. But the booster/mc is now out. Still haven't gotten the last line disconnected from the combination valve.

I bought a set of swivel head ratchet wrenches but I couldn't get the box end on the nuts, the bracket is too close to the nut. And since the handles were short, it took me a lot of attempts to realize what was happening. So they were useless not to mention frustrating.

I also bought a set of long reach combination wrenches. That only helped to get the upper nut off and it was very slow, only could swing a fraction of a turn at a time.

The lower left side nut luckily broke free without having to whack the wrench.

I could only use my regular combination wrench on it.

The problem was the horn relay, it prevented me from using the long reach wrench on the lower nut. I can't see any way to remove the horn relay with the booster in the way.

I thought this was going to be an easy job when I started, I can't believe how many hours it took to just remove the thing.

I am NOT looking forward to the reinstall.

I also took off the wiper motor this morning, I'm pretty sure that would have made removal of the right side nuts go much quicker so should help on reinstall.

But I'm not sure what will help with the left side reinstall.

SMW, what is involved with removing the inner fender?

Were you able to work around the horn relay with the inner fender off?

[SMW]

When you remove the inner fender the horn relay is right there. There was no need to remove the hood. The inner fender is just bolted on. You may have to remove the bolts from the lower part of the fender so it will pull out. It is very easy to do.

[John V.]

Just to be sure, were you able to leave the horn relay in place while you removed/reinstalled the booster nuts?

What kind of wrench did you use?

Just eyeballing it, even with the inner fender removed, it looks like the horn relay AND the firewall fuse block connector (I think that is what it is) would still be in the way.

I can remove the horn relay with the booster out of the way but I couldn't see any way that I'd be able to remove it or reinstall it with the booster in place, so seemed to me, the horn relay needs to be mounted when the booster gets reinstalled.

Actually, I can see where removing the firewall fuse block connector, or at least the wire harnesses plugged in to it might help. But now that the booster is off, I can't tell if it would be possible to reinstall any of those connectors after the booster is reinstalled.

I'm all for pulling the inner fender off if that helps with the reinstall but trying to get a better picture in my head of how you were able to do it.

A further explanation would be VERY much appreciated. Thanks!

[SMW]

I don't remember if I had to pull the relay off to remove the booster. I did pull the relay when I replaced it. Once the wheel well is out it is easy to get to.

[dpoltzer]

Can you tell me the correct orientation of the 3 wires that go to your horn relay please? Here is what I "think" it should be but need confirmation:

Black with pink stripe=driver side end
orange=center
green&black pass side end.

Thx and pardon the interruption.

[John V.]

I can't swear mine is correct, so much has been messed with, but here is what I see.

End wire on driver side I saw pink stripe on black wire. That checks with you.

Next to that turned 90 deg is Orange wire.

Next to that I have 2 wires in a single Brown connector.

Closest to firewall is a green wire, next to that is a black wire (closer to the front of car).

I didn't pull the connector off but judging by feel of the connector, the terminals on the relay may be 90 deg to each other so that the connector would only fit one way.

Found a pic of a '73 Firebird horn relay, shows the 4 terminals just as mine is, so seems like you are short a wire and perhaps a terminal? Edit, Oops, rereading you do mention the 2 wires on the pass side end, threw me off when I read "3 wires".

Hope that helps.

SMW, thanks for the pic. And I can see that 2 wire brown connector for the horn relay dangling in your pic (plus the connectors for the other 2 wires also).

I will pull my inner fender off for sure. Does look like good clearance. I'll guess that doing so will allow the horn relay to be off while the booster is installed and then install the horn relay after.

Thanks for the excellent advice.

[dpoltzer]

My car is a 1970 and there could be differences between a 73. I have a new and correct wire harness and there are just the 3 connectors that go to my relay. I believe my relay is original as it has the "Remy" on it. There is a green wire & a black wire that join in to one connector that I have on the passenger side. Orange in the middle and the Black w/pink stripe on the driver side of the relay. The spade connectors on the relay are pretty muck in a strait line as I recall. Anyone else with a 1970 that might chime in on this? I may try a generic relay from a parts store if my relay is no good. Anyone try this? Thx.

[Held for Ransom]

Wiring sounds correct. Here is a picture of a '70 LeMans unit.
There are Borg-Warner units on eBay as well as The Parts Place unit. Pontiac PN 1115893.

[John V.]

Ditto HFR. My bad for misinterpreting your 1st post. I thought you only had 3 wires. You have the correct 4 wires, the 2 on the pass end have a common connector so just 3 connectors.

Same as my '73. Same as the relay and wiring posted by HFR.

[West Coast GTO]

70 GTO with in line splices before new wiring harness. Same colors and connections.

[Held for Ransom]

Well, really they can only go on one way, as long as you have the correct three connectors. The tang prevents the one wire (orange) from fitting on the end terminal.

[dpoltzer]

Perfect! Thanks much gents.