Power booster interchange?

[eaglefreek]

Does anyone happen to know if the 82+ power booster will install into an 81? I'm concerned about the brake pedal side and need to know if they are the same at that end. I can't give specifics, but I need a master cylinder that has the lines on the right side. The 80-81 use a GM short pushrod style and I've tried a couple different master cylinders that have the lines on the right side but they are too wide. So I want to change to the later style that seems to use a Ford style master cylinder but concerned the pedals might be different between the different styles.

[captspillane]

I wasn't aware of the difference and am intrigued by the answer. I might almost be intrigued enough to shift through my pile of old ones to compare. Hopefully someone else knows the answer sooner, if not bug me and I'll find it.

[AMC of Houston]

Well, I'm guessing "yes".   Here's my reasoning -- although the boosters are different part numbers (riveted-on booster mount bracket vs. the later bolt-on mount bracket), the under-dash pedal mount bracket (that the brake pedal pivots from) are the same part number for all years, and the pedal assembly is also the same part number for all years.   That should mean that the distance from the firewall to the pedal rod is the same for all years.    Just an educated opinion tho!!

[eaglefreek]

I wasn't aware of the difference and am intrigued by the answer. I might almost be intrigued enough to shift through my pile of old ones to compare. Hopefully someone else knows the answer sooner, if not bug me and I'll find it.

Dave, the 80 and 81's use a Delco master and booster and the lines exit on the driver's side. There were casting numbers on the bottom of my master and I found some info on the net that the casting number is from 60's-70's Oldsmobile and uses a GM short pushrod. The 82+ lines exit the passenger side of the master and has a more standard style pushrod and seems to be more like a Ford master cylinder.

Well, I'm guessing "yes".   Here's my reasoning -- although the boosters are different part numbers (riveted-on booster mount bracket vs. the later bolt-on mount bracket), the under-dash pedal mount bracket (that the brake pedal pivots from) are the same part number for all years, and the pedal assembly is also the same part number for all years.   That should mean that the distance from the firewall to the pedal rod is the same for all years.    Just an educated opinion tho!!

Thanks George, I think I might gamble and get the later style booster. I can't seem to find a master that will work with the earlier booster with what I'm trying to do.

[eaglefreek]

Here's the early style


Here's the later style

[AMC of Houston]

So you'll have to track down a later-style mount bracket maybe??   Or try to un-rivet the old-style bracket and see if it'll work??   Just wondering.

[eaglefreek]

Just wondering.

You and me, both. 

[carnuck]

The whole units swap. I did that on SOTE so the lines would be towards the fender for clearance to put 4.0L EFI in.

[eaglefreek]

The whole units swap. I did that on SOTE so the lines would be towards the fender for clearance to put 4.0L EFI in.

Thanks. I looked at my 86 and 81 side by side and I thought it would so I ordered the later style booster and master. I need the lines to exit the other side due to interference that I can't discuss right now. 

[carnuck]

I think the 89/90 XJ booster MIGHT fit. I know the master swaps because I put an '89 MJ used master on SOTE but didn't change the booster.

[Nightpath]

If you have your old one and can weld a tiny bit and have your old brake booster here is a backup/upgrade/whatever :

- Jeep Cherokee XJ brake booster (mounts directly to the firewall of the XJ. Mine is from a 1994 XJ but I think others are pretty well the same. The rod may be the only thing that changes, which doesn't matter)
- Stock Eagle brake booster with the stand off mounts

1 : Remove the stand off mounts from the Eagle brake booster
2 : Slide them onto the XJ brake booster.
3 : Cut off the long metal rod that attaches to the brake inside the Eagle, a few inches off the booser
4 : Cut off the rod from the XJ, make sure that the stud that's left is the same length as the one that is left on the Eagle
5 : Weld the rod that was on the Eagle booster to the Jeep booster stud

The new booster should fit right in like it belongs there. And since the newer XJ boosters are MUCH more common, it's a quick simple solution to a broken rare Eagle booster.

[carnuck]

I would cut and thread the shaft to the booster rather than weld because the heat will ruin the booster. Then use a joining nut with lock nuts front and back to keep it tight.

[Nightpath]

Hells yes, that's a really good idea and much more simple, especially since you can just keep the original shaft and reuse it.

[eaglefreek]

I installed the 82+ master and booster in my 81 today. I ground the rivets and removed the bracket from the 81 booster. The studs on the back of the 82+ booster are approximately 3 7/16" on center where as the holes in the bracket are 3 9/16" on center. No big deal, I just elongated the holes with my die grinder. It bolted up to the car just fine. I won't go into too much detail with the lines here because mine is a unique situation and the stock brake lines aren't on the car. But, the rear port(front brakes) are different  between the two master cylinders. 9/16-18 on the 80-81  and 7/16-24 on the 82+. I didn't feel like putting a new tube not on,s o I used a couple adapters. After trying 3 different master cylinders, I was happy to have no interference with the shock tower. Luckily, I happen to notice the master cylinder looked a bit high. I slowly closed the hood and yes, now it interferes with the hood.  Only finding a couple pics online to go by, it appears that the 82+ have less of an angle in the booster bracket. I could cut and weld the bracket so it has less of an angle, but I'm going to try to see if someone has the correct bracket from a parts car.
80-81

82+

http://amceaglesden.com/guide/images/9/92/Hydro3.jpg

[eaglefreek]

I went to the junkyard today since they had 2 Spirits there, but both turned out to be manual brakes. Rob, AMC1320, came to the rescue and let me take the brackets off his Spirit parts car.

Here's a pic showing the 80-81 bracket on the right and the 82+ bracket on the left.  You can see the 80-81 has more of an angle. Now I have brakes and can close my hood.