|
By peteyg - 7/5/2009 2:21:33 PM
|
We put the Scrambler back on the road about 3 months ago, and it has been great...except for the brakes. The Scrambler is rolling 37's, and the manual brakes leave a LOT to be desired. What to do? I know that a YJ booster and MC is a bolt-in solution, but they are hard to find in local junkyards and I'm too cheap to buy new.
So, I've had this TJ vacuum booster and master cylinder laying around, and finally this weekend we decided to put it in. Chris was the man with the plan, and came up with the awesome bracket solution.
First things first...
There are some major differences between a TJ and CJ brake system. Most notably, the bolt pattern of the mounting studs is way different between the two Jeeps. We matched up the TJ pattern and drilled it into the firewall. This turned out to be a mistake, but at the time it seemed like the right thing to do.
So, after we drilled the pattern we mounted the vacuum booster up and found that the rod was about an inch and a half too long. Here's where drilling the firewall turned out to not be needed. Instead of cutting up the TJ pushrod, we decided to just mount the booster further back, using a bracket welded to the studs. Looking back, we could have just welded the bolts on using the CJ pattern and we wouldn't have had to drill the firewall. Lesson learned. So we fabbed up a bracket and welded it to the booster. It took about 1/2 hour, total.
First, we needed to drill a large hole in the middle of the plate for the large TJ pushrod to go through, but the hole saw took a dump, so we did it the old fashioned way. I worked out pretty well.
Then we welded the plate to the studs, and then the bolts to the plate.
Then, we needed to come up with a master cylinder solution. We wanted to use the CJ manual MC, but at first we couldn't get the rod length right, and the manual MC doesn't have a provision to seal against the booster like the TJ MC does. So then we looked at using the TJ MC, and at first it looked like it would be workable, but then I would have had to run all new brake lines because the CJ fittings are SAE and the TJ fittings are metric. After looking all over town for a way to adapt the CJ brake fittings to the TJ MC, I came up empty handed. At that point we decided to give it a shot using the CJ MC.
So, the first thing you notice with the CJ MC is that the mounting holes don't quite line up with the mounting studs on the booster. No worries...we drilled out the holes to a larger bore and it fit right on. The next problem is dealing with the sealing of the MC to the booster. At first we tried to line up and use the o-ring that was on the TJ MC, but that didn't work, so we gave up and just gooped it up really good with RTV. That worked fine.
And then we played Rock Band 2 for the Wii (it rocks!) for three hours waiting for the RTV to set up enough to hold the seal and then we test drove it....WOW! What a difference! We can now lock up the 37's. And that's with a bad bleed. I've been burping air out of the lines all day, and every time the pedal gets better. I know the MC needs a better bleed. I'll get there. But even with a bad bleed, the tires lock up. NIGHT AND DAY difference! I'm very pleased with this solution, and would recommend it to anyone.
Today I finalized the conversion. When we put in the vacuum booster, it took up the space where the stock air box was wedged in, and I was running with an open throttle body. Unacceptable. So today I went over to ricer-land (er...Pep Boys), and found a filter and some tube adapters. Chris has a spare TJ intake tube, so I cut that up the same as how I did my TJ, and this was the result. All done! It works GREAT!!!!
|
|
By Nightclaw - 7/6/2009 12:07:40 AM
|
You didn't happen to make a template for the bracket, did you...? I'm betting it would work nicely for a YJ too. 
Nice work!! 
-Brian
|
|
By Robert-R - 7/6/2009 5:02:01 AM
|
That's some great booty fab/mech gentlemen!
|
|
By JeepinScott - 7/7/2009 6:27:07 AM
|
|
Nice work. Does the booster seal air or fluid?
|
|
By peteyg - 7/7/2009 7:41:46 AM
|
quote:
Originally posted by JeepinScott
Nice work. Does the booster seal air or fluid?
Air. Without a good seal, you get vacuum leaks and it degrades the effectiveness of the booster.
|
|
By oldnslow - 7/7/2009 11:33:00 AM
|
|
Thanks for this much needed info.
|
|