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I did the same swap on my '74 last year. It was a night and day difference! I went with the newer style mc but otherwise a pretty simple swap.

Bleeding brakes can be a pain.

I "bench bled" my MC while it was installed in the jeep. My assembly was taken off drained and painted up, but I never took the MC off the booster. So fast forward everything is hooked up but no fluid in the reservoir. I just connected a fitting to each port with a connected tube going right back up in to the reservoir. I used rubber hose clamped over the fittings, but you could use chopped off chunks of brake lie too. Just pump until the bubble go away.

Next put lots of towels below to catch drips. As fast as you can unscrew one bleed tube and connect your regular hard line. Repeat for the second line.

Now it's just normal bleeding starting from the farthest wheel back two first, front passenger next and last front driver. I used one of those vacuum bleeders and they are worth every cent!

I have seen that you may need to hold a pin at the proportioning valve so that it allows you to bleed the lines but I did not using my method and it bled fine.

Hope this helps!

ScottsMojo wrote:I did the same swap on my '74 last year. It was a night and day difference! I went with the newer style mc but otherwise a pretty simple swap.

Excellent! I can't wait to try it out!

Nutz-n-Bolts wrote:Bleeding brakes can be a pain.

I "bench bled" my MC while it was installed in the jeep. My assembly was taken off drained and painted up, but I never took the MC off the booster. So fast forward everything is hooked up but no fluid in the reservoir. I just connected a fitting to each port with a connected tube going right back up in to the reservoir. I used rubber hose clamped over the fittings, but you could use chopped off chunks of brake lie too. Just pump until the bubble go away.

Next put lots of towels below to catch drips. As fast as you can unscrew one bleed tube and connect your regular hard line. Repeat for the second line.

Now it's just normal bleeding starting from the farthest wheel back two first, front passenger next and last front driver. I used one of those vacuum bleeders and they are worth every cent!

I have seen that you may need to hold a pin at the proportioning valve so that it allows you to bleed the lines but I did not using my method and it bled fine.

Hope this helps!

Thanks for the tips. The following post addresses the proportioning valve...

I've done quite a bit of research and think I've narrowed it down to the combination/proportioning valve. I've never messed with these things before but here's what I've gathered...

The valve allows brake fluid pressure to flow to the front and the rear. If it senses too much flow to one or the other, it will close off that side as it sees it as a potential leak. The purpose for this is to allow you to still have [some] brakes if a line were to burst. When this happens, assuming everything is working, your brake light will come on. Last night I verified that my brake light is now on. Since I have no pressure to the front, I'm assuming the switch triggered to shut off the front.

My solution?

I bought some short brake lines and fittings. I'm going to pull the master cylinder and bench bleed it the proper way to ensure all of the following work is not a waste of time.

Next step - If you don't have the special tool used to keep the valve/switch/pain in the *** yet awesome safety feature in place, there are a couple options. I've read that an 8 penny nail with a rounded off tip is the same diameter as the switch plunger. Poking that around in the hole may reset it. I'll consider this method.

The other method seems like it could be more fun. I've read that if you pump up the brakes and really mash them down while cracking open a bleeder valve on the working side of the system, the valve will reset. Hopefully anyone trying this will wear safety goggles. I sure will!

Either way, if you're brake light is functioning as it should, you'll know the valve reset if the light goes off.

Once the valve is reset, if you have the tool to hold it in place, you're set. Bleed the brakes as normal. I've always heard to bleed from the furthest bleeder from the master cylinder to the closest bleeder to the master cylinder:

Right Rear
Left Rear
Right Front
Left Front

Now, the factory service manual from 1976 states to bleed as such:

Left Front
Right Front
Left Rear
Right Rear

This doesn't make sense to me but then again, I'm no master technician. My advice would be to pick your favorite method and give it a try.

OK - That seems easy except for the part where I don't have the tool nor care to buy one. Instead, I'm going to be difficult.

Let's assume the valve has been reset and we're ready to bleed the brakes. Here's what I've read on how to bleed the brakes, including how to fill dry lines, without popping the valve.

GENTLY bleed one front wheel, then one rear wheel. Repeat until you have fluid at all 4 wheels. Once fluid is at all 4 wheels, the valve should have enough compression to allow you to gently bleed all 4 wheels in the proper order. For me, I'll bleed from the furthest wheel to the closest:

Right Rear
Left Rear
Right Front
Left Front

I'm not sure when I'll get a chance to go at it again. I'd like to do it this evening or at least before Friday but we all know how busy life can get, especially with a wife and a 1 year old. Either way, I should know what's what by the end of the weekend (or earlier hopefully). That being said, I'll continue to research and will update this thread with any news. If anyone has any information, please don't hesitate to chime in!

Sources:

(Hopefully I can link another forum here. If not, my apologies!)

http://www.jeepforum.com/forum/f8/brake ... d-1797153/

8 Penny Nail 'Tool': http://www.jeepforum.com/forum/f8/brake ... st18246162

1976 FSM on Brakes: http://oljeep.com/gw/76_tsm/Section9.pdf

as previously suggested, one of those $12 vacuum bleeders found at any parts store is the best way to go.

You don't spill a drop of fluid, can do it yourself, and it works every time!

I have a Mityvac sitting on the work bench. I've never been super fond of it as it appears air pulls past the threads of the loosened bleeder valve. Maybe I'll give it another try...

Update time:

Diagnosis and repair thread: http://www.jeepforum.com/forum/f57/mast ... ir-2462353

Again, I apologize for linking a different forum. My intent is to provide helpful information.


After finding that I probably had a bad master cylinder, I ran to town and picked up a NEW M/C. After bench bleeding, I assembled it to the brake booster and bled all the brakes again. I was pleased to find each corner bled well, especially since the NEW master cylinder still seemed to bench bleed a little funky (perhaps it was the operator, not the M/C). Either way, I was ready for a test drive since the pedal was holding pressure. I immediately noticed how much less pedal was required to stop the vehicle and I was pleasantly surprised to find I can lock up all 4 wheels (not that this is an ideal way to stop a 4,500 lb truck, more just please that it's possible). All in all, my problems/solutions were that the re-manufactured A1 Cardone master cylinder was bad right out of the box AND my proportioning valve/combination valve/metering valve was blocking fluid from the front until it was reset.

I still have an issue with the truck wanting to die when I hit the brakes. It happens much less frequently than before the swap but it still occurs. I'm in the process of narrowing down what's happening but we think we may have it figured out. In lieu of pretending I'm not an idiot, I'll reveal what we think is happening and the extremely simple steps I'll take to hopefully resolve the issue tonight. Please don't throw sticks at me for this...

We think the fuel is sloshing in the bowls when I come to a stop thus starving the vehicle. Why do we think this?

1. The vehicle doesn't die when the brakes are aggressively applied while the vehicle is standing still.
2. I didn't adjust the float level when I installed the carburetor (stupid) and we KNOW the fuel level is quite low via the site plug.

This could also explain why I have a flat spot in my acceleration at higher RPM. I very well could be sucking the bowls dry requiring the carb to use only what is being supplied via the fuel pump.

Solution - Turn off the 'idiot' and adjust the darn floats!

Issue number two that may also play a role in this is the vacuum hoses. We noticed the inside diameter of a couple of the vacuum hoses are a touch too large causing the lines to not seal. One location we tested a line was at the vacuum advance on the distributor. I was not able to build pressure using a hand pump unless the line was clamped to the advance port.

I'll update this thread once I've resolved the issues listed above, hopefully with a final resolution.

Thanks for the help everyone. The advice has been greatly appreciated.

Final update on the brakes (hopefully)...

I adjusted the floats and installed smaller vacuum lines where necessary and was pleased to find the truck no longer dies when braking. I really believe the floats were set too low and the fuel was sloshing when stopping causing the engine to starve.

Now, I haven't taken the bowls off the carburetor but when adjusting the floats, I found that I could only raise the float height a certain amount before I could no longer tighten the lock screw. With the adjustment nut adjusted out as far as possible and the lock nut tightened, I'm still a little low on the fuel level. Fortunately, it's high enough that if I shake the truck, a little fuel will splash up to the threads. Keep in mind, this is identical for both the primary and secondary fuel bowls. I'll probably leave this alone for now as it's much better than it was but when things slow down a little, I'll need to pull the bowls off and see what's going on.

Something else that came to mind - After messing with things (replaced leaking booster and leaking vacuum lines), I decided to check the timing. I set the idle to about 650, plugged the vacuum advance, and threw the light on the warmed up truck. It had adjusted itself to TDC and was running fine at that. Back in December when I installed the D.U.I. distributor, I had it cranked up to 15° advanced on 87 octane without pinging (http://fsjnetwork.com/forum/viewtopic.p ... =40#p50805). I figured, since it worked before, I'll try it again. At 15°, I had no pinging but felt that the truck was very sluggish in 4th while trying to heavily accelerate. It felt like the clutch was half engaged. I also noted an odd smell, almost slightly like burning rubber.

Since I didn't have time to fiddle with it, I stopped by the house, set it at 10°, and took it for another quick spin. It drove much better and didn't have the smell that I noticed before except possibly on one small occurrence.

Does it sound like at 15° I was sparking too soon? What surprises me most is I didn't notice any pinging. On top of that, shouldn't I be able to crank out a little more than 10°?

Feel free to throw in comments!

I thought this was a neat picture from yesterday when I was out testing the brakes...

A friend recently informed me of a car show in my hometown and suggested I enter since there aren't many Jeep trucks running around here. I figured, why not? I headed to his house Saturday and paid him to detail it up (he used to work in auto body and knows a thing or two about this stuff ).









Left is polished, right is unpolished.







Tucked away in a very tiny garage for the night. We didn't want it to get dirty before the show the next day!



Not a great picture as I was at the edge of the show. Some pretty sweet cars and trucks made it out for the day though! Most were classics but as you can see, there were a few newer vehicles near me.



Annnnnnddddd.....

3rd place in the truck category!

Congrats! She sure shines up nice! Glad she is running better too, that stuff can get real fustrating.

Shines very nicely. Very clean looking rig.


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Certainly looks like a first place truck to me!

Thanks everyone! It was a fun experience.

In other news, I have yet to change all the fluids in the truck, though I've put a thousand or two miles on it since I picked it up. Needless to say, it's time.

First off, my father-in-law said he changed the transfer case oil before he sold it to me. My research tells me that the transfer case and transmission share oil and should be changed at the same time (D20 and T18a). I also found I need gear oil that is safe for yellow metals. As you'd expect, this is a little difficult to come by and the staff at the auto parts store weren't sure what would fit the bill. Does anyone have any advice?

Secondly, I picked this up for the front and rear differentials. The rear differential is tagged for the factory limited slip, though I'm not positive it is an LS/it is working. I think I've spun one tire and not the other in the snow. Also, I jacked up the rear and spun the tire while the truck was in gear. The other tire spins the opposite direction compared to the one I'm spinning. Holding one tire and attempting to spin the other results in neither spinning. Is this any hint as to whether I have an LS?

Either way, I won't fully know until I pop open the differential. To be on the safe side, I picked up limited slip gear oil. Will this be good for both front and rear? I mean, It's liquid engineering!

You either don't have it or it's worn out but there's no harm in using LS oil with a conventional diff.

The factory LS wears out pretty quick. Like mentioned above, having the modifier in there will not hurt anything, and most newer GL-5 fluids have it built into them.

Thanks for the advice. I found the rear DOES have the limited slip clutches. I also found a little more...

Saturday I started on the differential fluid and cover swap. The fluid in the rear was NASTY.







Once the fluid was out, I found this...







Since that clearly isn't good, I jacked it up to check the back side of the spider gears. Everything else looked good, including the pinion gear. I also noticed that with the old fluid out, the limited slip clutches were engaging again. We think the spider gear was broken before I even bought the truck. One tiny pebble sized metal was found in the bottom of the differential but the other pieces were nowhere to be found. That tells me someone pulled the chunks out years ago and drove it as is.

That being said, I slapped the new cover on and filled it up with fluid so I can still use the truck until my parts come in. Worst case scenario, I can always shift the D20 into front wheel drive to get me home if something happens.

As for the parts, Kolak over on JF hooked me up with Spicer brand spider gears, limited slip clutches, and all 4 axle seals shipped for well under what the spider gears/clutches cost online before shipping. Thanks Nick!

Anyway, here is the rear cleaned up:



Rear differential tag, painted with grill paint (sometimes you have to work with what is on hand! ).



Limited slip tag, not as pretty.



New cover:



A picture of the front stock cover, because I happen to have it. I forgot to snap a picture of the front with the new cover though. I will mention that the fluid in the front looked almost new!



Lastly, I love looking under the truck now noticing no drips from the differentials!

I'm putting this here for future searchers as well as myself when I get a chance to change the transfer case and transmission gear oil. I believe the D20 and T18a want 75W-90 gear oil that is safe for yellow metals. Such a gear oil will not be safe for hypoid gears (differentials). Someone correct me if I'm at all wrong!

http://www.redlineoil.com/product.aspx?pid=46&pcid=7 wrote:
Red Line MT-90 75W90 GL-4 Gear Oil

• 75W90 GL-4 gear oil (similar to SAE 5W40/10W40 engine oil viscosity)
• Popular in Nissan, Mazda, Mitsubishi, VW/Audi, Lotus Elise/Exige, Toyota
• Offers quicker shifts, perfect synchronizer coefficient of friction
• Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage
• High performance gear protection and longer synchro life
• Eliminates notchy shifting, even when cold
• Satisfies the gear oil viscosity requirements of 75W, 80W and motor oil viscosities of SAE 40, 10W40, and 15W40
• Recommended for GL-1, GL-3, and GL-4 applications, as well as where most special synchromesh fluids are specified
• Appropriate coefficient of friction for most manual transmission synchronizers (other's synthetic gear oils are often too slippery for proper synchro engagement)
• Red Line offers lubricants to pinpoint nearly every transmission application
• MTL, MT-85 & MT-90 are not for use in differentials with hypoid gears
• Excellent gear and synchro protection, balanced slipperiness for easier shifting in cold climates
• Excellent for high- and low-mile transmissions
• Compatible with petroleums and other synthetics

Amazon sells it for about $16/quart with prime shipping: http://www.amazon.com/Red-Line-50304-Tr ... s=red+line

Hey, thanks for the tip Chris ! I have been putting off changing out the oil in my trans just because I wasn't looking forward to tracking somthing compatible down. I'll be loking for that local or ordering some if I can't find it on a shelf.