MomoJeep

Moses, thanks for your response. I find this helpful when considering beam cutoff: https://www.retrofitlab.com/blog/dot-vs-ece-beam-pattern/ And this makes me lean toward the European style. I think my plan now is to try some H4 European, http://www.rallylights.com/hella-super-7-round-h4-for-2-headlamp-systems-each-with-city-light-hl39519.html and see how I like them. I think I will wait for the LED's to get better/cheaper. I'd like (a) LED's that defrost (b) better light pattern (smoother, a bit more diffuse), and better price. Anyone, please chime in!?!

Hi, CJ oem headlights leave a lot to be desired. I drive a lot of twisty mountain roads and highways. I've had encounters with wildlife on the road at night that would have been much better if I'd seen them sooner! I want better headlights. I also want fog lights that can also work as supplemental lighting to headlights. Then there is the wattage / amp draw / wiring harness issue. When turning on the oem headlights (especially while running the heater and wipers), the voltmeter on the dash drops significantly and the dash lights dim down a bit as well. LED's seem to "solve" the electrical draw issue, since they are very low wattage, with even brighter light. However, there are a few things I don't like about them (I tried the Quadratec reflector style). (1) The beam pattern is too "boxy", the top of the beam cutoff goes from light to dark very sharply. They do not illuminate trees or anything much above the street level. (2) Apparently, they do not get warm enough to defrost themselves in a good snowstorm. I don't have any experience with this problem, so I don't know how bad it is. But I'd prefer not having to worry about it. (3) Perhaps these problems could be solved with a higher quality light, but then the cost becomes very, very high. There is an H4 option (European spec) that is much better than oem/DOT spec. Much cheaper than LED. And no defrost problem. However, they still seem to have a very sharp upper beam cutoff. Also, they are the same wattage as oem, so I assume the electrical drawdown issue will be the same. They sell a headlight wiring harness that runs right off the battery. This will make the lights perform better I assume. I'm not super good at understanding electrical issues, but if the wattage of the bulb is that same, even with the improved wire gauge (harness), won't it still pull the same amount of electrical power away from the rest of the vehicle? Can you recommend a headlight set up that would resolve these issues (1) smoother beam cutoff to be a bit more like the oem beam pattern, but with brighter lights that project further down the road? (2) less electrical draw on the rest of the electrical system and (3) if LED, no issues with frosting up? PS, if sharp beam cutoff lights are the best idea, are there fog lights that are street legal that would illuminate a bit more like a flood light, giving a smoother transition to the upper beam cutoff? Thanks! James

Hi Moses, So I have the 4.0L head on the 258 block, with the Mopar/Hesco MPI kit installed. I love it, except for the vapor lock problem, and that the gas mileage still seems poor (14.5mpg) MILEAGE AND HEAT I experience vapor lock after long drives on hot days and/or going up mountains. There is a pressure and return line running up the driver side, where the exhaust is also located. External fuel pump mount near the exhaust pipe on drivers side of the rear cross member, filter also on cross member in center of vehicle. I tried wrapping the exhaust from manifold, over cat conv and muffler (and put a heat shield fabric tube over the fuel lines from firewall to injector rail). This did not fix the problem at all. However, the gas mileage jumped up to 16-17mpg! Why do you think this happened? I am guessing that since the air intake sits right about the exhaust, cooler air into the engine is more efficient since it can expand more in combustion than hot air? I also heard something about "Scavenging" with hotter (insulated) exhaust, but I don't understand that.. Why do you think the mileage got better? Any tradeoffs to keeping it this way (exhaust wrapped)? VAPOR LOCK Then with the vapor lock, there are a few ways to go, and I'm not sure which to try: (1) Move fuel lines to passenger side, route under radiator and back up to injector rail. However, I've read some people have this set-up and still experience vapor lock. Some speculate because of the radiator, but I'm guessing it's the low pressure line before the pump. (2) Switch to using a regulator near tank, instead of in the fuel rail. Hesco sells parts for this. The advantage is there will be no return line. I heard that gas vaporizes much easier at low pressures, but I'm really not sure if vaporized / aerated fuel returning to the tank is the problem? This could be combined with (1) above to make things easier and cleaner. http://www.hesco.us/products/7902/40l-conversion-parts/313496/hes409606-1-regulator-kit#.WbbvWmeWzIV (3a) Novak sells an in-tank pump. I like this idea because currently fuel travels across the rear xmember from passenger to driver side at low pressure (the external pump is on the drivers side). I am suspicious that this low pressure run before the pump is where the vapor lock might be happening. The in-tank pump would eliminate this. (3b) I believe I'd also still have the option of locating the regulator in the rear and running a single line up to the engine (and could also be on the passenger side?) https://www.novak-adapt.com/catalog/fuel-system/cj-fuel-module The drawback I'm concerned about is that I do a lot of outdoor adventure road trips and remote backcountry travel. I carry a spare external fuel pump. If the in-tank pump fails, wouldn't this be much harder to replace on the trial? Do you think a spare external pump could still be installed inline if the in-tank pump failed to get me home? Or would the failed in-tnnk pump prevent fuel from flowing? So, which option do you think makes the most sense? (1), (1) & (2) Combined? or (3a) or (3b) Thanks!

Thanks for all your help. I just did a long road trip in my Scrambler, 3 people and lots of camping/adventure gear. Although I still wish it could "stop on a dime" the way little economy cars do, the brakes performed well in a variety of conditions. My next upgrade will be hi-performance slotted (not through) front disks and composite pads for maximum stopping power. About trailer brakes, what would you advise for a 16' boat trailer (gross weight 1800-2000lbs)?

Yes, thank you, I checked the fluid and the levels did not drop. Great tip on how to adjust the brakes! You're right. I was not aware of the lining break-in procedure.. Yes, for the boat trailer I'm considering trailer brakes, as you suggested. To upgrade my CJ brakes and further seems like too much work and complexity. Thanks so much for all your help!! -James (MomoJeep)

Great, thanks! My combination valve (1983 - I heard this was a year where they switched types in mid-year) seems be the kind with the push-in button. So I made a tool to hold it in out of a stout wire. Everything went well, except I forgot to turn the star wheel rear adjusters up to 3/8' threads showing as the repair manual says to do. I had maybe 1/16" of threads showing. I tried backing up and stopping over 15 times, then realized I could open the adjuster access hole and turn in manually. It had already adjusted a fair amount (about 1/4"). I turned it until I felt some resistance. Do you think not having started with 3/8" thread showing caused any problems? I'm afraid this could have caused the wheel cylinder piston to over-extend?

Yes, thanks. I replaced everything. I also had to replace a brake line and in the process let the MC run dry. I'm assuming this means I should pull it out and bench bleed it?

Yes, thank you. One of the wheel cylinders had lots of fluid behind both piston caps, maybe they were extending too far. The other one seemed have corrosion around the outside of both pistons, as if they were NOT extending as far as they should. This might makes sense considering two long shoes on one side, two short ones on the other. So I decided to replace the wheel cylinders as well. Thanks for your help on this. I'm looking forward to seeing how the brakes feel once I put it all back together correctly, with all brand new parts!

The wheel cylinders appear to be fine. I do not know how to test them or otherwise determine if they are binding or otherwise not working well. They are about 5 years old with low mileage on them (not a daily driver -maybe 30k miles). Would you suggest replacing them with new ones, or going with the "if it's not broken, don't fix" philosophy? Honestly, my concern is that I'll install new ones and then one of them will leak. For some reason, my experience with hydraulic parts is that they either leak soon after being installed, or they last a long long time. Any idea why they sometimes leak when new? Would you suggest replacing or leaving alone? The drums don't look bad. The friction surfaces are a little shinier than the new ones, but not exactly "glazed". I'm thinking of replacing them as well..

and for clarity sake: The metal frames of the brake shoes are all the same length. It's just the linings on the shoes are either around 8" or 10".

Update: After removing both rear drums, I found a LOT of black dusty powder in each of them. I also notices that the rear shoe on the driver side is cracked in the middle, and on the passenger side some of the rivets are no longer in their original location relative to the lining, as if the lining has "pushed past" them, stretching the original holes out-of-round. THEN, I noticed the two short shoes are on the driver's side, and the two long ones on the passenger side. This may explain the inconsistency in which rear wheel would lock up. Other than this everything else looks in order. I check for a fluid leak from the MC all the way through the Combo valve to each rear wheel, and I do not see any obvious leak. The inability to lock up both rear tires and kill the engine (wheels off the ground) could be explained by the mismatched shoes rather than air in the line, but I still don't understand where the fluid went. I just put in a new MC about a week ago, and filled it to within 1/4" of the top, Now the Front is still properly filled, but the rear has dropped about 1/4". Any idea where than fluid went!? (maybe I just forgot to top it off after final bleeding - but I that would be an odd mistake for me to make...) ?? While I'm in there, I'm thinking of replacing everything: wheel cylinders, shoes, and hardware... Do you think that's a good idea?

Well thank you for suggesting the wheels off the ground test. When I stomp on the brakes, the Jeep does lurch forward, so I figure the front brakes ARE working. So I jacked up the rear (I'm also more suspicious of the rear) and put it in gear. With the rear wheels both turning, I noticed: (a) Braking does not engage right away as I put pressure on the pedal. I would have expected them to engage right away, but they didn't. (b) With more pedal pressure, I killed the engine, and also heard a loud snapping sound. (c) When I tried again, I could get one rear wheel to lock up, or the other, but not both, and the engine would lug a little, but not die! Brake pedal fully depressed, one or the other of the rear wheels still turning...! If just one of them locked up consistently, I'd suspect that specific wheel to have a problem. But since that's not the case, my best guess is that there is air in the rear line somewhere. I also noticed the rear reservoir in the MC has lost some fluid. I don't see any obvious leaks at the MC or at either of the rear wheels, so I'll check the lines underneath...

After shutting of the engine, if felt like I got one power assist, but not two. Then put my vacuum tester inline between the vacuum hose and the fitting on the booster, and I get 16-17psi. I also noticed that after shutting off the engine, If I pop the booster fitting off, it goes "Whoosh" and sucks in a bunch of air. So it seems to be working. When I slam on the brakes, none of the tires will lock up, and the jeep doesn't exactly lurch to a stop. Apparently the front tires should lock up first by design. But since they're not, I figured I'll add friction there. I've order some front composite brake pads that claim to be about 20% more friction. We'll see how that goes. I'll also pull the rear drums off, and do the off-the-ground test.. I was wanting to go from 10" rear drums to 11", but I've been told the 11" backing place are almost impossible to find for my amc20 rear axle. They only used the 11" on '76-'77 CJ's... Apparently the oem 10" drums are pretty good, but the oem from disks are more like "car brakes".

Thanks! MC brake lines: Yes, the oem setup is (not coiled) straight up the firewall, then 90deg bend to the MC. The 90deg bend seems to serve the same purpose as the coils, because the lines are now in an "L" shape, so there is room for movement as compared to if they went straight to the MC. Booster: yes, I checked my combination valve. I checked by cracking open the front bleeders and stepping on the brakes. I heard it "pop" and the brake warning light came on. Then I bled the brakes with the combo valve "button" held in the pushed in position, and it seems to have reset because the warning light went off. But I have not checked the brakes by having the vehicle off the ground. I also replaced the MC (bench bled). And I know my front brakes (oem setup) are in good shape (just replaced them last year). However, I have not inspected the rear (I replaced them a few years ago). I know the booster is "doing something" because if I put my foot on the brakes and then start the engine, I feel the boost in the pedal, just like I used to feel with the single diaphragm. But I still don't understand why the dual-diaphragm doesn't feel noticeably different than the single in terms of stopping power..

Also, I had to pull the brake lines forward about an inch with the Dual-Diaphragm setup. No coils. but they come up the firewall and turn 90deg and head to the MC. I also have a 1" body lift, so after the 90deg bend, they now angle upwards to reach an inch higher. I was afraid I'd need to get new longer lines, but there didn't seem to be any real added strain on the lines. They simply pulled forward away from the firewall a bit. Do you think this is fine, or should I worry about replacing them?

Well I installed the 8" dual diaphragm and honestly I don't notice much difference over my oem single (9" I think, it measures about 8-3/4" dia). When I first installed it, it almost felt like no booster at all. Then I noticed the plastic vacuum hose fitting seemed to be defective, it was hard for me to suck air through it with my mouth. So I replaced it, but also noticed that they are using check valves. My oem did not seem to be a check valve.. (a) should I not really expect any noticeable difference in braking power with the 8" dual over my oem single? (b) Why would they be using a check valve? Shouldn't it just be a through fitting?

Hello again! At this point, I feel like I'm asking too many questions, but thought this one was worth bringing up. Brake line fittings that seize and then the nuts strip. So common, so frustrating. To possible fixes aside from re-doing the lines with SS lines: (1) Carefully use ant-seize on the threads. But is it not worth risking possibly contaminating the brake fluid, either now or at some point in the future when I may have forgotten I used it and I'm replacing something.. (2) Stop over-tightening them. Apparently they don't have to be super tight, and if they weren't, they wouldn't seize. Make em' snug, then check for any leaks. If s small leak, make 'em a tad snugger. Which is the better plan? Thanks, and I super appreciate any responses!

Thanks for this post! I'm also planning to upgrade my MC and single-d booster on my 1983 CJ8. I did put a vac gauge on the booster vac line fitting with engine running and saw around 18psi at idle. That's with a rebuilt 258 with 4.0L head and MPI conversion. When I do the pedal test, it's clear that the booster provides assistance when compared to no boost (test with engine not running). However, I'll be interested to see the difference with the dual-d booster...

Any recommendations on where to purchase MC and dd-booster? I see "Restoration Performance" mention in your other thread...

Moses, Thank you so much! This is all very helpful and I feel ready to start by replacing my MC (the lid seal is leaking) and figure I might as well try replacing the single diaphragm booster with a new double-diaphragm while the MC is being changed. Lastly, from this conversation I'm now confident the oem Combination valve is fine, however, what do you think of replacing it. I do not know if it's the original one, but I think it probably is. I bought this Scrambler about 15 years ago as a pile of parts (some else's rebuild project that they gave up on). I took about 10 years to slowly do a frame-up restoration, and have been driving it for the last 5. So that's the history of the current Combination valve. Do they tend to last forever, or might I be wise to also replace it with a new one while I'm doing the MC? Thanks!

Wow! Thanks for all the great answers! And thanks for mentioning trailer brakes! That would really address a lot of my concerns. Because I launch mostly into salt water, I wanted to avoid trailer brakes. I've heard the salt water makes them a pain to maintain. However, I believe Stainless Steel trailer brakes would be a good option? A few clarifications: Brake Fluid: Does DOT4 offer any advantage over DOT3 other than higher boiling point (which I assume is not an issue in jeeps)? My Questions 2&3: I see what you are saying, that activating the rear brakes just before the front in the most important function of the Combination Valve. However, I'm still concerned about the front / rear braking force ratio. Pardon me if I'm over-thinking this, but this is how my brain works... The 10% more braking I was referring to comes from going from the 10" Drum diameter to 11" (about a 10% increase). The 20% percent difference in the front is about what I've been told high performance composite pads and rotors will gain me. Now, lets say the stock setup is for 30% of the braking force coming from the rear, and 70% from the front, and the proportioning part of the combination valve is calibrated to send the right amount of pressure to the rear, and the right amount (but different) to the front, to support the 30%/70% rear/front braking force ratio, (and also because calipers and drums require different pressures). Therefore say there's Xpsi going to the rear, and Ypsi to the front. I'm assuming the front / rear braking force ratio is set by the oem designers for optimal braking(?). Now say I make these changes to the friction surfaces, such that it throws off this ratio: (1) Is it bad that the prop valve is delivering pressures to match the front and rear oem friction forces respectively, but I have altered these friction forces (in other words Xpsi to the rear and Ypsi to the front in no longer the correct psi's to match the new friction forces)? (2) My guess is that as long as the gain in the rear doesn't exceed the gain in the front, I'm ok (because the rear would not lock up first)? (3) Is it possible to get a combination valve with a different front/rear proportioning ratio that could fit my new setup? (4) And my numbers "10%" and "20%" are only estimates anyway, so I don't even know what the new ratio would really be. So do you think I should consider also adding an adjustable prop valve in addition to the oem Comb valve to dial things in better. Or will it be close enough? OEM MC's vs aftermarket: I read somewhere that oem MC's had a check valve of some kind that maintained 10psi of residual pressure in the rear brake line. This kept the rear brakes ready to engage quickly. But aftermarket MC's don't have this feature. Is that true? If so, is it worth adding a 10psi residual pressure check valve to the rear line? Drilled Drums: I have read some people had DIY driller small 1/8" holes in a pattern in the drums, to allow them to dry out quicker if they went into water/mud deep enough to flood into the drums. Is this a good idea? However, I don't do a lot of that kind of off-roading. But I do drive a lot on wet roads with water splashing all around. In this case I'd be worried that drilled drums would actually let splashing water get in. Agree? Thanks!

Oh, and, I'm considering switching to Silicon dot5 Synthetic fluid, mostly because it doesn't absorb water. (The Jeep spends most of it's time in Seattle area - wet climate). Is this a good idea? (I'd vac pump all the dot3 out and possibly flush with denatured alcohol before adding the dot5.)

Hi, I'm, new here but excited to have found this website! I have owned the "Jeep Owner's Bible" for a long time now and have gotten a lot out of it! I have restored and upgraded a 1983 CJ8 Scrambler in almost all ways, but not the brakes. I use it to tow a #2000 boat, for outdoor expeditions and some off-roading. 32" Duratrac tires on R16" steel wheels. Backseat and Full hardtop. Rebuilt 4.2L with Mopar MPI and 4.0L head conversion. Flanged Axle d20 rear. AX15 trans. Twin stick d300. 2.5" spring lift / 1" body lift. Recently I was driving at night near Moab, with 4 people in the Jeep (no boat). I come around a corner and there was a cow in the road... I nailed the brakes and they did not lock up! We came to a stop about 4' away from hitting the cow, but it didn't feel like we had adequate brakes! With larger than stock tires, and the extra weight of boat, gear and potentially 4 passengers, I want better brakes! Currently the seal on the top of the MC is bad, and I'm losing paint on the inside of the fender. I tested the OEM Booster and it's definitely assisting the pedal, but I don't know how old or good it still is. Here's my plan/questions: (1) It makes sense to start with the friction surfaces (and this is what most people seem to recommend). Get more stopping power without jacking up the pressure, right!? But since my MC needs to be replaced, I figure it's a good time to consider a new booster. (2) For the front I am considering "Stoptech" Kevlar/Aramid composite pads and slotted Cryo-treated rotors. The tech guy at buybrakes.com says I can expect around 20% more stopping power in the front with this setup. (3) For the rear I'm considering swapping the 10" oem drums up to 11" CJ drums. I believe this will create around 10% more stopping power in the rear. I'd also consider composite liners but not sure if anyone makes them. (4) Replacing the rubber brakes hoses with braided SS. Questions: (1) Were the stock oem tires 28" or 29"? (2) Do the 11" drums have larger capacity wheel cylinders than the 10", and if so does this require and change to the Proportioning valve or MC? (3a) If I get 20% more stopping power in the front and 10% more in the rear, does this throw off the ratio for the safest possible braking? (3b) Will the stock Proportioning Valve be OK now that the front and rear no longer have the same ratio of stopping power relative to each other? (4) Is there anyone who sells linings for the rear drum brakes that are high performance composite to match the front? (5) If I upgrade the friction surfaces according to this plan, will the addition of the Dual-diaphragm booster be overkill? Would it make the brakes too touchy? (I also drive on snow and ice). (6) Will doubling the pressure (Dual-diaphragm) be too much for any part of the oem system?