ADD System Clarification -95 4runner
01-30-2014, 11:43 AM
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ADD System Clarification -95 4runner
Hi All,
So I have a 95 4runner 3.slow and I need some help clearing up the A.D.D. system. I have looked around and can't seem to find the info I need.
Right now 4wheel is shot. No sure why. I can hear my solenoids clicking, hoses look fairly new, 4wd light flickers and then no engagement.
When I look @ the ADD system I can see that there is only one hose going under the wheel fender into the vacuum tank. However when looking at the fitting there are two ports- currently one is open. Is this suppose to be like this?
If so that's fine I'll continue reading and poking around- I know there is a lot of info on this already.
You can barely seen the open port below: (click on it to see better)
So I have a 95 4runner 3.slow and I need some help clearing up the A.D.D. system. I have looked around and can't seem to find the info I need.
Right now 4wheel is shot. No sure why. I can hear my solenoids clicking, hoses look fairly new, 4wd light flickers and then no engagement.
When I look @ the ADD system I can see that there is only one hose going under the wheel fender into the vacuum tank. However when looking at the fitting there are two ports- currently one is open. Is this suppose to be like this?
If so that's fine I'll continue reading and poking around- I know there is a lot of info on this already.
You can barely seen the open port below: (click on it to see better)
Last edited by 40alpha; 01-30-2014 at 11:45 AM.
02-04-2014, 06:17 AM
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02-04-2014, 11:55 AM
#3
like posted already, your quickest reference will be to find a diagram of the vacuum lines for your ADD system.
personally, i would disable that ADD system and add manual hubs to the front - you'll have less wear and tear on front 4wd system and might even pick up 1-2mpg afterward.
personally, i would disable that ADD system and add manual hubs to the front - you'll have less wear and tear on front 4wd system and might even pick up 1-2mpg afterward.
02-04-2014, 01:12 PM
#4
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you can test your ADD by bypassing all the solenoids and hooking the ADD engagement side directly to a vacuum port on the motor. I did this temporarily when I got manual hubs before I swapped in a manual hub full axle
02-06-2014, 05:07 AM
#6
like posted already, your quickest reference will be to find a diagram of the vacuum lines for your ADD system.
personally, i would disable that ADD system and add manual hubs to the front - you'll have less wear and tear on front 4wd system and might even pick up 1-2mpg afterward.
personally, i would disable that ADD system and add manual hubs to the front - you'll have less wear and tear on front 4wd system and might even pick up 1-2mpg afterward.
But that's just me...
02-06-2014, 08:45 AM
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I think it's urban legend that manual hubs are more reliable than ADD. My guess is that, in terms of MTBF (mean time between failures), the ADD system is considerably more reliable than a manual hub. It's mechanically simpler and stronger, runs in a sealed, well lubricated environment, and uses only relays and vacuum solenoids, which are highly reliable devices, for actuation. It's as reliable as your starter relay or your fuel injectors, and gets a whole lot less use. Mine has never hiccupped in 200,000 miles.
Manual hubs, on the other hand, look like a swiss watch inside, get contaminated with water and dust, get stiff in the cold and refuse to slide in and out of engagement, and will almost definitely need servicing before the 200K mile mark, probably more like every 50K miles.
As far as wear, the CV joints don't wear out from spinning with no load. They break from abuse, and wear out due to lubrication failure because the boots break. The boots break because the rubber ages, and that will happen pretty much whether they're turning or not. My boots finally cracked after spinning 190,000 miles over 19 years. Hardly a high failure rate item.
The best way to measure the difference in drag is to do some coast-down tests with a stop-watch with CV joints spinning vs. not. I think you'll find the differences are very subtle, if you can reliably spot them at all.
Finally, if the ADD relay/vacuum actuators do get stuck for some reason and refuse to switch to 4wd, all you have to do to engage the ADD is to open the hood, swap the two vacuum hoses on the vacuum actuators, and you'll be in business. That's a lot easier than taking apart a manual hub on the trail to get it to lock in.
Manual hubs, on the other hand, look like a swiss watch inside, get contaminated with water and dust, get stiff in the cold and refuse to slide in and out of engagement, and will almost definitely need servicing before the 200K mile mark, probably more like every 50K miles.
As far as wear, the CV joints don't wear out from spinning with no load. They break from abuse, and wear out due to lubrication failure because the boots break. The boots break because the rubber ages, and that will happen pretty much whether they're turning or not. My boots finally cracked after spinning 190,000 miles over 19 years. Hardly a high failure rate item.
The best way to measure the difference in drag is to do some coast-down tests with a stop-watch with CV joints spinning vs. not. I think you'll find the differences are very subtle, if you can reliably spot them at all.
Finally, if the ADD relay/vacuum actuators do get stuck for some reason and refuse to switch to 4wd, all you have to do to engage the ADD is to open the hood, swap the two vacuum hoses on the vacuum actuators, and you'll be in business. That's a lot easier than taking apart a manual hub on the trail to get it to lock in.
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02-06-2014, 10:32 AM
#8
It can be argued both ways and I'm not trying to get into that, but this is how myself and many 4x4 enthusiasts see it: Reliability is debatable since both systems can be reliable when maintained. Strength, amount of friction and wear on parts are hard to argue don't differ when comparing the two systems. We likely wouldn't even have seen the ADD system until a later date if it weren't for the trend of "convenience" and making it more appealing to a broader consumer group.
The multi-part axle design of the ADD system is inherently weaker than the one-piece axle on a non-ADD differential simply because it's not one-piece and the splicing of what was a solid unit results in several areas of potential failure. Also, if your passenger side CV axle and internal components have been spinning for XXX,XXX number of miles because they've been locked into an ADD system that whole time, the parts all have more wear on them (vs a non-ADD) and consequently would be more likely to fail under certain circumstances. It is definitely arguable that addition of items like needle bearings on the ADD diff is a stronger design than the bushings on the non-ADD.
Both systems require maintenance to assure operation when needed. Many people find their ADD system inoperable due to lack of maintenance on their vacuum system. Since there are so many parts moving on the ADD system, more wear gets put on the parts and would require more maintenance.
Manual hubs do need maintenance, but so do items like wheel bearings (who's recommended service interval is every 30k)...it just happens that you have to take off your hubs to get to bearings, and you would likely service them or at least re-lube before re-installing and while you have the grease out and have everything open.
As for economical gains...when you have a wheel locked into a differential, spinning other moving parts like CVs and internal differential components, you will inevitably create friction and drag - Take that away and you're likely to gain fuel economy. I have seen dozens of ADD toyotas slinging CV grease all over their passenger wheel well because that CV is locked in. Lack of grease = more friction and wear on the CV joint, thus you're more likely to have to put $ into parts and labor.
There's no arguing that it's more convenient to get out of your rig in the nasty weather to lock your hubs vs simply putting it in 4wd from your cab. As for having to get out in the middle of a trail to fix a hub - I dunno who doesn't lock their hubs at the trailhead and leave them locked until they're ready to head home.
I will add this though: if you are out on the trail and you were to break something like your front carrier, gears, CV, etc and cannot repair on the spot - it is definitely more convenient to be able to unlock the hubs and keep driving in 2wd.
The multi-part axle design of the ADD system is inherently weaker than the one-piece axle on a non-ADD differential simply because it's not one-piece and the splicing of what was a solid unit results in several areas of potential failure. Also, if your passenger side CV axle and internal components have been spinning for XXX,XXX number of miles because they've been locked into an ADD system that whole time, the parts all have more wear on them (vs a non-ADD) and consequently would be more likely to fail under certain circumstances. It is definitely arguable that addition of items like needle bearings on the ADD diff is a stronger design than the bushings on the non-ADD.
Both systems require maintenance to assure operation when needed. Many people find their ADD system inoperable due to lack of maintenance on their vacuum system. Since there are so many parts moving on the ADD system, more wear gets put on the parts and would require more maintenance.
Manual hubs do need maintenance, but so do items like wheel bearings (who's recommended service interval is every 30k)...it just happens that you have to take off your hubs to get to bearings, and you would likely service them or at least re-lube before re-installing and while you have the grease out and have everything open.
As for economical gains...when you have a wheel locked into a differential, spinning other moving parts like CVs and internal differential components, you will inevitably create friction and drag - Take that away and you're likely to gain fuel economy. I have seen dozens of ADD toyotas slinging CV grease all over their passenger wheel well because that CV is locked in. Lack of grease = more friction and wear on the CV joint, thus you're more likely to have to put $ into parts and labor.
There's no arguing that it's more convenient to get out of your rig in the nasty weather to lock your hubs vs simply putting it in 4wd from your cab. As for having to get out in the middle of a trail to fix a hub - I dunno who doesn't lock their hubs at the trailhead and leave them locked until they're ready to head home.
I will add this though: if you are out on the trail and you were to break something like your front carrier, gears, CV, etc and cannot repair on the spot - it is definitely more convenient to be able to unlock the hubs and keep driving in 2wd.
02-06-2014, 11:27 AM
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You make a lot of reasonable points, but I simply wanted to point out the fallacy of thinking that by defeating the ADD and going to manual hubs (assuming an open diff), one is going to significantly increase reliability and fuel economy. Just isn't going to happen. The economy gains are very slight, and the reliability is truly an open question. You've made your vehicle "different", and that's your choice, but not necessarily "better" in any kind of objective sense.
I like having the ADD active even though I have manual hubs now. I added those because, with the Aussie, the passenger side CV now turns the entire ring and pinion and front drive shaft even when in 2wd, and that is more stuff than I like to see turning on the highway. But, with the ADD, once I shift to 2wd with the hubs locked, the two front wheels are truly disconnected from each other, and I'm not at the mercy of the ratcheting of the Aussie locker when driving in 2wd on pavement or on patchy snow and ice. In fact, under patchy snow and ice conditions, where 2wd is generally adequate, I unlock the right hub and leave the left hub locked. That way, in 2wd the front drive train doesn't turn at all, but if I need a bit of extra help to pull out of a snowy driveway or something, I can engage 4wd, the ADD locks to the differential, and the driver's side wheel will give me the extra boost I need to get going. I then go back to 2wd, the ADD disengages, and everything up front stops except the driver's side CV, and for all practical purposes I'm in summertime 2wd.
I also added a switch to disengage the ADD when in 4wd. In some cases that can help on tight corners on the trail when in 4-lo, although the Aussie corners very well even in full 4wd. I haven't used the switch as much as I thought I would, and if I was doing it again I probably wouldn't bother.
I guess I just can't see purposely defeating something that works so well and is so handy. I suspect it's more a "real offroaders use manual hubs" thing than anything else. I'm 64 years old and I got over that a long time ago:-)
I like having the ADD active even though I have manual hubs now. I added those because, with the Aussie, the passenger side CV now turns the entire ring and pinion and front drive shaft even when in 2wd, and that is more stuff than I like to see turning on the highway. But, with the ADD, once I shift to 2wd with the hubs locked, the two front wheels are truly disconnected from each other, and I'm not at the mercy of the ratcheting of the Aussie locker when driving in 2wd on pavement or on patchy snow and ice. In fact, under patchy snow and ice conditions, where 2wd is generally adequate, I unlock the right hub and leave the left hub locked. That way, in 2wd the front drive train doesn't turn at all, but if I need a bit of extra help to pull out of a snowy driveway or something, I can engage 4wd, the ADD locks to the differential, and the driver's side wheel will give me the extra boost I need to get going. I then go back to 2wd, the ADD disengages, and everything up front stops except the driver's side CV, and for all practical purposes I'm in summertime 2wd.
I also added a switch to disengage the ADD when in 4wd. In some cases that can help on tight corners on the trail when in 4-lo, although the Aussie corners very well even in full 4wd. I haven't used the switch as much as I thought I would, and if I was doing it again I probably wouldn't bother.
I guess I just can't see purposely defeating something that works so well and is so handy. I suspect it's more a "real offroaders use manual hubs" thing than anything else. I'm 64 years old and I got over that a long time ago:-)
02-07-2014, 05:45 AM
#10
RJR, no reason to feel that anyone is picking on you or trying to make you feel that the ADD system is bad. I agree with Mr.High's points he made in his last post that the ADD axle is weaker than the non ADD; the ADD system was probably designed out of convenience more than it being a better system; both systems do require maintenance and this also includes our wheel bearings; the CV's being locked in do create drag as opposed to non ADD systems; the ADD diff is better because it has needle bearings as opposed to the bushings in the non ADD diff; if something broke on the front drive system, with a non ADD system you can unlock the front hubs and drive it home.
Both systems have their good points, no doubt. If you are comfortable with ADD and lockouts, then stick with it. This is just another option to consider. The 4.56 third I bought here is a ADD third which means it has the needle bearings and I am putting a first gen axle tube/axle on it. I had the lockouts on currently before I started so I had the same setup as you. I just wanted to get rid of the vacuum lines and get a stronger axle in front.
I do prefer lockouts over the ADD system because both my previous vehicles had lockouts on them, the 88 4runner and my 96 F350. I do think that they are better than a vacuum system but that is my opinion and we all know about opinions and ______....everybody got one. I don't mind getting out and unlocking/locking them in inclement weather when need be. Personally, I'd rather have a well maintained mechanical system than an electrical system with vacuum lines. But that is my preference and about Aisin hubs, everyone on here who uses them will tell you how durable they are when maintained.
And this is not because I feel that "real offroaders" use manual hubs. I like them and that's why I use them. And about "one is going to significantly increase reliability and fuel economy", I never said that or implied that. All I know is that when I go up Lower East Hill Road in dry conditions, I can use third gear; with the hubs locked in, only second gear. Like I stated before, those little four bangers need all the help they can get. And if I get some more fuel mileage whether negligible or not, I'll take it.
About CV axles, I know that the boots wear out before the axle joints themselves but I'd still prefer them not to spin when not needed. Again, personal preference. But also for more power for hills and potential better MPG.
RJR, you sound like a pretty cool dude. You'd have to be because you drive a Yota and four wheel. You made some good points in your last post and sound like you have some good experience. You go with what works for you and with what's there -- nothing wrong with that.
Both systems have their good points, no doubt. If you are comfortable with ADD and lockouts, then stick with it. This is just another option to consider. The 4.56 third I bought here is a ADD third which means it has the needle bearings and I am putting a first gen axle tube/axle on it. I had the lockouts on currently before I started so I had the same setup as you. I just wanted to get rid of the vacuum lines and get a stronger axle in front.
I do prefer lockouts over the ADD system because both my previous vehicles had lockouts on them, the 88 4runner and my 96 F350. I do think that they are better than a vacuum system but that is my opinion and we all know about opinions and ______....everybody got one. I don't mind getting out and unlocking/locking them in inclement weather when need be. Personally, I'd rather have a well maintained mechanical system than an electrical system with vacuum lines. But that is my preference and about Aisin hubs, everyone on here who uses them will tell you how durable they are when maintained.
And this is not because I feel that "real offroaders" use manual hubs. I like them and that's why I use them. And about "one is going to significantly increase reliability and fuel economy", I never said that or implied that. All I know is that when I go up Lower East Hill Road in dry conditions, I can use third gear; with the hubs locked in, only second gear. Like I stated before, those little four bangers need all the help they can get. And if I get some more fuel mileage whether negligible or not, I'll take it.
About CV axles, I know that the boots wear out before the axle joints themselves but I'd still prefer them not to spin when not needed. Again, personal preference. But also for more power for hills and potential better MPG.
RJR, you sound like a pretty cool dude. You'd have to be because you drive a Yota and four wheel. You made some good points in your last post and sound like you have some good experience. You go with what works for you and with what's there -- nothing wrong with that.
02-07-2014, 01:29 PM
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Thanks for your kind words, Daved5150. No worries about my feelings. Yotatech is a board full of enough opinions to make it entertaining and enough good facts thrown in to make it pretty useful. Just a matter of sorting out which is which:-). I enjoy this board, and I've learned a lot here.
02-10-2014, 04:27 PM
#12
You're welcome, sir.
"Yotatech is a board full of enough opinions to make it entertaining and enough good facts thrown in to make it pretty useful. Just a matter of sorting out which is which:-)."
Your words ring true, no doubt. I've learned a lot here myself...I am thankful for the guys who take the time to post FSM links, part numbers, helpful tips, how-to threads with pictures, etc. But mixed in with all this information is a lot experience as well as opinions and attitudes. But I like it here.
"Yotatech is a board full of enough opinions to make it entertaining and enough good facts thrown in to make it pretty useful. Just a matter of sorting out which is which:-)."
Your words ring true, no doubt. I've learned a lot here myself...I am thankful for the guys who take the time to post FSM links, part numbers, helpful tips, how-to threads with pictures, etc. But mixed in with all this information is a lot experience as well as opinions and attitudes. But I like it here.
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