SAS/SAC debate thread

[flyingwil]

Well I am starting to encounter some IFS issues with my Tacoma. So I am going to dig up some good old debate material, is it better to keep things stock, or swap it on over to a solid Axle.

BajaTaco has some great info and points on his website (thanks Chris):

To be quite honest, I had no idea when I bought my Tacoma, that it would ever reach the level of performance that it has. Granted, I researched the available trucks at length before making my purchase, but since owning this vehicle for so many years I have been pleasantly surprised that it has met my expectations and surpassed them. My original intentions were to get the most reliable and capable light truck that I could, in the hopes that I could reasonably develop it as a "road trip" machine that would aid in my pursuit of an outdoors and travel related lifestyle. I found out that the more I used this truck and gained experience from it, the more I found myself carefully developing it, and the more I enjoyed it. This has turned out to be the "perfect" expedition vehicle for me, because it suits all of my needs for what I want to accomplish.

I like to think of my camper and modifications as "backpacking equipment" for my truck. I have tried to design everything with the "go light" philosophy in mind. Every ounce counts. Yes, there are ways I could have made some components even lighter, but unfortunately, cost has to be considered when evaluating these things. I like the fact that I can get on the highway in this truck, and cruise comfortably at high speeds with amenities such as cruise control, air conditioning, premium audio and refrigerated refreshments (haha!). Then, I can pull off of the highway, air down the tires, and venture into inhospitable terrain (trails rated at 3.5 + on 1-5 rating scale) to get into some remote areas, or just to have fun challenging myself and the vehicle. When the day turns to night, I can find a place to park, crawl into the camper, and sleep in a comfortable bed. If I really like the place, I can set up a base camp and stay awhile. When the trip nears an end, I can air up the tires, get back on the freeway, and this truck will still drive straight as an arrow with no vibrations. I have been using this truck like this for years and years, and it always makes me smile.

To summarize my truck, I would say that it is a light expedition vehicle, for the minimalist traveler, who wants the capability to traverse difficult terrain, yet maintain long distance efficiency, with the option of traveling self-contained for up to two weeks at a time.


A very popular modification to the Tacoma these days is what has become known as an "SAS", which is an acronym for "solid axle swap". Basically, it is removing the IFS (independent front suspension) and replacing it with a straight-axle. Here is my take on the SAS with regards to an expedition vehicle on a Tacoma platform:

1. If you can justify the cost of the swap for what you will be doing with the axle, then that is a big part of the decision. What I mean is that, in my opinion - you will not really see 100% of the potential of the SAS if you put it on an expedition vehicle. The reason is that an SAS has some incredible trail capability, but only if it is matched with a lighter truck, 35" or 38" tires, super flexy suspension, and low gearing. 3 out of those 4, you wouldn't ideally see on an expedition rig. Although the suspension issue might be worked out with additional project time and expense.

2. If you do decide to SAS after considering the above, you would probably want to keep the amount of lift considerably lower than the average swap that is seen done so often. The first reason being the center-of-gravity. You are already at a disadvantage with COG because of the weight (and possibly height) of your expedition rig/gear. If you put full width axles in front and rear, this would help, but can lead to more decisions when considering Tacoma platform. The second issue being your rolling resistance or profile where fuel economy and power-robbing wind, and are concerned. This also gets into the issue of tire size. 35" or 38" tires are generally not considered efficient or economical for long distance touring on a light truck like the Tacoma.

3. By increasing the trail capability of the rig with the SAS and the things that come with it (larger tires, more lift, more articulation) you are inviting yourself to tackle much more technical obstacles and therefore you get into issues of strength where the frame and cross-members, shackle hangers, etc. are concerned. If you have a heavy expedition rig, these considerations are amplified.

I have definitely entertained the thought of doing an SAS for a few reasons, but so far I have decided not to do it for the reasons I mentioned above. I don't claim to know it all though, and I certainly might change my mind - only time will tell. For now, I am more than happy with the Tacoma IFS. I think it is a very strong, reliable, and comfortable setup - for being an IFS. As long as I am doing long-range trips and have 33" or smaller tires, I'm pretty happy with it.

I am confident that these points are valid. However, on an international trip, I am not certain if the Tacoma IFS and HiLux IFS parts are interchangeable?

Well I am open to thoughts and comments... but let's keep costs out of the picture for the time being.

 

[Jacket]

What sorts of issues are you seeing? CV failure? Ball joint wear? Diff failure? Although you said to keep costs out, that's tough to do when the cost is major $$$$$$$ to do it right. Is that cost comparable to the cost it would take to overall your IFS and get it back to nearly new?

I agree with Chris' points on bigger tires and tougher terrain. Running 35's with the Tacoma IFS is a stretch; bigger would be pretty much out of the question. I've thought about bigger tires just to improve my ground clearance and shorten my wheelbase, but the risks and wear on the IFS makes it tough to justify. But I enjoy tough trails, and while I've had good success on them, I can't pick the same lines as trucks with 100-110" wheel base and 35 or 37" tires.

Tough decisions: expo truck or trail beast? SAS, or jump over to existing SA platform?

:lurk:

 

[DaveInDenver]

I am confident that these points are valid. However, on an international trip, I am not certain if the Tacoma IFS and HiLux IFS parts are interchangeable?

This is a tough question for the Tacoma. In the case of 1986-95 trucks, there is very little custom stuff necessary. The frames are not the same live axle vs IFS, but the actual parts are 99% the same and you can use stock hangers, springs and shackles if you want. Repairs require a Toyota dealer or supply shop and a welder, nothing exotic really. The propeller shaft parts are the same, even if the length is not exactly. The axles parts are 100% identical to the 1997 and older live beam Hilux. Really the only question mark is the weld quality and the type of hanger bracket you go with (be it a custom job like All-Pro or semi-stock just using factory parts).

The Tacoma can't take a stock Toyota right-side drop front 8" axle without some significant mods. You can cut and rotate the knuckles, which means a field repair on a broken housing to keep the steering angles right needs to be carefully done. You could swap t-case drop sides, again that means a pretty unique custom mod that will bind you to North America for repair parts. So the question is really which left-side diff axle is most common worldwide. I would say a Jeep Cherokee or Wrangler is common enough to qualify maybe. But that means you need to find potentially both a Toyota and a Jeep supplier.

Then the suspension, what do you do? Coils makes most sense, but the Hilux never got coil sprung live axles. So do you retrofit leafs on the Tacoma? I say no because that means a very custom SAS and unlike the '95 and older SAS you can't necessarily use Toyota hangers.

So in that sense being that the Hilux IFS is now identical to the Tacoma IFS, spare parts and repair experience for the IFS might actually be easier to find than a super custom SAS. IOW, finding a CV axle for a Tacoma IFS that shares lineage with the Hilux and Surf could be easier to find than a u-joint for a relatively NA-centric 2001 Grand Cherokee axle. I dunno, just thinking out loud there.

If it was me I would stick with the way the factory did it or as close as possible to retain supplier options. The benefits of increased articulation have to weighed against how much extra junk you have to pack to fix your truck. The Hilux Surf has been IFS since 1986, so any country that got the Surf would have Tacoma IFS parts from the era.

FWIW, the 1986-1995 IFS we got here is 100% identical to the 1986-2002 (or is 2003?) IFS overseas in Hilux (the torsion bar IFS). My understanding is that the current Hilux now shares the same coil sprung IFS as the 2nd gen Tacoma, but I do not know if the axles are the same length and the coil are the same, etc. But if I took my 1991 to Australia or Europe, I would get the exact same torsion bar spring, tie rod end or ball joint from a dealer there as I would here. In fact the version of the EPC (electronic parts catalog) that I have is actually Japanese, but the part numbers I ask my dealer for are the same or superseed to new numbers properly (my EPC version is from 1998, so lots of numbers are superseeded). So stock IFS or stock-style leaf SAS, my truck being a Hilux is very close to being universal.

 

[Applejack]

I am imagining traveling in remote parts of Africa...hungry lions...hyenas.....angry cape buffalo. Which would I feel more secure in? Mmm.....a solid axle rig. I really wouldn't want to be changing an axle or CV boot in those particular locations. That being said I don't think I'd swap, I'd just move up to something that's factory, like an LC.

 

[xechcorx]

The part failure issues need to be converted into a planned failure. You will always have a weak link in the driveline. For example beefing up the front axle your going to push the driveline's weak link somewhere else. If you went to a custom Dana 60 that is somewhat "common" in SAS Taco's the rest of the driveline can become questionable when compared with such a formidable axle. You just have to consider what the weak link is going to be once all is said and done.
If you went with a custom toyota housing you could use the short side axle on the passenger side and long on the right. Essentially just making a standard axle with opposite side drop. In this scenario you can run Longfields normally and use factory spares if you ever popped one. Keeping you afloat on the commonly available parts, worldwide.
Suspension-wise I'd have to recommend a link suspension. Being able to dial your alignment/ spring rate/ dampening is the way to go IMO. You bend a shock you'll still be SOL on finding a coil-over shock laying around in a third world country.

This is all hypothetical if you went SAS.

 

[DaveInDenver]

I am imagining traveling in remote parts of Africa...hungry lions...hyenas.....angry cape buffalo. Which would I feel more secure in? Mmm.....a solid axle rig.

Mentioned it before and will again, Rubicon ate a leaf spring on my truck, IFS unharmed. I dunno, luck probably, certainly not driver skill... I think maintaining your junk, knowing how it works, knowing its limits are more important than any punch list of hip mods. I don't expect my IFS to articulate like an SAS and so I don't push to do that and have bump stops to keep it within its limits. That has probably has helped keep me from destroying as much stuff. I mean trying to do the Hammers with IFS using cranked torsion, slivers for bump stops and lots of front locker and then being surprised that you blew a CV is just naive.

I really wouldn't want to be changing an axle or CV boot in those particular locations. That being said I don't think I'd swap, I'd just move up to something that's factory, like an LC.

True dat.

 

[Rexsname]

I have decided that the Toyota engineers know much more about how the truck is supposed to work than I do. I like how my truck rides, I like not having to get out and lock the hubs, and I like that it has lasted more than 200,000 with minimal expence on maintainance.


I would much rather use my truck than "wheel jackstand alley".



REX

 

[Hilux_Max]

Pretty certain the current tacoma and hilux have the exact same front end suspension and drivetrain.

the hilux chassis is alot stronger than the Tacoma , because we use them more here for load carrying and towing.

I too would love an SAS conversion on the hilux, but I could not justify the expense of it.

also, I well equipped IFS Hilux/Taco would be more than enough to tackle most trails within reason on the mountains.

suspension, gears, lockers, bigger tyres, go a long way.

 

[ntsqd]

I try to follow a simple rule when creating custom stuff: No custom wear parts. Anything more or less consumable (rotors, calipers, Tie Rod Ends (TRE's) things like that) have to be bolt-on parts. Preferably parts from the same brand of vehicle. If it is a metric vehicle, don't use SAE hardware on it. Same if an SAE vehicle, don't use metric hardware on it. That's a whole duplication of sockets and wrenches that you don't have to carry.

Extending the concept to accommodate going overseas I would add the sub-heading that custom parts must be steel weldments only. No custom machined parts. I'll venture that it would be much easier to find someone with the skills and equipment to weld a broken part back together than it would be to find someone with the skills and equipment to machine a whole new part. I'm not saying that the machining won't happen outside of the U.S., that would be unsupportable. Just that anywhere, even in remote U.S. areas, a weldor is easier to find than a machinist.

Were I going to consider swapping a Live Axle (LA) I would be looking to do so with as many stock parts as possible. So out goes the trick 4 link "Heim" jointed linkage and in comes the FJ80 radius arms. Out goes the 'Heim" joint trac-bar and in comes a Marlink using FJ80 TRE's as a trac-bar. Out goes the trick King/Fox/SAW/Bilstein coil over and in comes the stock Tacoma "coil-over". Any of these parts can be expected to be found as replacement wear parts, or can be repaired by a weldor.

All of that said, I see no reason not to simply repair worn parts in an existing system whose flaws are known. Doing an SAS means that to do it correctly that you will need to have several to many "Sea Trials" trips to hopefully find all of the flaws and fix them. I can not conceive of shipping a vehicle to another continent that I do not feel that I KNOW that it will perform for the duration of the trip. Whether that is what actually happens is another matter. Stuff happens, but to go not having the utmost confidence in the vehicle or having elevated expectations of what the vehicle is truly capable of doing would be foolish, at least it would be to me.

 

[flyingwil]

I have decided that the Toyota engineers know much more about how the truck is supposed to work than I do.

That also was my line of thought for a while. Once load increased, and suspension changed (coil overs and new rear springs/ shocks), I honestly can say that we all have changed this well thought out suspension in favor of an aftermarket part or parts to get the vehicle more how we'd like it to be.

So, with solid axle swaps being fairly common, (I see at least one SAC'ed Taco a day), there is plenty to be learned from other's and other's mistakes. However the majority of these rigs are used for rock crawling and much more hard core offroading than one typically would encounter during an expedition, especially if in a foreign country.

While there is many pro's and con's to each side of each modification done to every one of our trucks, from stock to not so stock. The conversion is something that seems to get brought up more and more, and thought it would be good discussion here.

While at SEMA this fall there was an current gen Taco with a an 80 series front end. While not on 40"s this rig made me drool every time I walked by it. As mentioned above, this does move the weak point else where that would need to be found.

Keep the discussion going! So far it has been great feed back and great to hear your thoughts.

 

[BLKNBLU]

Just to emphasize a couple of points made.

Jacket's point about cost.
Yes we want to leave it out of the equation, but realistically, how many times could the entire IFS front end be rebuilt for the cost of the axle alone? Just as a wild guess, I'm going to say 2 or 3.

Dave's point about the large amount of custom stuff required to SA this gen of rig. It makes sourcing parts more complicated out in the boonies. And true, how common is Dana stuff away from North America?

ntsqd makes great points about KISS. One parts manufacturer, one tool system.

The 2 guys I wheel with that have this gen rig with SAs both have lots of non-toy parts and it can make things complicated even by something as simple as a bolt not fitting through a hole on a replacement part because it was clearanced on the original part. I don't know enough about them to speak in any depth, but Kent's Taco is HUGE with spring over dana in the front and Chevy springs in the rear. Of course it was not designed for expeditioning from the get go so I'm not sure how or if that could have been addressed from the start. Steve's 4Runner is a spring under D44 that sits much lower but still has it's fair share of customized engineering to it.

Just to throw one more wrinkle into it, what about the stuff Steve Schaefer is doing with Tundra parts up front? Are those available worldwide? The nice part there is it stays all Toyota/metric and can run 35's if desired though trimming is necessary. It also stays reasonably low. With his system though, you can use LC coils on the rear on 4runners but the Tacos need custom leafs which could present a problem in the middle of nowhere.

 

[DaveInDenver]

So, with solid axle swaps being fairly common, (I see at least one SAC'ed Taco a day), there is plenty to be learned from other's and other's mistakes. However the majority of these rigs are used for rock crawling and much more hard core offroading than one typically would encounter during an expedition, especially if in a foreign country.

This true, doing an SAS on a Taco is not unknown territory at all.

The point is that they are to some extent all custom. Doing an SAS on my generation of truck can use all Toyota parts with minimal custom work and as long as care is take in placing the hangers the swap is basically factory. But you don't necessarily gain a ton of articulation or lift, sticking with stock means sticking to limitations no matter what.

But I would suggest as an example, try and find Toyota parts in Moab, UT. Not exactly the most unknown spot for Yotas, but NAPA is it and there is a good chance if you didn't bring it, you're waiting a few days from it to come from GJ or on the next truck. Now take that custom 4-point, hybrid Dana/Toyota and get a heim joint for it. And this is in an acknowledged 4WD capitol of the SW.

I also don't think it's a small coincidence that a lot of the people who are running more exotic SAS also have on-board welders and tools for booty field fabrication. Sometimes boring and common is good, at least when you're trying to find that spare this or that...

 

[cruiseroutfit]

...While at SEMA this fall there was an current gen Taco with a an 80 series front end. While not on 40"s this rig made me drool every time I walked by it. As mentioned above, this does move the weak point else where that would need to be found...

FWIW that was not an 80 axle, more likely a narrower 70 Series axle of some variant. Not that its a huge difference but consider parts availability even here in the US for items such as inner shafts, etc. Sure you can go with chromo options from one of several vendors, but it could easily add $1k to the cost by the time you get an HD set and a spare set of shafts for remote travels. Judging on that build, sourcing the parts and the conversion to do a "low height" build like that on a Tacoma could easily hit the $5k mark, likely much more by the time its dialed in.

I always told myself I would do a SAS on my old Tacoma when it was paid off, every other 4x4 I have owned was solid-axled. But by the time that happened it just no longer made sense to me. I had my Land Cruisers for the trails that I feel warrant a solid axle and beefy drive train, and the Tacoma for the things that warrant some serious speed and handling. That's not to say a suspension and axle can't be built to be good at both, its just very difficult and often times the tradeoffs leave you wishing for the money spent back. Fast forward 5 years and I'm onto my second Tacoma and have absolutely zero intentions to do a SAS, despite the fact I'm more set up fab and parts wise to do it than ever... just doesn't appeal to the inented use and terrain that truck will ever see and the reliability of the IFS system is fairly robust IMO. I think many of us (myself absolutely included) take the IFS's reliability for granted. I don't know how many miles your truck has but I put nearly 175k on my 96 x-cab with nothing more than CV boot replacement and a new steering rack on the front end (aside from modification such as suspension), I'm at ~85k on my 04' DC and have done a rack but nothing else to the IFS. I do carry a spare half-shaft, but knock on wood have not needed it. A Toyota based solid axle will likely need a similar or greater amount of maintainance, knuckle overhauls, TRE replacements, etc.

That said if I were to ever entertain the idea, I think the Toyota style front radius arms setup would be my approach. Its clean, its solid, and many of the parts would be somewhat common here in the states or could be ordered with a bit of advance notice.

...try and find Toyota parts in Moab, UT. Not exactly the most unknown spot for Yotas, but NAPA is it and there is a good chance if you didn't bring it, you're waiting a few days from it to come from GJ or on the next truck...

You just need to know who to call I ship stuff same-day (courier) or overnight to Moab on a somewhat regular basis

 

[Nullifier]

Personally I do not think that doing a sas on an expo rig is anything out of the ordinary or that big of a problem. Look at all the Quigley and Sports Mobile rigs that folks here drool over as an expo platform. You can't tell me that sourcing parts for those rigs is any easier then a sas tacoma, yet no one brings that up when talking about them on this forum it's just pure :drool:

I think what is important and relavent is knowing the short comings of the system and preparing for those things appropriatley in your tool and spares kit. There is really no problem that could arise from a dana axle vs a toyota axle that could be any worse then the other if you are not properly prepared.

Personally I say go for it. I would plan on 2 things in the build. First is that I would design a weakspot into the mod by limiting the size of the ujoints to say 1310. Those should fail before anything critical like a gear or axle shaft, and in comparison is an easy trail fix. Next is that I would avoid the whole 37+" tire thing common with sas tacomas. I would make it more like the toyota rig you mentioned at sema. try to run the same size tires or maybe one size up from where you are now to maintain durability and limit you ability to push the rig. As for leaf or coil spring it is preferance. Leaf is simpler and caries a load better but coil offers a beter ride with more potential breakpoints. I think it will be easier to keep the rig lower with coils so for that factor I would go the later.

:coffeedrink:

 

[Martinjmpr]

Well, I've got nowhere near the level of knowledge or skill that the other posters here have regarding fabrication, welding, modifying, etc, I'm just curious about what specific issues or problems you're having with the IFS.

I've said here before that I think a lot of people "fetishize" about SAS, primarily people who 'came of age' during the IFS era. There is, IMO, a tendency to over-romanticize the solid-axle trucks as being "real" 4x4s, much stronger and more capable than the vehicles available today.

Well, as someone who was around during the Solid-axle era (my first 4 4x4s were all solid axle and leaf sprung) I have to say that for the vast majority of users worldwide, IFS is superior. It is particularly superior in two areas: Paved roads, and washboard.

Solid axle trucks, OTOH, seem to be superior in two categories only: Hardcore rock crawling where articulation is everything, and very heavy duty applications (like 1-ton dually crew cabs) where the simpler components of the solid axle can be made to heavy-duty standards less expensively than an IFS could (it's interesting to note that both Ford and Dodge run SAS on their 3/4 ton and up 4x4 trucks, but that Chevy/GMC is all IFS, even on the heavy duty models.)

When we were in Moab last week we saw a few rock buggies out playing in the recreation area East of town (past the Lion's Back.) I pointed out to Liz that, although all these buggies were street legal with the required lights, turn signals, license plates, etc, every one of them arrived at that location on a trailer - a trailer that was pulled, in most cases, by a pickup truck with, yup, you guessed it, IFS!

My final thought would be this: If your truck, in its current form, is not capable of doing what you need it to do, then rather than engage in some major mechanical surgery using custom, one-off parts, might it not be better to perhaps look for a different vehicle? One that is more capable of doing what you need a vehicle to do without all the major modification?

I mean, you could, theoretically, put a heavy duty SAS system on a Taco, put in a 4:1 T-case, heavy axles, and then throw in a TDi motor to boot. But by the time you've done all that, between the $$ and the time you've put into it, you could probably have gotten a vehicle that had the HD SAS and the diesel engine from the factory.