Locker with IFS?

[michaelgroves]

I have very little knowledge of IFS vehicles, but wondered if it's a problem to fit a front diff locker to one? Are they generally strong enough to take the increased torque? (Obviously it can vary from vehicle to vehicle, so I suppose what I'm really asking is what IFS models, if any, are suited to full locking diffs up front?)

 

[HongerVenture]

Michael,

You can definitely lock IFS. There are several Toyota Tacomas (Scott Brady and BajaTaco to name a few) on this forum with ARB air-lockers in their IFS differential. More than anything it depends on the availability of the part on whether or not you can do it.

The differential itself can handle the stress, it's usually the axle that will suffer from the stress. I'm sure there are some IFS systems that are more prone to this than others. I know that Toyota front IFS axles do break, though usually from wheel spin. I'm not sure if I've heard of one breaking due to a locker.

Joel

 

[michaelgroves]

Thanks, Joel. Yes, my thought was that the axle-shafts have two sets of UJs, and the outer ones must swivel around two axes, as opposed to a solid axle, which has just a single, one-axis swivel. The open diff guarantees that both shafts share the available torque, whereas when you lock it, you can get all the torque on just one, possibly awkwardly-angled shaft.

It's encouraging that they make lockers for IFS, though - presumably it implies that the manufacturers think the axles are up to the job.

 

[Scott Brady]

Michael,

I am very cautious with locker use on my Tacoma, mostly because the CV can be placed under steering AND extension stress (when the suspension droops).

The main benefit is a much stronger case to help limit deflection in the carrier. Then, it is an insurance policy. I think in total, I have engaged the front locker three times, and once was to make sure everything was working.

So, only in a straight line, and sparingly is my advice.

 

[DaveInDenver]

I have the RD90 in the front diff of my '91 Hilux. While I'm not hardcore rock crawler, I have taken my truck up some harder things without issue. I've had it about a year and a half and probably have used it maybe 2 dozen times. I'm like most people, in that I leave it open until I really need it. My $0.02 is that a front locker is really just insurance, but it came down to it was really the best time to add it when I was spending the money to regear.

 

[michaelgroves]

I think lockers are great to have, but are certainly not the be-all and end-all of off-road capability. I rate tyre selection (and pressure) and axle articulation way above diff-locks. However ARB diff centres (and several other types) are much stronger than Land Rover diff centres, which is an additional reason to fit them. (I assume that's what you were also referring to in regard to the Tacoma, Scott?)

Let's also not forget that judicious use of a locker can actually reduce the chances of breaking something, mainly because they can reduce the shock-loads caused by spinning wheels (but also in other circumstances, e.g. cross-axled with only the rear locked puts all the available torque through just one shaft: lock the front, and the torque is shared between two shafts).

 

[blaze one]

I have researched the idea of putting a locker in the IFS of my Blazer . Basically , the front ends of my paticular truck is know to be weak . But... when you install a locker , you will find that you don't need as much of the "go pedal" to get over obstacles . The use of a locker in the front(and rear assuming) allows you to have more "finesse" . Slow and steady . And keep your foot out of the pedal too , you will have much more traction than before , so tire spinning is a no no .

Also consider a winch instead of a locker . At about the same price , you can mount a nice winch up front . And if you use a reciever style mount , you can transfer it to the rear if you need to pull from that end .
A winch may offer you more offroad capabilities than a locker might .

 

[vanguard]

I try to use mine sparingly but I tend to wheel with guys in more capable rigs. I've probaby engaged mine 100 times. Sometimes I've done it just because something hard was coming, other times it was because I tried it with just the rear locker several times and it was either lock the front or smash it harder.

I have broken a CV. I was near the top of a hill that had a 3' berm and I had the wheel turned at full lock (to the left). I had hoped that if I did everything very controlled I'd get away with it. I was just above idle in 1-lo when it snapped. No bouncing, no revved motor, just a turned wheel.

Having said that, I have a friend that beat the dickens out of an IFS taco that was locked in the front/rear and he had 38" boggers. If you keep the wheels straight, CVs are stronger than they get credit for. I'm happy I locked the front. It's made it a better machine.

 

[michaelgroves]

I have broken a CV. I was near the top of a hill that had a 3' berm and I had the wheel turned at full lock (to the left). I had hoped that if I did everything very controlled I'd get away with it. I was just above idle in 1-lo when it snapped. No bouncing, no revved motor, just a turned wheel.

That certainly bears out what Scott said above: use sparingly and only in a straight line. Of course that advice applies to all front lockers, but especially to IFS vehicles. I would imagine that with IFS you are also at increased risk when the suspension is fully extended because the CV is being driven at an angle (but fortunately the extended wheel is likely to be the one with less traction).

I suppose it goes without saying that you are more likely to break something up front if you lock the front without locking the rear!

 

[DaveInDenver]

That certainly bears out what Scott said above: use sparingly and only in a straight line. Of course that advice applies to all front lockers, but especially to IFS vehicles. I would imagine that with IFS you are also at increased risk when the suspension is fully extended because the CV is being driven at an angle (but fortunately the extended wheel is likely to be the one with less traction).

This is true of all trucks, the CV or u-joints in the front are far more prone to break with the wheels turned. I do think you hit the nail on the head, though. IFS trucks allow the CV joints to move in several directions, so you do need to be careful of breaking a CV at droop or compression as well as left or right. Live beam trucks don't need to be concerned with the up/down travel and this is obviously a big difference. But left-to-right with the CV joints level, an IFS axle should be no more prone to breaking the CV than a live beam. Naturally having a CV on each end of the half shaft does double your chances of finding the flawed one, though.

In my case, I broke a Birfield in an unlocked FJ40 and not yet in my IFS and locked Hilux. I'm sure weight and available torque being so different between the two (2F and 22R-E) is a part, as is driver skill, but I personally don't think it's a big deal to worry about a locked front in an otherwise sound IFS truck. It also just occurred to me that my truck has manual hubs and I'm sure that has not spinning the 200K mile old (although recently serviced with new boots and grease) CVs all the time also keeps the wear and tear to a minimum and has also helped increase their lifespan. Now that I've jinxed myself with that, I think I need to start carrying that spare axle all the time, eh?

 

[Scott Brady]

I do carry a spare CV axle (thanks Brittan).

CV's are very strong in a straight line. Much stronger than a u-joint due to total surface contact. However, in a turn or droop the cage has less coverage and the strength drops considerably.

My issue is not a concern of the quality or strength of the Toyota CV axles, it is that my truck is at GVW all the time. So in a turn, I just leave the front locker off. No problem with traction yet for the trails I drive.

On my Jeep, I do use the front locker often, even as a tool to move the front end in one direction or another on a rock face (due to the understeering effect).

 

[BajaTaco]

I too have the ARB RD90 locker in the front diff of my Toyota Tacoma. I agree with all that has been discussed here so far. I use it sparingly and try to use discretion on when I think it will be a good idea to engage, or too risky. It's very nice to have the added capability though.

Scott happened to shoot a little video of my truck that is a good example of using the ARB locker on an IFS truck. On this climb, you can see my driver side tire get air (bi-product of the IFS) so I back off a touch, engage the ARB, and get pretty much instant results by putting the power to the pass. side front tire.

I too, carry a spare CV half-shaft and the tools to do a field repair.

 

[michaelgroves]

My issue is not a concern of the quality or strength of the Toyota CV axles, it is that my truck is at GVW all the time. So in a turn, I just leave the front locker off. No problem with traction yet for the trails I drive.

On my Jeep, I do use the front locker often, even as a tool to move the front end in one direction or another on a rock face (due to the understeering effect).

I think this is an important point - there is a big difference between an expedition vehicle and an "off-roader". An expedition vehicle is less likely to lift a wheel because of the weight, so lockers are not as important. They are also more likely to break something, again because of the weight, so lockers are not as attractive. And the consequences of a breakage are much more serious, which makes the use of lockers something to be considered even more carefully.