4Runner FAQ

4Runner FAQ

This page outlines the most frequently asked questions about 4Runners and Off-roading

Home

1. What are the different generations of 4Runners I keep hearing about?
1st gen = 1984-1989
2nd gen = 1990-1995
3rd gen = 1996 - 2002
4th gen = 2003 - present

2. What is the largest tire I can fit under my stock 4Runner?
For 1st and 2nd gen 4Runners and trucks you can safely fit 32x11.5s with little or no rubbing. For 3rd gens you can fit 265/75 R16.

However, tire size varies by manufacturer so some may rub a little more than others. Mud tires tend to vary more than street or A/T tires so they may rub even more. Also, 2 hidden concerns with going bigger are the speedometer offset and the possible loss in power. The loss in power is the result of the change in the effective gearing by going to a bigger tire. The severity of the power loss is dependant on your present gearing and how large a tire you moved up to. To remedy the loss of power you should change your gears in your differential(s).

Having said that, usually if the tires are only enlarged 1 inch most people just live with the loss of power and speedometer error. Most 3rd gens don't feel the loss of power because the engine is more powerful.

3. The rear of the 4Runner seems to be sagging. What can I do?
The springs on all the generations of 4Runners are notorious for sagging. Usually people replace the stock springs with after market springs from Downey, Performance Products or Old Man Emu. Less popular methods are to add spacers on top of the coil springs, add spacers between the coils of the springs or add air bags.

Yotatech has more info about suspenstion options here.

4x4wire has more info about suspension options here.

4. How do I know what gear ratio I have in the differential(s)?

For 1st and 2nd gens click here.

For the 3rd gens, click here.

5. What do the Overdrive and ECT buttons do on an automatic transmission?
With the overdrive off the transmission will not use the highest gear. This is useful for towing and keeping up your speed up on the hills. I especially like to use it to slow me down fast without hitting the brakes which is useful when I see a cop. The disadvantage of turning off the overdrive is the high engine RPMs at freeway speeds and the resulting noise and poor mileage.

The ECT button stands for Electronically Controlled Transmission and it essentially changes the shift points. It will let the engine rev higher before shifting to the next highest gear. This is useful for faster take offs and climbing those mountain passes. Again, use of the ECT button can diminish mileage.

6. What can I do to increase power of my 3.0 Liter V6 engine (1st and 2nd gens)
In short, nothing. To get any appreciable power gains from the 3.0 you must throw in lots of money. The most popular and cost effective change is to go with headers. Next is to change the differential gears because you probably switched to larger tires. All the other engine mods out there either do nothing or cost more than an engine swap.

7. The mileage of my 3.0L V6 is really bad, is this normal?
Yes it is. I get around 17 mpg freeway and about 12mpg city (maybe less). My mileage is actually considered normal for a V6 auto transmission. During freeway driving I can get about 250 miles per tank while I've heard of people getting about 200 miles per tank. Both are normal, it all depends on your tranny type, your style of driving, and most importantly your gearing.

8. When I go around a corner in 4wd it feels like I have a lot of friction in the drivetrain. What is happening?
When a car goes around a corner each tire travels in a slightly different path and as a result each tire is turning at a slightly different RPM. A differential (diff) allows each tire to turn at different speeds. For a 2wd truck there is one diff between the rear tires. For part time 4wd trucks there is one diff between the rear tires and one diff between the front tires. For full time 4wd and all wheel drive trucks, there is an additional diff, known as a center diff, between the front drive shaft and the rear drive shaft. This takes care of the speed difference between the front tires and the rear tires.

The "friction" is binding in the 4wd drivetrain and it only happens with part time 4wd systems because there is no center diff. When making a turn using a part-time 4WD system, the front driveshaft and the rear driveshaft are locked together, turning the front and back tires at the same speed. In order for this to work properly there needs to be slippage of the front and/or rear tires, otherwise, tremendous stress is put on the transmission and tires. This is why you should not use part-time 4WD (or more specifically, turn) on dry pavement, or high traction surfaces.

Alternatively, full-time 4WD, otherwise known as all-wheel drive, usually has a center differential which allows the front driveshaft to turn at a different speed than the rear. This allows for the use of 4WD on all types of driving surfaces."

While full time 4wd is good for driving on the road, it is far from ideal off road.

9. What is a locker?
A "Locker" is short for differential locker. It's almost like a limited slip differential (LSD) or Positraction, but it's much better for off roading.

An open differential (that is, one without a LSD or locker) will always send the most power to the tire with the LEAST traction. That's why when you burn rubber only one tire left a mark on the road. It's even worse when one tire is on sand or ice, that tire will spin and the truck goes nowhere.

A LSD helps a little by using clutch plates or gears to send more power to the other tire. This is fine for sand, snow, or ice, but when you are off roading it is quite easy to lift a tire completely off the uneven ground. When this happens to both the front and rear then the LSD can only do so much and all the power goes to the tires in the air and you go nowhere.

A rear locker will positively lock the left and right tires together no matter what. This is the ultimate traction device used for off roading. However, when traveling on icy roads they can send you out of control because when you go around a corner the locker forces the tires to slip (remember, they have to travel different paths). To remedy this potentially dangerous condition some manufactures make the locker selectable or ratcheting.

Newer 4Runners, have a selectable center lockable diff. so that one can drive on hard packed surfaces. This is NOT the same thing as the selectable TRD rear diff lock found on the Tacomas and the '96-2000 4runners. The center diff lock does just that, it locks the center differential only.

10. Should I get weld on or bolt on sliders and where can I get them?
Really, it doesn't matter whether you weld on or bolt on. Both methods, if designed properly, will provide plenty of strength to hold up the truck. Both methods, if done improperly, will fail.

Weld-ons have the advantage of being simpler to mount. Many people will say they are stronger, but I don't believe so (and I'm a mechanical engineer). The disadvantages are they have to be welded on by somebody who is very good at welding and they can't be removed easily. The geometry of the weld to the frame and the amount of heat can potentially weaken the frame.

Bolt-ons have the advantage of being removable. The down side is they are more difficult to mount and some designs still require small amounts of welding to the frame. The sliders that bolt completely through the frame require reinforcments in the form of sleeves to prevent the frame rails from being crushed. These sleeves should be welded in.

Yotatech has a list and description of available rock sliders here.

4x4wire has a list and description of available rock sliders here.

11. My 2nd gen 4Runner/Truck makes a loud popping/grinding noise when I make a sharp turn. What is this noise?
Don't worry, most of the time this noise is just the steering stops rubbing on each other. Normally there is a plastice cap covering the metal preventing this noise. However, these quickly wear away and fall off. You can get replacement caps for a couple bucks at the dealer, but most people just grease the metal stops, or live with it.

12. What is this headgasket recall I keep hearing about and how do I know if my 4Runner/Truck has been worked on?
Technically it's not a recall, it's a "Special Service Campaign." It affects most, but not all, 3.0L V6 engines. While the 3.0L is a reliable engine if maintained, they are notorious for the head gasket going out relatively early.

To find out whether your 4Runner/Truck has had the headgasket fixed, give your VIN number to your dealer, or call Toyota's helpline. If your head gasket has not been fixed, they should still honor the campaign and fix any damage free of charge, this includes a new engine if the block is damaged.

13. What is the deckplate mod?
The deckplate mod is a simple performance modification made to the airbox of the 3.4L V6 found in the 3rd gen 4Runners and Tacomas. Basically, the mod entails cutting a 4-6 inch hole in the top of the airbox to improve breathing. The "deckplate" mod gets its name from the cover used to seal the large hole in the event of deep water crossings, mud, and rain. Deckplates are watertight covers used in the marine industry. If you do an internet search you will find many writeups on how to perform the deckplate mod.

Home