Solving Confusion Between So-Called "4 Cyl" and "V6" Gears: LPH vs. SPH

Don't read this article unless you really need to. Normal people should go to our regular Toyota gear and differential page. The below info may be confusing, and isn’t necessary knowledge for a typical gear purchase. This information is useful if you're swapping gears between Toyota diffs or doing some other nitty-gritty stuff. If you're simply buying new gears for a Toyota differential, this information is more detailed than you need for a normal gear install.

We usually think of “4 cyl” gears and “V6/turbo” gears. When you buy gears, this is how they are sold, and this is how we all generally refer to them. In fact, we could be thinking in terms of “4 cyl” differential housings/carriers and “V6/turbo” differential housings/carriers. While it does matter what gears go into what housing, Toyota 8” ring and pinion gears do not break along 4 cyl/V6 designations. They break along long pinion head or short pinion head. LPH and SPH is the only difference between Toyota 8” gears in this article.

How do they set up?

The differences in mounting these gears is primarily in the size of the inner pinion bearing. In 4 cylinder housings it is either “thick” or “thin” depending on whether the R&P is SPH or LPH. In a V6 housing it simply uses a V6 bearing. Take a look at our table to get an idea of what you have and what you need.

Aftermarket 4 cylinder gears will come with a short pinion head and the corresponding setup kit will have a thick inner pinion bearing. This setup will fit ALL 4 cylinder differential housings from 1979-1995.

Aftermarket V6 gears will come with a long pinion head and the corresponding setup kit will have a V6 inner pinion bearing.

If you think you have the wrong gears for your housing, read this section. If your pinion depth is completely off, it’s probably because you have the wrong ring and pinion for your housing.

You can most likely shim the pinion or use a thin bearing from Toyota to install your gears into your third. The only thing we would caution is that some people say the amount of shimming to get SPH gears into a V6 housing is excessive and will be weaker than just using LPH gears. For most people, this probably won’t matter, but if you’re hard on your rig, think about it.

The thin pinion bearing is not normally available in 4 cylinder install kits since the thick bearing is normally used. If you need it, you can pick one up at the dealer. It’ll be a 4 cylinder ‘86-‘95 inner pinion bearing for a Toyota pickup or 4Runner.