4x4Wire's TrailTalk Forums: Birfield/Longfield/IFS CV joints compared w/ pics. Shocking results!!!!

I've been meaning to do this comparison for some time. Now that I have all three outer CV joints in my possession, this would be a great time to compare the measurements of all three.

First let me preface by saying that I am no birfield or CV expert by any means. I tried to be accurate with my measurements, but they may not be perfectly accurate. I used millimeters, because it's easier to compare metric measurements. And finally, I had to guess as to where the best places to measure would be. Obviously, the most accurate way to compare would be to compare three completely dissembled joints, which these were not. Also, any heat-treating advantages that one joint might have over the other, such as the Longfield, can't be measured here.

After taking a close look at all three CV joints and taking some measurements, I came to some very startling conclusions. The most startling is that of the three joints, the IFS CV joint appears to have the largest and thickest bell and internal cage! The second startling thing is that the Longfield joint does not appear to use a stock OEM birfield as the basis for the build up. In fact the internal cage matches the dimensions and design of the IFS joint cage, which are both larger than the OEM birfield joint! It appears that either Toyota redesigned the birfield joint or the Longfield is based on some sort of aftermarket birfield joint.

Measurements and Pictures are below:

This pictures show the three CV joints, stock IFS, stock birfield, and Longfield joint, plus an inner solid axle.

This pictures proves once and forall that the IFS CV joints and the birfield CV joints use the exact same 27 inner spline count. What you see here is an '85 solid axle inside an '89 IFS joint.

This pictures shows the weak points on the solid axle and the IFS axles. On the left is a solid axle shaft. Where it necks down is 24mm. This the weakest point on the solid axle, baring the stock birfield. On the right is the outer stub on an IFS joint. This stub measures 23mm. This is the weakest point of the IFS axle. The rest of the IFS axle in between the inner and outer CV joints, measures 25mm. You can see the size of the weak points of both the solid axle and IFS axles are nearly the same.

This picture compares the Longfield (left) with the stock birfield (right). The Longfield has a ring welded to the outside diameter which is then grounded down. This makes the bell slightly longer and adds significantly to the Longfield's strength advantage over the stock birfield.

All three CVs. Stock birfield (left) Longfield (center) IFS CV joint (right). Here can see two things. That the IFS CV joint is obviously larger and that the Longfield and IFS CV joint use the same size and design internal cage which is thicker than the stock birfield cage design in between the ball bearings. What is not so obvious, is that the bell housing diameter of the IFS joint is significantly thicker than the other two joints.

Again, all three CVs. Stock birfield (left) Longfield (center) and IFS CV (right). Here you can see that, again, the IFS CV is the largest of the three joints. But the birfield and Longfield's outer stub is much larger than the IFS stub. 27mm verses 23mm.

These measurements don't really prove anything by themselves. They only bring up more questions. Is the IFS CV joint stronger than the stock birfield? It probably is. What about being stronger than the Longfield? Well, probably not. We all know that the Longfield is very strong and held up to some very serious field abuse with very large tires. Whereas it's not unheard of to have an IFS joint break with 31" or 33" tires. But then again, the IFS joint does always see more angles and on two different planes.

And if you think the IFS axles are weak compared to stock solid axles, just remember the stock solid axle might be 27mm most of it's length, but is only 24mm where it necks down to go into the birfield. The IFS axle is 25mm along the main shaft. I'm not sure what it is where it goes into the CV joint, but not likely any smaller than 24mm. However, the IFS outer stub is only 23mm. This apparently is the weak link in the IFS axle, whereas the weak link in the solid axle is where it necks down to go into the birfield.

As for the "new" Longfield joint, it appears to be based on an aftermarket birfield type joint, but not the OEM birfield joint. If you look at the internal cages, Longfield appears to use a cage of the same design and thickness as the IFS joint. And if you wondered about what he does on stock OEM birfields that are sent to him for treatment and exchange? Well, he replaces those cages with a new one. Likely the same ones that you see in the brand new Longfield pictured above. The only original part of a core birfield that is used by Longfield is the bell and stub. And then the bell is modified.

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Edited by Brian894X4 (09/25/03 06:27 AM)

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