IFS Driveshaft CV Modification for Increased Angle
Toyota drive shaft CV joints, also known as "double cardan" joints, come in several different varieties. The ones in the front of straight axle (pre-'86) Toy's came from the factory with a max operating angle of about 35 degrees. The '84 and '85 versions are especially sought-after since they will bolt right up to later model trucks and the pre-'84's use smaller, weaker bolts. The joints that come in the front of IFS Toy's can usually only go to about 25 degrees or less in stock form, and the ones that came in two-piece rear drive shafts are similar. The max angle of these later joints isn't enough for use in the front of a lifted, flexy, straight-axle rig without damaging the joint (pushing it past its max angle), but it can be modified to achieve the higher angles. And since IFS CV's are generally cheaper and easier to come by, this is modification is fairly common. Some drive-line shops like High Angle Driveline can modify your joint for you, or you can do it yourself. All that needs to be done to the joint is some minor clearance (grinding) inside, but to do that you have to disassemble the joint-- and that can be the tricky part. This article shows the method I use to get the joint apart, and where and how to clearance it for more angle.
The tools I used for this project are an angle grinder, a die grinder with a carbide burr, a small sledge hammer, a flat-head screwdriver, a sturdy vise, some small washers, and a small pick or piece of wire and a magnet in case I end up needing to fish out needle roller bearings.
1. Start by removing the grease zerks and c-clips from the u-joint caps you plan on taking out. Use a flat head screwdriver to dig into the grime and to pry and hammer the clips off.
2. Support the flange end of the CV on top of the jaws of the vise. Pound on the "H" with the sledge hammer. A few good whacks will bring the cap up.
Flip the joint over and do the same thing to the cap on the opposite side. Hold the joint at a certain angle to get the cap to be able to be pounded out as far as possible, however this still wont be far enough to get ahold of the caps to get them out.
3. At this point, you should be able to move the joint cross back and forth between the two caps. If any of the needle roller bearings have fallen out of place, use a pick or some wire and a magnet to get them all out. If you don't, they will be ruined when you try to pound the caps the rest of the way out, and then you will need a new u-joint. The same goes if you lose any of them, so be very careful if you plan to re-use the joint (Hint- pumping some new grease into the joints prior to disassembly may help keep the bearings in place).
|Pounding out the caps |
as far as they'll go.
|Removing the needle|
|Using washers for|
4. If the rollers have stayed in place and you can freely move the cross back and forth all the way into each cap (or you've successfully removed all the bearings), move the cross all the way to one side exposing a gap between the cross and cap.
5. Take some washers that have a smaller diameter than the outside diameter of the cross, and slip them through the gap and into the cap one at a time until you have a stack of them inside about 1/4" tall. If necessary, use the pick to get them to lay in there flat.
6. Take the joint back to the vice and pound the cap with the washers in it the rest of the way out.
7. Remove the cap.
|Cap all the way up.||Second cap removed.|
| || |
|Flange yoke removed.||Knock remaining cap out.|
8. At this point you may be able to get the cross out of the "H," or you may need to repeat the procedure using the washers for the cap in other side.
9. When you separate the flange yoke from the "H" and drive shaft yoke, there is a spring and more needle roller bearings that the pin part of the flange yoke rides on. Remove the spring, and stuff a piece of paper towel in the hole to help keep the rollers in place and dirt and metal out. If any of the rollers fell out of place, you'll need to grease them lightly and put them all back in place (easier said than done!) or the pin will not fit back in properly.
10. This time I was able to get the cross out with only one cap removed, so I just knocked the remaining cap out with a punch, being very careful not to drop it and send the rollers into never-never land.
11. Repeat steps 2 through 7 to remove the caps in the other end of the "H."
12. The three main parts of the joint can now be separated.
|Repeat process for|
the other end.
| Removing cross from|
|Removing dust shield. |
13. If you intend to replace the u-joints, you can continue removing caps and crosses from the yokes. I re-used the joints so I just removed one for the picture, although it did make removing the dust shield a little easier.
14. Support just the dust shield in the vice and remove and discard the shield. The dust shield opens up and exposes the insides when the joint is flexed anyway, so not having it there shouldn't be a problem.
15. Now you can put the joint back together without the "H" to see where the two surfaces of the joint meet and will need to be clearanced. I basically just grind the the flange yoke flat. The other yoke I grind at an angle all the way around until I just hit the metal part of the seal that holds the ball in. Make sure to cover any bearings and exposed u-joint surfaces to keep the grinding dust out of them.
|Viewing interference.||Notice metal removed.|
|Trim for zerk clearance.||Reason to trim zerk area.|
16. A little area in the "H" also needs to be clearanced for the grease zerk or the zerk will get smashed when the joint is used at its new higher angle. I use a carbide burr in a die grinder for this part.
17. Now all you need to do is reassemble the joint in reverse from how it was disassembled. Reassembly is basically the same as in the article mentioned earlier, however, since the caps are recessed into the "H," you'll need to use a socket or something to get the cap pounded in all the way. Be extra careful that the needle rollers stay in place in the cap during reassembly or you'll be needing a new u-joint after you try to pound them in while out of place. When you put it back together, make sure that the spot that you clearanced in the "H" gets put where the zerk fitting is or you'll be taking it all back apart again. Make sure the caps with the zerk fittings all get put in on the correct side as well.
18. Once the joint is fully reassembled, check to make sure the joint moves through its range of motion smoothly, and should be ready for use!
Before clearancing, I measured the max angle of this joint to be about 22 degrees. Afterwards, it went to about 35 degrees, which was the same as the stock '85 CV I happened to have to compare it to. The whole process took me an hour or two at my usual slow pace, but the results are worth it.
|Clearanced joint, left.|
Stock joint, right
|Front and rear|
CV drive shafts.
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