Hi angle CVs again

[blakrapter]

Hi everyone, I am new here. I am working on a long travel IFS suspension project and found you guys through google. From what I have been able to find on this board, it sounds like many of you have done quite a bit of work with CVs, and maybe even some slip shafts. So, I need some help with a project.

I am lowering a GM 2500 HD 4wd with airbaggs for wheelchair access. It will be lifted back up to STOCK height for driving. So, I need joints that are capable of some pretty extreme misalignment (~40 degrees), but only when they are not operating. They will only be used to transmit torque or speed when the truck is at factory ride height, which puts the joints at virtually 0 misalignment. I have looked into the lobros, but it doesn't look like they can handle that much misalignment, even when they aren't being used to transmit power.

I would like to use two Rzeppa joints with a slip shaft in the middle, but there are 2 problems. First, I cannot find a Rzeppa joint with a flange mount, and I do not want to weld a flange on because that would kill the heat treating. Second, I am worried about the slip shaft binding under hi torque loads. The stock geometry doesn't require much plunge at all under normal suspension travel, but it doesn't really matter if it is a lot or a little, if the splines bind something gets over stresses. I have done a similar setup before on a mini baja car, but there is a big different between 450 ftlbs or torque and 4500 when binding is a concern. I believe the mid 80s ford trucks used a slip shaft in a similar way b/c they used u-joints with their ttb suspension. Anyone recall any problems with binding?

I took some crude measurements and put them in cad. It appears that I will need right at 40 degrees of misalignment at the inside joint when its lowered all the way with a maximum plunge of .9" at the axle, or 1.05" if the plunge is horizontal at the joint like it is with the factory tripod joint.

Any suggestions or info from your experience will be greatly appreciated.

[FABRICATOR]

Just a dumb question...Tripod joints don't work at much of an angle, but have you checked their limitations in a static condition? There are a few aftermarket Rzeppa joints that are drilled for a bolt up application.

[blakrapter]

Thanks for the info. I checked the stock joint that way laying around at a shop. Unfortunatly, i did not have an angle finder, but it appeared to be 30-35 degrees, but I am unsure of the plunge in the factory location. I have considered just limiting the drop to whatever the stock joints can handle, but if I do that, I need a more definate answer as to how far they can go. I would also like to have a backup plan worked out if I end up breaking factory joints.

Where can I find these bolt on Rzeppa joints along with their specs?

Thanks again, keep the replies coming.

[WOOPRDR]

if you have 1 inch of plunge(1/2 in 1/2 out) and you get enough room in the cup behind the axle you should be able to do what i did. Use a non plunging 930(they get 45 degrees) on the outer and a race prep 930(i think 30-32 degrees) on the inner. the inner cv will plunge and the axle will plunge just be sure to double clip the axle on the outer cv- good luck sounds cool!

[blakrapter]

Thanks for the info. Let me double check to make sure I understand what you are doing. You are using a 930 joint with a custom axle whose splines are machined for a slip fit, rather that machine or press. So, you are getting plunge by letting the axle slide in and out of the inner joint race, correct? It also sounds like you may be getting plunge at the other end as well, which unfortunatly will not be an option if the max angle is 32 degrees.

I also considered that setup, well still considering it, but many have warned that this will cause excessive heat and the possibiliy of getting shavings in the joint, both of which will cause pre-mature wear. This will be a daily driver, so reliability is more of a concern than high performance.

On the good side, it sounds like you do not have a problem with the splines binding under load, so theoretically, a slip joint in the middle of the axle would not bind and would isolate the extra heat and possible shavings.

Also, after reading that, I have one more question. It appears that there are two 930s, a plunging version and non plunging version. How much plunge does the plunging one have, and is the 30 degree limit set when it is fully plunged or not? When I need the high misalignment, I am at minumum plunge, which may offer more misalignment (does with a tripod anyway).

Sorry for the long post. Thanks for all of your help and any more you can give me.

-david