Using the Isuzu Pivot Box on Rack & Pinion Conversions

A few have conversion projects involving rack & pinion installations.  Some have used the VW van pivot box (also known as an upper steering gear) and other have used or would like to use the Isuzu unit since they are readily available new at a low cost on ebay.  The problem I have run into is finding the correct u-joints.  One can always modify the stock units, but the results, while serviceable tend to look like someone cobbled something together.  The shafts on the Isuzu box are 5/8" with a spline count of 36.  You would think that a 5/8'-36 joint for a Vega box would work, but it WILL NOT.  The correct joint is a 5/8"-36 CHRYSLER.  Borgeson part # U16N-7DDX636C 014921 is the correct spline on one end with a 3/4" DD on the other. They are double the price of Vega joints, but again, the Vega joints don't work - ask me how I know.

Hi ! New to the forum, and have just purchased a 1966 A100 van. I'm wanting to do the M2 IFS conversion myself, and, saw your thread about the Isuzu steering box. First question is, what year, model, or part number, etc., is the Isuzu steering box that I should be looking for ? Secondly, what IFS kit did you use ? I've been looking a Fat Man, but, concerned about which width will be the closest one to use, without major modification. It seems the E100 and A100 are closely related in design and dimensions.

Welcome aboard!  If you use the search function you'll find quite a few IFS builds that should give you some good idea of what you are in for.  My current A-100 build is here:

https://vintage-vans.forumotion.com/t46504-a-100-project

This one is an IFS and IRS from an 84 C-4 Corvette.

The Isuzu upper steering gear is here:

http://www.ebay.com/itm/1998-02-ISUZU-Rodeo-Amigo-HONDA-Passport-USED-upper-steering-gear-box-2180-0036-/391372073751?hash=item5b1f97eb17:g:TyUAAOSwAKxWUy6r&vxp=mtr

Normally you can find them on ebay without any problem.  Another option is a steering pivot box from a VW van.  A more compact design, but harder to find.

Thanks for your reply, and good information. Have you ever heard of anyone using a Corvair steering box on one of these ? They used to be popular with street rodders in the past, and, I've seen reversed Corvair boxes in Speedway's catalog.

Not sure if the Corvair box can be made to work with the stock steering set-up, but it can't be used as a pivot box on a Mustang II conversion. The Corvair box input and output are at right angles and the gear is not at a 1:1 ratio. The only job a pivot box has is to change the direction of the steering shaft without altering speed of the shaft - the final steering ratio is determined by the steering rack only.

I decided on, and purchased the Isuzu Rodeo Upper Steering Box, as they are a bit more reasonably priced, and more readily available. Regarding the Borgeson joint, you are right, they're not cheap, and, I will need two of them...right ?

Hello,

Not sure if you’re still active as this is an old post but I have a question about how you mounted the Rodeo transfer box. I am mounting mine now and I am struggling with the correct position in relation to the column and rack. My problems with the ujoint angles. I am using the same ujoints as you did which are limited to 35 degrees. Do you have any pictures showing the mount you fabricated and how it was installed?

I truly appreciate the tip about which ujoints to use. Thank you!

radicalran wrote:Hello,

Not sure if you’re still active as this is an old post but I have a question about how you mounted the Rodeo transfer box. I am mounting mine now and I am struggling with the correct position in relation to the column and rack. My problems with the ujoint angles. I am using the same ujoints as you did which are limited to 35 degrees. Do you have any pictures showing the mount you fabricated and how it was installed?

I truly appreciate the tip about which ujoints to use. Thank you!

Sorry for the delay, I just noticed this post.  The mounting bracket is just plate steel.  It helps to cut a template from thick carboard and play around with it before cutting any metal.  It is not difficult to mount the box, but is does take some trial and error on exactly where the shaft needs to split and where the support bearing is located.  The 2 constants that can't really change much are the mounted box location and the input shaft of the steering rack, so the real challenge is laying out the path of the shaft.  Depending on where everything falls for your specific build, you may need a "double" u-joint connection at some point, or you might need to split the shaft in more than one spot and use 2 support bearings.  If you could post a picture of what your install looks like I'm sure we can figure some way around it.

Here is another pic that shows the path from another angle.  My frame is highly modified from stock so looking for frame "landmarks" may not be helpful to you.  There are more helpful pics on the last page of my build thread too:

https://vintage-vans.forumotion.com/t46504p100-a-100-project