[genericwood]

Thanks. But I was more interested in how the pivot mounts to the aluminum casting of the differential?

The watts in one of my cars has the pivot mounted to the chassis as Pete described. But it isn’t adjustable in its’ current form.

Erik

The t-bar is replaced with a u-shaped (cross section) heavy-duty steel bar that has a mounting point for the adjustable rod off the top of the diff. This simplified things since we didn't have to try to mount this rod to the roll bar and/or reinforce the floor. One complaint... I haven't torqued it down yet but there's about a 1/2 inch gap on both ends and I'm concerned about what's going to "give" when I tighten it.

 

[ThePaddock]

This? It screws into the oil fill hole. There's a bearing with the kit that gets pressed in and is held with a retaining clip.

 

[genericwood]

Thanks. I wondered if it used the fill hole.

 

[Alfar7]

Use spacers to true the direction of the upper link. Don`t try to tighten it as is! Whats the downward angle on the upper link at ride height?? Critical!
There is tremendous force on that cross member. I`d like to see a pic of it Mike.

 

[PSk]

Spacers/shims required, surely

Pete

 

[ThePaddock]

Use spacers to true the direction of the upper link. Don`t try to tighten it as is! Whats the downward angle on the upper link at ride height?? Critical!
There is tremendous force on that cross member. I`d like to see a pic of it Mike.

Thanks Richard,

This entire test install was simply to locate the brackets on either side so they can be welded in before we finish the boot area so there's nothing in the way. We're going to use the spare tire well for a fuel cell and we have the AH fiberglass storage compartment that goes in place of the original fuel tank.

We'll make up some spacers for the cross-member. I'll get you a pic of it. With the setup at ride-height, I stretched a line down the center of the tunnel for the driveshaft to the front cross member in the engine compartment. This was to make sure the diff was centered. Even if I'm off a little bit here I made sure there's side-to-side adjustability in the Watts setup.

I also remembered that you recommend at least a two-inch drop in the angle of the upper link from back to front. I eye-balled this and it looks right. I'll know for sure when we do the final install. I also had to swap out the trunnion pivot at the top of the diff with a donor to fit the larger heim joints supplied with the kit (5/8"?). It needed to be turned down on the lathe a little but this part is really beefy.

Mike.

 

[Aggie57]

The most applicable and correct build info can be found in the 5 book series by Carrol Smith. If you want to buy the most useful regarding chassis & suspension, steering etc buy his book TUNE TO WIN.

I'm late to this thread but 2nd, 3rd, and 4th this statement. Tune to Win was without doubt the most useful and interesting book I ever read in the days when we were building and developing track cars. By the time I got to it we'd moved on from 105/115 to 116 and using the principles it explained we were able to tweak and tune our wee 1.6 (later 2.0) Alfetta GT to times that we never thought possible. Later on I translated the same learnings to a couple of GTV6's with similar results. Great book, glad to hear it's still as relevant today as back then.

 

[ThePaddock]

Thanks. Just ordered it from Amazon.

Roger Barr (in picture above) loaned me a book entitled "The Grand Prix Cars" and tagged the pages for me to read on roll centers. While I understand the concepts it was written for engineers and a lot of it went way over my head. Maybe Tune To Win will be better...

 

[ThePaddock]

Pics of cross member attached.

 

[bianchi2]

High Roll Center: "Use in high grip conditions to avoid traction rolling"

View attachment 1670125

that looks a wee bit exciting