Narrowing 85 C4 Batwing for a 36 Chevrolet

[Stovebolter]

I know this question has already been asked...but I need to ask again. Tiger and I both are running into the same scenario. I'm hoping a Pro Tour guru can help us.

I need to narrow the batwing for my 85 C4 batwing 4" each side. I had concidered cutting the ends of and having a local shop tig weld but apparently they also need to know the material. I also concidered making some sort of custom (1/4" plate?) backing plate to take the batwings place? If I narrow it this much I may have camber issues. I'll be running a 18X10" rim with a 3" backspacing. From what I can tell, when I narrow the half shafts (and links) 4" each side, the hubs (knuckles) will have clearance issues and hit the batwing. Any ideas?

Also, the angle the drive shaft will be at is 3 degrees....but angled up to the rearend from the transmission. I cant raise the transmission any more unfortunately without heavily modifying the floor pan and losing precious space.

Also, what angle should I set the half shafts at and how much suspension travel to you guys suggest? 3 degrees? 0 degrees? I'm fairly new to the IRS thing....but understand how it functions and the arc of travel. Links below. Thanks everyone. These are pictures just to give me an idea of placement. So far...I can tell I need the differential about 2" higher in the frame which means I have to recess the frame or raise it on a single plane for clearances. I didnt want you to think that was how I was placing it. Thanks. Dave

https://static1.pt-content.com/images/pt/2008/03/2356581328_6828b506a3-1.jpg

https://static1.pt-content.com/images/pt/2008/03/2355750191_4fa195ae45-1.jpg

https://static1.pt-content.com/images/pt/2008/03/2355753217_5ca15e9f20-1.jpg

https://static1.pt-content.com/images/pt/2008/03/2355756347_50b9bf4609-1.jpg

https://static1.pt-content.com/images/pt/2008/03/2356617984_410c38ec7b-1.jpg

https://static1.pt-content.com/images/pt/2008/03/1799637686_22764ac014-1.jpg

https://static1.pt-content.com/images/pt/2008/03/2320308187_0221ff90f4-1.jpg

[Stovebolter]

I have another idea. Maybe. How about fabricating a spacer 1" wide between the differential and the cover to move the differential cover back 1", which in turn would move the batwing mounts back 1" as well as the toe links. This should allow the rearend to be narrowed up to 3" each side with-out hogging out too much of the hub. I'm concidering this. The rear surface under the differential cover is flat. Anyone's thoughts?

Anyone know much we need to allow for suspension travel? Approximately? And at what angle the frame braket needs to be set at for the dogbones? Taking it through its arc of travel.....55 degress looks like it should work.

Dave

[MrQuick]

You might get more bites if you had this moved to the suspension area.

Looking at your situation I would lean towards the custom bat wing design. Even the Viper unit would be in the way.
We made one out of mild steel and due to its smaller it wasn't too much heavier than the stock unit. Not sure if weight is an issue.
You are building new frame rails no?

[Stovebolter]

You might get more bites if you had this moved to the suspension area.

Looking at your situation I would lean towards the custom bat wing design. Even the Viper unit would be in the way.
We made one out of mild steel and due to its smaller it wasn't too much heavier than the stock unit. Not sure if weight is an issue.
You are building new frame rails no?

I found a custom stainless steel Viper based batwing....somewhere....$1500. Ouch. http://www.electro-dynamics.com/chassis/viper.html. I want this truck to be slick....but the bling will have to come later. More concerned about driveablity, so the mile steel idea is a good one. What did you use as a starter for the bolt pattern.....1/4" plate?...and build off of that? Could you drop me a picture to get ideas? Weight really isnt an issue. I am having new rear frame rails made and can offset the rails to clear the knuckles and half shafts no problem but still will have some clearance problems with the knuckles hitting the batwing unles I modify it as well. Do you have any idea if the 91 Dana Cover has a narrower mounting position between the ends? The 85 is 37.5" between the mouting holes on the batwing. Just eyeballing the thing, looks like the 91 is narrower but I can't find the info I need.
I'll try to find a moderator and have this moved to the suspension area. Thanks.

Dave

[MrQuick]

No pictures, this was a few years back when we didn't really think of taking pictures of our projects.

It was 3/16" MS and the mounts were 2" above the housing 3" out from the cover edge. The nose mount was 1" higher and mounted solid to a subframe which was mounted using bushings.

If you can mock up where it needs to go and work your way out from there. Make the cover fit your needs.

[perry mitchell]

I narrowed my half shafts 4 1/2'' each and was concerned about the same issue you have. I was planning to extend the toe arms off the knuckle to avoid hitting the mounting bracket on the frame but it turned out to not be an issue. The arms curved around the bracket and fit perfectly. They were close, but in this business, close is good. I used an '88 IRS unit but I believe it has the same batwing dimensions as the '84. Are you using the mono-spring or are you going with coil-overs?