Pirate 4x4 banner

121 - 131 of 131 Posts

·
Registered
Joined
·
17 Posts
You might as well use the AAM 9.25 diff from the 2500/3500 GM vehicles. It is pretty much the IFS version of the semi float 14 bolt and has the disconnect... ant it was meant built for the full size Chevy vehicles.
I looked into the 9.25”, but the problem with it was that I was thinking about using a Detroit TruTrac for the front diff. Although I could potentially get one for it, I was worried about the trutrac making the front axle turn all the time, since the cad on it (just like my stock 8.25” I have now) only disconnects the passenger side wheel. Based on that I guess to do this I would need to take a 9.5, cut it down and add a cad to both sides, effectively acting like it had lockable hubs, allowing me to run a trutrac. The only problem with this is that to have a cad on both sides of the diff I would almost certainly need to center the diff to give enough room for the cads, which would then conflict with my oil pan and the front drive shaft being still off centered
 

·
Premium Member
Joined
·
2,483 Posts
That would make your center extremely wide and kill any articulation. I have the same issue and just going to let it run. You wouldn't want this on anything that put down major mileage but many rigs did that for years before hubs. I don't think I have seen a 14 bolt for a center diff. I bet it is wider and deeper than a 9". Figure the largest half shaft will be 35 spline.

Nothing is impossible. My first Independent center was a model 44 that came out of a 49 Mercury. Slid the tubes out and welded on the outer bearing assembly. Then had a short stub made of U-joints at the time. The flange to flange distance is 21" where a model 44 corvette is 17" . A 9" is about 14.5" and can be cut down to 12.75". Not sure about any other OEM or foreign diffs. That Mercury is still in a Flatfender 60 years later....but only 8" suspension with half shafts about 12" long.

I would never run IRS again. Since 4 bar systems have been designed for anti's and no rear steer on body roll, there is just no advantage. And with the advances in hydro steering accuracy, IFS is getting harder to justify except for really high end........ But I had to go through the process to prove it to myself. Do the same as you may find that golden path. New stuff is being made every day that changes the options.
 

·
Registered
Joined
·
17 Posts
Right, the more narrow the center box unit is, the more suspension travel you’ll have, that’s what I was running into. With that being said, an idea popped into my head this morning of a way to make a CAD that could be scaled down to work on both sides, if designed properly. It uses a splined shaft on the axle hub side, which then is given pressure to lengthen, and then lock into place with couplings on the diff. I’ll attach some pictures of a simple sketch I made, hopefully it’s enough to get my idea across. I plan on making this truck into an overlander, so it’s not going to see really heavy terrain, and mainly this whole IFS thing is just me trying to think outside the box. I just wanted to see if there could be a way to make a fully road-able IFS that could give a solid axle a run for its money.
3113055
3113056
 

·
Premium Member
Joined
·
2,483 Posts
The axle shaft is really the easiest. It doesn't have to be rigid in length but usually is because of the "complexity of splines" and that you usually strive for no or minimal axle plunge. Getting the CV's to mate up to the center and upright is usually where the thinking gets consumed.

An axle can be first machined to a diameter in the center, cut, and sleeved to the length you want. It is not a real high speed item. The axle can be sleeved longer or shorter.

It was a lot easier in the days of u-joints. Just driveshaft tube. Or a combination of splined yokes similar to auto transmission yokes. On my ' 76 IRS, I slipped two yokes together that also took care of plunge.

What is unique about the older Corvette centers is the plunge is actually taken care of in the outside bearings of the center. The outside bearing is actually a wide roller bearing and the differential centers the end of the stub. The diff chunk has the same standard hold-in bearings...so think double bearings per side (and why so wide flang to flange) I have never had my Corvette alum model 44, with a detroit locker apart in 40 years. 33" max tires helps that situation but the 450HP is there and the way we play in the dunes, we can put all that HP to one downside axle. (My son found that out this week in the dunes on his CanAm Turbo SXS. A broken CV from that action (A downhill uturn on a dune face) actually caused a roll on it's side (luckily))

I guess I should inspect that Corvette center but ignorance is bliss..........

Some of you are also talking 33" max tires so the big diffs may not be necessary anyhow.//
 

·
Registered
Joined
·
17 Posts
The axle shaft is really the easiest. It doesn't have to be rigid in length but usually is because of the "complexity of splines" and that you usually strive for no or minimal axle plunge. Getting the CV's to mate up to the center and upright is usually where the thinking gets consumed. ...
Right, I want to make it as narrow as possible so to get all the articulation I can. I looked at the corvette 44 but for my truck I need the pumpkin offset for my transfer case. Really the whole thing of why I was wanting to look at doing a cad on either side is because of the output bearing on my transfer case. If I didn’t do a cad on either side and use the trutrac, my front driveshaft would be spinning all the time, using that bearing on the front of the transfer case, which in its original configuration wouldn’t spin unless in 4wd, so I don’t know if it would be big enough to withstand a change to spinning all the time.
 

·
Premium Member
Joined
·
2,483 Posts
I went with the low pinion 9" and cut off the excess material on one side. That made the F-F 12 3/4". But what it really did was move the pinion over. It is now offset 2" and low pinion. Backside of the gear is true, but I can just squeek a driveshaft by the crank without lifting the motor too much. I will offset the pan sump to the passenger side to help that clearance also. If I have to offset a motor, it should only be a couple inches. My plan is to mochup without a pan and go from there.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #128 · (Edited)
Hello Gentlemen.. Many apologies for the long delay with no updates on the buggy build.. The Covid disaster certainly altered my plans.. So, during all that downtime I put together my shop.. Buying and then chopping up a chassis did not make much sense to me, given my suspension design.. So I'm committed to a ground-up build.. More progress to come.. Got the Mig and Tig machines set up, and the chassis table is just about ready.. It has been a loooonng road..




3116289




3116290



3116291



3116292




3116293
 

·
Premium Member
Joined
·
2,483 Posts
Looks like you followed a good plan. Now you know how "easy" it will be to make the stuff you are designing......

My shop looked that clean 40 years ago....Now I have to walk sideways for all the do-dahs we collect.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #130 ·
Looks like you followed a good plan. Now you know how "easy" it will be to make the stuff you are designing......

My shop looked that clean 40 years ago....Now I have to walk sideways for all the do-dahs we collect.
Yeah the chassis surely will not be easy.. But certainly a challenge I will enjoy..
 
121 - 131 of 131 Posts
Top