Leaf Spring to Rear Trailing arm swap

[terrylgreenjr]

I've been exploring all different types or rear air suspension options. I don t want to cut up the rear floor of my 91 Suburban so I don't have to go that low. I've ordered the Porterbuilt 2 piece C Notch so I have a little time before it gets here. I've decided to try the trailing arm swap and put the bag in the middle of the arm on the inside of the frame rail.

Questions I have

Would the crossmember location measurements be the same as on a long bed?

I have a 2 piece driveshaft already is it the same length as a trailing arm truck?

I'm sure there will be more questions but this is a start. Any info about the swap is much appreciated

[bluex]

First did you order the truck C notch? Suburbans are a little different in the area over the axle than a truck and I'm not sure a truck notch will "bolt in" on a burb.

All trailing arms are the same length. What I think you should do is install the notch, center the axle in it and then mock up the arms and crossmember to find its location.

On the subject of crossmembers which one are you using? A 67-72 wont work in a 73+ truck without some serious modificaitons. I would recommend seeing if CPP would sell you one of theres seperate from the kit. It would probably have the best chance of an easy install in a suburban.

The axles location isnt changing just the way you're attaching it to the truck. The driveshaft should still work. It might need a little shortening depending on how low you go.

Your biggest problem is going to be the axle hitting the floor before it hits the frame. Less room there than in a truck.

[terrylgreenjr]

I talked with Nate and we exchanged measurements of the frame where the notch goes and it is supposed to fit

All the frame measurements for C notch were the same as a truck so I'm thinking the crossmember location measurements would be the same too. What kind of mods do you think the factory crossmeber is going to take? The width and the height of the crossmeber should fit between the frame rails

The driveshaft is a 2 piece and I was trying to see how long the back half is to see if the carrier bearing on my factory shaft in the same place as a trailing arm truck

I'm just wanting to go as low as I can with the factory floor. When the diff hits that's all I want

[bluex]

The large hump in it for driveshaft clearance is going to hit the floor. Once you trim that for floor clearance then the driveshaft will hit it. I'm not sure how the frame is on a suburban but the way a 73+ truck frame kicks up after the cab to meet the bed also puts a stock 67-72 crossmember higher than it is on one of those trucks, which changes all the angles. I'm not saying it can't be done but its not going to be as simple as bolting it in either. If you are going to use a stock crossmemeber also plan on taking the arm mounts loose and flipping them over to lower the mounting point. That will help some and is a pretty common mod for those trucks.

I dont know of anyone whos put this suspension on a 73+ suburban so all I can say on your driveshaft questions is you'll just have to check it during mock up/install. Its hard enough finding info from someone whos put trailing arms under a truck much less a suburban/blazer.

[terrylgreenjr]

I picked up some rear trailing arms and I bought a factory crossmember online that should be here in about a week I'll let you know what I find out

[terrylgreenjr]

I'm trying to keep everything in one spot to save the info. I got my crossmember and I'm going to try to look at everything this weekend

Does anyone know where to get the spring perches to weld to the bottom side of the axle?

I've found the leaf spring style but I assume the trailing arm style are different because they angle inward

Thanks in advance

[bluex]

https://www.performanceonline.com/19...g-Rear-End-Pr/

[terrylgreenjr]

Thanks for the reply.

Is that all I should need to locate the trailing arms to the axle?

I emailed POL to see if the axle tubes for the 60-72 trailing arm axle and the leaf spring axles were the same dia.

[bluex]

Your also going to need a panhard bar. it goes from one side of the frame to the axle on the opposite side. You'd be better off fabbing that yourself or possibly adapting parts from porter builts 67-72 stage 2 kit or more cpp parts.

[terrylgreenjr]

Definitely going to need a panhard bar. I was thinking of making one that goes from the frame rail to the opposite side trailing arm to limit the side to side movement of the diff as much as possible.

Sorry no pics yet. Im still waiting on the axle saddles to come in. I did put the arms under the rear end and ratchet strapped them the under side of the axle. The factory trailing crossmember is the correct width to fit the frame and it going to end up within a inch or so to where the 91 Suburban carrier bearing crossmember is. Everything is so close I'm going to have to remove the 91 crossmember to test fit it further. The Suburban us my daily driver so I have to make sure I have everything I need before I break it down.

I'm wanting to do air suspension. What size bags should I use? On the front I'm just planning on putting the bag in the factory spring location. In the rear I'm going to put it on the inside of the frame rail about in the middle of the trailing arm.

[bluex]

My kit came with dominator 2600 bags for all 4 corners. That should probably be good for you as well. That's pretty much standard bag for 1/2 ton trucks

[SCOTI]

Typical recommendation for truck arm C10's would be 2600's in front, 2500's out back. You would be fine w/the 2600's @ all 4 corners w/the burbs extra girth out back.

[terrylgreenjr]

HAPPY THANKSGIVING EVERYONE

Thanks for the info. Now just wanting for a Black Friday sale

[terrylgreenjr]

Just figured I would give a parts update for what I've collected so far

[terrylgreenjr]

I'm on my phone so it's only taking one picture per post

[terrylgreenjr]

Number 3

[terrylgreenjr]

Just to update. The porterbuilt truck notch did not work it doesn't match the contour to the suburban frame so I built one out of 2x4x1/4 and installed it. Then went on powertour with the drop spindles and a flip kit. I waited almost a whole year to start the air ride but it was worth it. I have to thank Jason for making everything work and putting it all together. Now for the pics.

[terrylgreenjr]

Pics did not work the first time

[terrylgreenjr]

Sorry some are sideways not sure why

[terrylgreenjr]

Pics

[SCOTI]

Nice. How are you liking the ride? Notice a difference vs the leafs?

[RDrancher]

Looks great. Do you happen to have any pics of the notch?

[terrylgreenjr]

The ride seems about the same to me. I did have a full leaf pack plus a 2 inch lift spring before so it was a little stiff before. I can get a pic of the notch but it's jus a basic box tube step notch that the top of it is about 2 inches above the factory frame rail.