Anyone running trailing arms? Worth the upgrade?

[Mattchu60]

I am gathering parts for a 85' short box build currently. One thing that has caught my eye is the CPP 73-87 trailing arm conversion.

I did some searches and cannot find much on it. Seems like Hot Rod did a write up on the install almost 10 years ago but that's about it.

Anyways - my main goals for my build is smooth ride along with a 6.0 LQ4 swap and 4L80e. I'd like to do either a 2/4 or 3/5 drop. Trailing arms seem like a good way to improve the rear ride quality and also the ride height would be easier to change (by swapping out spring heights or using airbags).

I would love some input from anyone that has done this - is it worth it? Does it ride nice? Any other thoughts on trailing arms on these trucks?

[Ziegelsteinfaust]

They are a great riding conversion, but at your drive train probable length. I would verify that it will work. On the 64 I had the drive shaft was the same length as the arms. This could be a issue since the OD trans can be quite long. Compared to a traditional non OD trans.

For the same amount of work I would do a parallel 4 link, and not worry about the driveshaft length.

Or if your mildly inventive I watched a friend of mine swap in a Impala tri-angulated 4 link into his truck in a long day. He got some custom tube arms from some place. Set the truck on stands, and set the axle at it's desired height. Then got to making some tabs to connect the new axle in. From what he told me it worked really well, and handled great.

[Mattchu60]

With the driveshaft length mentioned below - why would this be a concern? Does the driveshaft need to be similar or longer or shorter than the length of the trailing arms?

I would guess it has to be longer or maybe same length?

[Ziegelsteinfaust]

From everything I read there supposed to be the same length.

How important it is I truly do not know, but they seem to make it seem like a big deal.

[Mattchu60]

Since last night I have done lots of researching on the length of the driveshaft compared to the trailing arm length. I have found lots of pictures of cars/trucks with driveshafts 6"-1' longer than the arms (driveshaft travels through the crossmember into the trans), and also 6"-12" shorter than the arms (trans is sticking through the crossmember/2-piece shaft that has a u-joint a distance behind the crossmember with a slip yoke). I also read some about the 67-72 short boxes - some guys are running 1-pc shafts that are quite a bit longer than the trailing arms, some are running stock 2-pc shafts which end up being shorter than the trailing arms. Both seem to work fine.

My guess is that the important factor is to make sure your driveshaft allows for enough slip yoke travel to work with a suspension so that its not close to bottoming out at full suspension compression. I think I am comfortable with this, I'll be making a custom shaft anyways so I can get the length set correctly.

[bluex]

I converted mine and I am very happy with the end result and the ride/handling after. The journey to get there however was horrible, but I didnt use the CPP kit. I would recommend that kit over the one I had. I dont think porterbuilt sells the conversion anymore so it doesnt really matter on that point.

I have an OD trans and no issues with my driveshaft (other than it hitting the trailing arm crossmember which was a design issue I had to solve) and its the same shaft I used with the leaf springs.

One thing to remember/know if you ever get to the point where super low, like laying frame is your goal you wont get there with this rear setup. The arms will hit the frame way before the frame gets to the ground. My truck sits the stock front crossmember about 1/4" off the ground and is fairly level when aired out. I was considering how to get it lower but I think I will leave it as is. My ride height is maybe slightly lower than a 5/7 drop. I have 2600 bags all around and it rides higher than I'd like in the rear at pressure so I think I'm going to swap to a 2500 just to get it a little lower at the same pressure.

There is a link in my signature to my swap install. Thanks to photobucket the pics are dead though. They probably wouldnt be very helpful though since I didnt use the CPP kit.

If you can find a 71/72 5 lug rear axle they are the same width as 73-87 and you wont have to weld on the axle perches.