The Stovebolt Site Forums The Shop Area The HiPo Shop 4 link rear suspension

I was looking into replacing the rear springs but after looking over prices, I’d be better off upgrading to a 4 link kit. There are a plethora of kits for the 1/2 ton but few offerings for the 3/4 ton. I see Fabquest makes one that interests me. Anyone have any experience with this company?

https://www.fabquest.com/search-by-t...reet-rods.html

That link doesn’t work for me.
I just did a complete (all 4) spring/shackle/bushing/pin replacement on my 3600 for right at $1000

Yeah, that's about what i had calculated, but for about the same price i can get the 4 link and a set of the Viking coilovers.

This link should work:

https://www.fabquest.com/search-by-...pan-hard-from-full-tilt-street-rods.html

That’s a cool set up.
I can see doing it for street rod, but not a 3/4T thats going to haul stuff.

Some questions come to mind
-what axle tube diameter are the bracket radiused for?
-what rate springs
-are the shocks rebuildable / revalveable

Mine has carried its last load, purely a street rod now.

They're designed for 3" axles, standard spring listed @ 275 but other sizes available. Idk if they're rebuildable.

No need to keep the heavy load leafs and rough ride then!
A 3” tube should allow you to fit just about any 1/2T axle out there. The newer 8lug stuff uses larger tubes.

I ended up ordering the TCI kit from Speedway. They offered the best price and had a small discount and free shipping that saved a couple hundred bucks. Only problem is it's back ordered.

Hey Robert,
You need to stop posting links to sites which have "Add to cart" on them. You almost caused me to hit the button and order that 4 link!
It is kin to sending links from Jim Beam to alcoholics.
Yes, once again, it is "your fault."

Hey man, I'm sorry! lol!

Oh wow! One of the main reasons why I went that route (aside for the cost savings offered by Speedway) was I thought they had a reputation for engineering quality products! I wonder if that issue was resolved? I'm going to call them to see for sure & if not i'll cancel and order the Fabquest kit.

If I were you I would contact the fellow on the post I linked. He has the answer.

I did, sent him a PM on yesterday but he hasn't responded yet. Also called TCI to ask about the issues he listed in his post. The particular tech I spoke with didn't know anything about it. Not feeling comfortable with that response, I cancelled the Speedway order and refocused my attention on the Fabquest unit.

OK, let us know if the member here contacts you. Don't want to be against TCI if they have cleaned up the issue. for 3/4 T Chevy 4 link.

I did hear back from Gary. After his experience I decided to order the Fulltilt unit. They look super simple to install based on this video:

https://www.fulltiltstreetrods.com/rear-suspension.html

Cant wait until it gets here!

What did Gary say? What was the final outcome? Why did you decide not to go with TCI? Did they not fix the problem?

Basically that the TCI unit was a nightmare and took months and numerous calls to the vendor to install. He thinks that Fabquest will be a better choice. I found out that it’s actually made by Full Tilt so I gave them a call and ordered it from them. They’re made to order so it will be a few weeks before I receive it.

Got the kit in this weekend. Didn't have a lot of garage time, but I did manage to get the passenger side mocked up. After removing the leaf springs, the bracket is oriented using the two existing holes on the frame, then marked the spot to drill the remaining holes. I still have to figure out how to mount the pan hard bar, I'll follow up with the vendor to see how that's done.

I noticed the "C" notch in your frame, how low are planning to have the truck set?

Can't see the whole notch and don't know if it is finished, but if I am seeing it correctly, it is about 65% weaker than the rest of the factory frame and could cause a catastrophic failure. Especially with the "Hot Rod Street machine" you seem to be building.

I'm with bartamos on the notch. With over half of the frame height cut away, you've severely compromised the strength or the frame. Strength is dictated mainly bu the depth of the section.

It's a mini c-notch installed on the opposite side. I had initially decided to notch it and flip the rear but in doing so it only left me with about 3" of travel. I didn't feel too comfortable with that fearing that it would bottom out. The pic below shows how low it was. I want to raise it about two inches from what you see there.

That's' a bad installation of that "mini" c-notch. That part is designed to be bolted in, not as a boxing piece. You've got some sharp transitions to the frame flanges on the inboard side that cause stress risers that could initiate cracks on the frame flanges, not to mention some less than smooth welds (I guess I did mention those).

Was the frame modified like that when you bought it? I understand your wanting to raise it 2", it was pretty close to the axle. As Kevin and Bartamos have said the "C" notches were not meant to be reversed and welded in that way, you may want to look at that. The 4 link kit looks to be a nice part, clean welds and nice ends. Keep us posted on your plans...

Bartamos: Some good reading, my frame is not notched so I don't really have an input in this. I know people who have done this though, one with some very bad results after being rear-ended at speed. Food for thought.

Yes food for thought.

Thanks for the insite on the notch. I’ll have someone to reenforce that area for sure, especially since the coil overs and pan hard bar will be in that general vicinity.

Progress has been slow, primarily because I've been waiting on the correct panhard bar to be shipped by the vendor. While I was waiting I did go ahead an fill in the notched area with a piece of 1/4' steel from the old leaf spring shock mount so I'm pretty confident it's solid.
I am trying to figure out the best place to mount the panhard bar to the frame. It is a universal bar & will definitely have to be shortened, but does it matter if it's on top, inside or bottom of the frame rail?

Progress has slowed to a crawl on my 4 link install. Still mocking things up, had the drive shaft shortened and realized the axle yokes were different & the ujoint wouldn’t work. I picked up a different one not thinking that the newer one wouldn’t fit the driveshaft and foolishly threw the old one away so I have to figure out which joint will work. It dawned on me that the old rear was also an 8.5 so I decided to just swap the yokes. This leads me to a couple of other potential issues that I need some advise on:

1. In my haste to remove the yoke, I didn’t count the threads before I removed the nut. What do you recommend I do as far as tightening it up.

2. As you can see there is a little play on the yoke. Is this normal?
https://flic.kr/p/2kh2mTn

The differential yoke nut is tightened to a torque spec. Probably 150 ft lbs. Check that spec. The rotational "play" you are showing has nothing to do the the tightening of that nut. You are feeling the pinion/ring gear backlash. The tightening of that not can have an affect on the axial end play/preload of the pinion gear if the backlash is previously set. Tighten it tight and you are done.
You may want to wait for other answers before tightening to 150.

Also search "phasing" of a drive shaft to be sure you install it correctly.

Thanks Bart. I'd searched on line for the specs and the numbers are all over the place. I see anywhere from 10-12lbs to 24 lbs to your 150lb suggestion.

What you are reading is the set up spec for someone doing a ring and pinion and bearings install. When doing the new gear set, you tighten the pinion nut until you get 12 - 20 INCH POUNDS (depending on old or new bearings) as a "rotating torque" for the pinion shaft. Meaning, you rotate the yoke and the whole gear set up by using a inch pound torque wrench on the big nut to see what it takes to turn the whole diff. This confirms the correct preload on the pinion bearing. Some diffs have a crush sleeve, some don't and so on.
Search as if you were installing a new pinion seal and you will see that some say to use a new crush sleeve. Dana 44 has no crush sleeve. Most will say you need to recalibrate the "rotating torque". I believe you will be OK to just tighten to 150 ft lbs. I don't know what diff you have but over torque would be bad. Some specs go up to 250 ft lbs. Marking the nut before removal would not have technically helped.
See what others say.

What Bartamos says is correct. On replacing a yoke on a crush sleeve differential, I've seen some procedures calling for checking rotating torque BEFORE removing, then tightening the new yoke nut till the rotating torque is just a few inch-pounds above the original number. They also specify that you CANNOT back off the nut if you overshoot, and if you do overshoot, you need to install a new crush sleeve. On a differential that uses shims for bearing preload, it's much easier. You just tighten the new nut to spec, although I've seen specs up to 450 ft-lb (Dana 80's for instance). The issue with getting that much torque on a nut is being able to hold the yoke stationary while torquing. And DO NOT use an impact wrench.
You need to determine if you have a crush sleeve or a shimmed differential and proceeding accordingly. If it's a crush sleeve type, using a new crush sleeve and torquing a NEW nut to factory preload rotating torque would probably be your best approach.

If you can make the panhard rod longer and horizontal, you will have less bump steer, even on the rear end, axle will stay more centered with differing loads.

Ed

Thanks for the tip Ed. Although it’s hauling days are pretty much over, less bump steer is always welcome.

Anyone ever use the Watts link from Speedway motors?

This video on YouTube was quite helpful in regards to setting up the a panhard bar. I’ll be making some modifications this weekend.

There, that should do it. Couldn’t get it perfectly level but close.

I took it back apart to put on a coat of Por-15 and to have the 4 link brackets welded to the axle. That leads me to a question on welding costs. The shop that shortened the drive shaft for me said they would do it for $120 mig or it tig. I also checked with a mobile welder, he would charge $275, $55 of that would be the travel fee. That seems like a bit much just to weld two brackets ($275) or am I out of touch with welding charges?

That should track much better... As for welding, the hourly rate here locally is $75.00, that's me taking it to them. Another thought would be to buy a small welding unit, no doubt you will use it again.