Dan Wheeler's Rear 4-Link Thread

[Yeller]

I second getting it fully loaded and breaking in the ori's more. It could be not enough anti dive in the front geometry, it would have to be off pretty far to feel unerving. I know mine drives totally different with and without the back seat and tools.

 

[Apogee]

The pedal may always have a little more squish due to the amount of flex hose you're running, but even with that, you should be able to achieve lockup given the heavy rear bias you have on your setup...you are running front GM calipers in the rear, correct?

 

[DanWheeler]

yeah 3/4 ton GM front brakes in the back. I use a bias valve to dial them way down or they'll lock up way before the fronts. I opened that valve up all the way last night but no help. Bout to head home to try re-bleeding and add some weight.

more I think about it, more rear brakes make sense. If the fronts stop but the rears want to keep going forward, it's just going to turn into an accordion. Guess I'll find out.

 

[nvrstuk]

Yep fix those brakes in the rear get them to lock up--fix that problem first then head towards the suspension/ORI potential issues.... I know you know this Dan, but for those on the list that are going to tell me you don't want your rear brakes to lock up - of course adjust the bias

 

[DanWheeler]

well still no luck. Got it loaded down with all the gear, bled the heck out of the brakes, cranked down the damping on the ORIs and tweaked pressures over and over but still no good. The ride is firm - I'm at 100PSI lower and about 280 upper. Hard to figure it could be a shock issue with them being so firm.

I'm having a rough time getting it to sit level, seems like I'm playing whackamole filling the upper chambers on the left and right. Seems like I'm off by about 60 PSI between the sides to get it level. I'm just going back and forth, left side too high then right side too high then left too low then right too low. I guess for all I know, these things could be dry as a bone inside or have different fill levels. I know there's oil in them because a little comes out when I depressurize.

I can't be sure the rears are locking up because it's too late to take it out to a parking lot and not draw attention. I'm wondering if the master cylinder needs to be bench bled since it's been sitting for so long. pedal still feels really soft.

 

[Apogee]

...I can't be sure the rears are locking up because it's too late to take it out to a parking lot and not draw attention. I'm wondering if the master cylinder needs to be bench bled since it's been sitting for so long. pedal still feels really soft.

I would start there...plugged port bench bleed on the MC. I don't recall how much braided stainless hose you're running up front, but I would connect whichever circuit has less flex hose first and bleed it until you get a good pedal. Then connect the other circuit and repeat. This should reduce the number of variables at any given time to a number you can troubleshoot should there be any issues.

I wouldn't get too excited about tuning the suspension until you have good brakes (and steering).

 

[nvrstuk]

X2 what Apogee said... if you have a soft pedal you know you have problems with the brakes so make those perfect and then move to the struts.

If the seals are sticky enough then you can have the same amount of pressure in each side and your rig won't sit level --- just always park on a curb or on the side of a Honda or something and nobody will notice that you're suspension isn't even.

 

[DanWheeler]

Pretty sure I've got the brakes sorted out and it's still doing it even in 4wd which should eliminate any possibility of brakes being the issue since front would be locked to rear.

Hate to say it but I think my geometry is messed up. Too much angle on the uppers. I'm going to have to lower the upper frame mounts or raise the upper axle mounts.

I've got a thread going on Pirate and it sounds like my AS/AL numbers are too low and causing this.

guess I gotta drag the welder back out

 

[Yeller]

Pm sent, give me a shout if you'd like to discuss

 

[DanWheeler]

well I'm back to brakes. I've got the rear tires off the ground and I can still spin them unless I have the pedal completely mashed. Still soft pedal.

I've switched to a different master cylinder, same results. I've bled the brakes so many times now it just can't imagine it's that.

Could it be the brake hoses? They are russel -3 AN. Maybe they are too squishy not allowing pressure to build?

 

[nvrstuk]

Can anybody be pumping the pedal while you are looking at the brake lines??? See if you can see them expanding when pushing on the pedal? Can you throw a gauge on one of the lines at the wheel (caliper) Usually only happens on old lines but either there's a restriction or something is blocking fluid/pressure

 

[Yeller]

Ive been battling the same issue with mine and it's hard lined, I've changed everything but the calipers, even tried different pads. I even removed my proportioning vavlve, made it stop better but pedal is still soft. I really doubt it's the hose. We plumb the racers with 3/16" Poly line (like small nylon air line) and the brakes are always great.

 

[nvrstuk]

Swap the lines on the m/c, put the rears on the front. Also, did you bench bleed the m/c? Sometimes it's hard to get the air out of the m/c.

Important to isolate the issue so you can be 100% sure what the real problem is...

 

[DanWheeler]

OK after 5 hours struggling with bleeding brakes, I finally got the rears to lock up. I swapped in a Corvette M/C I had laying around that I removed because I could never get the fronts to lock up. That just happened to be exactly what I needed to rule out rear brakes.

So with the rear brakes locked up - still have the problem. MAYBE a little better but still not drivable.

Next test was to lower the ride height so the uppers were flat or even angled a little bit down. Well - that did the trick - problem solved.

So I know what I have to do and back under the knife it goes. Only question is, raise the uppers at the axle or lower them at the frame... or a little of both.

I'm going to put this thing away for a while, I've banged my head on every sharp object under the truck and spilled brake fluid at every chance - a little frustrated

thanks for all the help, guys. More updates to come maybe next week. Gotta start looking at bracket options.

 

[DanWheeler]

hey guys, here are my actual numbers as built

 

[nvrstuk]

I'm not qualified at all but I've learned a lot...let Steve or others help you get the IC # dialed in and since the upper needs to flatten out, my .01 says to raise the axle uppers... but I will be interested in what guys that know what they're doing say!

Glad you got it narrowed down... wonder what was wrong with that first m/c you had???

 

[DanWheeler]

Glad you got it narrowed down... wonder what was wrong with that first m/c you had???

who knows - it'll have to go back on (or a new one - this one was a junkyard find) because I remember this Corvette one is weird. With both of them, I just kept getting constant bubbles when bleeding. I've still got a really soft pedal but I think it's more related to the hydroboost and the stroke of the M/C. I'm guessing I just uncovered a different, unrelated issue. My concern is that if my h-boost went out, I wouldn't be able to stop in an emergency. Without the engine running, I really have to mash the pedal to keep the wheels from spinning using my hands. Something's not right but it has nothing to do with the 4-link.

According to the calculator, I get a little more antisquat by lowering the frame mount 2" vs raising the axle mount 2".

BTW - brian, I'm gonna try to get that floor piece cut today and ship tmw.

 

[302BRONC]

I'm using the Ruffstuff adjustable links like yours. The bottom of the bracket hangs about 1.25"-1.5" below the frame rails in the spot yours are. Currently i'm running the link in the lowest hole in the frame side. The uppers definitely slope up to the axle at ride height.

I did have the upper link in the middle hole to begin but i had a bit too much lift off camber. Dropping to the lowest hole cured the symptom. Never had enough lift to notice on braking or acceleration.

 

[DanWheeler]

i'm not running anything ruff stuff on the links that I can remember. My upper frame mounts are these:

https://www.ballisticfabrication.co.../inner-frame-bracket-lower-link-bracket-combo

how did you get the upper frame mount to sit below the frame? any pics?

 

[Yeller]

Dan, now that I've had a chance to look at your numbers, I can confirm our conversation about raising the uppers 2" at the axle as long as it will clear your floor. It will help the load numbers on the links (on the second page of the calculator) a lot, the separation at the axle is pretty close for the gearing and tire size your running.

If at all possible this is the course of action that would take, you will be surprised at the difference that will make in performance on the street and on the trail. I'm a firm believer that the best performing well rounded rigs in the dirt have excellent street manors as well.