Adding front bump stops?

[Fifty]

Anybody have any ideas on adding front bump stops with factory arms?

Offroad, and even just crappy roads on road and the front just gets hammered.

Even with a 2.5” coilover and 600# spring and the bump on the coilover shaft… it’s just not enough.

I truly wonder if this is why the magnetic shocks don’t last very long on our vehicles.

 

[Oh Kee Pah]

@Fifty -> what 2.5" coilovers are you running?

I was told straight away by BDS Suspension that "upgraded" front bump stops are NOT recommended. Would probably make for an even rougher ride. An example is the Timbren SES Suspension Enhancement System.
https://timbren.com/i-30497743-timb...e=CHEVROLET||model=TAHOE||submodel=ALL MODELS

Perhaps take a look at the Timbren "Active Off-Road Bumpstops"
https://timbren.com/p-35852-active-off-road-bumpstops.html

Unfortunately, Timbren does NOT produce this product for or GM rigs

 

[Fifty]

Bds only wants to sell bds. It is what it is.

But that kit may work awesome

I’m running the ads coilovers.

They have a little more travel than stock, which is nice. But my wife drives like it’s a tank or bulldozer.

They are off for a rebuild right now and a little stiffer high frequency valving. But a set of bumps to stop the bump on the shaft from hammering the main seal would be nice!

 

[Fifty]

Huge thank you btw!! Ordering those fronts now

 

[Oh Kee Pah]

@Fifty -> Keep us posted. I too have had similar thoughts on the front bump stop, hence my research leading you to the Timbren stuff. I'm running the 4-6" Fox 2.0 coilovers (set at about 4.25"). Going to try to contact Fox and see if they will provide specs on my coilover's spring... Looks like the majority of front bump stops are applied to LONG TRAVEL front kits. ie: Baja designs, etc. I'm thinking your new valving may solve the problem all together.

I spoke with a BDS tech rep a few weeks back and he had recommended using chalk to confirm that suspension was are was not bottoming out. I was looking at rear charged off-road bumps at the time.

 

[Fifty]

Chalk?
Does your coilover have a bump on it?
Just move it to the top of the shaft and see if it makes it to the bottom. I’m attaching a pic of my rear shock. I wanted to see how much travel I used during a certain drive.

I keep forgetting you have the bds kit. I was going to ask you to give me a measurement from the center of your wheels to the lip of your fender.

That will give a “ride height” that is not tire size effected, and bypasses the “ 2inch advertised or 4 inch advertised” lift estimates.

Actually, if you get a chance can you measure front and rear center of wheel hub to fender lip front and rear?
I’ll go do mine as well.

 

[Fifty]

I found some notes. This is for a 2015i GMC Yukon XL, 4wd, 6.2l 8 speed with 275/65/18 cooper atp 2 at 38 psi.

With z71 rear springs:
Rear ground to lip is 38 1/4

Rear Center of wheel to lip 22 3/4

With ADS coilovers, 600# springs, I adjusted the preload to give me these numbers:

Front ground to lip 37 1/4 and center of wheel to lip 21 3/4



Oem rear ground to lip 37

Oem front with 1.5” level 36.5

 

[Oh Kee Pah]

Back in Maine on Saturday (visiting grandma and grandpa in FL!).
Will take measurements once we get things settled back in

PS - had fun in grandpa's '73 gold 454cu Stingray!!! NOT the Tahoe

 

[Oh Kee Pah]

@Fifty - apologies for the delay. Just feel "caught-up" and what do you know, snowing again.

I spoke with Fox, and they were informative. More than I thought they would be; but perhaps that's because my Cognito branded Fox 2.0 adjustable coilovers are now no longer being sold. Cognito offering 4" and 6" specific for their kits now.
Anyways, they told me that the Front Fox.0 IFP Adj. coilovers (4-6" lift) are shipped from the factory preset at 6". I had mine brought down from factory for sure. Not 100% sure where they came down to. I had that written down but now can't find details. I want to say something like 1/2" on the preload = 1" ride height change to the vehicle. Forget how many turns equals 1/2"...
That being said, my gut says I'm somewhere around 4-4.5" inch ride height realization from the Fox coilovers.
They also told me that the springs are produced by Eibach, and are rated 600 lbs. Travel was 4.89"; not sure if she was referring to the shock or the actual coil.

Measurements (it was cold, had a pretty shaky time getting the hub to fender measurements) Also have the z71 rear springs installed on my '15 Tahoe.
Front: 41 3/4" - ground to fender lip
approx. 25 1/4" - hub center to fender lip
Rear: 41 5/8" - ground to fender lip
approx. 25 3/4" - hub center to fender lip

Compared to your supplied 2015 GMC Yukon XL measurements:
Front: I look to be avg. of about 4" ride height increase
Rear: 3" ride height increase

My original measurements on my 2015 Tahoe LTZ with Max Tow rear springs and Magneride shocks at all 4 corners:
Front: 34 3/4" - ground to fender lip
Rear: 36 3/4'" - ground to fender lip


Any updates on your new valving with the ADS coilovers?

 

[Fifty]

Not yet. They were supposed to be shipped yesterday but I have a feeling they forgot to extend the reservoir hoses and did it after i asked them to confirm it yesterday.
So that means I won’t get them until Friday or Saturday.

 

[Fifty]

Ok.

So I got everything back on and tried the timbren bumps.

The bumps are huge and where they contact the lower control arm, it’s skinny.
The other problem is the bumps contact the arm at ride height, and that’s even with the coilovers having lifted the front an 1 or so over stock.

Ride became very stiff and raised the front, making it so the coilover had very little droop available. That will make the ride suck.

I didn’t want to drive around hoping the bumps will settle.

I reached out to timbren to see if they think the bump rubber material will stay together if I cut the bottom third out of it.

They asked me to send pics and measurements. Maybe they will send a new shorter bump?

I reset the “bumps” on the shocks to see how much shock I’m using on daily driving. The front is everything. The rear is what you can see on a 10” travel shock.
The front is a 4.9” travel coilover which is standard for king, fox, ads. I would like to see if there is a droop block that can be taken out to get “extended travel” numbers which is another .5 inch.
I’ll advise.

 

[Fifty]

Ok. Sorry for the delay.

I cut an inch out of the timbren mount. Hoping that would be enough to work, and it would give me more data.

Yea. Still terrible. And the sway bar, even with the their extension parts hit really bad
.
So I reached out to Perry’s bumps to see if they could sell me a skinnier bump to sub in.

I started taking measurements and calculating travel at the lca where the bump will hit etc. And cycling the suspension etc.

So here is the crappy thing. I cut an inch out of the timbren mount. And if I don’t run a rubber bump, the lca will just “kiss” the bump mount at full compression.

So that means I need to cut it shorter. And get the squish number for the bump rubber and make those numbers match etc. so the bump rubber will fully squish before the shock fully compresses.

I think I’m going to go with a 1.5” or 1.75” thick bump.

But this explains why timbren completely redesigned their bump mount. It’s shorter.,,

Kind of pisses me off that they won’t send me a set since I brought this to their attention and they redesigned the part.

And to the snow plow people. This set up would not work. You will be fully extended with no droop, and your entire front end will be using the upper control arm mount to carry it. It is not designed for that. At all.

The bump if properly designed will share that worst case scenario for short events. Not a constant load