bump stop design/what to avoid (1 Viewer)

[jeremy56]

Folks, I just installed my new Dobinsons tapered 2.5 springs and I have bumpstops in the coil housing (front and back) but the frame rail bumpstops are missing from the OEM location. I was going to order the Slee bumpstop spacers for the rear but have no rubber there anyway. There are various aftermarket bumpstops for sale and I will have to make something. My question is, what do I avoid in the meanwhile? Wouldn't I have to do a lot of articulating to even worry about the 6 inch shocks? How do I determine what length to make the bumpstops coming down off the frame?
FWIW both of my oem front springs were broke near the top and springs were in bad shape all around. Im likely going to have a lot more than 2.5 inches from where it was. Its still on stands waiting on other additions before I can see what total gains are all around.

 

[inkpot]

Most folks just put a 2-3” spacer under the factory snubbers.

 

[White Stripe]

Flex it out until it almost rubs and then take your measurements to see what length bump stops you need.

 

[cjmoon]

What size tire with your 2.5” lift with 315 maybe a 1” spacer or 2 depend My on the run point when you flex it. 285 you prabably do not need to worry about spacers with the oem stops. I have a set of oem on the shelf.

 

[-Spike-]

The spacers are there to protect the shocks first, body second. Everything has to work together, or it won't work at all. What works for some setups won't work for others.

 

[MoJ]

The answer depends on tire size, not amount of lift. No matter how much you lift, you’re still trying to put a tire of x size into a wheel well of y size. A 315/75/16 (35-ish) typically takes 2” of bump stop drop in the rear to avoid rubbing at full stuff. The emphasis is on FULL stuff as you can complete many moderate obstacles without rubbing while using factory bump stops. Of course actual versus calculated tire size makes a difference. I’ve never found a need to drop the fronts with 315’s. A 285/75/16 (33-ish) works fine with factory bump stops.

 

[-Spike-]

The answer depends on tire size, not amount of lift. No matter how much you lift, you’re still trying to put a tire of x size into a wheel well of y size. A 315/75/16 (35-ish) typically takes 2” of bump stop drop in the rear to avoid rubbing at full stuff. Of course actual versus calculated tire size makes a difference. A 285/75/16 (33-ish) works fine with factory bump stops.

Not only tire size. If you overcompress the shocks you'll damage them. Shocks are usually sized to the lift. Bumpstops are very lift-dependant.

 

[MoJ]

Not only tire size. If you overcompress the shocks you'll damage them. Shocks are usually sized to the lift. Bumpstops are very lift-dependant.

For concerns of rubbing, it’s only tire size.

 

[-Spike-]

For concerns of rubbing, it’s only tire size.

I didn't see anything in the thread about tires. The OP asked about shocks.

The bottom line is, take out the springs, cycle the suspension, measure, fab. Or go with proven designs that mirror your setup.

FWIW you may not need bumpstops other than in the coils.

 

[Sharky1528]

It sounds like his Original bump stops have rusted away and with the price of Mr. T’s replacement bump stops I think the OP was wanting to know if anyone had a source for Aftermarket “ Less Expensive “ bump stops that were available in different height’s that would bolt to the factory location....

 

[jeremy56]

I was out of pocket thanks for the reponses. I'm running 285s at the moment and will probably keep them with the mountains here unless I can regear later.
I'm concerned with ruining shocks on moderate forest obstacles not necessarily wheeling. Sounds like this is not the case and I would have to be really stuffing the tire to get to that point. My oem bumps are gone and broken bolts where they were.I have sourced some easy to fab alternatives just curious how one figures out drop and so forth. If taking the springs out is the best way I'm not going through that again for a minute. I'll just hit the hills and see where my flex is at, slow with a spotter to see the areas of concern.

 

[cjmoon]

I’d go slow and figure out where you need them. I’m running about 3.5” of lift with small body and suspension lift. no bump stops at all with 315 and only minor rub. But I don’t treat it like a prerunner. Shocks do bottom out but go slow when in those situations. Some shocks have small bump stops to protect the shocks under light bumps but had could distroy shock or mounts and what not. My shocks to have small rubber isolators that I do hit

 

[Biggreener]

Source a set of OEM bump stops from a wrecking yard, and ad 2" spacers--should be a cost effective way to get what you're looking for.

 

[baldilocks]

You got the Dobinson 6” shocks with 2.5” taperd coils? That’s what I got with my 3.5” taperd coils and I would think that shock will allow the coil to completely unloaded leaving it loose and flopping at full droop. Also, up travel will be more limited.

You would be wise to follow the earlier suggestion of removing your spring and cycle the axles through every possible scenario to avoid damaging the shocks, the body and the tires.

I was unaware that dobinson paired those long shocks with the 2.5” taperd coils.....

 

[Qball]

With 4 inch shocks you will only need 1.25 inch spacers, you probably will need 2.5-3 inch spacers for 6 inch shocks because the shock body is longer. For 35s you don’t really need spacer as it really hardly rub at all and the 1.25 inch spacer will take care of that. 37s will need 2 inch spacers or more depending on tire and rim combo.


If you wanna go fancy hen call king’s and get their 80 specific hydro bump stop, no spacer will be needed.

 

[jeremy56]

You got the Dobinson 6” shocks with 2.5” taperd coils?

Yep, its perfect for the 285s. If I go up to 35s I would want a regear so it's great for my application. Sitting at around 3 inches right now but barely hit the ground so I expect a little settling

 

[David Otero]

You got the Dobinson 6” shocks with 2.5” taperd coils? That’s what I got with my 3.5” taperd coils and I would think that shock will allow the coil to completely unloaded leaving it loose and flopping at full droop. Also, up travel will be more limited.

You would be wise to follow the earlier suggestion of removing your spring and cycle the axles through every possible scenario to avoid damaging the shocks, the body and the tires.

I was unaware that dobinson paired those long shocks with the 2.5” taperd coils.....

Jeremy went with our 4"-5" shocks to pair up with the 2.5" tapered coils.

This is what i have in my notes for bump stop extensions for those shocks.

4"-5" shocks:
GS45-912 needs about half inch of bump stop extension with a minimum of 525 coil length
GS59-687 - needs a 2” bump extension approx. With a 505mm minimum coil free height to stay trapped

But that is to protect the shock from bottoming out, i would think that tire size also plays a role on the size of the bump stop extension.

 

[DirtaddictLC80]

How do you test for over-compression of the shocks? That is, How much is too much?

 

[jeremy56]

I don't think I can get full droop with sway bars in and the arm design, the springs are pretty damn long, I don't see them ever coming out of the buckets....especially with as far as I had to lift the frame to get them in. I guess that's the beauty of the tapered design.
I was a little nervous about tackling this job by myself but its super easy...........if it weren't for broken bolts and stubborn brake lines it would have been half day in the garage. turned into about 2 days of drilling and extracting

So measure my shocks collapsed length and see where my axle needs to stop travelling up to determine where the rubber should be and add an inch or so for rubber reflex? Can someone give me a measurement of their OEM mount and rubber and I will add 2 inches as suggested to start with and then may fine tune it later according to flex.

I stand corrected. I thought I had 6 inch shocks looking at part number and with Davids notes now I see. I am really impressed with the size and quality of the shocks. They make the bilsteins that were on there look like they belong on a KIA.

 

[Lumpskie]

@jeremy56 @baldilocks
FWIW, the free height of the 2.5" and the 3.5" Tapers coils is only about 1/4" different, according to the compiled suspension thread.

Jeremy,
I am interested in the 2.5" tapers as well. Do you have any pictures or any hub to measurements you could share with me? (I'd love to hear your impressions of the springs after you get out in the rocks too!)

Thanks,