Collapsed shock minimum length question (1 Viewer)

[rc51kid]

I was looking at a chart on Fox shocks and something dawned on me. But please correct me if i am wrong. On full compression the suspension should hit bump stops first, right? I would think that a tire rubbing or a coil spring binding would be bad right? So if running factory bump stops and things are RIGHT in our setup then we should be running the factory minimum shock length. This should be known common resentment that all 80 series with factory bump stops share, right? I mean unless you are binding coil springs or your oversized tire is hitting the body should the suspension compress right up into the OEM bump stop? Does anyone have these measurements for the front and rear on a 80?

 

[scottryana]

That's the ideal situation but with 4" bigger tires; stock vs 315's(30.5"-34.5"), you have 2" more above the centerline of the axle. So to keep the stock Toyota engineered clearance with a 315 tire you should run a 2" bumpstop spacer. Now of course none of us really fall into the Toyota engineered clearance crowd, so some people let the body be the bumpstop. Lol.

Really it's all up to you but ideally you want as much up travel as possible without getting into the body. This is going to vary person to person and truck to truck. If you're in the hot desert and just run slickrock you could probably get away with less body clearance than if you're running chains in the snow. I ran 315's without bumpstop spacers for a while and it wasn't bad but with really heavy loads and g-out type situations I would hear tire to body interference. I went with 1.75" if I remember correctly.

 

[AutoCraft Aus]

405mm front shock comp length is about it on the after first 2 years prod.

395 mm odd rear comp is rear.

Given I have had custom shocks made to fit these lengths with 12" stroke for 80s for ever, though we did got to 30mm longer rear bump stops for larger tyres and then coil block out height for slinky coils to fit in the given space makes 425mm to get 12" stroke with a custom body/shaft set up. This amount of stroke will need sway bar spacers, brackets, and coils that wont fall out as well though.

The better your shocks are, the less "bottoming out" will happen generally too.

 

[Shoredreamer]

My findings show that with 30mm bump stop spacers(in pic), the bump stop and coil bumper hit simultaneously. So, stock bump stops hit after the coil bumper would. This is ideal since in a bottom out situation, the coil bumper absorbs a lot of the upward energy reducing the impact of the actual bottom out on the bump stop. Well designed. Extending the rear frame bump stops 2" would have you hit harder, and hit first on the frame stops in comparison.

Compressed shock length with stock bump stops on rear is 15.5" (16.6" in picture with 30mm spacers)

 

[GW Nugget]

My findings with no coils on the bump stops the longest compressed shock length one can have with 1" of shock shaft left is 16" front & 15.5" rear which is the same conclusion from above posts. These are measured at the insides of the shock collars.

As far as rear bump stops I agree with @Shoredreamer that a 1.25" rear bumps will still let the rear coil cone bumps still play a vital roll in bottoming out the suspension. I now have 2" in the rear & find that it is much harsher of a hit when bottoming out. I need to now lower my rear cone bumps to bring them back into play.

 

[GW Nugget]

This as good as any to post up some questions...

It has been mentioned that adding spacers to bump down the rear cone bumps to put them back into play as designed after one adds frame bump stops past 1.25" is a good idea, I agree.
So my question since I haven't taken my rear cone bumps apart myself what size of material do I need to get.
Has anyone done this?
Has anyone traced out the spacer needed?
Does anyone have access to a spare set of cone bumps to trace out a set?
@Hitit66 would you consider selling some spacers?
Is this even worth the effort?
I remember @DylanICON writing about this subject in another thread.

 

[jcardona1]

Another thing to keep in mind when looking at bump stops and suspension movement...bump stop height for full stuff on both sides (like landing from a hard jump) is different than bump stop height when the axle is articulating from side to side (one side stuffed, the other side fully drooped).

I realize this won't apply to most with a radius arm setup due to the limited suspension movement but on my truck that is 3-linked in the front, this become really apparent. I have 2 stages of bump stop; "1st stage" using the built-in bump stops of my coilovers to control tire-to-fender clearance (side to side flex), and "2nd stage" for full bump using the hydraulic bump stops.

Here's what I mean:

In this photo the passenger side tire is fully stuffed yet you'll notice my hydraulic bump stop is still several inches away from the bump pad (hydraulic bump stop is empty and compressed here but you get the idea).

Instead of using the air bump to limit how far the tire goes into my fender during articulation (full stuff on one side and full droop on the other), I am using the bump stop built into the coilovers:

Using these built in pads works because the suspension travel I am limiting in these situations is slow-speed crawling. You would NOT want to use these built-in pads to serve as a normal bump stop at higher speeds because you could damage the shock.

To set the height of my hydraulic bump stops (the ones that will be doing most of the work), I compress the axle equally on both sides. The bump stop height is then set at the point where it stops the axle and links from crashing into the frame and engine bay if you were to hit a hard landing at speed. This isn't the actual picture of equal bump on both sides, but shows how I determined how far the bumps stops should hang down:

I don't have a photo to show it, but if I compressed the front axle equally on both sides and still had the tires on, the tires would be several inches away from the top of the fender and it would appear as if I wasn't using all of my up-travel. But this is necessary to avoid damaging the axle and suspension when coming off a hard landing.

Conversely, if I used the hydraulic bump stops to limit side-to-side flex AND equal full bump, the bump stops would need to hang down much lower as you saw from the first pic where there was big gap between the hydraulic bump and the pad. This means the bump stop would be at the wrong height and would be hitting them constantly when driving on washed out, rutted roads at moderate speeds. It would get annoying very fast.

Just something to keep in mind as folks start to search for more travel out of their 80s. Proper bump stop length and height was a bit of a mystery for me until I had to set it myself with nothing to go off of. It has since become pretty simple to understand.

 

[jcardona1]

And to further expand on my previous post, I recently went through the same exercise on the rear suspension. My rear suspension is still pretty much stock. I relocated my rear shock mounts to fully utilize their travel more efficiently but the process was the same.

Fully stuffed one side of the axle. Determine where I want to stop movement side-to-side movement. As the rear fenders have less room to work with, stopping tire movement here is more important. This is about as far I could get a 37" tire into the fender:

I then set my rear shock height according to that. Again, using the built-in bump stop to stop the side-to-side movement:

Once I had the shocks set to the right height, I fully stuffed the axle on both sides to see how far I could go before it could cause any damage. On the rear axle you actually have a lot more axle up-travel compared to the front. I then made custom bump stops at that height. On the rear, my full bump and side-to-side bump ended up being pretty close to each other, unlike the front where you have very different heights:

 

[LFD2037]

Install the shocks you intend to use & remove the springs.
Compress the suspension until you have ~1.5" left of the shocks compressed length.
Make your bumpstops this long (the gap between frame & axle bump location).
This will give you worst case scenario bumpstop length.
Then extend the suspension just shy of shock max extension. Make a limiting strap @ this length. This is your max extension.
Then install springs & see if the tires rub. If they do, & that bothers you, now you can extend the bumpstops to prevent rubbing.
This process is time consuming & labor intensive but it is the correct way to get max compression & extension w/out ruining your shocks or subjecting them to over compression/extension.

 

[jcardona1]

I just realized this thread is a year old and I'm talking to myself. Thanks @GW Nugget

 

[GW Nugget]

You're funny @jcardona1. ... this thread would be revalent if it was 10 years old or more. I just didn't want to start a new thread.

If we all agree that the front mounting point to mounting point is 18.5" without coils on stock bump stops and the rear mounting point to eye bolt center measurement is 16.5" while on stock bump stops we have a good starting point on properly spacing out shocks. Then from there you just have to get the listed shock length then add 1" for each collar & bushing then 1" for bump cushion. Again this would be a great starting point & rule of thumb... not exact science. Only way to know for sure is do it yourself.