Outer Limits 4x4 Board

Whats a good measurement in mm of shock up travel?

Leaf sprung over setup

My shock has 350mm of overall travel and at the moment i have it setup with only 85mm of up.

Thoughts?

Does it bottom out??

Can't you flex it up and inboard them till ya get the droop and compression pretty close to using the complete travel of the shock?

add 50mm from the point the bumpstop makes contact with the diff.

joeblow wrote:add 50mm from the point the bumpstop makes contact with the diff.

I setup in a similar way, except I spec the shock to allow max down travel of the spring and get what you can from the bump travel. I'd work on about 20-25mm on the bumpstops before the shock bottoms.

We work on 30mm bump stop crush, and normally, you set a vehicle up for handling using a 1/3 up and 2/3 down rule of thumb.

Auto-Craft wrote:We work on 30mm bump stop crush, and normally, you set a vehicle up for handling using a 1/3 up and 2/3 down rule of thumb.

Pretty much exactly the set-ups I go for also. Although I am going to be using 4"airbumps which at ride height will be about 1/2" off diff pads.



brooksy

Auto-Craft wrote:We work on 30mm bump stop crush, and normally, you set a vehicle up for handling using a 1/3 up and 2/3 down rule of thumb.

Pretty much the best general setup. Unless you've got some more unique requirement then this is the go.

Auto-Craft wrote:We work on 30mm bump stop crush, and normally, you set a vehicle up for handling using a 1/3 up and 2/3 down rule of thumb.

Just be carefull with the bumpstop compression measurement of 30mm,, i use 80 series cruiser rear bumpstops on the front and rear of my ute and they will "crush" up to 70mm.
they are 145mm free height and 75mm compressed height.

Z()LTAN wrote:Whats a good measurement in mm of shock up travel?

Leaf sprung over setup

My shock has 350mm of overall travel and at the moment i have it setup with only 85mm of up.

Thoughts?

With the style of driving you like ( high speed, big landings ) i reckon you could have a bit more uptravel Tom. Limited compression and lots of droop will work well for a crawler, but for high speed high flying driving the extra travel in compression will give more progressive handling and better control over tuff terrain.

ive managed to set the shocks up with 120mm up so thats 35% up 65% down. Coupled with the right bumpstop i think this will give me the best of both worlds.

steel wrote:

Auto-Craft wrote:We work on 30mm bump stop crush, and normally, you set a vehicle up for handling using a 1/3 up and 2/3 down rule of thumb.

Just be carefull with the bumpstop compression measurement of 30mm,, i use 80 series cruiser rear bumpstops on the front and rear of my ute and they will "crush" up to 70mm.
they are 145mm free height and 75mm compressed height.

Factory style bumpstops as rule of thumb is 50% crush. Progressive style normally have a stated force load & percentage crush.




brooksy

How much uptravel you need really depends on what you are doing with the vehicle.
Rock crawling is going to be completely different to a high speed setup.

Air bumps are very cool - http://www.azrockcrawler.com/_images/te ... bumps.html" onclick="window.open(this.href);return false;

Its an allrounder mate. 50/50 Race style and rock crawling events.

What i had b4 was working well but i was going through front shocks every event.

I think now things should last a bit longer.

Cheers for all the input in this thread guys much appreciated.

zzzz wrote:How much uptravel you need really depends on what you are doing with the vehicle.
Rock crawling is going to be completely different to a high speed setup.

100% on the money. I have also read the pro's making the same comments in articles in relation to uptravel vs down travel.

And the amount of down travel relates weight/spring rate. I think that its better practice to setup with the correct spring rate for what you're doing and get all the available travel from those springs rather than looking for % up/downs.

Slunnie wrote:

zzzz wrote:How much uptravel you need really depends on what you are doing with the vehicle.
Rock crawling is going to be completely different to a high speed setup.

100% on the money. I have also read the pro's making the same comments in articles in relation to uptravel vs down travel.

And the amount of down travel relates weight/spring rate. I think that its better practice to setup with the correct spring rate for what you're doing and get all the available travel from those springs rather than looking for % up/downs.

IMHO, have a ballpark travel (e.g. from available/preferred shockies) and ride height - ride height is a judgement based on use, as discussed in above posts, but possibly limited by regs (e.g. VSI 50) for road use.

From there the 1st pass will start with up travel (from ride height to compressed bump stop) and hence down travel. As per above posts this

Then start looking at available spring free height and rate. The spring is compressed by 'Z' from the free height to static ride height by the static load/weight on the spring (excludes unsprung weight), so target spring rate is:
Spring Rate (lbs/inch) = Load (lbs) / Z (inches)

Available spring rates will probably be higher/lower than what was determined so pick the best by calculating how far it is compressed by the static load:
Z (inches) = Load (lbs) / Rate (lbs/in)

Check new static ride height using the new loaded spring height:
Loaded Height (inches) = Free Height (inches) - Z (inches).

From there if you want to do things properly you should calculate that the wheel frequencies are within acceptable limits as is the ratio of rear to front wheel frequencies - but that could be getting a off topic. I have discussed this in the past in a thread on coil overs in General Tech. The is plenty of info elsewhere - Rancho published a spring selection guide http://www.gorancho.com/assets/applicat ... _guide.pdf that gives the required info together with recommendations on wheel frequency that are in reasonable agreement with others that have a better knowledge on suspension than me, or search on pirate for posts from goat.