Let's talk ifs

Bmxer524 · **Posted:** Wed Feb 19, 2014 2:40 pm

I wanna learn some more about our front end, just for the sake of knowing. CVs are biggest limiting factor correct? After that I'm assuming the a arms contacting springs? With that said then the amount of travel we have will always be the same no matter what. So say we have 10" of travel and stock put us in the middle at 5" up 5" down, then wouldn't a 2" lift only allow for 3" down and theoretically 7" up? Am I understanding this correctly?

tommudd · **Posted:** Wed Feb 19, 2014 5:34 pm

Partly correct in that CVs do limit the amount of travel we can expect to have, but also the suspension design itself. As you mentioned when using an aftermarket set of springs, and sitting it up close to 4 inches of lift on the down travel the UCAs will contact the springs which limits travel overall.
Also depending on what lift is used it will be different somewhat in the amount of travel.
Bilstein and OME front shocks are the same length as stock, where as the Ironman are longer so there should be a little more overall travel. ALSO the JBA adjustable coilovers give more overall travel than regular aftermarket springs.
To have a really nice setup with our IFS a set of upper and lower arms would be needed to push the wheels out to 4-6 inches wider per side ( or somewhere there abouts for general conversation here) then with the right CVs you could have 13-15 inches of travel or more even ( again just for discussion here)

Bmxer524 · **Posted:** Wed Feb 19, 2014 6:58 pm

So what's the point of the extended bump stops up front? No matter what were only gonna tuck as far as stock(talking about OME/bilstein shock setups). The only thing I can see is to stop tires from rubbing when tucked. Or am I missing something here?

tommudd · **Posted:** Wed Feb 19, 2014 7:37 pm

You're missing something
Bumpstops are like an insurance policy so the shocks do not overcompress too far and blow out , same in the front and rear.

Bmxer524 · **Posted:** Wed Feb 19, 2014 7:44 pm

But if the shocks are the same length as stock, how would they over compress? That's what confuses me lol

tommudd · **Posted:** Wed Feb 19, 2014 10:00 pm

Bmxer524 wrote:

But if the shocks are the same length as stock, how would they over compress? That's what confuses me lol

Well you have bumpstops from the factory don't you? They stop the suspension from coming up too far and also so the shocks don't over compress.
Think about it for a little while. You install a lift and what do you do? You have raised the suspension/body up 2.5-3 inches or more, so you install longer bumpstops to keep it from doing the same thing as it may of done stock :banghead:

tommudd · **Posted:** Wed Feb 19, 2014 10:04 pm

The old rule of thumb from back when I started in the 70s was for every inch of lift, one inch of bumpstop. Keeping the same amount of travel of course but lifting for larger tires/ more clearance over whatever you drive over .

Maybe its time for a class, I'll see if my assistant wants to teach it :wink:

Erikg84 · **Posted:** Wed Feb 19, 2014 10:50 pm

tommudd wrote:

The old rule of thumb from back when I started in the 70s was for every inch of lift, one inch of bumpstop. Keeping the same amount of travel of course but lifting for larger tires/ more clearance over whatever you drive over .

Maybe its time for a class, I'll see if my assistant wants to teach it :wink:

Does she do one on one tutoring?

Bmxer524 · **Posted:** Thu Feb 20, 2014 2:03 am

I was just confused as to why we needed extended bumpstops up front when we have the same amount of travel as stock, but if she's gonna help teach me.... :wink:

tommudd · **Posted:** Thu Feb 20, 2014 8:23 am

So now do you understand why you need longer bumpstops or are you only looking at her now ?

TheBlueKJ · **Posted:** Thu Feb 20, 2014 9:00 pm

tommudd wrote:

So now do you understand why you need longer bumpstops or are you only looking at her now ?

Wait she's teaching a class? :ROTFL:

Scar0 · **Posted:** Sat Feb 22, 2014 2:08 am

tommudd wrote:

Bmxer524 wrote:

But if the shocks are the same length as stock, how would they over compress?That's what confuses me lol

Well you have bumpstops from the factory don't you? They stop the suspension from coming up too far and also so the shocks don't over compress.
Think about it for a little while. You install a lift and what do you do? You have raised the suspension/body up 2.5-3 inches or more, so you install longer bumpstops to keep it from doing the same thing as it may of done stock :banghead:

Reading the above in red he is using the same length shocks as stock.
In this case you do not need longer bump stops because the stock bump stops will stop the rig before it over compresses the stock length shock absorber, regardless of spring length. (We are not talking about a clevis lift, OTT, or spacer lifts as those are a different story. We are talking about longer springs for the lift.)
This does not mean he won't ruin the longer springs by over compressing them and slapping them together.

However, Because he raised the rig with longer springs, and did not get longer shocks, he is very likely to do the opposite and "top out" the shock absorber on suspension drop, and blow out the shock absorber that way. In order to prevent that he would need drop limiter straps.(That is if the UCA does not hit the spring and limit drop that way. Not a good thing BTW.)

Now on the other hand, if you install a "spring" lift along with longer shocks. That is a different story all together.
The new longer shocks will not compress as far as a stock length shock absorber, simply because they can not. In which case it is absolutely necessary to also get longer bump stops.

Tom's point is that you need to limit the travel of the suspension to prevent your shocks and springs from compressing beyond what they are designed to, by using bump stop lengths that will do just that. Too short of a bump stop and your shock absorbers over compress and will blow out. Too long and you limit your articulation.
Same is true for drop. If the suspension drops too much it will "top out" the shock absorber and pop them that way, thus the need for longer shocks and/ or drop limiter straps.

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