Shock travel selection help!

[Fancy]

So i narrowed it down to 2 (maybe 3) shocks im looking at for the front of my blazer with 52" spring swap and 5" shackle in the rear. They are linked by desired order below and are all Bilstiens.

Ok here are some numbers:

It is 24" from lower shock mount to upper shock mount (static level).

If i get shock #1 that gives me about 3" upward travel and about 11" downward.

If i get shock #2 that gives me about 6" upward travel and about 6" downward

However after taking some measurements and play with my axle geometry i am leaning on shock #1 and this is why...

measurement from wheel center to wheel center is about 74". So with the assumption that the center of axle is the rotation angle that leaves a distance of 37" from center axle to wheel center. Lower shock mount measures 16-18" from wheel center (assume 16" to be safe). This means an upward travel of 3" at the shock mount location should net a little over 6" at the center of wheel as illustrated below.

The distance from my tire to fender is only 8" so i thought this should be perfect being that shock #2 would net a little over 12" and i would not be using all of its throw.

SHOCK #1 http://www.summitracing.com/parts/bsn-33-185576/overview/

SHOCK #2 http://www.summitracing.com/parts/bsn-33-185569/overview/

Is my logic correct is my question? what would you choose and why?

This brings me to my last question and shock #3. Is 255/70 valving good for a k5 blazer? Would shock number three be a better choice? it is right in between the two but has 360/80 valving.

SHOCK #3 http://www.summitracing.com/parts/bsn-f4b460350h1/overview/

 

[ccarley]

I'll just give you some info from my experience...

'89 Suburban, Tuff Country HD 4" springs with Bilstein 7100 12" travel short-body shocks up front. I don't recall the compressed/extended numbers...

I was easily seeing 3" of uptravel on the shock shaft driving daily. I think there was 6" of shaft showing, and my axle should hit the big bumpstops before the shocks bottom, although I never pushed it hard enough to hit those bumpstops yet.

255/70 valving is what I have in them now, and it's too light. On large dips, the front bounced (tires stayed in contact with the ground), and on short abrupt hits, I think the rebound was so fast it gave a rough feeling. Washboard dirt was soaked up nice though.

I believe 275/78 is the next step up? Which seems to be the general "should be OK" valving. I picked up a set of 360/80 valves and will be changing to that soon, but I do have the old 5100's installed now. I'm unsure of the valving in those, but it may be 275/78 and feels "OK". They do top out on one road I drive with some "whoops" on it, as they are pretty short even though they are spec'd for the 4" lift.

Also, check allshocks.com; that's where I've purchased all of my Bilsteins. The prices are good and shipping is pretty quick, even with the "custom" 7100's.

Oh and one more thing; I am using the "quad mount" for the 7100's; that's why I could use such a long shock on the front with only 4" lift springs.

I hope this helps,
Clay

EDIT: photo

 

[miniwally]

You can't do shock travel by math, sorry.

Install springs, flex it until the springs are just shy of flat, pick on shock mount or the other to stay and measure off of it. Adjust other mount to work.

Do the same for droop.

Off the shelf shocks work well with moved mounts.

 

[Fancy]

thanks for the input ccarly about the website however i do not see that valving?

After what you have said tho im am leaning towards shock #2.

what made you choose 360/80 valving

 

[ccarley]

Hey I just noticed you are in Santa Cruz; right on dude, I was born there I might be working downtown there today too.

At allshocks.com, I worked a bit with Kevin Foote, and when I did order my 7100's, he had said to just put the valving in the comments of the order. He's pretty responsive to questions. I looked through my email, and using that upper mount my measurement was 22 inches i2i, shock part number AK7112SB.

http://www.allshocks.com/OFFROAD/OFFROAD/2000/AK7112SB

As for the valve stacks, I have been searching and searching for info on what to get. I found some info on dezert-race.com and some full size Bronco forums that seem to indicate heavier vehicles will work good with the heavier rebound. Since the valve stacks are $15 each, and then there's whatever to refill the Nitrogen, it's pretty inexpensive (other than labor) to change out the valves rather than get different shocks; which is the nice thing about the 7100s. You can revalve them at home!

https://www.youtube.com/watch?v=IGCmAzSZz_k

I would definitely go heavier than the 255/70 valving though. It's so light, you would think it's a dual shock valve setup. The 275/78 valving would probably give you a very nice ride even still; it's what I had at all 4 corners in my Wagoneer and it was nice. It's definitely a good starting place.

I have to get my transmission in before I work on my shocks though; but I will be sure to post on how the ride is after the valve change.

Clay

 

[Fancy]

Ya located in aptos actually!

Anyway im talking about just getting some cheep 5125 series shocks for now! I like the idea of the 7100 and may move to those in the future but i just need to get something with more travel and better than my procomps for now.

I plan on moving my upper shock mount location in the future (i have ford towers for now) so when i do that i will spend the money on good shock like yours

It doesn't look like i can order the 5125 series in a custom valve set up? just 255/70

But yes please do get back to my on the valving you like! would be good to know! I understand transmission problems tho... just rebuilt mine

 

[ccarley]

I would contact Kevin at allshocks.com, and ask him about the valving. 255/70 is just too light for the front
[email protected]

When I picked up 5125's in the past, they had a much easier valve selection (3 choices), but it looks like they have a bunch of different valvings in different length shocks now.

Believe me... it will be worth it to go at least slightly "stiffer"!
Clay

 

[muddermilitia]

You can't do shock travel by math, sorry.

Install springs, flex it until the springs are just shy of flat, pick on shock mount or the other to stay and measure off of it. Adjust other mount to work.

Do the same for droop.

Off the shelf shocks work well with moved mounts.

This. I have 52" springs too. I can max out my 15" travel ProComp cheapos. I'm setup for 4up/11down

 

[Fancy]

So here is the deal i am really looking for just a cheap pair of shock to get me by for now that's why i went with the 5125's, there about $80 each im going with the 14" travel for now.

ccarley: After emailing Kevin Foote he was way more help than i needed at this point! great guy tho!

Also i emailed a few other places and Bilstien and found out they don't offer 275/78 off the self in the 5125 series and would be an additional $100 to re-valve. So unfortunately it is going to be 255/70 valving for now however i will be moving these to the back of my rig when i am ready to purchase a real pair for the front so i think the valving should be OK for now.

I am really just looking for the travel at this point since the pro comps i have on there now are only like 8" travel or something small.

unless anyone has any other recommendations, that's my plan as of now

 

[ccarley]

I'm glad Kevin was helpful, he seems to be a cool guy.

Too bad Bilstein doesn't offer that 275/78 valving anymore; but I have a feeling it will work better in the rear once you move them. The 255/70 is "ok" in the front, but you will use a lot of travel in day to day driving. Even still you will be better off then using some emulsion/ twin tube shock.

PS I stopped by burger.aptos the other day; if you have time next time I'm in the area we should have lunch or something!

Clay

 

[muddermilitia]

If you are just looking for something to get you by, why not get a set of the 15" travel Procomps that Summit sells? They are like $30-35ea. Also, keep an eye out on the superlift scratch and dent store on ebay. If you can find the right shock, they are like $7ea. That's what I did for the rear

 

[Fancy]

muddermilitia: ya i was looking at those but i have used procomps and ranchos and just hate those shocks! I even considered the more pricy ones but have just heard way to many poor things about them and everyone praising bilstiens. Plus i can have the bilstiens re-valved if i desire later. Do you drive your rig on the street much? or just for offroad?


Clay: Ya that place is pretty good! i actually live right near there. I'm generally pretty busy but i would definitely be down. let me know next time your planing on being down this way and ill PM you my number