Zbroz 36" a-arms and rear skid geometry?

AaronBND · Dec 14, 2018

Those with Zbroz 36" front end and shorter shocks, did you drop your skid to the lower holes and run anti-stab wheels or does it do ok without doing this? Finally figured out with the help of a guy on here that the the Zbroz 36" a-arms and the way it rides so high with them on, that it can really mess up the rear skid geometry and it getting up on the snow correctly. Torn between getting new a-arms or dropping skid down to lower holes and running anti-stab wheels.

MTNRCR · Dec 14, 2018

I run 36" Zbroz. Take a look at Skinz video on setting up suspension using scales. You will not need to remount rear skid to make the sled amazing in the snow. you will need to make some changes but not remounting. Yes you have the correct length front shocks at 16 1/4"

AaronBND · Dec 14, 2018

MTNRCR said:
I run 36" Zbroz. Take a look at Skinz video on setting up suspension using scales. You will not need to remount rear skid to make the sled amazing in the snow. you will need to make some changes but not remounting. Yes you have the correct length front shocks at 16 1/4"

What do you mean by some changes? Also, you running the swaybar or not?

MTNRCR · Dec 14, 2018

it will take limiter strap length changes. spring adjustments are very critical. Once you put one of these on a scale you will be amazed at what 1/2 turn on a spring does to sleds balance. Yes I run sway bar and Zbroz spring set.

diamonddave · Dec 15, 2018

Out of curiosity, what kind of shocks are you running?

Watch all 4 parts I think it's part 4 you may be looking for.

https://www.youtube.com/watch?v=O8FFQHetosw

tdbaugha · Dec 15, 2018

AaronBND said:
Wrong! I have the proper shocks that are 16-1/4" for the arms. Still rides pretty high and messes up the rear skid geometry. The track doesn't even touch the floor until behind the front shock lower mount point.

You have the "correct" length shocks per z-broz recommendation, yet it still rides too high in the front and screws the balance of the sled.

Maybe the z-broz recommendation isn't correct? Maybe you should just shorten the shocks so you have a legitimately correct ride height and overall balance. Problem solved.

frntflp · Dec 16, 2018

I'm confused. I just changed over my stock front end to a z-broz 36" front, using stock shocks with zbroz 2 stage springs and no sway bar. No other changes.

Should I expect to need to make a number of adjustments ? And to what ? Limiter strap, rear preload ? Or something different?

Sled is a 18 Pro 155 SC.

Tnx !

AaronBND · Dec 16, 2018

Did you shorten your shocks at least?

AaronBND · Dec 16, 2018

diamonddave said:
Out of curiosity, what kind of shocks are you running?

Watch all 4 parts I think it's part 4 you may be looking for.

https://www.youtube.com/watch?v=O8FFQHetosw

Mine is going on the scales tomorrow. I will report findings.

rydningen · Dec 17, 2018

Another option is to try to run proride spindles, it will lower the front end.

I found the same thing running zbroz 38’’ width and fox rc2 shocks, even with allmost no air in the shocks i thought it was to high in the front and messed up the rear, and yes, the shocks are the correct setup and length

frntflp · Dec 17, 2018

AaronBND said:
Did you shorten your shocks at least?

No change to shock length. Was told by Z-Broz that I could run the stockers.... [WE Piggy Backs, that came on the sled from Pol].... for now. I also installed the Z-Bros 2 stage front springs. [I can see how slightly longer shocks on the front compared to the 16.25 ideal length has potential to push the front end down farther].

Anyone know the full length of a '18 WE Piggy Back shock ?

Watched the video from Skinz referenced above. Trying to figure out how to put together a simple system of 4 bathroom scales to see the weight distribution. Will report back.

AaronBND · Dec 17, 2018

I bet your lugs aren't even hitting the floor until behind your front skid spring.

frntflp · Dec 18, 2018

Will soon find out ;-) I have scales with remote readouts on the way (found on Amazon for $30 ea). [Didn't want to buy 4 scales but riding time is short and valuable, so I'm trying to be as prepared (in advance) as possible].

Going to be measuring and balancing out the weights with spring preloads based on the guidelines in the SPG video suggested above. Objective is roughly 150# on each ski, and the rest balanced 50/50 between front and rear track shocks of the rear skid. Adjustments will be based on rider on sled.

Rear springs are stock..... Z Broz is selling stiffer springs for the front shock of the rear skid on the grounds that the orig is too soft. Any one have this experience ?

AaronBND · Dec 18, 2018

Did the whole scale thing yesterday. Sled by itself with 1 gallon gas and full oil tank is #438lbs for anyone that cares.

I ended up being 43% front and 57% rear in the end which should be close. Very, very sensitive just moving scales or feet back on the rails even 1/4". This is with 8 gallons total, tunnel bag installed and me on the sled standing up just like I was riding it. Kinda fun seeing how everything reacts to different scenarios.

kidwoo · Dec 18, 2018

AaronBND said:
Did the whole scale thing yesterday. Sled by itself with 1 gallon gas and full oil tank is #438lbs for anyone that cares.

I ended up being 43% front and 57% rear in the end which should be close. Very, very sensitive just moving scales or feet back on the rails even 1/4". This is with 8 gallons total, tunnel bag installed and me on the sled standing up just like I was riding it. Kinda fun seeing how everything reacts to different scenarios.

Now you've got to put all the stock stuff back on and repeat the process to see if the front/rear bias is changed by the zbroz arms like you postulate. :face-icon-small-hap

AaronBND · Dec 18, 2018

Won't be able to tell that by scales. That's just a simple front/rear percentage ratio. That will be known by riding it and seeing how it does in deep powder. From what I have heard and read the Zbroz drop out in the front while sidehilling and make the sled trench worse. Have to blip the throttle to keep the front end from diving downhill. We'll see.......... The scale thing was for there dual rate springs on the front shocks to see where I was at with preload.

kidwoo · Dec 18, 2018

Ah. gotcha

How do a-arms cause trenching? I was assuming (maybe incorrectly) that you were saying they put too much weight bias on the rear from perching the front of the sled up too high, and that's what you were checking with the scales.

MTNRCR · Dec 18, 2018

Those are pretty good numbers on the scales!! Its really interesting to see the effect of small suspension changes. Thanks for posting results

frntflp · Dec 19, 2018

kidwoo said:
Ah. gotcha

How do a-arms cause trenching? I was assuming (maybe incorrectly) that you were saying they put too much weight bias on the rear from perching the front of the sled up too high, and that's what you were checking with the scales.

I'm learning and thinking as I go here - but in my case, I am still using my orig factory shocks (for the 39" arms). So they are little longer that "ideal". This means that the front skis could end up too heavy and pushing down farther into the snow, then I can see the skis diving ..... and not enough pressure on the track, particularly in the front. The resulting increased attack angle (remember front of sled is higher relative to the track) would just dig a trench rather than climb up and out on top of the snow - I think .... what am I missing here ?

Balancing the preloads out using scales to something close to the "preferred" balance and weight distribution will help the suspension better act/react to the different demands of running in deep snow. Perhaps we are saying the same thing ? Again, learning as I go....

AaronBND · Dec 19, 2018

The bottom line for this thread is that I had my new zbroz dual rate springs preloaded to tight. It was holding the nose way to high compared to stock. Once I talked to a couple reputable people in the industry they both said the a arms would really mess up the rear geometry because they didn't agree with the design of them and had a lot of customers get rid of them because of side hilling and trenching issues caused by them. I have yet to ride them, but will keep this post updated. I used the scales to get my balance point with these dual rate springs. It looks right now, but the riding part and a arms is still unconfirmed.

Zbroz 36" a-arms and rear skid geometry?

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