HELP ME MEASURE MY CORNER WEIGHTS

[JEEPKEVIN]

So, I have my rig for the most part figured out. The chassis is sitting on a table, engine, trans, t-case mounted, radiator will sit in place. The suspension is all in place. I just have 2 tires on the rig and suspension full flex so that I can allow for tire clearance and room for shocks during the build.

I have chosen a shock company and they are ready to build but they want me to provide unsprung corner weights so they can valve accordingly. That's where I'm a little confused. I have an engine hoist and ordered a 660lb digital meat/game/luggage scale off Amazon. It was cheap, maybe a mistake. But If I grab any corner of the rig, I'm really picking up more than the weight of just that corner. The chassis is just going to pivot diagonally on the table.

I have a chart with engine weight, trans, t-case, all the tube. I can guestimate my total weight, I can throw a floor jack on either side of the lower chassis and get a balance point. Then I can get a weight balance, %, or whatever you want to call it, but I still don't have an actual corner weight.

If I put all the tires on it and let the frame drop down and rest on the links, if I lift one front corner I fell like I'm really picking up half the vehicle, not just one corner.

How do you think I can get some kind of accurate number? The shock guys don't charge to valve for me, but have to build something and are willing to start me off in the ballpark. I would like to provide some kind of accurate number. I know the shocks aren't going to be perfect/magic from the get go. Might as well order the spanner wrench with the shocks for future changes.

I'm guessing my complete chassis would be between 1750 and 2000 lbs complete, then somewhere in that range for axles and tires.

The internet said I should drive up on a bathroom scale? Build a fulcrum arm, result is a ratio. Should I go buy 4 scales instead?

What did you do?

Thanks!!

 

[bbtank45]

Save yourself the headache and wait till you have everything done....filled with fuel, typical passenger, all tube work, topped with fluids. Variations in that will change your corner weights. I use a lightweight spring and mock it up on the coilover, then calculate your corner weight based on the compression of that spring. Example: 150lb/inch spring that compresses 4" is a 150lbx4 = 600# corner

 

[smbroady82]

Honestly I would find someone who races circle track, dirt or pavement. They usually have to have their weights dialed in within a few pounds. My future father in law races and they have scales for the race cars for each corner.

 

[RustyC]

The angle of the shocks will effect the springs needed. Wait till you get them mounted. Then find someone local with a pair of springs and use them to weight the --sprung weight-- of the chassis. Then call Ryan at AccuTune Offroad or another vendor who and get you the springs needed. It's worth the effort.

 

[Rokcrler]

Re: Re: HELP ME MEASURE MY CORNER WEIGHTS

Honestly I would find someone who races circle track, dirt or pavement. They usually have to have their weights dialed in within a few pounds. My future father in law races and they have scales for the race cars for each corner.

That measures total corner weight (sprung and unsprung)
Need unsprung for springs

 

[JEEPKEVIN]

The shock guy wants unsprung weights for valving. I'm comfortable figuring out springs, I think, and several venders do spring exchange which really helps. I will wait on springs for the time being but was hoping to get some kind of numbers so I can get in line to have the shocks built.

 

[smbroady82]

Re: Re: HELP ME MEASURE MY CORNER WEIGHTS

That measures total corner weight (sprung and unsprung)
Need unsprung for springs

Good call!

See..right there.....that's why I keep you around

 

[whiskeymakin]

That a goat built sub frame?

 

[Bebop]

http://accutuneoffroad.com/articles/how-to-calculate-new-preload-and-springs-by-using-existing-springs/

Everything you want is right there.

Borrow 4 springs and bam

 

[JEEPKEVIN]

That a goat built sub frame?

Yup. Nice product. Took 2 magnets to hold entire subframe together on workbench. Laser cut and keys together. Makes a real simple and quick start to a project.

 

[JEEPKEVIN]

Save yourself the headache and wait till you have everything done....filled with fuel, typical passenger, all tube work, topped with fluids. Variations in that will change your corner weights. I use a lightweight spring and mock it up on the coilover, then calculate your corner weight based on the compression of that spring. Example: 150lb/inch spring that compresses 4" is a 150lbx4 = 600# corner

I think this idea might work best. I'll get 4 springs under the vehicle and measure compression. Fun part will be rigging up something to hold them in place.

I have some OEM Jk springs. I can sit on them while on a scale to get a baseline then transfer to under buggy. Wife is prob gonna ask questions why the scale is in garage and why she is sticking a tape measure under my ass and measuring. Wonder if my wife can even read a tape measure? Hmm. Everybody learning something new this week!!

I know my weight will change, still other parts to add, I just want to get shocks ordered, not springs.

Thanks!!

 

[TacomaJD]

I think this idea might work best. I'll get 4 springs under the vehicle and measure compression. Fun part will be rigging up something to hold them in place.

I have some OEM Jk springs. I can sit on them while on a scale to get a baseline then transfer to under buggy. Wife is prob gonna ask questions why the scale is in garage and why she is sticking a tape measure under my ass and measuring. Wonder if my wife can even read a tape measure? Hmm. Everybody learning something new this week!!

I know my weight will change, still other parts to add, I just want to get shocks ordered, not springs.

Thanks!!

He is saying go ahead and buy your coilovers in the length that you want to run, but you only need 4 light test springs (probably at least the length of the shock travel - 16" spring for a 16" shock), and use the dual rate stop ring to only run the spring on the bottom of each coilover. Mount the coilovers with the bottom springs on them, let the rig down and see how much the spring compresses on each corner when the shock compresses enough to engage the spring, measure that for each corner and do the math, and you have accurate sprung weights. No need for a scale.

Just throwing old Jeep coils under it between the axle and frame will not be the same because it won't account for the location and angle the coilovers will be mounted in.

Suspension gurus, correct me if I am wrong.

 

[gottagofast]

Don't weigh corners.... weigh ends and divide by half... ie rear centered between shock mounts is x lbs then each rear corner is 1/2 x lbs

 

[bjeep]

The shock guy wants unsprung weights for valving. I'm comfortable figuring out springs, I think, and several venders do spring exchange which really helps. I will wait on springs for the time being but was hoping to get some kind of numbers so I can get in line to have the shocks built.

Unsprung weight is the axles and tires. Not the chassis.

What the hell ???

 

[JEEPKEVIN]

Your totally right. I have so much on my mind that I've been saying the wrong thing. Sprung weight is all that matters right now.

 

[TacomaJD]

I would say unsprung weight does matter for valving, (how much mass is pulling down on the shock during rebound), but probably only important for more advanced (race) application tuning. Yer on the right track to getting it figured.

 

[gottagofast]

Don't weigh corners.... weigh ends and divide by half... ie rear centered between shock mounts is x lbs then each rear corner is 1/2 x lbs

To add... support the other end on 2 points under the shock mounts....

 

[617_Racing]

Hit up Ryan from Accutune. I basically told him what I'm doing, the parts I'm using and sent a picture similar to yours.

He did his smart guy brain work and selected the valving and springs. I have only rode around in 2 wheel peel but I have jumped it. It is extremely close to what it needs to be.

He does the spring exchange as well, I'd hit him up.

 

[stano]

I say tell them what your doing with the rig. (Crawl/trail riding/racing). Have the shocks built and install them, then do just as others have said, measure compression with a spring on known rate and order from there. My guy put a "bench tune" in they use for rec wheelers and it rocks over the stock tune. If you are going racing, it's going to take tuning sessions any way once u get done, so they should be able to get close enough for the girls I go with..


Sent from my iPhone using Tapatalk

 

[JEEPKEVIN]

I say tell them what your doing with the rig. (Crawl/trail riding/racing). Have the shocks built and install them, then do just as others have said, measure compression with a spring on known rate and order from there. My guy put a "bench tune" in they use for rec wheelers and it rocks over the stock tune. If you are going racing, it's going to take tuning sessions any way once u get done, so they should be able to get close enough for the girls I go with..


Sent from my iPhone using Tapatalk

Yup Yup!!

I'm just a rec guy. Order coil overs for past 2 rigs they were always the stock shelf valving. Always way off. I tore town the shocks 7 times on the last rig to get them where I was happy. Springs seem to allow for a little more tolerance, But stiff valving sucks!!