My long promised blog

[h701micra]

Now why do I say consistency is more important than the number?
Well it doesn't matter if a scale reads 25kg or 2500kg. If it reads that figure either side you've clearly got a 50/50 balance regardless of weight

These scales were pretty consistent for £3


Moving on to corner weighting itself. Once the car was lowered onto the scale setup in pic2. Lets says the Fr/Rt corner so we can refer to pic 3. That scale read all of the weight in the shaded area.
Why? Because the 2 wheels which the line is drawn between becomes a pivot point and the Rr/Lt corner will absorb the weight transfered (that's crossweight) however tge springs will resist and push the weight onto the Ft/Rt corner.

So here's my numbers with me, subaru box and rear subframe added
Ft/Rt - 248kg
Ft/Lt - 236kg
Rr/Lt - 143kg
Rr/Rt - 142kg

 

[Kamarley]

Corner weighting for £6 and scraps complete

It was entertaining to say the least

You lost me??


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

You lost me??


LEEEEEAVVVEEE ITTTTT YEAHH!!!

You'll see if you read it

 

[Kamarley]

Still following!!' But... Here's where I'm scratching my head, would a full tank/ empty tank of fuel throw this off and what if you carry passengers (ie chloe?)


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

Still following!!' But... Here's where I'm scratching my head, would a full tank/ empty tank of fuel throw this off and what if you carry passengers (ie chloe?)


LEEEEEAVVVEEE ITTTTT YEAHH!!!

Good question
Yes a full tank and empty tank of fuel will make a difference. 40l of petrol is a fair weight to add to the back. This is halfway at the minute I prefer to corner weight on half a tank but sometimes I use what I'm given. I moved my tank to adjust rear balance sad or genius you choose
Corner weighting gives you figures to work with so you can pick correct spring rates


As for passengers if you're expecting to carry one then don't corner weight with you in it and just get the car even
If you're not like myself. Balance it with just your weight

 

[h701micra]

Ft/Rt - 248kg
Ft/Lt - 236kg
Rr/Lt - 143kg
Rr/Rt - 142kg

This totals 143kg extra. That box and subframe must weigh some serious weight (have to admit I did struggle) but it gives me a ballpark figure for Nissanubaru
769kg. Target 400-450hp. Gives 520-585hp/tonne... nervous.. no.. terrified more like

 

[h701micra]

Moving on from Nissanubaru
Lets work out some balance percentages
Front balance, rear, left and right

Then we'll do cross weights

First side balances to show balance front and rear
Lets do Rt balance first;
Ft - 248, Rr - 142
Total 390kg
Ft percentage 248/390 = 63.6
Rr percentage = 36.4

Now the rest using the same method

Left balance
Ft - 236, Rr - 143
Balance: Ft - 62.3% Rr - 37.7%

Now left and right balance on each axle

Front
Lt - 236 (48.7%)
Rt - 248 (51.3%)
Total - 484

And the rear
Lt - 143 (50.1%)
Rt - 142 (49.9%)
Total - 285

That's my balance numbers

Individual weight percentages are
F/Lt - 236 - 30.70%
F/Rt - 248 - 32.25%
R/Lt - 143 - 18.50%
R//Rt - 142 - 18.55%

Moving onto cross weights
As I said earlier they are each corner tied to the opposite corner
So Ft/Lt & Rr/Rt (1)
And Ft/Rt & Rr/Lt (2)

Cross weight 1 is
236 & 142 = 378
And 2 is
248 & 143 = 391

Divide these both by the total weight to get your cross weight percentage
1 - 49% 2 - 51%

I'll let you digest that while I work out how to explain adjustment

 

[Kamarley]

Moving on from Nissanubaru
Lets work out some balance percentages
Front balance, rear, left and right

Then we'll do cross weights

First side balances to show balance front and rear
Lets do Rt balance first;
Ft - 248, Rr - 142
Total 390kg
Ft percentage 248/390 = 63.6
Rr percentage = 36.4

Now the rest using the same method

Left balance
Ft - 236, Rr - 143
Balance: Ft - 62.3% Rr - 37.7%

Now left and right balance on each axle

Front
Lt - 236 (48.7%)
Rt - 248 (51.3%)
Total - 484

And the rear
Lt - 143 (50.1%)
Rt - 142 (49.9%)
Total - 285

That's my balance numbers

Individual weight percentages are
F/Lt - 236 - 30.70%
F/Rt - 248 - 32.25%
R/Lt - 143 - 18.50%
R//Rt - 142 - 18.55%

Moving onto cross weights
As I said earlier they are each corner tied to the opposite corner
So Ft/Lt & Rr/Rt (1)
And Ft/Rt & Rr/Lt (2)

Cross weight 1 is
236 & 142 = 378
And 2 is
248 & 143 = 391

Divide these both by the total weight to get your cross weight percentage
1 - 49% 2 - 51%

I'll let you digest that while I work out how to explain adjustment

I'm loving this it's making me feel like I'm back in my mechanical principles classes!!!


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

Adjustments

So we now have all our percentages written down.

Now first let's write down our targets
L/R balance - 50/50
F/R balance - 57/43

Our current figures are
L/R > F - 48.7/51.3, R - 50.1/49.9

F/R > L - 62.3/37.7, R - 63.6/36.4

So from this we can see that we have too much weight over the front wheels so adding any weight to the front is a big no no.
We need to some how increase weight on the Ft/Lt corner and reduce weight on the Ft/Rt corner. If you can lift up the bonnet and move something over to the other side or anything ahead of your CoG.
For my car I moved my washer bottle to the left and inside. Added my fire extinguisher, footplate, swirl pot and pump setup to the left this for me gave me 50/50 balance. Yours will vary.
But this example we have 248 and 236. That's a 12kg difference. You'd think we have to find 12kg to the left. If we're shifting weight we need to move 6kg. 248 - 6 is 242. Add that 6 to our left weight of 236 is 242 also
The closer to the strut you put the weight the greater the effect it has and vice-versa

I need to take a break and eat my food now
I'll chuck up a quick way to find your CoG

 

[h701micra]

I'm loving this it's making me feel like I'm back in my mechanical principles classes!!!


LEEEEEAVVVEEE ITTTTT YEAHH!!!

So it makes sense then

 

[h701micra]

For CoG.
Measure you wheelbase.
On the right. In this example the front rear balance is 63.6/36.4.
Say your measure from front wheel centre to rear wheel centre is 2metres.
You flip the percentage... so measure 63.6% of 2metres from the rear. 127.2cm and mark it
Same on the left with that percentage and same with the left right percentage. You'll find you CoG from that

This picture should hopefully explain it alot better



I'll do it tomorrow and show you with more pictures

 

[Kamarley]

So far yes, I'm waiting for the bomb she'll there was always one in mech princ.


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

Right must continue. Got to get back into that frame of mind again now. And I don't wanna so bare with me
So we've shifted weights so the left right balance is 50/50 this means that the car will corner evenly.

Now we need to adjust the front rear balance. This will affect traction and understeer/oversteer balance

First we need to recalculate our cross weights... our corner weights have changed so our cross weights willl have changed too.

For simplicity. Say the front is now 242/242 and the rear is now 142.5/142.5
Our crossweights are both 384.5kg and 50%

Now we dont need as many percentages floating about.
L/R - 50%
F/R - 62.9/37.1
We want 60%
0.60 x 384.5 = 230kg near enough for both sides

To move the weight around you would evenly adjust ride height
Say 10mm difference was our solution.
Youd raise the front 5mm both left & right and lower the rear 5mm left & right. Rather than lowering the rear a full 10. Its not for aesthetic purposes its for keeping within the shocks travel.
If you need lots of height adjustment then adjust your weight, i.e further back in the car.
(People with roll cages have a distinct advantage here)

Or move onto spring preload

So what about spring pre load? Firstly what is it? For example on my 100lb springs yesterday 100lbs would have moved the spring one inch. If I add 1/4inch of preload the spring is now preloaded with 25lbs and will now need 26lbs of weight before it will move again. Preload has no effect on spring rate or ride height.
How is this useful to us?
Well in our example we had 63% front balance. And we adjusted this with ride height adjustment. If you need to move the heights too much then you can soak up some of the weight with preload. We need to move 12kg (26lbs) each side or make it 'disappear'. If we have a 104lb/in spring on the rear we would take the spring rate and divide by the weight we need to move
104 ÷ 26 = 0.25 (convenient eh )
Now we know that if we preload the spring 1/4 inch it will 'soak up' 26lbs of sprung weight it will also slightly increase ride height.
This should help move those few kilos you can't shift by ride height alone. This means you now only have to move the front height up 5mm as there's no need to lower the rear
This is where we start changing spring rates and lengths so we can reduce preload and have a more effective working spring

Once you have your targets you can then adjust height to affect oversteer/understeer.
There's a lot more to it all than that but that's corner weighting in its entirety. It will give you final corner weights so you can then choose your spring rates which will be best suited to you and your driving style, terrain, lateral g-forces, your front weight percentage etc etc

 

[h701micra]

So far yes, I'm waiting for the bomb she'll there was always one in mech princ.


LEEEEEAVVVEEE ITTTTT YEAHH!!!

No bomb shell here mate hopefully but it always seems simple to read... to do its a nightmare. Its the snowflake on the tip of the iceberg of suspension. So should be simple to understand

 

[h701micra]

@skinner_87 that long winded description should help you with those springs
Picking the right rate then applying it to your cut springs

 

[Skinner_87]

@skinner_87 that long winded description should help you with those springs
Picking the right rate then applying it to your cut springs

Cheers bud il have to put me thinking cap on

 

[h701micra]

Cheers bud il have to put me thinking cap on

Enjoy
As always. Give me a shout

 

[h701micra]

I got back into the corner weighting mood and re-read my own posts... safe to say I wasn't happy with them not a mention of preload shocking
Anyway I've now edited them to make more sense and have a little more detail for ypur adjustments

http://www.micra.org.uk/index.php?posts/653888.

I'll carry it on tomorrow (looking at the clock.. later on) and show you what where and how to adjust things to get the desired results
Also how the cut spring principle can help us when preload isn't available

 

[h701micra]

I didn't bother with suspension today in all honesty. I went to get on with my gearbox and have a look to decipher why it has been deemed "knackered"

Here it is. I'm sure you've seen one before


One pic per post so I'll just write it up with each picture

 

[h701micra]

Inspection cover off and I knew what had happened straight away. You can't see it but you can feel it

 

[h701micra]

Cover off. Common misconception is that as soon as you remove the cover a million things will fly everywhere. Simply not true

Not looking promising inside

 

[h701micra]

Yup its thoroughly destroyed

 

[h701micra]

Remnants

That's why the previous chap blamed the synchro.. its jammed full

 

[h701micra]

Damage 1

 

[h701micra]

Damage 2

 

[h701micra]

Damage 3

 

[h701micra]

Bell housing
Shows where the failure occured

 

[h701micra]

Close up for those that don't know what happened


It was a shaft bearing failure. Which allowed the gears to smash together causing all the above damage

Moral of the story:
Gearbox oil is as important as engine oil

 

[h701micra]

While I was at it I calculated my gear ratios.
@kamarley this should make sense to you

Divide mesh gear by drive gear and I got these
1st - 59/16 = 3.6875
2nd - 52/22 = 2.36
3rd - 45/29 = 1.55
4th - 37/41 = 0.90
5th - 34/45 = 0.75
Rev - 59/11 = 5.36

Final drive - 85 (teeth on diff)/27 (teeth on final drive gear) = 3.148

Wonder what my DS box is... as I know it has higher ratios... tempting

Calculating road speed using RPM and these ratios

Say 3rd gear at 2000rpm
Step 1:
Roadwheel rpm = (Engine rpm/gear ratio)/final drive
So 2000/1.55 = 1290.323
1290.323/3.148 = 409.89

Step 2:
Roadspeed (metres per minute) = Roadwheel rpm x Pi x Wheel diameter (in metres)
So 409.89 x Pi x 0.481 = 619.38

Step 3:
Convert metres per minute to miles per hour
(Metres per minute x 60 = metres per hour
Convert metres per hour to miles per hour (÷1609.344)

Sooooo
(619.38 x 60)/1609.344 = 23mph

So 3rd gear, 200rpm I'll be doing 23mph

 

[pollyp]

hey andy I have a set of ruggles scale frames I designed n made that halves the load value on the scales but I never used em (cos I recently got the 300kg scales instead) and is just in storage.
would u be interested in em?

http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-74#post-569888

 

[h701micra]

hey andy I have a set of ruggles scale frames I designed n made that halves the load value on the scales but I never used em (cos I recently got the 300kg scales instead) and is just in storage.
would u be interested in em?

http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-74#post-569888

I've always got my corner weighting scales to use


However its a good idea that can be used in conjunction with the £6 scales

Although mine only measure up to 680kg iirc, I'll give it some thought thanks for the offer

 

[pollyp]

shall I bang it in buy sell?

 

[h701micra]

shall I bang it in buy sell?

Sure
It'd be worth it to anyone considering the corner weighting process

 

[Kamarley]

While I was at it I calculated my gear ratios.
@kamarley this should make sense to you
View attachment 27314
Divide mesh gear by drive gear and I got these
1st - 59/16 = 3.6875
2nd - 52/22 = 2.36
3rd - 45/29 = 1.55
4th - 37/41 = 0.90
5th - 34/45 = 0.75
Rev - 59/11 = 5.36

Final drive - 85 (teeth on diff)/27 (teeth on final drive gear) = 3.148

Wonder what my DS box is... as I know it has higher ratios... tempting

Calculating road speed using RPM and these ratios

Say 3rd gear at 2000rpm
Step 1:
Roadwheel rpm = (Engine rpm/gear ratio)/final drive
So 2000/1.55 = 1290.323
1290.323/3.148 = 409.89

Step 2:
Roadspeed (metres per minute) = Roadwheel rpm x Pi x Wheel diameter (in metres)
So 409.89 x Pi x 0.481 = 619.38

Step 3:
Convert metres per minute to miles per hour
(Metres per minute x 60 = metres per hour
Convert metres per hour to miles per hour (÷1609.344)

Sooooo
(619.38 x 60)/1609.344 = 23mph

So 3rd gear, 200rpm I'll be doing 23mph

Argh Pi always coming into it!!


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

Argh Pi always coming into it!!


LEEEEEAVVVEEE ITTTTT YEAHH!!!

If involves something round there's Pi somewhere

I only remember 3.141592654

 

[Enuo]

3.1415926535 master race

 

[Kamarley]

Mmmmmm pie


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[Kamarley]

While I was at it I calculated my gear ratios.
@kamarley this should make sense to you
View attachment 27314
Divide mesh gear by drive gear and I got these
1st - 59/16 = 3.6875
2nd - 52/22 = 2.36
3rd - 45/29 = 1.55
4th - 37/41 = 0.90
5th - 34/45 = 0.75
Rev - 59/11 = 5.36

Final drive - 85 (teeth on diff)/27 (teeth on final drive gear) = 3.148

Wonder what my DS box is... as I know it has higher ratios... tempting

Calculating road speed using RPM and these ratios

Say 3rd gear at 2000rpm
Step 1:
Roadwheel rpm = (Engine rpm/gear ratio)/final drive
So 2000/1.55 = 1290.323
1290.323/3.148 = 409.89

Step 2:
Roadspeed (metres per minute) = Roadwheel rpm x Pi x Wheel diameter (in metres)
So 409.89 x Pi x 0.481 = 619.38

Step 3:
Convert metres per minute to miles per hour
(Metres per minute x 60 = metres per hour
Convert metres per hour to miles per hour (÷1609.344)

Sooooo
(619.38 x 60)/1609.344 = 23mph

So 3rd gear, 200rpm I'll be doing 23mph

Btw it would make sense if the diagram wasn't upside down. Just can't get the staff these days


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

Btw it would make sense if the diagram wasn't upside down. Just can't get the staff these days


LEEEEEAVVVEEE ITTTTT YEAHH!!!

True .. it looked fine on here... uploaded it... upside down

 

[Kamarley]

We always ran with Pi being 3.142


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[Huggy444]

We always ran with Pi being 3.142


LEEEEEAVVVEEE ITTTTT YEAHH!!!

I always run with it being in a calculator

 

[h701micra]

3.1415926535 master race

Screw you

 

[Kamarley]

I always run with it being in a calculator

Lazy sod!


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[Kamarley]

When's the next lesson Andy!?


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

When's the next lesson Andy!?


LEEEEEAVVVEEE ITTTTT YEAHH!!!

Pick a topic and I'll do my best
I've got a diff I can do. More suspension etc etc

 

[Kamarley]

I didn't think you finished the suspension??


LEEEEEAVVVEEE ITTTTT YEAHH!!!

 

[h701micra]

I didn't think you finished the suspension??


LEEEEEAVVVEEE ITTTTT YEAHH!!!

It's true I haven't. I never will. Just need to take pics on how to find CoG and how to make adjustments on various suspension

 

[h701micra]

 

[h701micra]

 

[Kamarley]

No words needed


LEEEEEAVVVEEE ITTTTT YEAHH!!!