Sirpent "Z"

[jeff43]

I need a bench grinder sanding disc which I am looking into at the moment because Im still not happy with the finish on the final items

 

Hi John,

 

The linisher belt on my bench grinder is my favorite tool, Love it, couldn't live without it.

 

Cheers Jeff

[Sirpent]

Hi John,

 

The linisher belt on my bench grinder is my favorite tool, Love it, couldn't live without it.

 

Cheers Jeff

 

Yep that's what I'm looking at adding to my armoury this week

[CBR Jeff]

Yep that's what I'm looking at adding to my armoury this week

It's a very good time of year to be purchasing those important things. Sales all over the place. I just love it.

 

Jeff

[Sirpent]

Only half a day available this weekend to get some more done, and I managed to trim both diff mount plates down and make a start on the second passenger side mount.

 

Now that I have it set at the same height and position relative to the LCA tube, I can measure up the 2 uprights and fabricate them next weekend.

 

Cheers

 

John

Edited May 29, 2016 by Sirpent

[Sirpent]

OK,

 

So one day a wek now devoted to the car and I intend sticking to it.

 

Today,

 

#1 Finished the second set of uprights for the passanger side diff mount.

#2 Final alignment and welding of the brackets

#3 The pretty mount circular access point I cut into one of the mounts didnt work, so Mr Grinder made short work of that. Will go back and linish it off to look half respectable later.

#4 Did the final piece of surgery to the rear moustache bar cross member

#5 Was very pleased to see the state of the inners once cut away, no rust and clearly the factory etch primer looked great

#6 Slotted in the diff recess / reinforcement set up and it just slipped in and sat there happily

 

Next week, chassis back on the car, then the rear diff cradle bits, followed by mounting the diff and finishing off the last of the diff mounts at the rear of the diff.

 

Cheers

 

John

 

 

[ric240z]

looks good john!

 

Ric

[Sirpent]

Thanks Ric

 

Looking forward to seeing the progress on your car also ;-)

[Sirpent]

This weekends effort

 

Diff is now nested with the chassis on the car, and all said clearances are great and looks like I got all the alignment and axle positioning spot on.

 

Pardon the blue support RHS in the photo as its a temp support for the diff until the final 2 mounts are added. 

 

All that's left is to

 

#1 Build the brackets for the last 2 rearward diff mounts

#2 Drop the entire chassis out

#3 Bolt in the motor/trans

#4 Marry the entire chassis back into the body

#5 Check clearances and adjust any sheet metal

#6 Drop it all out again

#7 Have all the final welding done

#8 Ring the engineers to come out and cross my fingers

 

Till next week

 

John

 

 

[CBR Jeff]

I do enjoy you engineering John.

I'm keen to see this in person one day as photos never give the full story.

Jeff

[Sirpent]

Jeff

 

Short drive down the Hume, always welcome to drop in and check out my chicken sh*t welds LMAO

 

I have to say though, I'm liking how its all come together, just cant wait for it to be welded up, media blasted and powder coated.

 

Thanks Mate

 

Cheers

 

John

[Sirpent]

So better part of today fabricating the final 2 rear differential mounts

 

 

Went a lot smoother than I anticipated and before any of you say "You could of lined the mount bolts up better" there was a reason for doing so, as the 2 arms on the alloy mounts that the bolts pass through are different lengths and therefore I had to rotate one so as the outer angles on each side matched.

 

 

The rear plate connects via a tube to the rear cradle so as to close the mounts into twin plate assy.

 

 

Tomorrow will involve spot welding the upper RHS mount onto the tube section and rounding off the corners.

 

 

Next weekend, the true test comes when I bolt the engine and trans back onto the chassis and trolley assy and attempt to raise it 40cmm up to the body and see what all the clearances are like. Failing any major surgery to the shell, it all comes out again to have a competent welder mig and tig all the joints and gussets on the trolley.

 

 

Cheers

 

 

John 

 

[Sirpent]

Fabrication done

 

Walk around

 

Now I need 2-3 people with a few trolley jacks to help me lift this F*cker into the body.

 

Edited June 19, 2016 by Sirpent

[CBR Jeff]

Video looks like it's locked out due to content John.

 

Jeff

[260DET]

The background music? A verbal commentary would be better anyway, hint, hint

[Sirpent]

Video looks like it's locked out due to content John.

 

Jeff

 

The background music? A verbal commentary would be better anyway, hint, hint

Yeah

 

Had the radio on in the background and they picked up a song, you could barely hear the track.

 

All fixed

 

As far as verbal commentary............... Don't like the sound of my own voice LOL

 

Should be up in the next few minutes, just deleted the sound track.

 

Cheers

 

John

[Sirpent]

While we wait

 

A couple of still shots

 

 

[CBR Jeff]

Well John that is going to be one wild ride. I bet you will be surprised at the spring rate you end up having to run due to the stiffness of the body more that the weight.

Jeff

[Sirpent]

Well John that is going to be one wild ride. I bet you will be surprised at the spring rate you end up having to run due to the stiffness of the body more that the weight.

Jeff

 

I certianly hope so Jeff ! 

 

Like to hear your thoughts on spring rates as to be honest I havent thought that far ahead as yet.

[CBR Jeff]

I certianly hope so Jeff !

 

Like to hear your thoughts on spring rates as to be honest I havent thought that far ahead as yet.

From what I can see John you have not changed and are not changing the geometry of the original suspension? So your role centres will be the same front and rear. But you're centre of gravity will change compared to a standard car as you have added and moved the weight distribution. The reaction of the suspension to external forces will also be influenced by the sub frame you are installing so the transfer of force will be increased (I think) more directly as the body flex or twist will be greatly reduced. In English what I'm saying is that as the car corners the forces will be more directly transferd to the loaded corner or side rather than having some compliance through the body. For a reference I'm starting with 6kg springs in the front and 4kg in the rear. To calculate a starting point you need to determine the use of the car, have your corner weights, unsprung weight, shock length and ride height. Then you can use one of the online calculators to gage a starting point. Or you could talk to someone who knows what they are talking about like Josh or Murray Coote at MCA. What shocks are you planing on running? I don't remember reading about these in the thread?

If you want to get very confused have a scan through this? It's good bed time reading.

https://www.slideshare.net/mobile/billharbin/vehicle-lateral-load-transfer-parts-iiiimar13

 

Jeff

Edited June 22, 2016 by CBR Jeff

[Sirpent]

Thanks Jeff

 

Your initial response of a few days ago got me thinking and surfing, and I came across a very enlightening article on the web.

 

http://www.superchevy.com/how-to/chassis-suspension/1002chp-how-to-pick-the-right-spring-rate/

 

I’ve pasted it here as it’s a great read.

 

I was looking at sourcing a complete new set up on all 4 corners with multi adjustable dampening, however if this article is accurate, which I am pretty confident it is, the need for multi adjustables may not be required in lieu of a top shelf set of dampeners.

 

The article as follows………….

 

Hitting The Sweet Spot
If the role of the springs is so simple, then why the big stink about picking the perfect set for your car? It all comes down to making sure that the shocks can operate in their ideal range of motion, and the importance of the shocks in relation to overall handling performance. "In my opinion, the only thing more important than the shocks in regards to handling is the tires. By dampening the motion of the springs, shocks control the rate of weight transfer in a corner," Chris explains. "Optimizing the rate of weight transfer is the essence of good handling, and the shocks control how the entire suspension operates.

 

That said, shocks have a very limited range of motion, and their performance degrades dramatically as they reach the extremes of their travel. It's up to the springs to make sure the shocks operate in their sweet spot, which is why proper spring selection is so important. If your car sits too high or too low due to having the wrong springs, it will take the shocks out of their sweet spot and they'll never perform well. People often think there's something wrong with their shocks, but 80 percent of the time perceived shock problems are a result of not having the right springs on their car."

 

Shock Travel

A typical A-arm-style front suspension has between 5 to 7 inches of wheel travel. However, the wheels are mounted farther outward than the springs and shocks, and travel in a longer arc. That means that the 5 to 7 inches of wheel travel necessary for a smooth ride and secure handling equates to just 3 to 4 inches of total shock travel.

 

When attempting to determine the correct spring rate for a car, the trick is to set the ride height so the chassis rests in the shocks' sweet spot within this small 3- to 4-inch window. A solid-axle rear suspension, on the other hand, is a bit more forgiving. Since the shocks are usually bolted directly to the rear end housing, the motion ratio of the wheels is more proportional to the total travel of the shocks. As a result, the shocks mounted to a solid-axle rear suspension typically have 5 to 6 inches of travel.

 

How much of a shock's range of travel is allocated to compression and rebound depends on a car's intended use? Street cars require more compression than rebound, while drag cars are the exact opposite. Cars built for the road course or autocross, on the other hand, can benefit from an even split of compression and rebound. "A street car needs about 60 percent of its travel in reserve for compression, and the other 40 percent for rebound (60/40).

 

The bias toward compression improves ride quality and has a built-in safety guard for unexpected road hazards," Chris explains. "Street/strip cars need roughly 40 percent of their shock travel for compression and 60 percent for rebound, as the extra extension assists in front-to-rear weight transfer. Since road course and autocross cars usually run on smooth surfaces which require less compression, they can benefit from a 50/50 split. However, variations in suspension geometry or track conditions may necessitate altering the travel percentages to prevent the shocks from bottoming- or topping-out."

 

Whether you bias the shock travel toward compression, rebound, or keep it neutral, the first step in accomplishing this is determining the total travel of your shocks. Chassisworks publishes the shock travel specs of all its shocks and struts, as do many other manufacturers. It just takes some research. Next, figuring out how much the springs and shocks should be compressed at ride height to get the shocks in their sweet spot is merely an exercise in simple math.

 

A street-oriented setup (60/40) requires that the shocks and springs collapse 40 percent from their free length at ride height. Consequently, a shock with 4 inches of travel should compress 40 percent, or 1.6 inches, at ride height. That results in 40 percent of travel reserved for rebound and 60 percent, or 2.4 inches, reserved for compression.

 

The Math
With all the foreplay out of the way, it's time to finally get into some number crunching. Calculating the optimal spring rate for any car can be expressed in the following equation, where "F" is the free length of the spring, "L" is the loaded length of the spring, "R" is the baseline spring rate, and "T" is how much the shock collapses at ride height.

 

For the sake of illustration, let's presume that a 500 lb/in spring ® measuring 8.94 inches (F) compresses down to 6.50 inches (L) at ride height. The difference between the two spring height figures is 2.44 inches, which yields a product of 1,220 when multiplied by the spring rate of 500 lb/in. When matched with a shock featuring 4.25 inches of travel, setting it up for a 50/50 cornering application requires the shock to collapse 2.13 inches (T) at ride height. Finally, dividing 1,220 by 2.13 results in a quotient of 572.77, which is the ideal spring rate for this application.

 

In this example, the baseline spring rate of 500 lb/in was too soft, which resulted in a shock that collapsed more than the desired amount at ride height (2.44 inches). Not only would this spring move the shock outside its sweet spot, it would also bias its travel too far toward rebound, not leaving enough travel for optimum compression valving and potentially degrading ride quality.

 

Although it may seem trivial, the extra 73 lb/in as calculated in Chassisworks' formula would effectively decrease the amount the shock collapses at ride height to hit the target sweet spot of 2.13 inches. That yields an equal amount of shock travel in each direction for compression and rebound (50/50), which is perfect for many road course or autocross setups.

[260DET]

One way to work out the spring rate has something to do with the spring frequency, I've never used it myself but there is a formula around which enables the calculation of the rates required, depending on car use of course. A bit of a google should turn it up.

[PeterAllen]

John. I have an issue with a 'knocking' noise in the car's rear end. I have rebuilt it a dozen times trying to firstly identify and then fix whatever is wrong. 

 

Someone came and strapped a Go Pro thingy under the car today and we did a bit of filming. I've loaded it to show the amount of flex the components are experiencing. Not happy Jan.

 

I think you are on the right track but it looks like I need to redesign a few components - Bugger!

 

[Sirpent]

Hmmmmmmmmmmmmmmmm

 

 

Pete, the original idea of the moustache bar was to dampen the diff assy torque, and that’s exactly what’s it is doing in your case in addition to the LCA's transferring load onto the assy and finding the least resistance in the bars bushings.

 

 

On acceleration you can see the natural attribute of the diff lifting at the front and causing the rear of the diff dipping down causing more motion particularly because the rear mounts pivot point is well outside the moustache bars alignment.

 

 

I'd say that with the motion, it’s going to chew up the LCA mount bushes sooner than later and you must feel it through the rear suspension in some form.

 

 

AT the 32 second mark, on the second pounce on the gas, you can see the diff force on the rear and then the resistive force of the wheel transferring force through the LCA's back into the LCA's as a momentary secondary movement.  

 

Does the knock sound like a gear change clunk? at the 31 second mark, watch the rear part of the LCA, and watch the movement, something in the assembly is overbaring a bushing and making contact where it shouldn't.

 

 

I can’t say for certain that my set up will work the way I envisaged it, but I don’t believe that I will be experiencing any of the movement I see in you vid, that entire rear cradle is solid mounted and acts as a single unit, the 4 Range Rover mounts will have to cope with all the diff motion hopefully translating to getting the power down to the ground.

 

 

Happy to share whatever I have as far as dimensional and material information if it helps you. I'm sure others will chime in with suggestions and opinions also.

 

 

Cheers

 

 

John

Edited June 26, 2016 by Sirpent

[260DET]

 Wow, some flex going on in that video. With the usual Z setup the rear diff mounting point is in line with the chassis points so no leverage, here with the offset diff mounting point there is a lot. It would also be interesting to see what the front mount is doing because it could well be at fault too.

[Sirpent]

This is my EOFY gift to myself, paid for today, should be in Melbourne with a week or two..............

 

No not the whole car, but the seats (Actual photo) c/o a W204 C-Class Coupe that was written off in NSW.