Daiyama Suspension

[Rally205]

Well I took the Leggy into work yesterday and crawled underneath to measure the suspension. Also weighed a spare disc, caliper, set of pads and one of my wheels. Thanks to Derek I now also have the weight of the hub carrier. A bit of guess work for the rest of the unsprung weight and the gross corner weight and I was able to calculate that the ideal spring rate for track use is 573lbs/in or 10.23kg/mm for the front. The maximum for road use is 429lbs/in or 7.6kg/mm so my guess wasn't far out.

Tein seem to have got it right. They sell the Super Wagon dampers with 5kg front and 3kg rear which would give reasonable road ride quality. I think that 12kg front and 6kg rear is way out

Most manufacturers dampers will tolerate +/- 2kg coil rate so I can't see being able to get the Daiyama setup to work satisfactorily unless they have misquoted the coil rates?

I also phoned Colt Cars on Friday and asked them to find out the standard coil rates for me. I will let you all know if they manage to get them and I will also ask about the MMCS Kieran

[Mac.]

Nope Daiyama aren't wrong, and most people fail to consider diminishing rates or return. For example, if you want to "support" a 1000kg steel ball 1 meter up in the air, will 1 sturdy aluminum tri-pod be enough? How about 10 of them? How about 100? If 5 do the job, then why would you need 10? or 50? or 100?

The point is, you reach a level with the suspension where going any higher becomes pointless because it's unnecessary.

If there's 800kg over the front axle, and 400kg over the rear then a 6:3 split is suffice.

[Kieran]

I also phoned Colt Cars on Friday and asked them to find out the standard coil rates for me. I will let you all know if they manage to get them and I will also ask about the MMCS Kieran

Brilliant work Marcus - Thanks!

[Rally205]

You are absolutely correct Mac. Your argument basically says that going any heavier than need be on the coil rates is overkill or am I reading it wrong?

All I did was take the facts and insert them into an equation to find the ideal coil rate. "Ye cannae change the laws of physics, Captain" This gives a starting point which may need a certain amount of fine tuning of the coil rates to get it perfect.

It goes like this. Over the years suspension designers have come up with a common denominator that any suspension setup can be compared to. This is the Natural Frequency at the wheel and it is measured in cycles per minute (CPM ). Further experience has shown that cars fall into certain categorys. The ideal frequency for a comfortable road car is 60-80, a sportier car is 80-100, Non-ground-effect racers is 100-125.

Below 50 the suspension travel will be so great that the car risks bottoming out and above 150 the ride will be so harsh that your teeth will be rattling.

So assuming a maximum for the VR4 of 115 cpm you can work out the coil rate.
You need to know certain data:-

Wheel Frequency(F) Assume 115

Sprung Weight(SW) This is the gross corner weight minus the unpsrung corner weight. As far as I can measure this is 1029.56lbs

Suspension Leverage squared(SL2)
This is 1.483524. It is the length of the bottom wishbone divided by the length from the inboard end to the shock mount squared.

Wheel Rate(WR) This is worked out as WR=F/187.8 squared x SW
I work this out to be 386.054lbs/in.

Coil Rate(CR) This what we want to know. CR=WR x SL2

So CR= 386.054 x 1.483524

= 573lbs/in.

If you assume a maximum wheel frequency of 100 then it works out to 429lbs/in. To convert to Kg/mm just multiply by 0.0178579673.

There was some guess work at the front corner weight but I will get down to the weighbridge and check it but I am not going to be too far out.

[Mac.]

Yep science aside, logic takes over. Why would you need a 10,000kg retaining wall to hold back a dam when 5,000 is more than enough? Why would you need a tripod that can hold a 20kg camera when your camera only weighs 1kg?

More often than not, people don't need 18kgF/16kgR because even at half that (9kg/8kg) there may still be NO play on the coilovers. The numbers are nice, but people usually get tied up in the "firmer is better" mantra (not pointing the finger here, just saying it as it is).

There comes a point in any given part where the performance return diminishes, and any further benefits become negligable.

[Kieran]

Mac - I don't understand your argument? You've just said the same as Marcus? And how can logic take over if science has been pushed aside?!

His point, as I read it, is that a default 12kg spring rate (which you said was the case on the Daiyama coilovers) on the fronts is way too stiff for the VR-4, and that 7.6 is probably more like the maximum?


Interestingly, I've just done the same calculation for a 80CPM car, which according to Marcus's figures is the cross between comfort and sporty. The spring rate works out at 4.9Kg/mm. Tein's Super Wagon Dampers are factory rated at 5Kg/mm.

[Mac.]

Yes, I agree with Marcus. My example could of perhaps been more extreme. There's obviously no need to 100kg front spring rates is there - you'd get 0 movement out of them. What about 50? 20? 10? There comes a point when anything higher than a particular spring rate warrants no further gain - that's all I am saying. So when you see brands offering 18kgF/17kgR as default, you have to question what you need all that for.

[Rally205]

Thanks for all your input Mac . The info was invaluable but personally I don't think that the Daiyama suspension is right for my car and I will continue the hunt for something that is right for my needs. However I am sure that some people may find it right for them.

Marcus

[Mac.]

Sure thing =]

[SGHOM]

You are absolutely correct Mac. Your argument basically says that going any heavier than need be on the coil rates is overkill or am I reading it wrong?

All I did was take the facts and insert them into an equation to find the ideal coil rate. "Ye cannae change the laws of physics, Captain" This gives a starting point which may need a certain amount of fine tuning of the coil rates to get it perfect.

It goes like this. Over the years suspension designers have come up with a common denominator that any suspension setup can be compared to. This is the Natural Frequency at the wheel and it is measured in cycles per minute (CPM ). Further experience has shown that cars fall into certain categorys. The ideal frequency for a comfortable road car is 60-80, a sportier car is 80-100, Non-ground-effect racers is 100-125.

Below 50 the suspension travel will be so great that the car risks bottoming out and above 150 the ride will be so harsh that your teeth will be rattling.

So assuming a maximum for the VR4 of 115 cpm you can work out the coil rate.
You need to know certain data:-

Wheel Frequency(F) Assume 115

Sprung Weight(SW) This is the gross corner weight minus the unpsrung corner weight. As far as I can measure this is 1029.56lbs

Suspension Leverage squared(SL2)
This is 1.483524. It is the length of the bottom wishbone divided by the length from the inboard end to the shock mount squared.

Wheel Rate(WR) This is worked out as WR=F/187.8 squared x SW
I work this out to be 386.054lbs/in.

Coil Rate(CR) This what we want to know. CR=WR x SL2

So CR= 386.054 x 1.483524

= 573lbs/in.

If you assume a maximum wheel frequency of 100 then it works out to 429lbs/in. To convert to Kg/mm just multiply by 0.0178579673.

There was some guess work at the front corner weight but I will get down to the weighbridge and check it but I am not going to be too far out.

SETTING CORNERWEIGHTS:
This step is optional, but provides the optimum handling for the car by making sure all 4 tires are doing equal share of the work. Weigh the car at all 4 corners after jettisoning unnecessary items for racing, disconnect the sway bar end links, and with you sitting in the car.
1.Add all weights together to find the total weight of the car.
2.Figure the percentage of weight front to rear:
Front %= Total weight on both front tires divided by the total weight of the car X 100.
Rear %= Total weight on both rear tires divided by the total weight of the car X 100.
These should add up to 100% of course.
3.Now you can figure the ideal weight for each wheel:
LF ideal weight= % on front tires X total weight on both left tires, divide by 100.
RF ideal weight= % on front tires X total weight on both right tires, divide by 100.
LR ideal weight= % on rear tires X total weight on both left tires, divide by 100.
RR ideal weight= % on rear tires X total weight on both right tires, divide by 100.
4.Now compare this to your actual readings and adjust accordingly. Note that they should all be off an equal amount. You may not want to bother with a 10 pound difference, but 50 pounds is excessive and should be adjusted. Do this by raising/lowering ride height at the proper corner. Adjusting the corner weight at one corner of the car effects the weights at ALL FOUR TIRES. Weigh the car again and check your work.
5.Reconnect your sway bars. When you do, if the endlinks don't contact equally on both left and right sides of the car, you will need to shim an endlink with washer(s). An unbalanced sway bar will throw off cornerweights.

This all sounds quite complicated, but once everything is in front of you it will seem pretty straightforward. If you have any questions/comments, let me know. Good luck. -SGHOM

[Rally205]

Have you done it then Derek?

[SGHOM]

Have you done it then Derek?

who ? me ??

no chance Marcus..... far to complexicated for my ickle mind !!

Just lifted it from another forum FYI.