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PostPosted: January 29, 2021, 3:45 am 
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Hello.

I got a Dax rush frame thats missing its suspension parts.
DJ sportscars International LTD's patent for Rush CC&AR have been sold some times, and also changed a lot. Ive tried to get my hand on the right parts, but it seems hard. I was there therefore thinking about building the suspension my self.

The camber compensation anti roll suspension CC&AR gives the frame very high upper mount for the A arms. Making it hard to use as it is. Ive put the messurements from my frame into VSusp to see if I could get an idea of how it should be.

Ive tried to use VSusp to make a normal dobble A arm front suspension.
From what I can see, they used Ford Sierra spindle on the normal dual A-arm suspension on the Dax Rush.
The value for the spindle is what I found on the internet, but I see theres a lot of different values for the same objects. And small changes makes it hard to find the perfect spot. (which, like on womens, does not exist... Or... :lol: )

I also got some Ford Cortina spindles, and I messured those. Here are the result:
(I kept the values for the frame as it is, so that if anyone of you wants to play around with values you can, its better to start with the right values other than the 1000 tests I've done)

Ruch mc frame with Cortina spindle

Rush mc frame with Sierra spindle



And also will a RC under ground level give that big of a problem if it doesnt move a lot?
the car will not have much weight. 990-1100lbs (200lbs driver)


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PostPosted: January 29, 2021, 7:33 pm 
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TMB wrote:
I got a Dax rush frame thats missing its suspension parts.
DJ sportscars International LTD's patent for Rush CC&AR have been sold some times, and also changed a lot. Ive tried to get my hand on the right parts, but it seems hard.
TMB, I almost bought a Dax Rush kit in the mid 1990's after visiting the works. But Ultima had just come out with their Spyder, so ended up going that way instead. However, seems I did purchase the Rush construction manual which I discovered on my bookshelf the other day.

Its pretty detailed with lots of drawings and photos, so I may be able to answer some questions for you.
Attachment:
IMG_0887-1.jpg
Attachment:
IMG_0888-1.jpg


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PostPosted: January 30, 2021, 1:06 pm 
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That upper A-arm chassis mount is giving horrendous camber curves with either upright. Just lower the chassis mount location so that there is about a 7 degree drop from the upper ball joint to the upper chassis mount. This will also result in a better roll center height. (above ground)


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PostPosted: January 30, 2021, 7:53 pm 
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The easiest solution might just be to re-create the CC&AR component. If you can make a-arms, you can probably make the rest of it. Since you have the chassis, there are enough photos online that I would think you should be able to get 'good enough' dimensions by visual comparison to items in the photo of known dimensions.

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PostPosted: January 31, 2021, 6:38 am 
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Driven5 wrote:
The easiest solution might just be to re-create the CC&AR component. If you can make a-arms, you can probably make the rest of it. Since you have the chassis, there are enough photos online that I would think you should be able to get 'good enough' dimensions by visual comparison to items in the photo of known dimensions.


Yes, I was also thinking about that.
But I have a problem with finding a good and easy program to calculate the ringt messures for the CC&AR.
VSusp only uses normal A arm suspension and MacPherson.
I've downloaded FreeCAD, but that program is not as good as I hoped. It will take some time to learn.
Image

At the rear Im thinking about using the DeDion suspension.
The concern is the height of RC at rear vs front.


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PostPosted: September 23, 2021, 9:50 am 
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I have had a long break from this project. But now I have to get my calculations right. :BH:

Im dropping the CC&AR suspension, and starts to build a dual A arm suspension. :cheers:

I've got a pair of Ford Taunus (cortina) upright, some Opel Kadett C (chevette ) uprights, and some Opel Ascona B uprights. :wink:

Ive used the measures from OpelGT source for the GT uprights. Those are far better than the Ford parts when it comes to scrub angle.

My upper A arms mounts are for DAX CC&AR suspension, and to hight up to use. So I'm planning to move them.
Here is a link to Vsusp. Feel free to modify it and make it better.

Alt1

Alt2

Thoughts;
- Will a higher rollcenter that is moves less be better than a lower rollcenter with a little more movement? (se alt1 and alt2 link)
- How much camber gain is the main goal to aim at?
- And how much change in track width in suspension travel is acceptable?


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PostPosted: September 23, 2021, 11:18 am 
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Good for you to realize that you aren't trapped within the design boundaries that the factory imposes, especially when you don't have all their parts. It's all metal and can be changed to suit, as you're finding.

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PostPosted: September 23, 2021, 12:49 pm 
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I would use Miata uprights and use the control arm kit from Jack an Kinetic

https://www.kineticvehicles.com/ControlArms.html

Graham


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PostPosted: September 23, 2021, 1:29 pm 
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I am concerned about the ground clearance you have at 110 mm- 4.3". that is very low. I would look at mounting the LCA lower on the frame and raise you ground clearance to at least 127 mm- 5".

Also, You can look at using one of the spindles and as FastG suggested, use the control arms from Kenetic.

Here is what I used with Mustang II uprights and tubular LCAs.

Attachment:
IMG_2181.jpg

Thom


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PostPosted: September 23, 2021, 1:31 pm 
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TMB wrote:
I have had a long break from this project. But now I have to get my calculations right. :BH:

Im dropping the CC&AR suspension, and starts to build a dual A arm suspension. :cheers:

I've got a pair of Ford Taunus (cortina) upright, some Opel Kadett C (chevette ) uprights, and some Opel Ascona B uprights. :wink:

Ive used the measures from OpelGT source for the GT uprights. Those are far better than the Ford parts when it comes to scrub angle.

My upper A arms mounts are for DAX CC&AR suspension, and to hight up to use. So I'm planning to move them.
Here is a link to Vsusp. Feel free to modify it and make it better.

Alt1

Alt2

Thoughts;
- Will a higher rollcenter that is moves less be better than a lower rollcenter with a little more movement? (se alt1 and alt2 link)
- How much camber gain is the main goal to aim at?
- And how much change in track width in suspension travel is acceptable?


I missed your original post asking for vsusp feedback from January.
For a base line of ALT2, I’ve added a ½ inch tire sidewall compression, switched from metric to customary measures since that is what we use here and you can always switch back, switched off the steering display, and added more specifications to the chart to include camber curves and RC X and Y.

TMB DAX RUSH Ascona Baseline

Before I try to tweak your specs:
What is the desired ride height and track width?
The scrub and static negative camber seem excessive. Consider wheels with more offset and a half degree static for even tire wear/heating.

A: RC stability is more important that height imho.

A: Enough camber to keep the outside tire perpendicular to the road is the goal.

A: It's all a compromise of specs deemed more important than track change.

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PostPosted: September 23, 2021, 3:36 pm 
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Miatav8,MstrASE,A&P,F wrote:
Before I try to tweak your specs:
What is the desired ride height and track width?
The scrub and static negative camber seem excessive. Consider wheels with more offset and a half degree static for even tire wear/heating.


Thanks for the feedback and the good advices.
Its a lightweight car with a very light engine; Yamaha YZF R1 2005mod (132.3lbs).
The 4.3" ground clearance is what DAX RUSH MC hayabusa have acording to some sources.
The normal DAX have a ground clearance of about 5" to 5¹/₈".

The differensial and driveshafts are from Ford Sierra 4x4 cosworth, so it makes the rear track width about 57.8" with cossi spec on tires. Does not remenber why I did make the track width so wide. But DAX list their cars as:

Quote:
Wheelbase – 2310mm (or 2385mm in extended wheelbase form)
Front Track – wheel centreline to wheel centreline – 1496mm (58,9")
Rear Track – wheel centreline to wheel centreline 1530mm (60.236") (with 9″wide x 16″dia. wheels)
Rear Track – 1511mm (59.49") (with 8.5″wide x 16″dia. wheels)

The DAX has huge rear arches that need to be filled.

The huge negative camber was a result of me trying to make the camberchange as low as posible when the car lifts over dumps. (Sorry, old habits, I'm used to rallycars..)


If I give it a less agressive static camber, adjust the wheel ET and shorted down the arms to get the track width at 59,5", and give it a little more ground clearance.
Then this is what I get;
Baseline


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PostPosted: September 23, 2021, 3:51 pm 
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Tweaked baseline to include camber and RC X (yellow) and Y (blue), switched from 0.5mm to 0.5 inch sidewall compression, narrowed chart to show up to 4 degrees roll.
TMB DAX RUSH Ascona Baseline

I will see if I can improve anything and stay with a 59.5 track and 3 inch ride height.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: September 23, 2021, 4:13 pm 
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More camber gain in roll, lower RC that barely moves through 4 degrees X and Y:

TMB DAX RUSH Ascona Baseline

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: September 24, 2021, 5:03 am 
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Miatav8,MstrASE,A&P,F wrote:
More camber gain in roll, lower RC that barely moves through 4 degrees X and Y:

TMB DAX RUSH Ascona Baseline

Looks very good. Thanks :D

I compared it with the westfield, same roll angle, same travel.
When you turn hard and you brake into a corner, the roll senter moves out. On the westfield its moves in.
What kind of behaver differenses will that make?
The westfield has IRS in the rear. Im going to use a De dion axle in a 3link. Will it make a difference?


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PostPosted: September 24, 2021, 6:42 am 
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It would be interesting to see the westfield specs in vsusp.

IMHO, shifting the fulcrum point (RC) to the inside adds weight against the outside corner, dynamically reducing the effective spring rate (i.e. a falling rate when fully loaded). If it must move, it should move to the outside, but that is just my opinion.

It depends on what you want to do. The de dion has advantages over a live axle but has limitations you don’t have on the IFS or an IRS. I think front and rear should have similar camber gain but with a slightly wider front track. You can trade off camber gain for a lower RC. I don’t see the benefit to having a front that handles a lot better than the rear if it can’t be utilized without leaving the road ass-first.

I’m not suggesting a live axle is a poor choice either or that IRS is best. There are advantages and disadvantages to every type.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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