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Author: Subject: Front Suspension advice?
kevyo89

posted on 1/2/19 at 12:42 PM Reply With Quote
Front Suspension advice?

Hi guys,

I've made wishbones as per the Haynes book but I am fitting them to a Ron Champion spec chassis, with mounting points repositioned. The guys at Procomp have been kind enough to give me some advice regarding position of the mounting points. I was advised that with the lower wishbone level, the supper wishbone should ideally have a 5 degree angle. That positions my brackets/arms something like so:



However, when retaining the original upper shock mounting position, it angles the shock very dramatically and I am wondering if this is ok? Bearing in mind that the lower wishbone is level, i.e. what it would be when at ride height, the shock would surely compress with full bodyweight and therefore the shock won't be positioned at such a dramatic angle like this?

Would it be more appropriate to position the shocks like so:



[Edited on 1/2/19 by kevyo89]

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kevyo89

posted on 1/2/19 at 03:11 PM Reply With Quote
Ahhhh - I made a mistake. I've just switched the shocks around as I realised I had the front shocks in the rear LOL! Now I've got the front sorted and I don't think I will need to reposition the mounts:




Now however, I have a 16" open length rear shock, which will be far too big! More stuff bought incorrectly!!



I do have about 2 inches of space where I could reposition axle shock mount lower down. The Ron Champion book suggests doing this and has pictures for reference where another builder has done this to accommodate a longer shock. Can you think of any reason why this shouldn't be done?

I could position the new shock mount directly below by 2 inches in the hope that the 16" shock would work fine?



[Edited on 1/2/19 by kevyo89]

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40inches

posted on 1/2/19 at 03:32 PM Reply With Quote
On the front suspension. Place the shock wishbone bracket as near to the ball joint as possible, and bring the top bracket out from the chassis. As in this photo:
Description
Description

Assuming that the shock will not foul the wishbone?

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kevyo89

posted on 1/2/19 at 05:40 PM Reply With Quote
quote:
Originally posted by 40inches
On the front suspension. Place the shock wishbone bracket as near to the ball joint as possible, and bring the top bracket out from the chassis. As in this photo:
Description
Description

Assuming that the shock will not foul the wishbone?


Thanks mate

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johnemms

posted on 1/2/19 at 08:18 PM Reply With Quote
Your rear shocks are correct..
You need to modify the rail under the axle to allow for adequate droop..
I recon...






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kevyo89

posted on 1/2/19 at 10:03 PM Reply With Quote
quote:
Originally posted by johnemms
Your rear shocks are correct..
You need to modify the rail under the axle to allow for adequate droop..
I recon...



Modify the rail under the axle in what way?

[Edited on 1/2/19 by kevyo89]

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Angel Acevedo

posted on 2/2/19 at 05:29 PM Reply With Quote
quote:
Originally posted by kevyo89
quote:
Originally posted by johnemms
Your rear shocks are correct..
You need to modify the rail under the axle to allow for adequate droop..
I recon...



Modify the rail under the axle in what way?

[Edited on 1/2/19 by kevyo89]


How about something like this upsde down?
[img]https://www.locostusa.com/forums/download/file.php?id=2481[img]





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PumaWestie

posted on 3/2/19 at 06:58 PM Reply With Quote
The front shocks look to be too long for the job. The lesser the angle on the shock the better. Moving the top shock mount outwards will help reduce the angle. The lesser the angle, the better the motion ratio and therefore a softer spring can be used to get a decent wheel rate

At the rear cut a section out of the chassis member under the rear axle tube and brace with a length of box section underneath it to gain more clearance

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Oddified

posted on 4/2/19 at 09:01 AM Reply With Quote
As with any suspension, it's a compromise. Shock angle can control roll to a point, reducing roll bar stiffness, decoupling the opposite side which helps grip on bumps. Down side is as mentioned above with the increasing spring rates/shock control because of the motion ratio. Ideally the angle shouldn't go past drawing an arc centred on the RC through the shock mounts though.

Ian

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rusty nuts

posted on 4/2/19 at 12:19 PM Reply With Quote
I’m sorry to be so blunt but I can’t help wondering how long it will take for some of those welds to fail ?
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froggy

posted on 4/2/19 at 11:34 PM Reply With Quote
I had to make some major changes to my front end to accommodate the v8 and I started by blocking the chassis up at a sensible ride height allowing for a 10-15mm drop without running out of shock travel then setting the shock at 70/30 bump to droop and making a dummy strut out of box section . Got my shock a decent amount under 45deg and built the top mounts to suit which in my case included a bolt in brace across the top to take the load off the top rail being a fairly hefty motor . Wheels were on as well and I glued a welding rod onto the bolt going through the inner bottom arm pivot to have a visible line showing the intersection through the steering rack pivot to the upper arm inner pickup to minimise any bump steer





[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]

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PumaWestie

posted on 5/2/19 at 08:24 AM Reply With Quote
There is no getting away from the fact that the shocks are simply too long for the job I'm afraid. You need to set the car on blocks at the required ride heights to determine this for yourself rather than playing around in mid air. The previous poster gives you a good idea of how to proceed.

My advice would be to sell the shocks that you have on and buy some of the required correct length once you have determined it

[Edited on 5/2/19 by PumaWestie]

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froggy

posted on 5/2/19 at 10:17 AM Reply With Quote
My front shocks are a similar length and the top mounts extend 4” beyond the frame rail with the brace to tie them together purely to run a decent angle and not have to run a massive rate spring to hold it up as it’s a heavy car





[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]

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