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KDF 831V Code Brown


Jonathan Pounsett
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  • 2 weeks later...
  • 1 month later...

We've come a long, long way together
Through the hard times and the good
I have to celebrate you, baby
I have to praise you like I should……….

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2 hours ago, Jonathan Pounsett said:

We've come a long, long way together
Through the hard times and the good
I have to celebrate you, baby
I have to praise you like I should……….

Project images are available to Club Members Only, Click to become an OMOC Member.

 

Project images are available to Club Members Only, Click to become an OMOC Member.

Thats a great pair of pictures indeed to show how far it has come and what a great job you done if it’s restoration 👍

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  • 3 weeks later...

I had a bit of time before the F1 started so took the Manta for a run round the block. It was mostly enjoyable but when I stamp on the gas the rear end feels like it’s going to lift off. Is there something wrong in the 5 link setup that lifts the rear of the car rather than propelling it forward?

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1 hour ago, Jonathan Pounsett said:

I had a bit of time before the F1 started so took the Manta for a run round the block. It was mostly enjoyable but when I stamp on the gas the rear end feels like it’s going to lift off. Is there something wrong in the 5 link setup that lifts the rear of the car rather than propelling it forward?

Yes, that’s the link angles mate, your instance center is off. Basically the top and bottom arm angles should point towards the front of the car , if the top arm is higher then on the axle it will cause an additional rotation of the wheel as the torque transfers, so it goes up.

https://www.onallcylinders.com/2015/04/23/figure-four-a-guide-to-tuning-your-four-link-suspension-system/

 

on the Manta, the lower and upper arms should aim towards the front of the car, between subframe and air dam.  If it’s like my crude drawing, they will aim backwards!

 

 

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That’s interesting reading Jess, but I’ll have to read it again (probably a couple of times) to get a full understanding.

I put a lot of effort in to getting the driveline angles as close as I could to the ideal 3 degrees to eliminate vibration during acceleration. From reading this I need to establish the best instance angle for my car and driving style first and worry about the propshaft driveline angles later. 

I suspect that only fine tuning will be required as the adjustments I’ve been making have been very minor.

Could I ask what instant centre you settled on for your setup Jess? The air dam is more than the 50” mentioned by Bickel.

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10 hours ago, Jonathan Pounsett said:

That’s interesting reading Jess, but I’ll have to read it again (probably a couple of times) to get a full understanding.

I put a lot of effort in to getting the driveline angles as close as I could to the ideal 3 degrees to eliminate vibration during acceleration. From reading this I need to establish the best instance angle for my car and driving style first and worry about the propshaft driveline angles later. 

I suspect that only fine tuning will be required as the adjustments I’ve been making have been very minor.

Could I ask what instant centre you settled on for your setup Jess? The air dam is more than the 50” mentioned by Bickel.

Yes, this not driveline angle but rather an effect based on the relationship between the angle of the top and lower arms. It effectively lifts when first starting under load, but then as the initial backwards rotation is overcome it will squat. But you would definitely feel it initially 

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I know, I was just a bit annoyed with myself that I hadn’t sorted this first. Anyway I’ll know for next time (there won’t be a next time) or I will sound like an expert when someone else has the same issue. 
 

Do you want to share your dimensions? 😉 

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44 minutes ago, Jonathan Pounsett said:

I know, I was just a bit annoyed with myself that I hadn’t sorted this first. Anyway I’ll know for next time (there won’t be a next time) or I will sound like an expert when someone else has the same issue. 
 

Do you want to share your dimensions? 😉 

Ofc I will once finished mate, but my pickups won’t match yours? 
(edit top)

Edited by Jessopia74
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  • 2 weeks later...

I reversed into that parking space and up to the front door - there were loads of people outside already cos it was such a nice evening but then people came out of the pub to see what had arrived. I’m sure some were disappointed but as I say all good comments. 

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I was not happy with the rear end lift on hard acceleration so following advice from @Jessopia74 I read up on “instant centre”

 https://www.onallcylinders.com/2015/04/23/figure-four-a-guide-to-tuning-your-four-link-suspension-system/

and watched a few YouTube videos by Kevin Wilson

 

One of Kevin’s videos has a link to an online calculator which has helped me to identify and hopefully rectify my problem;

My upper control arms are about 11.5” (it’s American advice) and this gives me an antisquat value of 103.22% . (More than 100% and the car lifts, less than 100% and the car squats.) By extending the links to 12.25” (that’s 19mm) the value is 98.62% - this is great because as the car accelerates the characteristics change and the percentage goes up.


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I also wasn’t aware of the benefits of shorter top links so I’m feeling quite confident about putting it all back together now.

I urge anyone considering a rear axel swap to watch the vids and read up as much as you can before reaching for the grinder or welder!

Axel out again 🫤

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Damage to the floor 🫤 Interesting that the shape of the floor almost accommodates the Commodore axle as I don’t think this would be required with the Manta torque tube.

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Damaged under seal where shock came adrift. Unrelated to the axle issues - just shoddy workmanship!

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The axle is back in and with the addition of a nice pair of new shocks the driving experience is the best it’s ever been. Just wondering if I’m brave enough to drive the 200 mile round trip to Sywell and back 🤔

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