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How's my numbers?

ryanw10

New member
Joined
Apr 22, 2021
Member Number
3843
Messages
3
Overall, not bad. Cg seems a bit high, that will change the antis some. Also the body all three roll axis are oversteer or neutral. Not necessarily a bad thing, but can be a problem if an unaware drive gets behind the wheel.
Thank you for the input. Im able to bring my frame side lowers in and get both the rear roll slope, and the body roll axis to understeer, would this behave better to an unaware driver? I also did lower the center of gravity, kinda hard to tell but it will be a pretty tall Jeep.

JK link data 1.5.png
JK link data 2.5.png
 

mano002

Newbie
Joined
May 20, 2020
Member Number
546
Messages
8
I noticed a big change in the roll oversteer numbers when I changed to the new version of the spreadsheet. I had scary roll oversteer, made some pretty invasive changes to lower the frame ends of the lower links, and it drives better, but the new spreadsheet doesn't really show that.

I'm not sure where to go from here.
 

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Treefrog

Book Wheeler
Joined
Jun 11, 2020
Member Number
1958
Messages
246
Location
Central Florida
I noticed a big change in the roll oversteer numbers when I changed to the new version of the spreadsheet. I had scary roll oversteer, made some pretty invasive changes to lower the frame ends of the lower links, and it drives better, but the new spreadsheet doesn't really show that.

I'm not sure where to go from here.
Which version were you using? A few versions ago, I caught a mistake in the front roll center math that would affect the body roll slope.

It is possible that a little change in the value had a large effect, it is also possible that lowering the links affected other aspects as well.
 

mano002

Newbie
Joined
May 20, 2020
Member Number
546
Messages
8
I started using 4.0, and updated to 6.1, and then to 7.6. The change I was talking about was between 6.1 to 7.6.
 

Treefrog

Book Wheeler
Joined
Jun 11, 2020
Member Number
1958
Messages
246
Location
Central Florida
I started using 4.0, and updated to 6.1, and then to 7.6. The change I was talking about was between 6.1 to 7.6.
Which roll slope changed? Body or front? The fix was implemented in 6.1, so all three versions should have the same output for the same inputs. I'll double check it with the 3 link setup this weekend. I did not spend much time checking the values for 3 link roll stuff.
 

mano002

Newbie
Joined
May 20, 2020
Member Number
546
Messages
8
Which roll slope changed? Body or front? The fix was implemented in 6.1, so all three versions should have the same output for the same inputs. I'll double check it with the 3 link setup this weekend. I did not spend much time checking the values for 3 link roll stuff.
Looks like it was a data entry issue on my end. I had the frame end of the pan-hard bar below the axle end.
 

TSG

New member
Joined
Apr 13, 2021
Member Number
3791
Messages
4
First go at rear 4 link numbers. Truck is a trail rig, mostly rock crawling in the southeast. 1981 Toyota, dual transfer cases, leaf sprung (RUFs) in the front. I'm thinking I need to drop the frame side lowers down some to get them flatter. I've got plenty of room to move things around, especially the uppers.

4 Link_v1-1.JPG
4 Link_v1-2.JPG


62136164608__60147FA4-C988-40F8-9694-1D8446E37C9B.jpg
 

Treefrog

Book Wheeler
Joined
Jun 11, 2020
Member Number
1958
Messages
246
Location
Central Florida
First go at rear 4 link numbers. Truck is a trail rig, mostly rock crawling in the southeast. 1981 Toyota, dual transfer cases, leaf sprung (RUFs) in the front. I'm thinking I need to drop the frame side lowers down some to get them flatter. I've got plenty of room to move things around, especially the uppers.
You are probably right about needing to drop the frame side lowers. It may be beneficial to widen the upper axle and lower frame points. The total combined angle only needs to be about 40*, having less angle will help with keeping the axle pointing in the right direction when the suspension is articulated. As for the upper frames, you may want to move them up, closer to parallel with the lowers. It would keep you from having to drop the lowers some.
 
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