1997 XJ, Coil-Over Project - Walker Evans Racing Shocks

S T O P !!!
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not-good-3.jpg
 
Priandhi Satria said:
that is SHRIFTER....

What I mean is my own up-coming PADLLE from ThomasWheel. Did you get it or still on back order ?
Can you take a picture and upload it ??, all I see so far is a small picture...
Click to expand...
my mistake, I copy/pasted wrong.

HERE is the bigger picture: http://www.awshifting.com/paddle.jpg
 
Priandhi Satria said:
The page cannot be found

The page you are looking for might have been removed, had its name changed, or is temporarily unavailable.
:helpme:
Click to expand...
well it looks like you got it working, I guess I just really suck at the internet today :rolleyes:

http://www.AWshifting.com/pictures/paddle.jpg
(I left the /pictures/ part out last time)
 
This looks to be a street/road build which you need the rear to slightly lift under acceleration. If it lifts then you are causing body separation and forcing the transfer of weight to the tires. If it squats then you are absorbing the transfer of weight with the springs.
 
cagedxj said:
This looks to be a street/road build which you need the rear to slightly lift under acceleration. If it lifts then you are causing body separation and forcing the transfer of weight to the tires. If it squats then you are absorbing the transfer of weight with the springs.
Click to expand...
It's difficult to judge accurately by the pictures since they are shot at various angles, but it appears as if you have build in a huge amount of anti-squat. As you've found out, this results in the rear lift under acceleration. The angle of the upper arms have as much or more to do with this as the lowers. The angle of both arms define the instance center, which in your case is very close to the lower link frame mount. The resulting anti-squat is well above 150%. Lengthening the lower arms will help, but you should do more.

Trying to hold the the 66% length rule is not a good idea considering the space limitations on your street application. The preferred thing to do would be to move the upper link axle mount down and back and move the upper link chassis mount up and forward. This, combined with the longer and potentially lower chassis mount changes to the lower link should make a difference.

There are no valid engineering reasons to have an anti-squat percentage above 100%. Contrary to common beliefs, anti-squat over 100% will not increase weight transfer to the tires. High anti-squat percentages increase the amount of weight transfer carried by the suspension links rather than the springs. In either case, the resulting weight ends up at the tire contact patch.

Another negative of high anti-squat is a tendancy for the axle to chatter or jump during heaving braking. High anti squat percentages stiffen the suspension during braking or acceleration; neither of which is typically a good thing.
 
cagedxj said:
This looks to be a street/road build which you need the rear to slightly lift under acceleration. If it lifts then you are causing body separation and forcing the transfer of weight to the tires. If it squats then you are absorbing the transfer of weight with the springs.
Click to expand...

Thanks for your input...
  1. When I built a couple of my TUBULAR RACE CAR, we designed it for always to SQUATS under accelleration. And this is what most of the people at RACE-DEZERT agree.
  2. SQUATS will cause the rear to lower a little bit and the front to rise, so when we encounter jumps, we can have NOSE HIGH during the AIR TIME. When it lands, ussually it will be on four wheel, instead nosed dive.
  3. I believe when it SQUATS, the weight are transferred to the rear, absord by the spring, then transferred to the tires for additional weight and better grip.
  4. At the moment, when it rise a little bit, it seems the weight are transferred to the front, and IT CAUSE the REAR TO SPIN SO EASY...!!!
  5. That is why on US DRAG RACE CAR, most og the car will try to lift the front end, so that all of the weight are placed on the POWER WHEEL (REAR WHEEL).
However, with my english to indonesian translation, I might be wrong....
 
MaXJohnson said:
  1. It's difficult to judge accurately by the pictures since they are shot at various angles, but it appears as if you have build in a huge amount of anti-squat. As you've found out, this results in the rear lift under acceleration. The angle of the upper arms have as much or more to do with this as the lowers. The angle of both arms define the instance center, which in your case is very close to the lower link frame mount. The resulting anti-squat is well above 150%. Lengthening the lower arms will help, but you should do more.
  2. Trying to hold the the 66% length rule is not a good idea considering the space limitations on your street application.
    1. The preferred thing to do would be to move the upper link axle mount down and back and
    2. move the upper link chassis mount up and forward.
    3. This, combined with the longer and potentially lower chassis mount changes to the lower link should make a difference.
  3. There are no valid engineering reasons to have an anti-squat percentage above 100%. Contrary to common beliefs, anti-squat over 100% will not increase weight transfer to the tires. High anti-squat percentages increase the amount of weight transfer carried by the suspension links rather than the springs. In either case, the resulting weight ends up at the tire contact patch.
  4. Another negative of high anti-squat is a tendancy for the axle to chatter or jump during heaving braking. High anti squat percentages stiffen the suspension during braking or acceleration; neither of which is typically a good thing.
Click to expand...
  1. "angle of both arms define the instance center, which in your case is very close to the lower link frame mount." It seem that it will "MEET" before the front lower arm bolt" !!!
    axle000.jpg
    "but you should do more.", Yes, I agree an this 100%
  2. "....66% length rule is not a good idea considering the space limitations". You are correct. I can not have a better upper control arem angle (as parraell as possible) due to the space limitations on the bottom of XJ. If this is to be achieved, then I have to make the upper control arm goes thru under the rear seat compartment. Then I'll have a good upper arm angle :bawl:
  3. This, I will not comment, as there are so many debate on the terminology and the meaning of "ANTI-SQUAT"....
  4. You are correct...
geee..... i should have ask you to help me design my new tubular race truck for some sort of dezert racing.

ps:
  1. have you used the 4 link calculator ?
  2. I am building a new tubular race car with front and rear four link set-up. It will be 4 wheel solid axle front and rear, as my current YJ set-up.
  3. However, this time I woud like to built it using the right number as close as possible (my YJ was built using trial and error but it still win...)
 
FINISHED Suspension Set-Up​
  • See from front, right, under bumper
  • Right Front Coil Over lower axle mounting, Sway Bar, Sway Bar Linkage
Fin-Fr-9.jpg

note :​
  • I will still need time to re-do the rear arm, then FINE-TUNE all of the COILS...​
  • Anyone knows what the figures / number on SPRING RATE for street applications xx/lbs ???​
  • How about SPRING RATE from one of the 3rd party suspension specialist... (deaver Spring, National Spring, .... I just need the basic number so that I can start to play around...​
 
I'm familar with the 4-link calculator, but most of the good or bad aspects of a suspension design are obvious just by looking at it. Yours is a good example. With the short links and steep angles, you know it's going to have alot of anti-squat. Draw a side view of your vehicle and locate the center of gravity or CG. Draw a line from the rear tire contact patch through the CG. That is the 100% line. Whatever design you choose for suspension links, try to keep the instance center below and ahead of the 100% line. Your rear roll center should be higher than the front roll center. Your's is where the two upper links converge, a little bit above the pumkin. With parallel lower links, your roll axis is at the angle of the links, which slope upwards. This will result in a bit of roll steer.

It also looks like your tender springs are very close to coil bind. After the first inch of suspension travel, the upper springs will turn into a spring spacer and contribute nothing to ride. This will use up an inch of your already limited bump travel. The front springs appear to be even closer to coil bind. Your spring rate should be based on the sprung weight at each corner and the target suspension frequency you are looking for.
 
MaXJohnson said:
  1. I'm familar with the 4-link calculator,...
  2. It also looks like your tender springs are very close to coil bind.
Click to expand...
  1. OK, you put it very simple and easy.... that I can understand now...
  2. As for the spring, I have not tune-it properly, as I would like to re-do the lower arm first, then go into the COIL SPRING Tune-Up. By the time, I will have a proper upper coil, lower coils.
  3. Do you have a magic number for combined rate that I should have aimed for street usage ?
  4. thanks....
 
Last edited:
Priandhi Satria said:
  1. OK, you put it very simple and easy.... that I can understand now...
  2. As for the spring, I have not tune-it properly, as I would like to re-do the lower arm first, then go into the COIL SPRING Tune-Up. By the time, I will have a proper upper coil, lower coils.
  3. Do you have a magic number for combined rate that I should have aimed for street usage ?
  4. thanks....
Click to expand...

I PM'ed you, but I'll repeat here. You should shoot for 180-200 lbs/in in the front. I think you'll have very good handling on the road and a stiff enough spring offroad for good control.

The rear obviously needs to be softer, but not that much. I'd shoot for 140-150 lbs/in.
 
CRASH said:
I PM'ed you, but I'll repeat here. You should shoot for 180-200 lbs/in in the front. I think you'll have very good handling on the road and a stiff enough spring offroad for good control.

The rear obviously needs to be softer, but not that much. I'd shoot for 140-150 lbs/in.
Click to expand...
the softer rear may be the ticket for an off-road setup, but for street use, the rear should be stiffer than the front. I'd try a 160 or 180 pound front rate and a 200 pound or greater rear. Once you have coil rates set, you will still have to fine tune stabilizer bar rates(for the street).
 
CRASH said:
  1. 80-200 lbs/in in the front. I think you'll have very good handling on the road and a stiff enough spring offroad for good control.The rear obviously needs to be softer, but not that much. I'd shoot for 140-150 lbs/in the rear.
Click to expand...
  1. OK, I'll try your recomended set-up. Since it is a dual rate coils, I'll air for a combined rate of the recomended set-up and have a stiffer lower.
 
MaXJohnson said:
the softer rear may be the ticket for an off-road setup, but for street use, the rear should be stiffer than the front. I'd try a 160 or 180 pound front rate and a 200 pound or greater rear. Once you have coil rates set, you will still have to fine tune stabilizer bar rates(for the street).
Click to expand...
This i'll try also once I have the rear lower control arm fixed.
Anyway, thank you very much for giving me a ballpark number to start with. ;)
 
C A U T I O N !!!
stop.jpg
​
  • Just to show the existing rear 4-link design.​
  • I have to admit that the following picture not the correct 4-link design & set-up at the moment.​
  • I'll re-do the lower control arm mounting.​
6-Rear-side-1.jpg
​
 
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