IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: good2win22 on July 15 2014, 09:25:37 PM
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Finished the install this evening along with centering the rear end and setting pinion angle to 2.5 degrees. Here's what the calculator came up with. I took a wild ass guess with the weight numbers as I haven't been to a scale yet. Do these numbers look somewhere in the ballpark of making a decent launch? Questions for you suspension smart guys, after centering the rear end, I could only get 2.5 degrees on the pinion angle as one of the upper control arms was bottomed out. How can I fix this?
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First off, are you sure on the tire height Jason. I think you're closer to a 25.4" height. Your car also weighs more than 3200 lbs with you in it. Take it to a truck stop with a scale and drive the front wheels on, get a weight, do it with all 4, and then just the back wheels. You should be closer to 3400 or 3600. A stripped bare T will be in the 33oo+ range. Did you take the measurements with the stock arms first so you can calculate original IC location?
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I think 2.5 degs, if Negative, is perfectly adequate for a four link car with an automatic transmission. After all, the pinion can only rise the amount that the bushing deflection will allow...that's the reason pinion snubbers are not needed on a coil spring car with a four link suspension.
At least your ic is under the car instead of out in front of the front tires. Might be nice to have it a bit further back but most G-bodies seem to hook pretty well in this area. It's close to the thrust line so the car should launch pretty much in a parallel line without the front end wasting motion going up instead of forward.
Pretty sure your weights are off quite a bit. I think one of my cars was more like 2200 on the front and 1500 on the back but I may be mixing cars up.
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You can improve the pinion angle with longer lower control arms or offset bushings.
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I did not take measurements before Charlie. Add that to the list of things I've forgotten lately. Adjusted the tire numbers and weight but didn't make much of a difference on the anti-squat. Need to get to a scale to see what she weighs. Offset bushing.... I was thinking of bringing the rear end ride height down another 1/2 to 1 inch. Right now she is sitting about 1/2 to 3/4 inch higher than the front
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If the IC is correct then you shouldn't have to worry about the height in the rear. The IC correction will actually help you transfer the weight better. The off set bushings are a real PITA to set properly, believe me. Since you've also got poly bushings in the lowers you should be about 1.5 degrees on the pinion angle. Rubber ones move more.
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No one asked for the easy answer. ;) But, there are lots of adjustable and double-adjustable LCAs out there these days.
I do know that my car performs well for having just a set of single-adjustable uppers and poly-U/roto-joint lowers - 1.7 60' on 315/35R17 drag radial off the footbrake (the transbrake will over-power the tires so it is never used).
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With everything being equal...how much torque does it take to get one of these bricks to go into the mid 1.5's for a short time?
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No one asked for the easy answer. ;) But, there are lots of adjustable and double-adjustable LCAs out there these days.
While that may be true, these arms aren't stock length or even usable in the stock location. These are designed to bolt to a bracket that mounts where the upper arm mounts on the frame. Then the arms attach.
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I guessed that was one of Kevin's set ups from the diagram...I really like the idea
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It is Steve. That's how I came up with the mods I made to my "new" frame. :rock:
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Called the local scrap yard and they have a scale. 3 weighings later and I have some usable numbers and it only cost 5 bucks! Anyway, total weight with me in the car and a half a bag of gas is 3560. Front is 2060 and rear is 1500. Motörhead, I have stock length lower control arms from UMI with poly bushings. Here are the new numbers
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With everything being equal...how much torque does it take to get one of these bricks to go into the mid 1.5's for a short time?
Depends a lot on weight, gearing, and torque multiplication in the torque converter. See the attachment (pardon the Chevy... it was a custom power curve).
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Thanks...need my reading glasses. Gettin' old ya' know.
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With everything being equal...how much torque does it take to get one of these bricks to go into the mid 1.5's for a short time?
Depends a lot on weight, gearing, and torque multiplication in the torque converter. See the attachment (pardon the Chevy... it was a custom power curve).
Does that chart show 600HP to make a 1.5 second 60 foot time?
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Thanks...need my reading glasses. Gettin' old ya' know.
Click on the pictures and they should be full size.
If you have an actual dyno graph I can replicate it. This is how I "hyper-tuned" our Camaro into the mid-12s on a stock motor. Dyno graph, gearing, weight = programmed shift points... just had to add some traction. ;)
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With everything being equal...how much torque does it take to get one of these bricks to go into the mid 1.5's for a short time?
Depends a lot on weight, gearing, and torque multiplication in the torque converter. See the attachment (pardon the Chevy... it was a custom power curve).
Does that chart show 600HP to make a 1.5 second 60 foot time?
No, it shows 600hp to run a 10.4; it is making less than 600hp by the time it hits the 60' mark (the engine is at 5800rpm). This is just a simple simulation, I was focusing on torque as per Brad's request, in a full weight street car, and Buick-like RPM. Nothing more, nothing less.
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With everything being equal...how much torque does it take to get one of these bricks to go into the mid 1.5's for a short time?
Depends a lot on weight, gearing, and torque multiplication in the torque converter. See the attachment (pardon the Chevy... it was a custom power curve).
Does that chart show 600HP to make a 1.5 second 60 foot time?
No, it shows 600hp to run a 10.4; it is making less than 600hp by the time it hits the 60' mark (the engine is at 5800rpm). This is just a simple simulation, I was focusing on torque as per Brad's request, in a full weight street car, and Buick-like RPM. Nothing more, nothing less.
Th second graph didn't show up until now. I was looking at the top chart trying to make sense of it. Thanks!
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Thanks...need my reading glasses. Gettin' old ya' know.
Just don't shrink anymore Scoob. :rofl:
I still think your tire height is off Jason. Worst case, take a level and go from the top of the tire to the ground to make sure it's right.
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Ordered another set of rear springs to bring down the rake in the car. Couple of pics of the current front and rear ride height. Probably not the correct place to measure the height but I measured just behind the front fender and right in front of the rear wheel. Of course the tape measure case and the concretes are your constants. When the springs get here and installed on the car I'll put up a new pic of the IC calculator to see how it changes
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Got the springs in. Moog 5413. Car is down about 3/4 inch in the rear and I'm sure it will settle a bit with time. This means that the rake on the car is now about 7/8 inch instead of 1 5/8ths.
Ran the numbers on the instant center calculator. Keep in mind that the goal is to remain on the thrust line (redline) and be directly underneath the CG of the car (the little blue circle). This is as close as I could get it to that intersection. As the car sits now with me in it, I have a 57% front and 43% weight ratio. So it appears that the only options are to remove weight from the front or add weight to the rear or do both. Thoughts?
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This is why you need to scale the car to see where the weight sits Jason. 100 lbs in the right side of the trunk should do wonders for traction. :rock:
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I did scale the car Charlie.
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I did scale the car Charlie.
You misunderstand me Jason. You got the car weighed but not scaled. Scaling will give you cross weights and front to rear bias as well as target areas where weight may need to be added, or moved.
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Do you have Dave Morgan's book on suspension set up? Door Slammers
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Do you have Dave Morgan's book on suspension set up? Door Slammers
I do not have that book. Looking it up now
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Do you have Dave Morgan's book on suspension set up? Door Slammers
I do not have that book. Looking it up now
Just ordered the book. Hope to have it before the weekend. Headed to the track this coming Friday evening for test and tune.
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That's the bible
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Ordered another set of rear springs to bring down the rake in the car. Couple of pics of the current front and rear ride height. Probably not the correct place to measure the height but I measured just behind the front fender and right in front of the rear wheel. Of course the tape measure case and the concretes are your constants. When the springs get here and installed on the car I'll put up a new pic of the IC calculator to see how it changes
Holy crap is your car sitting on jack stands?! :O Or do you plan on taking it muddin'? :hmm
That thing needs moar low. :icon_kidra:
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Ordered another set of rear springs to bring down the rake in the car. Couple of pics of the current front and rear ride height. Probably not the correct place to measure the height but I measured just behind the front fender and right in front of the rear wheel. Of course the tape measure case and the concretes are your constants. When the springs get here and installed on the car I'll put up a new pic of the IC calculator to see how it changes
Holy crap is your car sitting on jack stands?! :O Or do you plan on taking it muddin'? :hmm
That thing needs moar low. :icon_kidra:
Low enough for me brother. Texas roads ain't the best. Glad I don't have to deal with frost heave
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Glad I don't have to deal with frost heave
Meh... I just skip or launch the cars/truck over the bumps and dips. Sparks are always fun to see shoot out the back. ;)
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New personal best with this configuration. .. MT ET 255/50/16 streets at 17 psi. Temp at track was 55ish.
60 ft 1.58
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http://www.onallcylinders.com/2015/04/23/figure-four-a-guide-to-tuning-your-four-link-suspension-system/ (http://www.onallcylinders.com/2015/04/23/figure-four-a-guide-to-tuning-your-four-link-suspension-system/)
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That's a good write up! Thanks for sharing