Results for Stock Suspension Plotted out..

[KEVINS]

I got the stock suspension plotted out today for our TR's.. It's a mess.....even with aftermarket lower control arms. The Instant Center IS behind the car.

The lower the car is the better the suspension becomes, but it's still a mess.

I tried to post the direct link but I kept getting an error so you'll have to check the link from my Tech Page for more details.

hth's a bit..
ks

 

[Donald McMullin]

I will check your numbers against mine when I get home tonight. My lower arm is level and my upper rear connection point has been raised. My IC is just behind the CG, I know you are trying to place IC in front of CG.

My setup has advantage in that in hard corners the rear toes in reducing rear induced oversteer.

You might have to lower rear by 1-inch, lower upper front connetion by 1/2-inch, and modify the lower rear connection on the axle housing so you can lower the rear connection by 1-inch. This should give you a 70-inch IC arm.

Thanks for the update.

Deep Enough

Donald McMullin

 

[KEVINS]

Hi Don,
I didn't want it in front of the CG. I still want it behind, just not more than 10" behind the CG (it’s now 7”). When I mentioned that I wanted more leverage for the front I meant getting it as closer to the CG line. Many relocating arms only give an IC length of around 38-45” which isn’t long enough for what I wanted to try.
I did get it all figured out and I ended up lowering the front mounting point 1".

Here’s what I ended up with:
IC Length: ~54.75” (~7” behind the CG)
IC height: ~10.2”
Anti-Squat:~ 9%

Here’s the link to my web page. I have the stock suspenison linked here and my new setup linked also:

http://www.geocities.com/kdslaby/Tech_Page_Glossary.html

I’d like to see where yours ended up..

KS

 

[Donald McMullin]

To compare against my own measurements, I did a check calculation using your measurements. Using your measurements i came up with IC length of 54.9 inches and anti-squat of 103% or 3% above the neutral line. My calculated length is close to your calculation, but my anti-squat is lower (do not know why).

I also did a calculation with the rear dropped by 1-inch to simulate possible load during launch and the IC length was reduced to 36 inches with the anti-squat increasing to 23%.

To compare your setup with my WE4, my measurements and calculated results are as follows:

Upper Axle (-0.5 x 18.75)
Upper Frame (7.5 x 17.375)
Lower Axle (0.0 x 8.375)
Lower Frame(19 x 9.125)
IC Length = 48.7 inches
Anti-squat = 4%
IC Length (1.0inch lower) = 35 inches
Anti-squat (1.0 inch lower) = 18%

I made a mistake in a previous post to you about my anti-squat being greater than 20%, this was with a previous setting which I have since changed.

A couple of my measurements need to be re-checked which I did not do last night. I will keep you informed if my results change.

Deep Enough

Donald McMullin

 

[KEVINS]

COOL!!!

I think your measurements sound perfect! I like the low A.S. with your setup! Our suspensions are SO CLOSE in all values except the IC length. I was contemplating for about a week bringing the IC back to about where yours is but I wanted to try something a bit different with my combo and have it longer. The one thing that I was a bit concerned with is my air bags. The rear rises up when I add air to the air bags which shortens the IC. This is another reason why I wanted a longer IC. I don’t know how much it raises it though.

Did you get to compare your 2 different suspensions settings (20% anti squat vs 4%) at the track??????
Do you have drag springs on the front?
Your car must be lowered also by looking at your bracket measurements????
So, you are using the Miller upper brackets, correct?

VERY INTERESTING INFO!!
KS

 

[REDS HOT AIR]

you know if you get it right you can take the bags out.

leave em flat and get it to hook.

i still havent started on messing with mine but i was checking it out on the lift last night while fixing another blown out pump seal in my tranny..

 

[KEVINS]

That's what I'm hoping for!! I have so many different combos that I want to try but not enough time in a race day I need to rent the track just for ME

Your scaring me with your tranny problems!! SO QUIT IT! They better not rub off onto me!!!

ks..

 

[Donald McMullin]

I have some clearance problems with tires on the street so I use air bags as I drive to track. At the track I pull the Sharader valve so air bags are open.

Yes, I have lowered both the front and rear of the car. I have not tried lower spring rate on either front or rear with my IC setup.

Yes, using Miller brackets.

Limited testing between IC settings, but for my setup seems the lower anti-squat did not hit has has hard. With higher anti-squat I had trouble getting shocks set to prevent unloading after initial hit.

Enough for now, Donald

 

[KEVINS]

Super COOL!!

Man, I can't wait 'till I try mine!!!
It's sure sounding good "on paper"!!

hee hee...

ks

 

[Donald McMullin]

Just a note: All of my 60-ft times are with BFG-DR's not slicks. I am assuming that my 60-ft times would drop at least 0.05 to 0.10s with slicks.

I like the way the rear is working for 60-ft times, plus I have improved the road handling.

Remember as we increase the anti-squat under acceleration we have decreased the anti-squat under decceleration. Rear brakes become more sensative to lockup.

Deep Enough

Donald

 

[KEVINS]

I noticed your times were with DR's.. I agree that you can get A LOT more from it with slicks!!

My goal is to get some 1.54-1.57's on slicks with 11.9 to 12.0's.. I launch with 15psi of boost so I think it is very possible depending on engine tune. At this point, my car needs to be re-tuned with the new MEffort chip. "Hopefully" it won't take much tuning..

I wish one of us was racing this weekend...lol.. I'm dying to see how these setups work...

ks

 

[Donald McMullin]

I have a new TE44 sitting on the bench which I would like to install before I run again. Before I install new turbo I have a long list of things to do.

I will not be running for at least 2 - 3 weeks.

Donald McMullin

 

[Turbojorge]

Sorry to interupt, I have a small question.

My car is dropped 2" all around. Are their any down sides to that? I do have 2 air bags in the back. I do get some bad wheel hop some times. My best 60' foot has been a 2.0 w/radials! Is their anything I can do to improve that?
Thanks.

 

[KEVINS]

Actually lowering the car is better because it helps the control arm geometery get better.

Do you mean Drag radials or plain ol' street tires?
As far as hooking it up, sticky tires (Drag Radials or slicks) are the best/only way to get it to hook. If you already have DR's then softer front shocks are still a good thing to have to help get the front end to rise and play with air pressure.
Concentrate on getting the front end to rise easy.

Exactly what type of tires do you have?

ks

 

[Turbojorge]

All my track times have been with 235/60/15 BFG street tires. I now have a set of 26X10 mt's but I have yet to use them. Still, I have heard of peple going into the 1.75-1.85 with these same tires and running what I run with the 2.0's. My car would be at least 4 tenths faster with a 1.8 right?

I guess I need to get out to the track and try out the slicks.

 

[KEVINS]

Originally posted by Turbojorge
Still, I have heard of peple going into the 1.75-1.85 with these same tires and running what I run with the 2.0's. My car would be at least 4 tenths faster with a 1.8 right?

It's hard to say how much faster it will be w/o knowing what it currently runs. Street tires are not very forgiving once they lose traction and with the stiffer front end it makes it even worse..

ks

 

[John Larkin]

I think I am getting close to understanding this geometry lesson; however, here are some questions:

1)When you lowered the front upper control arm mount 1" at the frame, how much did that increase the length of the upper control arm (UCA) mounting holes?

2)Is it safe to say that this lowering could effectively be accomplished by raising the rear mounting points on the axle, say with No-Hop bars? Or is it more difficult with the No-Hop bars (i.e. since they are predrilled, you only have say two starting points, then vary the length of the UCAs). I'm not sure I want to have new brackets made.

3)What pinion angle did you end up with? It almost seems like you need to set your pinion angle first and then move everything around that setting to also achieve the AS and IC.

4)Why do you use 50% of the CG height as a "Normal Line"? Is that standard in suspension setup procedures? I see how it helps you calculate the AS.

5)How far below the intake is the cam, since that is being used as the CG horizontal line? Is it inline with the waterpump pulley? I just never have checked on these engines and figured I'd use the bottom of the intake as a reference point. I can probably get an angle using that reference.

6)Is the decrease in 60' times on your Mustang indicative of what would happen on a TR with similar settings?

I think I'm getting too deep into this. Time to slow down....

 

[KEVINS]

Originally posted by John Larkin

1)When you lowered the front upper control arm mount 1" at the frame, how much did that increase the length of the upper control arm (UCA) mounting holes?

2)Is it safe to say that this lowering could effectively be accomplished by raising the rear mounting points on the axle, say with No-Hop bars? Or is it more difficult with the No-Hop bars (i.e. since they are predrilled, you only have say two starting points, then vary the length of the UCAs). I'm not sure I want to have new brackets made.

3)What pinion angle did you end up with? It almost seems like you need to set your pinion angle first and then move everything around that setting to also achieve the AS and IC.

4)Why do you use 50% of the CG height as a "Normal Line"? Is that standard in suspension setup procedures? I see how it helps you calculate the AS.

5)How far below the intake is the cam, since that is being used as the CG horizontal line? Is it inline with the waterpump pulley? I just never have checked on these engines and figured I'd use the bottom of the intake as a reference point. I can probably get an angle using that reference.

6)Is the decrease in 60' times on your Mustang indicative of what would happen on a TR with similar settings?

1. It didn’t lengthen them at all. I drew an arc with the center being at the rear mounting hole and the arc going through the existing mounting hole and then drilled the hole along this arc. This keeps the UCA the same length so it doesn’t change pinion angle.

2. Yes it would be the same thing. It is actually easier with the pre-fabbed no-hop bars but you are pretty much stuck with the IC that the bars give you which could be way off. Most of those types of bars produce way too much Anti-Squat but you won’t know until you plot them out. I never trust anything unless I can mount them then return them if the IC is not “where I want it”. According to Donald McMullins measurements it looks like his no-hop bars raised the rear mounting hole 1” which is about perfect, BUT only with a lowered suspension. Without the lowered suspension the AS is to violent, IMO. Someone could mount the no-hop bars then lower the car until the IC is close to where they want it if they wanted to go that route.

3. My pinion angle ended up a little over 4*. I still use factory bushings and I didn’t want any less. If you were not going to use adjustable uppers then you are correct about setting the angle first so the holes can be drilled accordingly.

4. There is another term called “Pitch Rotate” which is used to describe how the front and rear of the car rise or fall with respect to each other. The 50% PR just means that the front and rear will not Pitch Rotate up or down with respect to each other if the IC lies on this neutral/normal line.

5. No idea..lol… I set it at the water pump centerline. I would love to know for accuracy though. Most 4-links have enough mounting holes that the true CG is not “all that important” because the settings are only for baselining and suspension tweaking is done later. The CG is more for a constant reference point. However, there is a method for MEASURING the height of the CG but it involves raising the front and rear of the car 2-3 feet in the air while sitting on scales, but I don’t know the exact procedure.

6. It just depends on how messed up the suspension was to begin with and the current engine/trans combo but yes it can make that kinda difference. If I had the $$ to put on adjustable struts and shocks on my Stang the 60’s would have been 1.40 or better. With the truck on my web page I was able to knock off .06-.09 on the 60’ just by the proper shock adjustments. I'm not saying that it will make that kinda of difference on all cars but it can help.<-----fine print

ks

 

[Chuck Leeper]

CG exercize

In the FWIW dept, heres the formula for doing a sure nuf CG check.
1. All 4 suspension points must be made solid, as in rods to replace the shocks.
2. The tires must be HARD.. to prevent deflection.
3. The gas tank has to be either totally full or completely empty.
4. Place the car on 4 wheel scales.
5. Read and record all 4 scale readings.
6. Jack the rear end up 10 inches as measured at the CL of the wheel.
7. Read ft wheel wts and record.
8. Subtract the 2 ft wts and record the total.

Hcg = change in ft wt X wheel base X cos of the tilt angle divided by total wt of vehicle X sin of the tilt angle.

Tilt angle = tan O=10 divided by the WB.

sorry I don't have a engineering keyboard!! DUH


Also: Gm engineering has stated for the "average" calcs, you can use the following:
passenger cars = 20 to 21"
12 - 13" formula cars.
16 - 18" sports racing.

ALSO, [Again!!]
There is a visual that can help understand where the anti squat is on a particular car. It involves watching the tires on launch. It goes something like this:

Tire wrinkles at the bottom = A/S is high. [6 o'clock]
" " " " front = A/S is low. [3 to 4 o'clock]

Further observation can tell something about pressures.. right or too low.

Correct PSI = wrinkles at the ft and towards the bottom. [5 o'clock]
Low PSI and Excessive anti squat = wrinkles at the bottom and excessively long footprint. IE: the rim is driven into the track.

just some "stuff" from the ancient one!!!

Stay tuned to this 'NBS" station for more in the ongoing saga of "Captain HOOK" !

 

[KEVINS]

We pause for a satation break....

VERY GOOD INFO!!!

I do pay attention to the tire wrinkle to determine if it is a "soft" hit or a "hard" hit but I never heard about the position of the wrinkle. I like that!! It makes sense..

I don't want an engineering key board.. this one spells enough words wrong...hee hee....

Now back to your regularly scheduled program...

ks