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View Full Version : HRpartsnstuff pieces - any experiences?


Keller
05-06-2006, 12:32 AM
Just got done installing a set of HRpartsnstuff bars (upper adjustable and lower stock length) on my high-11 second T. Also went with their airbag spacers. Prior to this, I had airbags and a homemade pinion snubber, but the arms and bushings were 100% stock.

Any experience or obervations with these pieces? Hope to have some of my own shortly...

PaCemkr86
05-06-2006, 02:38 AM
i run there motormounts and plan on using the antiroll/sway bar, they make excellnet products

Keller
05-31-2006, 11:05 PM
Made my first runs at the GS Nats. The car leaves very level. It used to raise the front end (but not off the ground) a fair bit. Or maybe it was just squatting the rear more.

However, my 60' times are now all over the place. Best was maybe a 1.67 or so. And this is on a fresh pair of Hoosier Quick Time Pro 27x11.50 DOTs. Have been able to do better in the past, though not much. My best 60' is a 1.59.

Had the bags at 10 PSI each side. Used to have them much higher. End of last season I was using 12-15 PSI left and 15-20 PSI right depending on conditions. The tendency for the car to go right after launch is gone. The last few days at the Nats I went to 7 PSI left and 10 PSI right. That seemed to help a bit. Considering going lower yet. (5?) The airbag spacers and pinion angle adjustment may make the bag pressure not necessary.

Tire pressures were started at 14 PSI and taken down to 12 PSI. Not sure how far down I want to go. Tires are not screwed to rims.

I also have adjustable shocks at all four corners. The rears are set roughly at 50% and the fronts at roughly 30-40%. I imaging some further tuning will be necessary there, too.

A lot of knobs to turn! :eek: I did solve the issue of the car wanting to head right after launch. Think that was mostly all the mushy ~20 year old control arm bushings and stock unboxed arms trying to hold back a lot more torque than they had at the factory. Now I want to see if I can get a *teensy* bit more out of what I've got under the rear end.

Any thoughts?

PaCemkr86
05-31-2006, 11:54 PM
what was the best 60 ft? any improvements there?

Keller
06-01-2006, 12:09 PM
My best 60' ever is 1.59.

My best 60' with the new stuff is 1.655. Granted, that was on the 11th run since the new stuff was bolted in. And not many more were made after. So I wasn't very far off. But a even a hundreth can mean a lot. Ask Marco Andretti. :D

The car used to leave with an attitude like you see in my profile pic. Now it leaves much more level. In theory, that might be a good thing. Less wasted motion.

So...still need to tune things. The car rides a tad stiffer, but not that much. Moving from the QA1 shocks from the stock shocks made a bigger difference there. It leaves *much* straighter at the track, and I'm able to use much less air pressure in the bags. In fact, I believe I may be able to go down further in bag pressure. Shock fine tuning for optimum leaves should probably be the polish on the tuning.

Open to any ideas or shared experiences. Digging for hundreths might sound a bit :screwy:, but I'll take every bit I can get. Just want to optimize everything.

kenmosher
06-01-2006, 12:25 PM
I don't think that's :screwy:


Those 5 hundredths on the launch can easily be a tenth or more in E.T.

My bet is that you could probably take all the air pressure out of the bags and see what happens ... I'm wondering if the improved stiffness in the control arms, the better control with the shocks and bushings will basically take the place of the air bags. With the air bags, I wonder if there's some conflict with letting the suspension parts work?

Also, have you checked the pinion angle? I wonder if it changed from stock? I noticed on my with the ATR extenders (basically did the same as the Southsides) that the car did almost exactly what you are describing ... left straighter and more level, but lost about 1/2 a tenth.

I went back to stock angle, and the car picked up again, so sold the extenders. (I've had a best of 1.51 short time and the car was consistently in the 1.53-1.56 range on a decent track ... "bad" 60s were in the 1.6s on greasy tracks)

I think some work on mine (better converter, update the rear bar, etc) should get the car to leave with 1.4s on a good track.

Keller
06-01-2006, 06:17 PM
Interesting that you mention that. I recall those posts from the "old days".

As the first post indicates, I have adjustable uppers, and stock length lowers. That is not a combo that HRpns has on their menu. The adjustable uppers are typically sold with 1/4" longer lower arms. I chose to do this because this car is street driven, and after reading all the info on their site it seemed like the way to go. I'm not in the 13's, and not in the 10's. So this half-breed combo seemed natural.

I'll have to look at my notes as to what I have my uppers set to. But they are set with a 50/50 mix of track and street use in mind. I also set them with an 11.50 target time. Dreaming, perhaps. (I split the number of turns between 12.0 and 11.0.) So there is a wee bit more pinion angle in, vs. the relatively neutral or perhaps .5-1 degree stock angle.

BTW, doing this at home is probably not an option, unless you have a lift in the garage. I had the adjustments made on an alignment rack, using one of HRpns' protractors and adjustment tools, in cooperation with a helpful mechanic willing to let me work with him. Getting the torque needed to cinch those adjusting nuts down is probably not possible on your back in the driveway.

I don't consider Beech Bend to have the best surface. However, they do have a new concrete pad. Prep is questionable. Might try the combo at Gateway in St. Louis tomorrow night for comparison before I change the setup.

Dropping the air in the bags to 5# or 0# is a definite possibility. Its already clear that less is called for and that the balance is better than (well used and abused) stock.

PaCemkr86
06-01-2006, 07:26 PM
from what ive found out is that adjustable lowers are only needed if you need to adjust your wheel base. So if your car is true and the tires arnet rubbin the adjustbale lowers arent really needed.
On a hard leaving car " my mustang" 1.31 60fts I found that gettin away from the air bags and going with a nice anti roll bar is the way to go.
More consistant straight lauches.

If you really wanna get down to the nitty gritty and get the most out of your car, 4 corner scales and see where you are at.

I personally have my own, and they are worth there weight in gold. This even works for cars that dont have coil overs.

PaCemkr86
06-01-2006, 07:28 PM
http://www.ccstreetscene.com/multimedia/phil/Manny1.jpg

Keller
06-02-2006, 11:07 AM
If you really wanna get down to the nitty gritty and get the most out of your car, 4 corner scales and see where you are at.
Interesting. How does this benefit a drag car? I would not think an incremental change in shock or pinion angle would be detectable. Are they?

Do you check with driver aboard?

kenmosher
06-02-2006, 11:30 AM
I found a pretty nicely written suspension tutorial ... thought it might be interesting in this context:

http://www.baselinesuspensions.com/info/Launching_A_Drag_Car.htm

PaCemkr86
06-02-2006, 12:45 PM
I do all my chasis adjustments with driver aboard. or atleast simulated weight in the driver seat.
The benefit of using scales is to see where all the weight is. Like for instance you dont wanna be heavier on the left rear. Ideal is to be somewhere 20+ lbs heavier on right rear.
Lets say you are heavier on the left rear, you can shim the coil springs to compesate. You would be suprized how much having the car set up right helps the 60ft and all around performace.

And this type of practice isnt for drag only cars, cause my mustang is a street car, with a/c , pwr windows tags, insurance and gets drivin to work once a week etc...

http://www.ccstreetscene.com/forums/vbgarage.php?do=view&id=16