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 1320 (Pontiac Straightline Performance)
 Suspension/sway bar setup
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 09 Jul 2013 :  09:52:05 AM  Show Profile  Reply with Quote
On my stock body, stock interior 72 Lemans (~3800lbs with driver), I'm wondering what would be good to try as far as different suspension set ups at the track:

As it sits now, it has:

(1)Front sway bar, NO rear sway bar.

next trip to track, want to try
(2) Front AND rear sway bar
(3) NO front sway bar, Rear sway bar

Also I have 3 way adjustable shocks, 50/50, 60/40, 70/30
Right now, iirc, they're set at 60/40. I'm guessing I may experience a better "lauch" with 50/50, but what do you guys think?

If it hooks and does not spin at the 60/40 setting, is it necessary to adjust to 50/50? I guess it would slightly affect weight transfer but would it likely result in lower 60'/et's?

*72' Pontiac Lemans* - Work in Progress

Bill Boyle
Horse Feathers (Charter Member)

USA
4797 Posts

Posted - 09 Jul 2013 :  11:18:45 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Matt--lots of cars are set up with a 60/40 and they fly. There is no one-size fits all formula.

The front sway bar: some say the sway bar slows down weight transfer to the rear. It might in some vehicles. I've run with virtually no working front sway bar, and the one with new polygraphite bushing and didn't notice any difference at the strip. But that is not a scientific observation just looking at time slips.

It appears to me your focus should be on tires and tire pressure. You want to dial in tire pressure that produces the consistent 60' times. Now, I'm not saying accept the 2.0 dial in, but one that is under that. How consistent is consistent. If you could repeat sub 2.0, say 1.900-1.930 that would be terrific consistency. Ambient temperature and surface temperature constantly change so consistency is always fleeting, like nailing Jello to the wall. By focusing on tires and tire pressure you will also develop your reaction time without concentrating on it.

Keep the car at 60/40 and just work on tires and pressure. Leave the sway bar in place too.

Keep a log or journal of what changes you make and other track conditions. Unless you do that you will get lost and have to start over. Keep as many things the same and alter one thing before going on to the next. That is not to say that you can't combine 2 or more slight changes and note them. Just keep good records.

What tires will you be running at the strip. How many passes on them at this point?

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 09 Jul 2013 :  1:31:22 PM  Show Profile  Reply with Quote
Good info Bill, you are right i need to get consistent with myself and find a good starting point.

Current rear tires are BFG G-Force T/A Drag Radials (http://www.summitracing.com/parts/bfg-54462/overview/), on which I have made 3 passes. They also have approximately 20 "road" miles. Just put these tires on about 2 months ago. For those three passes I ran them at 20 psi.

That day I made those 3 passes, these two timeslips (last 2 passes) were my best to date.

yellow slip was my 3rd pass, I'm the right lane
white slip was my 2nd pass, I'm the left lane.)



My 60' times were noticably better with the new Drag Radials - 1.92 and 1.81. Not very consistent yet but I will work on that, that mostly is on the driver.

*72' Pontiac Lemans* - Work in Progress
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Bill Boyle
Horse Feathers (Charter Member)

USA
4797 Posts

Posted - 09 Jul 2013 :  5:06:54 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
There are many variables to deal with...practice and more practice and assessing each run with a critical and objective eye will ultimately make a difference in you knowing the car and that will translate into better strip performance. Practice, practice, and more practice. That's the order of the day.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 10 Jul 2013 :  08:41:45 AM  Show Profile  Reply with Quote
Fair enough! I agree, until I become consistent, most any changes made will not accurately be measured.

However, when i do the "Pavement Pounders shootout", one thing they ask is that you make some kind of adjustment between each run to try to improve E/T... So I thought this would be something I could test, just to see if/how the car responds.

*72' Pontiac Lemans* - Work in Progress
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Bill Boyle
Horse Feathers (Charter Member)

USA
4797 Posts

Posted - 10 Jul 2013 :  10:48:05 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Ah Haa, they want you to screw with a good thing. What do that think this is Test and Tune?

If you must do something different, change tire pressure. Start out a little high and drop it to see if you increase 60'. Run with and without an air cleaner. Change you launch from off idle, lets say trying a little more brake and rpm on the converter.

I suggest doing as little to the car and engine as possible. Try to dial it in, as they say.

When we campaigned our 57 Chevy Wagon in '68, we did all of our tuning in the garage and worked on launch technique at the strip before competition began. We did have a small compressor tank where we could play with the air pressure a little, but mostly it was figuring out what rpm we should come "out of the hole" with to gain as much traction as possible. Back then there was no clock to measure 60' times, so we always looked at other things like steering straight, traction, shift points (no meter to tell you when and then reviewing the time sheets for improvements in ET. [Three of us owned the car but only two of us ever won trophies driving it. My future brother-in-law drove and broke things routinely. I don't recall him ever getting down the strip during competition without us hopping into the "chase" vehicle and getting the wagon pushed off the track.

Keep your changes simple. No carb swaps, jet changes, battery relocation, no header swaps, fuel injection, Nitrous, 6-71 blowers, rocket engines...leave that stuff for a 4-day weekend.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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GtoGuy32
Cochise

USA
842 Posts

Posted - 10 Jul 2013 :  7:11:56 PM  Show Profile  Reply with Quote
I was going to bolt a supercharger onto my setup in between runs just to see if it made a difference



joking of course
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 11 Jul 2013 :  09:43:12 AM  Show Profile  Reply with Quote
I was also contemplating a Straight-axle front suspension swap, be the only GASSER Lemans on the property.

also joking.

*72' Pontiac Lemans* - Work in Progress
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GtoGuy32
Cochise

USA
842 Posts

Posted - 11 Jul 2013 :  7:12:14 PM  Show Profile  Reply with Quote
quote:
Originally posted by PontiacMatt

I was also contemplating a Straight-axle front suspension swap, be the only GASSER Lemans on the property.

also joking.



haha I love it!
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RayK
Cochise

USA
925 Posts

Posted - 18 Jul 2013 :  9:38:59 PM  Show Profile  Reply with Quote
Actually Bill, they really do expect a "test and tune". Track rental is paid for by the magazine and so is lunch. All they ask is that you document EVERY adjustment, and the more you make the better it looks in the magazine. It's a fun day of making adjustments and running your car as many times as you want.
As far as the anti-sway bar, I removed mine. It seemed to launch a bit better without it, but I have a Bird and matt has a full frame LeMans. You just have to play around to see what you get. I talked with Jim Hand once about that very same subject, and he told me the same thing. It depends on vehicle, launch technique, etc.
I would leave the shocks alone if they are set at 60/40 just for a couple runs to get a baseline. Matt do you have to heat the living bejesus out of those drag radials or do they just need a bit of heat to hook? Just wondering.

1969 Firebird 461, #62 iron heads, Comp roller, Performer RPM, Q-Jet Turbo 400 w/ Continental converter. GM 8.5" 10 bolt with 3:73 gears.11.50's@ 119+ MPH
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 19 Jul 2013 :  09:39:55 AM  Show Profile  Reply with Quote
Ray, that was kind of the vibe i got from talking to the HPP contact about adjustments... doesn't have to be anything extreme, but they do want to see something adjusted to try to improve E.T.'s. As for my sway bar, removing the front will be no problem, something i can try after a couple of runs. what about adding a rear bar? because i currently don't have one back there. would it be worth the trouble of bringing one just to try i wonder?

As for my drag radials Ray, They don't seem to be as soft a compound as say the E/T streets, but my one trip to the track i did one "small" burnout (4-5 seconds) and one a little smokier (7-8 seconds), but the car hooked great with the small burnout. This was on a ~70 degree, just after dusk, spring test and tune though, so not sure how it will act on a hotter track.

I'd like to see a 1.80 60' and a 12.5 1/4 et at norwalk, but depending on weather I may be doin good to duplicate that 12.72.

*72' Pontiac Lemans* - Work in Progress
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 19 Jul 2013 :  09:42:50 AM  Show Profile  Reply with Quote
I can play with Launch RPM's some, haven't really nailed down what's a good RPM to launch from yet. Been launching anywhere from 1500 to 1900, I believe i was at about 1800 when i cut that .024 r/t and 1.81 60'. No trans brake, just footbrakin it.

*72' Pontiac Lemans* - Work in Progress
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bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 19 Jul 2013 :  10:00:24 AM  Show Profile  Reply with Quote
quote:
Originally posted by PontiacMatt

I can play with Launch RPM's some, haven't really nailed down what's a good RPM to launch from yet. Been launching anywhere from 1500 to 1900, I believe i was at about 1800 when i cut that .024 r/t and 1.81 60'. No trans brake, just footbrakin it.



Have you tried not foot braking it? I was advised to just mat the throttle and the converter should "flash" a little higher RPM on take off versus foot braking it. Depending on the range of your converter and cam, it could actually help getting the RPM's higher up into the preferred operating RPM. I believe it was Cliff that suggested that.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 19 Jul 2013 :  10:24:15 AM  Show Profile  Reply with Quote
Haven't tried that yet Brian... may have to give it a shot! running a Hughes 3000 stall on a TH400. 3.42 gear 12 bolt, Eaton limited slip (Posi) carrier.

*72' Pontiac Lemans* - Work in Progress
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Blued and Painted
Chief PONTIAC

USA
3409 Posts

Posted - 19 Jul 2013 :  10:33:41 AM  Show Profile  Reply with Quote
Pretty easy to take one sway-bar link out of the front. But i would want to have one working on the back @ 100 mph.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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pontiacchuck
Buffalo

USA
94 Posts

Posted - 27 Jul 2013 :  08:39:54 AM  Show Profile  Reply with Quote
i have a 80 gp 400 turbo 350 front sway bar removed 90/10 shock stock springs rear boxed stock arms stock springs and shock et streets brack till car rocks to rt hit gas 2500 stall 3:89 gear sixtys 1.61 lift fronts off abount 3 or 4 in. 3300 lb car

charles dixon
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