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Making it hook
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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Mon Jan 04, 2016 11:29 pm    Post subject: Making it hook Reply with quote

Where do I start when trying to tune the suspension for a hard launch? I thought I was getting all the right parts, but so far I see no difference. Here's what I have:
68 camaro small block 383, th400 w/3000 stall, 3.73 posi. Moroso trick springs up front with Comp Engineering adjustable shocks at all 4 corners. Factory rubber control arm bushings. Factory monoleafs with Caltrac bars on the back.

When I romp it, it just blows the tires off. If I stab half throttle & roll into it, the tires break loose.
I think I need to get the front end to come up, so weight will transfer and plant the tires. Do I change the front bushings to make it looser? Polyurethane, or Del-a-lum?

Yes, these are street tires I am talking about, but I did try a pair of slicks at the track this summer, and I'm not getting that kick in the pants that I should be.

How important is pinion angle? Any suggestions are greatly appreciated!
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10sec.et
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Joined: 29 Mar 2006
Posts: 3472
Location: Houston,Texas
346624.78 points


1969 Oldsmobile Cutlass

PostPosted: Tue Jan 05, 2016 2:25 am    Post subject: Reply with quote

best way we could answer that is for you to post up a video so we can see what the car is doing at launch. sounds like its not really planting the tires at all. does it squat? it should actually lift the back of the car (forcing the tires down). you didnt say what tires you have. if its BFGs, those wont do anything but spin no matter what you do.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Tue Jan 05, 2016 12:12 pm    Post subject: Reply with quote

Well they are just a Mastercraft street tire, 275/60/15. So besides stickier tires, I would like to spend some time over the winter setting up the suspension to plant the tires better. What is a logical process to improve the launch traction. I thought the Caltracs would make it plant better, maybe they just need better adjusting? Also, I have a set of multileaf springs that could go in place of the mono's. I read some other forums yesterday where guys said not to use mono's.

I'm working on finding a video, but don't think it will help much. There's really not much movement in any direction but forward!
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Big Dave
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Joined: 04 Dec 2005
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Location: Tampa Florida
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PostPosted: Tue Jan 05, 2016 4:08 pm    Post subject: Reply with quote

CalTracs spend a lot on advertising, but the idea of a pipe inside a bigger pipe has been around since leaf springs running fore and aft were first used on cars in the late thirties (prior to that they ran side to side above the differential and the front straight axle). They are adequate for limiting wheel hop but all of the pro stock cars of the late sixties used adjustable J-bolt traction bars. Here is an example of a 68 Camaro with slapper bars running in the high nines in 1968:



You can see the big Lakewood contingency decal in front of the rear tire in this shot.



With 14 inch wide compound W firestone slicks, an L-88 427 two 660 center squirt Holleys, a Vertex mag, Hooker 2-1/8th inch competition headers: basically I copied every store bought part that "Da Grump" had on his Pro Stock car and put it on my 1968 Camaro) I was running consistently a 10:06 to a 10:12 every time I went down the track; claiming B/MP (which I got away with because the four corner scales they used had a plus or minus of 20 pounds so I squeaked by when I should have been running in A/MP because I had gutted the car.

I was using the same trick Moroso springs, which I later figured out where just six cylinder A/C springs repackaged, 90/10 Gabriel shocks cast one piece aluminum wheels 7.75 tires pumped up to 50 psi, and no sway bar. I was using steel tapered roller bearings out of a spring car so that there was no resistance to front end drop (until it hit the chain I installed as a travel limiter). In the back I was using six leaf Trans Am service part springs (that is TransAm HD racing parts not the fire turkey) with 50/50 Monroe HD shocks an eighth inch thick safety plate covering the gas tank as ballast (though it did save my bacon once when I launched my Posi out the back of my 12 bolt rear end case, braking both axles and tearing off both differential caps). Put a crease in the tank and the safety shield which was impressive.

Copying with out knowing why Bill put those parts on his car will only get you so far, In my case I was 0.25 of a second slower than him though we probably spent the same amount of money on the car; considering he had sponsors like Chevrolet giving him parts, probably less than I was spending at the time. Bill Jenkins was a Mechanical Engineering graduate of Case Western which is a very prestigious engineering school on par with MIT or Cal Tech. He wrote books about building Chevy engines to make power but didn't get into the suspension much (even though he invented the first all round tube steel chassis door slammer the front strut drag racing suspension sold today by Strange Engineering, and pioneered slider clutches and data acquisition in race cars).

Another engineer did write the book on door slammer suspension, and I highly recommend you read it. It is called Door Slammers: The Chassis Book by David Morgan.

http://www.amazon.com/Door-Slammers-The-Chassis-Book/dp/0963121707

I just wouldn't pay this price when you can buy it else where for less. (my copy had the price of $29.99 printed right on the front cover and I only paid $23 and change plus S&H when I bought it new).

Big Dave
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Paul P
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Joined: 15 Aug 2002
Posts: 2393
Location: Townsend, Mass.
81240.86 points


1971 Chevrolet Chevelle

PostPosted: Tue Jan 05, 2016 4:34 pm    Post subject: Reply with quote

Dump the factory rubber up front and install some Prothane urethane bushings. Sounds like you are not getting any movement out of the front end at all. Are you foot braking it or just banging the throttle open? If the rear is too stiff it will also contribute to the problem. Once you get it transferring weight (Front end lifting rear squatting a little) you might have to limit front end travel by changing the shock valving. I found this to be the case with the Chevelle. 90/10 was just too quick to rise and fall before the car was actually moving down the track and it would do a sort of bounce after the launch.
_________________
2001 Focus 2.0 Zetec
15.63@87 MPH 1/4mi
1971 - Chevelle 408 SBC N.A.
6.95@98.6 MPH 1/8mi
10.97@121 MPH 1/4mi
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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Wed Jan 06, 2016 2:37 pm    Post subject: Reply with quote

heres a video (if I did it right)

https://drive.google.com/file/d/0B_K7jfth9MbmYzRwRTZQM1BhemM/view?usp=sharing

Does anyone not agree that loosening up the front end is a good place to start?
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Paul P
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Joined: 15 Aug 2002
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Location: Townsend, Mass.
81240.86 points


1971 Chevrolet Chevelle

PostPosted: Wed Jan 06, 2016 3:40 pm    Post subject: Reply with quote

Yes. Lower it a bit too in the front. Car should have a slight rake to it.
_________________
2001 Focus 2.0 Zetec
15.63@87 MPH 1/4mi
1971 - Chevelle 408 SBC N.A.
6.95@98.6 MPH 1/8mi
10.97@121 MPH 1/4mi
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10sec.et
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Joined: 29 Mar 2006
Posts: 3472
Location: Houston,Texas
346624.78 points


1969 Oldsmobile Cutlass

PostPosted: Thu Jan 07, 2016 3:10 pm    Post subject: Reply with quote

you will most definitely have to do some tuning on the front suspension. however, if it were me, the first thing i would do is get my hands on a pair of slicks. my car would do the same thing. it wasn't until after i put some tire under it that i could actually start tuning the chassis.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Tue Jan 19, 2016 2:18 pm    Post subject: Reply with quote

I found a pair of 28.5 x 9.00 Phoenix F/X slicks. Anybody have an opinion on this brand tire? I don't know what to look for in a drag slick, except to check the wear holes.
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10sec.et
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Joined: 29 Mar 2006
Posts: 3472
Location: Houston,Texas
346624.78 points


1969 Oldsmobile Cutlass

PostPosted: Tue Jan 19, 2016 3:23 pm    Post subject: Reply with quote

i have never used those so i really dont know much about them. you need to look at the year they were manufactured. there is a number on the sidewall. ill have to look at mine when i get home to be able to explain how to read it. as tires age, the rubber gets harder. you dont want a ten year old pair of slicks, if youre buying used.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Wed Jan 20, 2016 2:18 pm    Post subject: Reply with quote

OK - I think I will bite the bullet and get a new pair of slicks. I would like to hear opinions on what brands are best, and if I would be OK with a DOT tire versus a race tire. Pros and cons of each. Also, drag "radial" or bias tire?
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10sec.et
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Joined: 29 Mar 2006
Posts: 3472
Location: Houston,Texas
346624.78 points


1969 Oldsmobile Cutlass

PostPosted: Wed Jan 20, 2016 3:14 pm    Post subject: Reply with quote

i have used the MT ET Street tires. its just a slick with grooves in it. only thing i didnt like was how "bouncy" they were. i prefer a stiffer sidewall. i have the MT 3062S slicks now. i dont know much about drag radial tires. hopefully someone else will chime in here.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Paul P
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Joined: 15 Aug 2002
Posts: 2393
Location: Townsend, Mass.
81240.86 points


1971 Chevrolet Chevelle

PostPosted: Mon Jan 25, 2016 10:43 pm    Post subject: Reply with quote

MT ET Streets 3757s but they are no longer produced. I had to switch over to the Hoosier 17611s which are about the same sectional width with an inch more tread. These are both DOT street cheater slicks. No issues they hook well if the suspension is setup right.
_________________
2001 Focus 2.0 Zetec
15.63@87 MPH 1/4mi
1971 - Chevelle 408 SBC N.A.
6.95@98.6 MPH 1/8mi
10.97@121 MPH 1/4mi
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Knarley Darley
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Joined: 22 Apr 2004
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540230.26 points



PostPosted: Tue Feb 23, 2016 12:11 pm    Post subject: Reply with quote

Get the Mickey Thompson 275 drag radials and you will not even be able to spin that tire with your set up. Full stall full throttle as hard as you can and those will dead hook. They are also street legal.
I have drag raced with these, and run them on the street.
The last street car was a 70 Elcamino with a 540, dart 355 heads, roller cam, headers 3" exhaust, 1050 CFM carb ect. Ran in the 9s and we drove it to the track. Estimating 750 horse and running a t-400 trans with 2400 stall.
Even on the street that tire hooked from a 5 MPH roll
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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Fri Mar 11, 2016 12:27 pm    Post subject: Reply with quote

I now have 2 sets of MT ET DRAG tires. One set is 28 x 10.5 x15S - stiff sidewall. The other set is 28 x 10.5 x 15. So when I get to the track in a week or two, I will see if these help. They sure don't help in the driveway though, still spin like crazy. It would be cool if I could glue a spot in my driveway to test how it launches. Anyone ever try to make their own starting line at home?
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