Poor prep and Radials

Shocks, Springs, Brakes, Frame, Body Work, etc

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3window
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Poor prep and Radials

Post by 3window » Sun May 13, 2018 9:49 am

Ok guys, need a little help here. I’ve got a ‘70 Nova on a Nitto 275 drag radial. I run a turbo 5.3, th400 and a 3.31 gear. Caltracs, Landrum monos, sliders, plenty of travel front and rear. Viking DAs all around. I run the bars in the bottom hole with 1/2 turn preload. Conventional spring up front (165lb) and the car weighs 3450 with me. Sorry no corner weights. Let’s just say that the track prep is poor. I’ve tried quite a few different shock settings and have had the bars top and bottom holes. Maybe I’m just missing the setup. I’ve got a timing ramp setup for testing so maybe that’s the magic bullet. Any advice would be much appreciated. Let me know what you guys think. The car previously ran 107 in the 1/8 on 15 pounds and a dismal 1.89 60 foot (all my fault/boost controller brain fart). Should run 9.50s when figured out.

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Re: Poor prep and Radials

Post by 6.50camaro » Mon May 14, 2018 7:05 am

Do you know what the converter is flashing to at launch? Dan

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Re: Poor prep and Radials

Post by 3window » Mon May 14, 2018 10:36 am

I’m not sure exactly. I can footbrake it to about 3,100 and it’ll go 3,400 on the brake.

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Re: Poor prep and Radials

Post by 6.50camaro » Mon May 14, 2018 8:56 pm

I know hardly anything about turbos and how to launch with one . But I think you need more converter stall and more gear . When I ran 107+ mph my 60' was 1.385, 1/8 mile et 6.315 . This is a N/A sbc 422 , 11.5 CR 5300 stall, powerglide and 5.13 gears . Your mph says you've got up on the top end . But it taking forever to move off the line and wind it up to wear your making good hp with those gears and tight converter. Just my thoughts ,Dan

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Re: Poor prep and Radials

Post by 3window » Mon May 14, 2018 10:26 pm

Thanks Dan. Yah, the awful 60 was entirely my fault. Boost curve was all screwed up. Took 4 seconds to build 15 psi (typically takes a second or second and a half). That’s fixed, just haven’t been back to the track yet. I had a abc 427 back in the day similar to your 422 and ran indentical only I had a th400 and a 4.10. That was on a bias ply 9” slick though. The car’s on radials now and is a whole different story.

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Re: Poor prep and Radials

Post by steve cowan » Mon May 14, 2018 11:24 pm

3window,
can you test and set rear end up on a good track??
i know my last race car 8.9s @ 150 on a good track was dead straight easy to drive
on a test and tune track was out of control 2 out of 3 times anyway,i have drag radial on my 11.0 streeter so we cant compare apples to apples,but been around a while and if the radial tyre starts to lose traction its over,
what tyre pressures? i am at 16 psi and they turn on the rim slightly,
the whole no prep deal is tough,man those kats wreck bigtime.
i have no experience with turbo so no help at all really,
i do know of a lot of cars who have the caltracs set the same as you and i,bottom hole and 1/2 turn preload at full race weight,i run my shocks at soft compression and hard rebound.
steve c

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Re: Poor prep and Radials

Post by 3window » Tue May 15, 2018 12:39 am

I’m about to do some more testing. It’s not a no prep surface, just poor. However, I’m destined to make it work. I’ve always run the tires at around 19 psi (probably not helping). Also, I’ve always been under the “stiff compression, loose rebound” ideology for the rear shocks. I’ll admit I never tried it the other way around. I’m also in the bottom hole with a half a turn. So here’s my plan, set the tires to 15-16 and take the shocks to soft compression and stiff rebound and see what happens. Also, last year I had qa1 singles up front. Very hard to make the car work with those. Any adjustment affects the other discipline of the shock the same way. For example, you tighten compression, you also tighten rebound and vice versa. Not good for what we’re trying to do. I now have DA shocks up front and it’s night and day.

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Re: Poor prep and Radials

Post by 6.50camaro » Tue May 15, 2018 3:09 pm

My car is a 72 camaro 3200lbs w/fuel and me @the start line . Landrum 225# parabolic mono leaf springs ,calvert bars bottom hole 1-1/2 turns preload right side 1 turn preload left side . Koni single adjust fronts set full soft ,koni d/a on rear set 1 click from mid point on comp. 2-3 clicks stiff from midpoint on rebound or extension. 9 or 10 clicks total adjustment on my shocks . Start mid point and stiffen 2or 3 clicks then go 2or 3 click soft from midpoint see what it likes ,then work from there.If you can have some one video the first 60' and play it back in slow motion it helps a lot . Watch for initial loading of the tires at the hit . Then how the side walls react as the car moves forward . Watch how the rear of the car lifts . To soft of a rebound setting and the rear separates to fast . You use up the suspension travel and stop loading the rear tires. You get good initial bite then lose traction sometimes not full spin but just a little slippage that can be seen if you have white lettering on an white line on the tires. Compression setting does not do much , if the cal tracs are working proper they are trying to separate the rear, lifting the body and pushing the tires into the track. Pinion angles has a lot to do with traction also . Just a few thought to hopefully help you in the right direction Dan

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Re: Poor prep and Radials

Post by steve cowan » Tue May 15, 2018 6:02 pm

hq holden waterpump 002.JPG
Dan,
good info there,my car has run consistant 11.10 @ 121.45mph @ 3645 pounds with me so it probably makes a bit over 500hp
you mentioned about turning the tyre from the hit and this is exactly what i went through when i had stock gas rear shocks on the car,i seen photos of how the car launched and came to the assumption the car was unloading the tyres.
like i said we are not comparing cars because my car is a bit slower and reacts different.
i was lucky enough to get my car to work way better just from a shockie change with basic settings am in the process of engine upgrades to find another 50hp
but there is so much work in suspension,shock,sway bar tuning etc
its not about the most horsepower wins all the time :D
my car goes 1.53 60ft
7.0 1/8 mile @ 100mph
3WINDOW,
keep us posted with your results,it is frustrating to try and tune a car on poor track prep,from my experience you can chase your tale forever if not careful.
steve c

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Re: Poor prep and Radials

Post by 6.50camaro » Tue May 15, 2018 10:13 pm

Thanks Steve , this set up seems to work good with my car went from running 6.96@98mph 1.46 60' best run and 7.0's @97 mph 1.49 60' all summer long with a hyd roller 377 sbc to a 6.41@106mph second run off the trailer with no suspension change with the 422 .went 6.31 the next week with a air pressure and timing adjustment If you don't have video, stills works just as good if you can taking them quick enough to get a progression of the tires and suspension working.Dan

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Re: Poor prep and Radials

Post by steve cowan » Tue May 15, 2018 10:53 pm

Dan,
thats bad ass ,looking at high 9s on the quarter
very impressive that car setup good even with a decent change in power
are you transbrake or footbrake?
i have not had much luck trying to hold the car on the footbrake so i usually only leave around 2000-2500rpm
steve c

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Re: Poor prep and Radials

Post by 3window » Wed May 16, 2018 12:06 am

Uh Steve, who’s drivIn’ in that pic? Lol. Just kiddin. Is that a spin off of an 71/72 El Camino? I was unaware they had leaf springs. In fact, I’m not sure if an El Camino has leaf springs! Either way, very cool ride. I love seeing cars from other parts.

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Re: Poor prep and Radials

Post by steve cowan » Wed May 16, 2018 5:24 am

3window,
LOL must look funny to you yanks with our right hand drive deals
my father has had a lot of cars from the USA imported to Australia and i have driven all of them but i will tell you it is stressful driving in the gutter in a left hand drive car here.
anyway my car is a 1973 HQ Holden (General Motors Holden) but the nose cone,mudguards,bonnet etc are off a 1975 Holden.
the sedans in this model are trailing arm coil spring rear end,
the utes are leafspring rear (my car is a ute) slang in Australia for utility or pickup
the ELcomino is a trailing arm deal most of them i think,
anyway i am going to throw another SNAG ON THE BARBIE MATE
talk soon and keep us in the loop with your car and i am keen to hear more about Dans car as well sounds awesome :D
steve c

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Re: Poor prep and Radials

Post by 6.50camaro » Wed May 16, 2018 6:46 am

3Windows,
I have put a lot of effort into making sure there is no bind or drag in the suspension movement so the shocks control the movement not a bind or fraction. I also have slider blocks instead of rear spring shackles. I took this from dirt circle track cars when I was building the car . Shortly after or about the same time caltrac started selling slider boxes .
Dick Miller has a good book called " How to Hook and Launch" giving good info on setting stock type suspension cars .
Steve , I use a t- brake and my ignition box has 3 rpm limits (hi-limit ,launch ,burnout).
If I'm bracket racing with .500 full tree I set the launch rpm @about 3200 set there my r/t's are in the teens much higher than that and I get more red lights .For .400 pro tree or instant green I'll go higher ,but over 4000 my 60' start to fall off.Dan

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Re: Poor prep and Radials

Post by steve cowan » Wed May 16, 2018 5:49 pm

thanks Dan,
i have seen a few cars with the rear slider deal,did you notice much improvement changing to the slider and do you think you can use these in a street car application??
i drive mine to the track 4hr round trip,
i have that book you are talking about its very good
i can run my car to 10.00 because it has a 4 point cage and 4 point harness and it is road registered.i am trying to find approx 560 hp out of my 383sbc and from there i am going to focus on suspension tuning from there,i am running a 255/60/15 tyre mickey T
i have used 265/50/15 radial but they rub on the guards to much so i want to concentrate on the 255,if you got any tips on the sliders or references would appriciate,
thanks
steve c

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