[tc]

I finally finished porting the heads, again and gained about 25 cfm at .500 lift. Although the car is not real fast, it is a fun street car that I race in the Sportsman class. 12.00 seconds is as quick as you can go.

I could feel something was not right and did not know if it was the tires or the carb, but the video, link below, shows the up, down, up of the front end. Also is an attached photo of my homemade 4 bar.

The front suspension is all newer factory/stock components, shocks, springs. etc. The front sway bar is attached and the rear has no bar. The battery is on the pass side in the trunk. I do have air bags, but must have blown something on Saturday's racing so on Sunday the passenger side air bag did not inflate. I have adjustable rear shocks.

Sunday morning time trials, the 60 ft was 1.67. Early evening 4th and 5th elimination rounds the 60 ft was 1.71. The video was the 4th round.

The instant center of the 4 bar is 39" forward and 1" below the frame of the car. I could set it at 59" forward and 1" below. Would this help with the launch?

Thanks for your help, Tom

http://www.youtube.com/watch?v=zEfqQ...1&feature=plcp

[cosgrove]

Tom,
Many of those factory components are not well suited for a good launch. Start with more upward travel in the front end. Your front is topping out almost instantly.Then the rear suspension unloads then loads repeatedly. Gain travel by lowering the front end, trim or remove the rubber stops on top a arms, bolt your upper ball joints on the bottom of the a arm. You need 5" of upward travel from ride height. Lower the front until you have that much travel. A change of front springs is likely needed. You should use a longer spring with a lighter rate, while giving correct (lowered) ride height. Stock shocks won't cut it either. Start with 90/10's. There is so much more but this is where to start. Good job running at least 5 rounds. How did you end up?

[blueghoast]

Are you using stock motor mounts or solid.?

GT.

[tc]

Cosgrove. Thanks for the info. I want to keep the car a street cruiser, so I am not sure about lowering the front and using 90/10 springs. I will check the other ideas. My mom, 79 and dad, 76 (years old) came out to cheer/watch me race and saw me win the final (5th) round. Two days later my mom calls and asks when I am going to race again.

blueghoast. I am using stock engine mounts. I do have a turnbuckle bolted to the head and a chain link welded to the frame.

[rod cole]

You 60 foot as good as my ladder bar car. So I don't know that you need fixing for a car at that e.t. Mine does 1.60-1.70 going 10.80 at 3400#. Rod

[blueghoast]

Originally Posted by tc

Cosgrove. Thanks for the info. I want to keep the car a street cruiser, so I am not sure about lowering the front and using 90/10 springs. I will check the other ideas. My mom, 79 and dad, 76 (years old) came out to cheer/watch me race and saw me win the final (5th) round. Two days later my mom calls and asks when I am going to race again.

blueghoast. I am using stock engine mounts. I do have a turnbuckle bolted to the head and a chain link welded to the frame.

Was curious my car used to leap frog when I had stock mounts.
I went to solid mounts and cured my problem. Thats why I asked.
The turn buckle works great too. Your 60's don't sound to shabby
to me either. Good luck with it.

GT.

[blueghoast]

Oh yea; Thats cool that your parents are into your racing.

GT.

[TEMPERMAN67]

Het TC
I had the same issues at one time then I tried new qa1 adjustable shocks and trick springs on the front, changed to upper adjustable control arms on the rear nothing would get the bounce out of it. Then a friend sad he thought i should change the rear shocks out that were adjustable to, but were 8 years old, I changed them out and problem was solved 60 foot times went from 1.60 to the high 1.40's
Might help Good Luck with it.

[455firebird1969]

Considering it is still a real street car, it seems to 60' just fine...

You might try disconnecting the front sway bar, allowing more upward travel. That is something you can reinstall between outings at the drag strip...

Ditto on your parents watching you race, that's cool...

[66bonne]

Originally Posted by tc

Cosgrove. Thanks for the info. I want to keep the car a street cruiser, so I am not sure about lowering the front and using 90/10 springs. I will check the other ideas. My mom, 79 and dad, 76 (years old) came out to cheer/watch me race and saw me win the final (5th) round. Two days later my mom calls and asks when I am going to race again.

blueghoast. I am using stock engine mounts. I do have a turnbuckle bolted to the head and a chain link welded to the frame.

Good story. Sounds like they had as much fun as you did. Congrats.

Jim

[tc]

Thanks for all the ideas.
Right now the car can go up 4 inches before the wheel come's off the ground. So for my car, the idea is to possibly keep the wheel from coming off the ground so the rear does not unload?
What does a front end limiter do on some race cars? Bring the wheels off the ground sooner?

[slowbird]

Tom, the more power you make the more you can tighten up your front at your current level there is no need to limit it. You need the travel to help transfer weight. Leave yours stock dont limit it. Just a fyi dad is at 4" and mine is 3".

[cosgrove]

Originally Posted by tc

Thanks for all the ideas.
Right now the car can go up 4 inches before the wheel come's off the ground. So for my car, the idea is to possibly keep the wheel from coming off the ground so the rear does not unload?
What does a front end limiter do on some race cars? Bring the wheels off the ground sooner?

Hey Tom,
The front end limiter helps control front end lift on cars that have too much of it. I prefer to control it by tightening the rebound on the shocks. Don't worry about the limiter at this point. Do look at front travel. You need another inch. Did you move the top ball joints under the arms yet? That's worth a 1/4 or so. The extra travel stretches out the upward motion so the weight can transfer to the rear smoothly. It gives the tires a chance to stay hooked until all the weight is on them. The rebound setting can stretch it out some more if needed. If the front end tops out too quickly it can unload the rear tires. That is what was happening in your video. The idea on your car is too get some front end lift and hopefully carry it aways so the rear tires don't unload.
Tom

[blueghoast]

Some thing I just noticed in the pic of your four link.
Your bottom bar seams to be flat and maybe even
pointing down just a little, That could be your problem
of the leap frog effect, If you could get a little upward
angel on your lower bar I think that would help trmendisly.
With tthe lower bar at that angel your car is trying to lift
weight way past your front bumper. Your instant center
is to fare forward. A qwick fix if you want to try it is,
Raise the back of the car to move the IC back a little
and see if that helps. By raising the back it will point
your lower bar upward some and should make a diff.
You can do it with your air bags and it won't cost you
anything but a little time. Good luck.

GT.

[tc]

Tom,I haven't done anything to the front end as I spent the last two weeks making a X-pipe exhaust system. Just finished welding it together Thursday and put it on the car. This week I'll look at the extra travel.

I do have a question, if/when I get some adjustable front shocks, would I tighten the rebound ( extension ) to slow the upward movement? Or just use them to slow the downward movement?

Some adj shocks have a 90/10, 70/30 rating. My factory style shocks probably have a rebound/compression percent. Lets say they are 70/30. Are the racing shocks harder to push/pull at their 70/30 setting then a factory shock?

I fixed the pass side air bag. The line got pinched above coil/shock tower/bracket. That side bracket is a little closer now to the trunk than the driver side. I re-routed the line.

I raced today at a street warz event. Open time runs, so I thought I would test. Only one run I hooked up. 1.66 60 ft. 11.88 at 113.0 mph. I forgot to shift at the new higher rpm that these newly ported heads like. So the next run, shifted at the higher rpm, but the tires spun, 1.81 60 ft, 12.00 at 114.1 mph. Next run, tires spin, 114.1 mph. Do you think that 1 mph ( from the higher shift rpm ) would give me at quicker et if the tires hooked?

Temperman67 brings up a good thought. Could my passenger side rear shocks be set too hard on compression and affect the front end lift/weight transfer? I have it set to where the rear (driver to pass side ) of the car stays level at the launch. And the car moves down very little, if any right above the center of the pass side rear tire. Car pivots at that spot. Then I loosen that pass side shock ( set it the same as the driver side ) for street driving.

GT,I just checked the lower bar at race settings of the car. The car frame sets level and the bar is up 3/8 inch at the front of the bar ( from the rear of the bar).

Rod and 455, yeah the 60 ft time is good, but now the tire spin is beginning to be a problem. Maybe I am at the limit of these American Racer DOT tires until I can smooth the launch out.

[cosgrove]

Originally Posted by tc

Tom,I haven't done anything to the front end as I spent the last two weeks making a X-pipe exhaust system. Just finished welding it together Thursday and put it on the car. This week I'll look at the extra travel.

I do have a question, if/when I get some adjustable front shocks, would I tighten the rebound ( extension ) to slow the upward movement? Or just use them to slow the downward movement?

Some adj shocks have a 90/10, 70/30 rating. My factory style shocks probably have a rebound/compression percent. Lets say they are 70/30. Are the racing shocks harder to push/pull at their 70/30 setting then a factory shock?

I fixed the pass side air bag. The line got pinched above coil/shock tower/bracket. That side bracket is a little closer now to the trunk than the driver side. I re-routed the line.

I raced today at a street warz event. Open time runs, so I thought I would test. Only one run I hooked up. 1.66 60 ft. 11.88 at 113.0 mph. I forgot to shift at the new higher rpm that these newly ported heads like. So the next run, shifted at the higher rpm, but the tires spun, 1.81 60 ft, 12.00 at 114.1 mph. Next run, tires spin, 114.1 mph. Do you think that 1 mph ( from the higher shift rpm ) would give me at quicker et if the tires hooked?

Temperman67 brings up a good thought. Could my passenger side rear shocks be set too hard on compression and affect the front end lift/weight transfer? I have it set to where the rear (driver to pass side ) of the car stays level at the launch. And the car moves down very little, if any right above the center of the pass side rear tire. Car pivots at that spot. Then I loosen that pass side shock ( set it the same as the driver side ) for street driving.

GT,I just checked the lower bar at race settings of the car. The car frame sets level and the bar is up 3/8 inch at the front of the bar ( from the rear of the bar).

Rod and 455, yeah the 60 ft time is good, but now the tire spin is beginning to be a problem. Maybe I am at the limit of these American Racer DOT tires until I can smooth the launch out.

Tom,
A 90/10 drag shock has little extension resistance, so yes, you do use the DA shocks to slow the upward movement.
The compression adjustment can be useful to lessen bouncing, lunging and unloading problems but it is better to find the causes of those problem than to even it out with the shocks.
With double adjustable shocks,you have so many options. You could make it a 70/30 ratio on the looser end of the range or 70/30 on the tight side. Or any other ratio you might need. But don't worry about that ratio too much. Use good starting points and let the car tell you what to do from there.
When you get the DA shocks, start out loose on the extension and tighten a little at a time to see if it lessens or eliminates that loading and unloading. If you spin right at the hit you probably went too tight. Run the compression just tight enough to control front end bounce for starters.
You won't know if that higher shift improves ET until you hook it up. I often MPH higher after spinning, pedaling.
And get some soft tires on there. That alone may hook you up.
Tom

[tc]

Originally Posted by cosgrove

And get some soft tires on there. That alone may hook you up.
Tom

My wife took a video of the rear tire yesterday. You can see it wrinkle right away, then come out of that and spin. I wondered why I had a red light and could feel it spin.

Any ideas for a tire? Should I give up on street tires ( and racing street classes ) and get some slicks? I still have bias ply on the front so not sure about using a radial tire on the back.

Thanks, Tom

[cosgrove]

Originally Posted by tc

My wife took a video of the rear tire yesterday. You can see it wrinkle right away, then come out of that and spin. I wondered why I had a red light and could feel it spin.

Any ideas for a tire? Should I give up on street tires ( and racing street classes ) and get some slicks? I still have bias ply on the front so not sure about using a radial tire on the back.

Thanks, Tom

Hey Tom,
There are very good tires you can use in those street classes. ET street radials hook great on cars faster than yours or mine. Many run bias on the front with the radials in back with no problem.
Tom

[tc]

Tom,
Thanks, I'll wait till next year for new tires. I hope the BOP event at Cordova has some great track prep so maybe I'll hook. Are you going? I would like to see you run a low 8 second pass!

[cosgrove]

Originally Posted by tc

Tom,
Thanks, I'll wait till next year for new tires. I hope the BOP event at Cordova has some great track prep so maybe I'll hook. Are you going? I would like to see you run a low 8 second pass!

Yes, I will be there. That event is always a good time.