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Technical => Roo Man's Room => Topic started by: Mister_Fitz on September 09, 2017, 04:13:41 AM

Title: How much ballast needed on a 60's FED?
Post by: Mister_Fitz on September 09, 2017, 04:13:41 AM
Hi
I have an old 60s FED with 150" WB, motor 30.5" out and a total weight of about 1250 pounds without driver.
I'm having some trouble getting the car to launch straight and have now started to think of adding some weight to the front of the car.
I have added a weight of about 30 pounds to the front axle and I will try this next weekend.
But will I see any difference with this 30 pounds? Or do I need to add much more? What weight ration between front and rear axle should I aim for?
Title: Re: How much ballast needed on a 60's FED?
Post by: rooman on September 09, 2017, 04:50:39 AM
Every race car is different due to variations in tires (and tire pressure), driveline, horsepower etc. Available traction, launch rpm etc also come into play. If the car is not going straight with the front wheels off the ground I would first check the rollout on the rear tires. Then make sure the rear end is square in the car. When such parameters are correct most cars can carry the front wheels and still go straight. If the car still wants to turn at the launch with everything square and even you may need to add a little pressure to the slick on the side that it is turning towards. Adding weight to the front end to enable you to steer the car is really just crutching the problem rather than curing it.

Roo
Title: Re: How much ballast needed on a 60's FED?
Post by: dreracecar on September 10, 2017, 09:21:23 AM
If it's a new crew, make sure they back you up far enough to allow you to drive the car straight into the beams. Too shallow and crooked in the beams is not good, just be careful that they don't put you back in the warer
Title: Re: How much ballast needed on a 60's FED?
Post by: racerken on September 10, 2017, 10:25:43 AM
Does the rear end have a spool ore is it an open rear end?
Title: Re: How much ballast needed on a 60's FED?
Post by: JrFuel Hayden on September 10, 2017, 06:49:13 PM
All the fast FED I know of run spools.
Title: Re: How much ballast needed on a 60's FED?
Post by: gregm784 on September 10, 2017, 07:48:17 PM
When i was learning to drive my car, i carried a lot of weight to help the steering.  I'm down to a 360# front axle weight now and it leaves nice. I've tried 330# and it hits the bar so hard it would unload the tires and the 60' numbers went down .040. 
Title: Re: How much ballast needed on a 60's FED?
Post by: Mister_Fitz on September 10, 2017, 09:48:28 PM
The rear end has a spool. The FED is all updated to the latest SFI spec. The "old" thing about the car is the engine placement that is way back. Shorty PG with coupler direct into the rear end.
I think we are quite good on backing the car up straight. I agree that it will make a big difference.
Roo. I agree that adding weight will not fix the real problem. I will try it next race and hopefully I can remove it later on.
When adjusting tire pressure to get the right traction and wheel speed. How small pressure adjustments will have impact? Is lowering pressure by 1 psi at the time a too big change?

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Title: Re: How much ballast needed on a 60's FED?
Post by: JrFuel Hayden on September 10, 2017, 11:37:53 PM
Yes a one pound difference will make too big of a change. We only made a 1/4 # difference from side to side. 
Title: Re: How much ballast needed on a 60's FED?
Post by: racerken on September 11, 2017, 08:06:49 AM
I enjoy the driving side more than the mechanical side so I don't profess to be very technical.  All I know is that I have a 185" Boogie Scott FED (Hall of fame chassis builder)  He says not to run a spool. I run 8.70"s 150 mph straight as a string..  Also,  about 15 years ago I bought  a Mark Williams car from a friend of mine. He never knew which direction the car would go in when he launched.  I put my motor in it and took the spool out and never had an issue going straight.  Like I said,  I can't tell you why,  I am only sharing my experience,  for what it's worth.
Title: Re: How much ballast needed on a 60's FED?
Post by: dreracecar on September 11, 2017, 08:36:49 AM
The open diff is masking problems with either the chassis or rear end housing. And I have run mis-matched tires with a spool, and the car still went straight
Title: Re: How much ballast needed on a 60's FED?
Post by: JrFuel Hayden on September 11, 2017, 11:22:34 AM
Ken, it might be going straight because you are running a kinda big tire to be running 8.70 @ 150, so you are kinda dead hooking the tires , not trying to get the tires to spin some to keep the motor in the rpm range where it's making good power. But if you are running an 8.70 or 8.60 bracket or dial in, then keep on trucking.
Again I don't know of any fast cars that run open rear-ends.

Jon
Title: Re: How much ballast needed on a 60's FED?
Post by: BK on September 11, 2017, 01:56:44 PM
 My FED had a short glide with a coupler direct to the rear but was 175" WB and had similar problem.
 I did get it to launch with about 60#s up front and set the wheelie bars to roll some weight to the right. Worked OK.
 I tried as much as 11/2# difference left to right in air pressure on Scott Wenys recommendation. It helped but not enough.
 I was bracket racing it and low ET wasn't my main priority so the thing that worked best was to put a pneumatic cylinder with a needle valve to slow the opening rate of the throttle a little. I lost 1 tenths in 60' and 2 at the finish line but it was deadly consistent. Still needing the weight and wheelie bar also.
 It would go 1.14 to 1.18 60s at 8.45 to .50 inconsistently with out the cylinder and 1.24 at 8.63 with.
Title: Re: How much ballast needed on a 60's FED?
Post by: slingshot383 on September 13, 2017, 05:48:33 AM
To large of a slick is a common problem with a FED having a launch problem. They work better with a narrower slick, especially if the engine is back.
Title: Re: How much ballast needed on a 60's FED?
Post by: gregm784 on September 13, 2017, 08:44:29 AM
To large of a slick is a common problem with a FED having a launch problem. They work better with a narrower slick, especially if the engine is back.

Agreed.  Tire speed is your friend.
Title: Re: How much ballast needed on a 60's FED?
Post by: PSweeney on September 27, 2017, 06:16:46 AM
I've had the same problem recently but it was down to a cold and poorly prepped track.  I run about 60lb on the nose of my 138in car with the shorty glide combo.  It still hits the bar but a lot softer now.  Running 31 x 10.5 tires @ 6.5psi.
Title: Re: How much ballast needed on a 60's FED?
Post by: wideopen231 on September 27, 2017, 07:59:16 AM
Interesting thread. I have been trying to decide rather to add some to front for first cpl runs and pull until front raises 3 to 6" for first n 30 or 40'. Right now I have 345 lbs of front end according to scales I borrowed. car with me race ready is 1600 lbs.
Title: Re: How much ballast needed on a 60's FED?
Post by: masracingtd1167 on September 27, 2017, 12:36:58 PM
Chris I have been finding with my car that a half lbs of air can make a big difference ! Even with the small 12 inch tire it can be too much and I have to lower the air pressure to get some wheel speed or the car will drive to the left or right ! Right now I have no ballast in the car but I also moved every thing I could to the front of the car .
Title: Re: How much ballast needed on a 60's FED?
Post by: wideopen231 on October 04, 2017, 04:22:48 PM
Hoping I don't need any ballast. Right now battery is in front of axle and tank is right behind axle. I have to 5lb fire bottles behind that. I could move the driver but then it would be RED like every other car at track. I do have mounts and 20 lbs of plates plus a weight tube mount,be prepare.d and hope not to use. If have to add I will get second battery,no work no ride.

Tires are big question. New 3074's M/T's/ 15x14x32.  7.5 lbs starting point.No runs since new tires.Lifes been getting in the way,well family members lives which seem to be my problem. Hopefully get some runs before end of month and good enough for thanksgiving money bash at Farmington.  Will keep pressure deal in mind and work in small jumps.
Title: Re: How much ballast needed on a 60's FED?
Post by: hemidakota on October 06, 2017, 05:56:00 PM
We ran 14x32 slicks on a fed, prob not as much power as your deal but from my time at the track I would suggest to start at 6psi or lower unless prep stinks. At Bakersfield we could not run much over 5psi but the track prep was excellent every time. 10' wheel stands and broken wheelie bars are not very hard to do even with 40lbs on the nose along with everything else... I am no pro but we have broken a few things in the learning curve.  ;D