Messages

541

Roo Man's Room / Re: caster and camber question

« on: February 11, 2013, 02:13:20 PM »

Alan,
       I may use regular ms rod ends on a cackle car but only use 4130 in steering and suspension applications. I try to position the ends in the bungs the same as you do leaving as little of the thread exposed as is required for "normal" adjustments. If the car is built right there should be no need to make major adjustments to any of the steering components. I usually do all of that on the jig with the spindles in the fixture so that they are aligned right from the start.

Roo

542

Roo Man's Room / Re: radius rods/steering arm dimensions

« on: February 11, 2013, 02:06:25 PM »

Tyler,
       the most common material for radius rods is 3/4" x .058. The same material is common for drag links but on my 225" cars I use 7/8" x .058 for the long link from the box to where the forward link attaches. I also use 3 slider brackets on my NT/F cars and run a short link from the box to just ahead of the mid plate to make a 3 piece link with the sliders at either end and in the middle of the center link.

Roo

543

Roo Man's Room / Re: caster and camber question

« on: February 11, 2013, 07:16:24 AM »

I usually run 0 degrees camber and 20 degrees caster. Back in the day cars had as much as 40 degrees caster but the most that I have used is 30 degrees on Brendan Murry's NT/F as he started out driving older cars and is used to that amount.

Roo

544

Roo Man's Room / Re: engine height

« on: February 09, 2013, 05:10:41 PM »

With a big horsepower car the extra drag of the 9" is not a problem but a lot of the small engine comp elim cars run a 9" style housing with a 12 bolt gearset. Strange and Mark Williams both make the required pieces. The 8 3/4" is still good for lower horsepower applications but there is not the range of parts to toughen it up compared with the 9" and 12 bolt.

Roo

545

Roo Man's Room / Re: twin engine dragster questions

« on: February 09, 2013, 04:12:23 AM »

John,
        I just went back and looked again at the pic's of your car and it does not look like you have enough tubing out in front of your current single motor deal to add another motor. The length is not a major problem (especially if you want an exciting ride) but a double should really be engineered for the weight of the second engine being so far out. I will have one going up on my jig soon so I will post photos as it progresses.
 Most of the early doubles used a pair of sprockets and a double row chain to link the motors although there are probably a lot of industrial couplers that would do the job too.

Roo

546

Roo Man's Room / Re: Welding Question: MS to CM

« on: February 09, 2013, 04:03:22 AM »

Yes,
       unless you run across some Chinese junk you will usually find that cold rolled is better quality. I try to use 1018 cr when I use mild steel.

Roo

547

Roo Man's Room / Re: Lenco CS1 or CS2 Transmission For A "AA/FA"

« on: February 08, 2013, 07:17:26 AM »

I tried to call you last night but the line was busy.

Roo

548

Roo Man's Room / Re: Welding Question: MS to CM

« on: February 08, 2013, 07:16:42 AM »

There are no problems welding mild steel to moly. Just make sure that the ms is reasonable quality, not some junk hot rolled full of impurities. The cheap stuff will weld to the moly but you take the chance of impurities in the plate contaminating the weld puddle. Also be wary of welding heavy plate to the thin moly as that can introduce a potential fatigue point. In other words don't try to weld a 3/8" thick bracket to .058 moly tubing--it can be done but is not good engineering practice.

Roo

549

Roo Man's Room / Re: slip joint fed

« on: February 08, 2013, 04:12:22 AM »

Alot of dorks hammer the ends of the tubes to make them fit on to the receptacle, ignorant!

I guess that Don Long is a dork then as that is how he did his front motor cars and they were probably the best engineered and constructed front motor frames on the planet. This is the front of Ernie Broughton's Commanche which is a Long clone but I used my real 69 Long as a template. Doing it this way gives the frame a little more vertical spread at the torsion bar and also wraps the rails around the torsion bar tube/ front cross member a little more.



Roo

550

Roo Man's Room / Re: Chassis question

« on: February 08, 2013, 03:55:54 AM »

Brian,
        as Chris recommends, get the SFI spec if you are going to build it yourself, although it only calls out the cockpit area. From the motor forward my frames use a 1.25 x .058 top rail and 1.125 x .058 for the lower. Uprights range from 1" at the front of the motor down to .75 at the sharp end of the chassis.

Roo

551

Roo Man's Room / Re: engine height

« on: February 07, 2013, 05:34:55 AM »

Frank likes them a long way out. His first junior fuel cars were 47" out and lately he has been doing the 50" plus deal. I have had success with my cars at 42" out with the motor level. I don't worry too much about crank centerline height apart from getting the rear end right relative to the tire diameter and getting the motor angle correct--usually level to half a degree down in my cars. A 9" rear end will put the motor lower than an 8 3/4" Chrysler or a GM 10 or 12 bolt as the pinion is lower relative to the axle centerline.

Roo

552

Roo Man's Room / Re: Master Cyl?

« on: February 06, 2013, 02:28:43 PM »

Master cylinder size is based on volume needed to move the pistons at the wheels and available leverage to move the piston in the master cylinder.  Disc brake pistons don't move far but they are usually quite large in diameter vs the wheel cylinders in drum brakes. In most cases a 3/4" bore master cylinder will do the job provided that the pedal/lever ratio is correct.

Roo

553

Roo Man's Room / Re: slip joint fed

« on: February 06, 2013, 10:20:23 AM »

Most front motor cars are shallow enough between the upper and lower rails to not require slip joints in the rails themselves. Frank and Scott Parks usually mount their uprights (ahead of the motor) on sleeves that are restrained by stop rings. The cross members are connected in the same manner and that allows the car to be a little more flexible in torsion.

Roo

554

Roo Man's Room / Re: Front axles

« on: February 06, 2013, 10:16:41 AM »

Larry,
         the NHRA rule book says that you need radius rods when the king pin is more than 18" from the mounting point of the axle and that seems appropriate.

Roo

555

Roo Man's Room / Re: FED Steering question?

« on: February 06, 2013, 04:52:53 AM »

Although a few people have run rack and pinion deals in FED's (as far back as the mid 60's) it appears that the conventional steering box is a better choice. Getting the shaft for a rack around the motor is a hassle (one 60's car ran it through the valley of the motor between the injector stacks) and as noted it takes some ratio juggling to stop it being too direct.
  The Strange and Flaming River boxes are virtual clones of the SPE (no longer available) which itself was based off the P & S Machine box (still available from Tom Hanna). The Stiletto box has what is probably a better internal mechanical package as Gary Wood always made very nice parts that are well engineered but it is a little bulky compared to the others. The Stiletto product line is now part of Stu Spears' Pro Werks/ Chassis Shop line.

Roo