Steering Ratio ??

just tring to help a guy out whats it to you merry xmas to you too
PS ANY TIME YOU WANT TO GO HEADS UP MIKEY BOOKS US A MATCH RACE AND I WILL SPANK THAT ASS FOR YA AND IF YOUR SCARED THEN SAY YOUR SCARED ( LMAO ) AND A HAPPY NEW YEAR AND I HAVE A RACE JAN 1 IN GA.

 

Hey Backmotor, if having trouble while shifting then just drive single handed. I mean its not a big deal, dragsters , promods and pro stocks do it. After all only standard (front drive ie real funny cars) are required to drive with both hands!!! Its just a fact, I have driven all cars type mentioned above> MERRY CHRISTMAST TO ALL!!!!!!!!!!!!!!!!!

 

i think more caster would help.... perhaps 22* total.... i'm not a chassis guy buy i know a dude that built a front motor dragster with out enough caster and it did the same thing.... just my 2 cents... Mike

 

I am not a chassis guy, but I try to listen when one is talking.

I think you are on to the problem, well at least the best place to start with your ratio thoughts. I remember Nasty Dave Benjamin talking about a rack in a car he drove, and the steering ratio was way too fast. If it were mine, I would start there.

On Scott's car {Nitro Madness 2007 Version} we had a wiggle at the end of the burnout, and when on the brakes. A steering dampner cured it with a soft setting. Our old Massey car didn't need one, but the new car did. It was a simple fix and worked for us. I don't think this is what is wrong on your car.

You could be inducing it, like at the shift, but for whatever reason, you need to slow the steering down so you can make decent safe runs. JMO

Rapid

 

I'm not one of those name dropper types, so lets just say a world famous nitro funny car crewchief, heard about my problems (he actually drove a rear engine funny car in the 1970's) got my phone number from a mutual friend and called me. My jaw about hit the floor he made a list of things to check/adjust and it ended with "if that don't fix it you'll need to slow the steering ratio down" so I'm about half way thru the list, and have not found anything wrong or loose yet, looks like its leaning towards a new rack and pinion, with a slower ratio. He also found it amusing that a couple people didn't like my choice of building a rear engine funny car, we run in a nostalgia group with the 1984 Vette body and get called all kinds of names like: newstalgia or transformer, and those are just the ones I can post
P.S. Its pretty cool to be able to get advice from talented people, like the guys and gals on here, plus Rapid and Mr _____ , Thank you all

 

Keep us posted on what you find out on your checklist.

EDB

 

When I finish going thru the list, and get to the track for a couple test passes, will definately post the results. Probably be a couple weeks before this all happens. Thanks again, Mike

 

Length

Steering arms come in 3 lengths, 4, 5 and 6 inch.

http://www.markwilliams.com/detail.aspx?ID=192

 

Results: wound up replacing all four tires, did fresh alignment, and added the body. Took it easy on the first run (wasn't sure what to expect) just wanted to get near 100 mph, and check the handling, no twitch at the shift at all, mission accomplished !! The starting line was slippery, but from about half track to the finish line it stuck good, straight as a string Just wanted to thank you guys for all the advice/help. Now we can work on the launch, need to go back on a Saturday (when they VHT the track)

 

Starting line was slippery not because of lack of VHT but because of cold tires.

Did I read that ET right? 7.9x in the 8th mile?

 

Yeah I know crappy burnout, they were brand new tires (I was told "don't do big burnouts til nubs are gone") which is about three runs apparently, plus our back up person was late and I didn't want to be at half track, trying to back up alone (it's harder with the body on, can't see the tires) we were only shooting for 100 mph, to make sure the body would stay on, ran a wussy 7.99 @ 96, came back later, and did a bigger burnout (our crew-guy got there ) still had lots of tire spin, and ran a 7.11 @ 112.53, better, was gonna run a 3rd time, and the track manager asked us to come back on Saturday because "that's when they VHT the track" got video of that second run also if you want to see it. The main thing is that it went straight especially near the shift point, which was our problem area.

 

Do you know how much caster it's got? A 'normal' TAFC should have about 11*. With your setup I expect you may need more because you have less weight on the front axle. What's the lowest tire pressure you've tried?

Longer pitman arms could help as they will give you more 'feel' and hence more control. The downside is you will have to turn the wheel further to get the same reaction. Make sure the centerlines of each pitman arm intersect in the middle of chassis at about the front of the center section.

 

Hey thjts, its got 15* positive caster, already running the long steering arms, front tire pressure we run 30 lbs, tried higher didn't like it, never went below 28. It has been handling much better (with new tires and adding toe in) We're running again this Saturday, trying to get the launch dialed in, now that it goes straight at the finish line