Ghia Road Course Setup

[petew]

bump; how much upward movement your suspension has
droop; how much downward movement your suspension has

[FJCamper]

Hi PeteW,

Thanks for the clarification. Are those dune buggy terms?

Our front suspension travel is stock, but on 53 using the extra-swivel ball joints for some safety at full travel, and the special Koni rubber bump stops atop the front shocks have been cut in half.

On 261, with it's link-pin front suspension, we use the neoprene-replacement front bump stop that mounts between the trailing arms, and a full-sized rear bump stop.

FJC

[petew]

no, standard terms for suspension travel specs on track cars.

[FJCamper]

Hi PeteW,

I guess I'm dating myself, but in all my BMW and Porsche schools, and setup on Formula Atlantic and Indy and GP chassis (the Saudia -Williams FW 07), we always called it max top and bottom suspension travel.

I do see the terms being used now after an internet search.

My guess is the terms have been used and accepted in English, as they wouldn't translate the same way in other languages, and on the international teams, you use more generic descriptions.

Reminds me of the American aircraft use of the term "doghouse" for a space in the aircraft galley. I was there when some Saudis, looking over our blueprints, asked us why we would carry a dog there!

FJC

[superstar]

If my memory serves me right from my motorcycle racing days, the reference for suspension spring pre-load adjustment was bump and drop. If my forks had 4" of total travel and I set spring preload to 1" I would have 1" bump and 3" drop. Also the fork and shock adjustment screws for rebound and compresion damping would be refered to as the bump screw (compression or bump damping) and re-bump screw (rebound or tension damping). These terms may have been racing slang.

[Dale M.]

To throw another term in the mix.... The book "Chassis Engineering" by Herb Adams, HP Books uses the term "Jounce" stop as the bumper and stated the jounce bumper should come into contact with the frame before suspension comes into "full compression"...

Dale

[Jadewombat]

Don't forget the fender flares,

http://www.shoptalkforums.com/viewtopic ... 3&t=129608

Looks cool anyway.

[4agedub]

FJCamper
What kinda toe do you run on your car in front?

I've checked my bug's front toe last night and found the reason for all the under steer we've had. It was toe in by about 30min (according to the dunlop toe gauge).

I've now changed it to about 30min toe out, does that sound ok??

Louis

[FJCamper]

Hi-

Our front toe is a stock 1/8" inch.

It's worked for us just fine.

FJC

[4agedub]

I tried it this weekend with about 15 min toe out, cannot remember what it comes out to in ". The car felt really good. Little to no understeer. Very neutral steering with a little bit of oversteer through the fast corners. Camber is set at 3.2' on both sides.

I cannot really comment about the other stuff, had a terrible racing weekend... fuel pump issues etc etc...

[FJCamper]

Hi 4AgeDub,

15 minutes toe-out (or toe-in) is approx 1/8" inch.

Front toe-in promotes understeer. Front tow-out promotes oversteer. All things being equal. But its reversed in the back. To really make a rear end go into oversteer, toe in the rear settings.

... but ... all that matters is what works. Wheels, tires, suspension flex, all these things stack up to influence toe settings.

The idea is that as you drive forward, the tires try to toe-out because of road friction, so you start off with a tiny bit of toe-in that becomes zero toe when the tires toe out.

FJC

[kdf]

Rule of thumb is that 1 degree of negative camber is 0.1 degrees toe in (per wheel). The tires try to steer into the direction where they are leaned (like a bicycle). With 3 degrees negative camber you have 0.6 degrees toe in (~40 minutes), so you need approximately 40 minutes of toe out so that your both front wheels track straight (lowest rolling resistance).

Loose sidewall tires (racing slicks) steer more with equal camber compared to stiff sidewall tires (street radial).

Usually the front end has some toe to keep the tires scrubbing so they work more. More work means more heat, which is good. Toe in has also a stabilising effect in the front. A car with toe out in the front is more difficult to drive in a straight line at high speed.

I've never run toe out at the rear. But I've never been adjusting rear toe either. I guess to be fine tuning rear toe you need to have the front end perfected out, and there always seems to be trouble with the front end. I maybe should have taken it more into consideration, but with factory race cars you know what the factory recommends for rear toe, and you pretty much know what your opposition uses and what suspension settings the opposition adjusts.

[r1cpowdercoating]

FJC
Thanks for all this great info. I am in the middle of building a 69 ghia for road racing. You have answered a lot of questions on suspension that i was scratching my head over. As i have never been on the race track, all my knowledge was from street driving. I was really fretting over what shocks to use. you answered some brake questions. we are running disc all around. Its different than street driving. I am good with the street use, but racing is a different beast. I live @ 35 minutes north of road atlanta and plan on running the TT this coming year starting in March over at Talelldega. If you dont mind, I may as your advice as the season goes on. I do hope you or somebody from your group is still running your little ghia.
again, thanks for the post.

Ron
R 1 C powder coating

[rfsalter]

I know you have heard it throughout this thread but, it is without a doubt the best, best, best thread I have ever read.
Educated, logical, to the point and most of all helpful.

[SuperRSi]

K e e p G o i n g . . .