Help me solve my front end lift

[Tims65]

So... how should I control my front end lift?

Static ride height:

Lift at speed:

 

[Anonymous]

List everything you've done to the suspension (or a link), that'll help to figure something out.

 

[Tims65]

Front:
- Global West UCA's
- TCP LCA's
- 620 springs (cut)
- OpenTracker roller spring perches
- Edelbrock IAS springs
- '70 big bearing spindles
- TCP strut rods
- Baer Tracker bumpsteer kit
- 1" front bar
- TCP manual R+P

Subframe connectors

Rear:
- Performance 4 leafs
- Panhard bar
- Edelbrock IAS shocks
- Afco spring rod modified Traction Bars.

No binding, no noticable bumpsteer.

Tim
(Edited to add roller spring perches)

 

[Mach1ne]

In the drag car world they use travel limiters.

http://www.madmanandcoracing.com/shop/item.aspx?itemid=12

Nascar uses a nylon rope to do the same thing. I would assume because it is lighter.

 

[BobV]

So, what are your bumpsteer measurements thru the travel range? :shrug

 

[Anonymous]

No roller perch?

Is there any bind in the front suspension (other than the stock perch) with the spring and shock off?

On the rear, I removed the traction bars when I added the panhard bar. I had a couple vintage racers tell me that one.

 

[Shaun]

Front:
- Global West UCA's
- TCP LCA's
- 620 springs (cut)
- Edelbrock IAS springs
- '70 big bearing spindles
- TCP strut rods
- Baer Tracker bumpsteer kit
- 1" front bar
- TCP manual R+P

Subframe connectors

Rear:
- Performance 4 leafs
- Panhard bar
- Edelbrock IAS shocks
- Afco spring rod modified Traction Bars.

No binding, no noticable bumpsteer.

Tim

Alignment specs are?

 

[Tims65]

Sorry, I've been out of town.

In the drag car world they use travel limiters.
Nascar uses a nylon rope to do the same thing. I would assume because it is lighter.

That is a possible solution, to at least limit the amount the front raises. Is there any down side to adding a limiter.

So, what are your bumpsteer measurements thru the travel range? :shrug

I did not measure it, I dialed out the very noticable bumpsteer by moving the shims on the baer kit until I found a setting that worked the best.

No roller perch?
Is there any bind in the front suspension (other than the stock perch) with the spring and shock off?
On the rear, I removed the traction bars when I added the panhard bar. I had a couple vintage racers tell me that one.

I do have roller perches (edited the OP to reflect)
No bind in the front.
I replaced the fixed bars on my traction masters with AFCO spring rods.

Alignment specs are?

We recently moved and I can find my printout, but basically:
Caster: +2
Camber: -1
Toe: -1/8"

 

[tarafied1]

the 67 and later spindles have a different Ackerman geometry than the 65/66 cars. I've read that swapping the spindles can cause the nose to lift due to changes in the toe-in. The Bear Tracker bump-steer kit may help but I would check the toe-in sitting on the ground and while you have it jacked up and see if it changes.

 

[opentrackerSteve]

surefire way to fix. slow down.,...

seriously, you may be getting aerodynamic lift on the front end of your car. try it without the hood?

 

[Fordrevhead]

ever try a bigger chin spoiler? I know it makes trailer loading a little tighter.

 

[Tims65]

ever try a bigger chin spoiler? I know it makes trailer loading a little tighter.

Yea, in these pictures my front spoiler is actually broken off. There's just one piece of the end on the passenger side still attached. I am considering doubling two spoilers together and adding some more mounging points.

I'd like to find a small splitter/dam from a new car that I could modify and attach. How close are early model front ends to the 2005 - 09 front ends? Anyone know or have one they could measure?

Tim

 

[Shaun]

I very much doubt its aerodynamic lift. There are tons of cars out there (mine included) without any splitters that are not getting front end lift. If it was aero lift then it would get gradually higher the faster you went as the high pressure built up and up. I bet as soon as you nail the gas up she pops regardless if its at 40mph or 140mph.

+2 Caster is nowhere near enough. Shoot for +4 or +5 and see what happens then.

 

[Tims65]

I very much doubt its aerodynamic lift. There are tons of cars out there (mine included) without any splitters that are not getting front end lift. If it was aero lift then it would get gradually higher the faster you went as the high pressure built up and up. I bet as soon as you nail the gas up she pops regardless if its at 40mph or 140mph.

+2 Caster is nowhere near enough. Shoot for +4 or +5 and see what happens then.

I do think this is aero lift. I think I get initial front end lift off of acceleration out of the corners, but it increases as I head down the straight. These pictures are down the straight at 100+. Several people who saw me at full speed on the straight commented on the lift.

In the pictures you can see a little of the front spoiler in the side view. The spoiler actually broke off on the second lap, leaving a small 8" piece at the end.

So any suggestions?
Do I need to increase the rear spring rate?
Do I need to add front aero?
Do I need to add more rake?
Will a front suspension travel limiter help? Where/how is this set up?

Tim

 

[Anonymous]

Toss in a 427, that should help keep the nose planted.




Seriously, you're beyond my limited skill set on this one.

 

[BobV]

Just for kicks, measure the toe at ride height, then put a jack under the front crossmember, jack it up a couple inches to match your pics, and measure again. Wouldn't hurt to measure the camber at both heights as well, just for reference.

I'd still spend the time to go thru and bump-steer the car correctly no matter what. I know many people "have no issues" with bumpsteer - and those same people have never measured bumpsteer nor driven a bump-corrected car, so how do they know? You can't just eyeball things with all the changes that have been made.

Global West arms with different spindles will basically max out the adjustment on the Baer Trackers. I used all but one shim with 65 spindles to get things right. You will also probably have to dial in more static caster just to stay within range. Looks like the strut rods were used to get the caster you have - you'll probably need to shim the UCAs to add more.

Just my .02

 

[BobV]

Just noticed your alignment specs too. I'd cut back on the toe-in - try 1/16 or even 0. Toe-in was basically used to "pull" the suspension forward to make up for the slop in all the rubber parts. With the aftermarket strut rods and arms, the suspension doesn't "flex" like with rubber-bushed rods. You basically don't need as much toe-in.

 

[Anonymous]

Some pics for comparison. I was probably somewhere near 70 or more in these pics.

Keep in mind I'm running 225/45-15's and they really are short tires! Sorry I don't have any at a standstill.

 

[Tims65]

Just for kicks, measure the toe at ride height, then put a jack under the front crossmember, jack it up a couple inches to match your pics, and measure again. Wouldn't hurt to measure the camber at both heights as well, just for reference.

I'll try this this weekend, but I don't have any toe measurement gauges. I can tape a laser pointer to the wheels and measure the change against the wall some distance away, but I don't know exactly what I will take away from this.

I'd still spend the time to go thru and bump-steer the car correctly no matter what. I know many people "have no issues" with bumpsteer - and those same people have never measured bumpsteer nor driven a bump-corrected car, so how do they know? You can't just eyeball things with all the changes that have been made.

I don't know, I look at it from the other direction. Driving a car with noticable bumpsteer and then making adjustments to the baer kit, you can tell real world, seat of the pants differences in the cars behavior. Measurements would be more accurate but I substantially corrected the diving and darting behavior of my car by moving shims and test driving.

Global West arms with different spindles will basically max out the adjustment on the Baer Trackers. I used all but one shim with 65 spindles to get things right. You will also probably have to dial in more static caster just to stay within range. Looks like the strut rods were used to get the caster you have - you'll probably need to shim the UCAs to add more.

I have almost the opposite setting on my bumpsteer kit, I have, only, the smallest shim on my set up with '70 big bearing spindles and Global West UCA's. I'll see if I can get some bumpsteer measurements.
On the Caster, you are correct. They used the adjustable struts to pull in my Caster, instead of using shims to add Caster and keep my wheels more centered. This is one of the things I am going to get corrected when I go in for a new alignment this Spring.

Thanks for your comments Bob, I will let you know how things turn out after I get back to the alignment shop.

Tim

Just noticed your alignment specs too. I'd cut back on the toe-in - try 1/16 or even 0. Toe-in was basically used to "pull" the suspension forward to make up for the slop in all the rubber parts. With the aftermarket strut rods and arms, the suspension doesn't "flex" like with rubber-bushed rods. You basically don't need as much toe-in.

Thanks, I'll try reducing the toe on my next alignment setting.

Tim

 

[Anonymous]

FWIW, I run 3/16" toe out and the car "turns in" much better. I haven't noticed any bad side effects at top end. On the street, that setting does cause the car to move around a little bit though.

To check toe, raise the front tires up, make a mark on the tread (spin the tire so it's in the same place all the way around). Measure front and rear with a tape measure.

You could make a simple toe gauge out of 1" and 3/4" box tubing like this.