LouieM

I recently had my 67 aligned at a highly rated shop, Custom Alignment in Mountain View CA, where racers bring their track and personal cars. I'm basically happy with their work, but the steering is way too light for my taste, and I wonder of the alignment specs can be improved upon. My 67 is a 327 roadster with stock suspension except for new Bilstein heavy duty (i.e., street) shocks, power steering, new tie rod ends, new steering everything, and new 215-65-15 Yokohama AVS radials. The present alignment specs are:

FRONT
Caster Left 1.8 degrees
Caster Right 2.4

Camber Left 0.4 degree
Camber Right 0.0

Toe Left (-) 3/16 inch
Toe Right (-) 5/32
Toe Total (-) 3/8

REAR
Camber Left (-) 0.7 degree
Camber Right (-) 0.9

Toe Left 1/32 inch
Toe Right (-) 5/32
Toe Total (-) 5/32

Thrust Angle 0.2 degree

All is OK except for the overly light steering. Any comments? Suggestions for change?

SWCDuke

Damned lousy job, IMO. Did they actually change anything?

Set front camber to zero, caster at +2.5. Cross values should be as close to zero as possible. OE spec is 0.5, which is pretty loose and should be improved by a good field alignment.

Your steering feel problem is probably the toe. Total toe should be about 1/16" IN, not 3/8" OUT. Who are these guys?

Rear camber can probably be left alone, but get the right toe corrected to 1/32 TOE-IN.

Duke

JohnZ

If you just "let them do it", you're likely to get almost anything, especially if the shop isn't really conversant with Corvettes and what kind of tires are on it (bias vs. radial). When I take my cars in, I give them the specs I want, and the car stays on the rack until the machine readouts match the specs I gave them; saves return trips, grief from the tech, etc. TELL them what you want, and GET it.

If the guy on the rack has orange hair and body piercings, go somewhere else :D :lolg:

jimdvan

Duke, I have always been greatly impressed with your knowledge and now beg of you to be very specific for me and others. Would you be so kind as to spell out the optimum specs for each part of the alignment, front and rear, left and right? I have a 63 covertible with 215/65/15 BFG Radial T/A's on 15x6 Cragar SS mags. By the end of next month I hope to be installing the Steeroids rack/pinion set-up. What alignment specs do you recommend?

Humbley submitted,
Jim

Rogs65

Hi Jim,

Funny you ask this question. I just purchased some fine knock offs and am planning to buy some radials. Would love to know the ideal specs as well.
Would greatly appreciate your vast knowledge and wisdom here Duke.
(John Z too)

Thanks!!!

Roger :cheers:


[Modified by Rogs65, 11:11 PM 4/27/2004]

jimdvan

Long time, no see, Roger. I told the other Jim to call you about his wheels.

Jim

SWCDuke

I know I've said all this multiple times before, but I'll repeat it. "Optimum specs" for alignment are like optimum specs for the ignition map, dwell angle, and valve lash. It varies from car to car based on many different variables, and it doens't have to be an exact number, but there is a range that should be acceptable based on driving conditions and preferences.

What IS important in alignment, is to set each side as equal as possible to the other side, and this includes the rear toe setting on each side.

The OE specs have a nominal value with a plus or minus tolerance, and may have ranges for "customer paid" or "warranty paid" and an even wider range for state inspection. The nominal OE specs are for average drivers on average roads. I assume that vintage Corvette owners are more picky and want good "handling" whether you define that as good steering response and feel or high lateral g capability. Within this context I recommend the following alignment targets or range for C2s with radial tires.

Front camber" 0 deg.
Front caster: 1.5-2.0 deg with manual steering: 2-2.5 deg. with P/S
Front toe: 1/16" toe-in (total)

Rear camber: minus 0.5 deg
Rear toe in: 1/32" per wheel

If you like to drive your car in a sporting manner and have performance oriented tires increasing camber in the negative direction at both ends - up to negative one degree - is beneficial and should also be accompanied with hard urethane bushings in the front anti-roll bar links.

Increased negative camber will also provide more fender clearance if you have wide wheels or tires. A one degree change of camber in the negative direction will increase fender clearacne by about one-quarter inch. This can either eliminate interference or provide more clearance if existing clearance is tight.

When you go to an alignment shop WRITE DOWN on paper what target specs you want and present them to the manager. Ask him the tolerance range - how close - plus or minus - he can get to these specs. Ask him if the the tech that will do your car has done a '63 to '82 Corvette recently. Ask him if he has front alignment shims. Ask to see them. Review the front and rear alignment procedure in your Chassis Service Manual, and bring it with you. Determine whether you have "captured" or slotted rear toe shims and be prepared to pay extra if they are the captured type, because the trailing arm bolt will have to be removed to change them. If the installed shim pack is sufficient to pack the space, changes in rear toe can usually be accomplished by moving shims between the inboard and outboard positions, but having some spare shims, particularly the thinnest might come in handy.

Tell the manager you what a print out of both the initial settings and the final settings that are achieved, and finally, ask for permission to watch the work from the shop floor.

If you don't get a good feeling that the job will be done properly, go elsewhere.

Assuming you don't bang into curbs and the suspension bushings are in decent condition an alignment should last a long, long time, so get it done right the first time.

Duke




[Modified by SWCDuke, 4:35 PM 4/27/2004]

LouieM

JohnZ -- Nope, no orange hair and body piercings (that I could see, I didn't ask). They seem to be pros and the error was likely mine in not telling them the specs I wanted, since I didn't really know myself. Can't use that excuse again.......

Duke -- Thanks a million. Your great store of knowledge and experience once again saves the day. I'll bring your specs to the alignment shop tomorrow with my car. I'll give them your email address in case they want to get mad -- Not! I'll report back when my car drives like I want it to, which I hope is REAL soon.

Louie

jimdvan

Thanks a lot, Duke, your figures will help me greatly. I was hip on the positive caster for a p/s car but was in the dark about the other specs. I've seen some posts re: the Steeroids and the people who've installed it liked it. Do you have any experience or opinions on it?

LouieM

The only concern I've heard about Steeroids is that it is the lowest thing hanging from the car, therefore possibly dinged if you run over the wrong thing. This may not be a problem for most.

SWCDuke

Don't really know much about it and don't have any interest. IMO the OE steering system does not need to be re-engineered.


Duke

Rogs65

Hi Jim,

Yes, I spoke to Jim. We may do something. I don't mind helping out a fellow c-2 owner. It really doesn't make much of a difference to me.

Thanks a bunch Duke. I printed your response out for future reference.
Can't say enough good things about you and John Z.
Rog :cheers:

jimdvan

Thanks for the input on the Steeroids. I think what I'll do is realign the car to Duke's recommended specs, readjust the steering box and see how that works. Maybe even replace the box with a rebuilt unit if the current one is too worn.

LouieM

Duke and JohnZ - The alignment shop will redo my 67 next week, to the specs you recommend. In the meantime, do these characteristics help to diagnose the alignment (or other?) problems: the car never seems to be "planted," especially going around even gentle 35 mph corners, but always seems to be "up on tip toes." This makes it hard to drive fast at all, since the car just doesn't feel to well connected to the road. Second, when I hit a bump in the middle of a corner the rear of the car hops sideways more than other midyears I can remember. Any thoughts? Since I'm heading out on a 3-week driving tour of the West in mid May in this car, I want to resolve this problem before rolling over 3-4K miles of unfamiliar secondary roads between here and North Dakota.

Louie

SWCDuke

What make, model, size tires? Wheels?

What are the installed shocks? How old are they?

Are the springs/anti-roll bar OE base suspension? If not, what are they?

What's the condition of all the suspension bushings including the anti-roll bar link and pillow block bushings?

Duke

TJefferson2020

Is it true that the sway bars should be disconnected and the car leveled before doing the alignment? My tech did a good job on the specs but never heard about disconnecting the anti sway bars - I know I read that somewhere...

pm

LouieM

Duke,
The tires are Yokohama AVS 215/15/15 on stock DC 15X6 steel rally rims. The tires have about 500 miles on them.

The shocks are Bilstein heavy duty (= street; not Bilstein Sport = too stiff for me) and are about 100 miles old.

The springs/anti-roll bar OE base suspension?

The front & rear suspension bushings, including the anti-roll bar link, are in excellent shape. I don't know what a pillow block is.

Hope this helps.

Louie

LouieM

Oops--- make those tires 215/65/15 instead of "15" series. I should also mention that the "up on tip toes" feeling and the rear skittering out when hitting a corner bump are --I THINK -- new characteristics that happened along with the recent alignment.

Louie

SWCDuke

The proper nomenclature for the tires is 215/65R-15 followed by the service description, which consists of a two (or three) digit load rating symbol and a letter symbol for the speed rating. The AVS Intermediate is a VERY GOOD tire. If the alignment is established in the range of the "sport" settings I posted and the shock damping rates are in the ballpark, your car should handle on a par with a modern sports sedan or mid-range sports car.

Your rear toe side to side mismatach could be causing the problem, which could also manifest as different right/left turn response. As the suspension goes through jounce and rebound the toe changes, so the initial toe setting is important and equalizing it side to side is EXTREMELY IMPORTANT.

It could also be shock related - too much jounce damping or insufficient rebound damping. I have NEVER, EVER found a set of fixed rate damping shocks that met my damping requirements on ANY car except the OE shocks on my '88 MBZ 190E 2.6.

This is why I ONLY recommend adjustable shocks on Corvettes or vitually any other car. If adjustable shocks are available off the shelf, I will pay any price to get them!!! Most guys pay virtually no attention to shocks, but they are CRITICAL to a car's transient response, such at turn-in and hitting a bump in a turn.

The "pillow block bushing" is the rubber bushing between the the "pillow block" and anti-roll bar that mounts the anti-roll bar to the frame.

Duke

brucep

Hey I notice that my 66 L-79 roadster handles differently as a function of the weight of my passenger and how much gas I have in my tank. What is the wisdom on alignment based on these factors? Should the tank be full or empty, should I be sitting in the car etc., or am I out to lunch on this? The last time I had an aligment done I conciously brought the car in with half a tank thinking that was the "average" condition, then again I wasn't in the car, so it may actually have be a "never this light" condition that I had the alignment done under. Do the spec's assume something about these factors, or are the settings robust to these factors?


[Modified by brucep, 10:00 PM 4/29/2004]