Anyone remember that article in CHP or HR magazine recently that took a first gen, removed the front spring and shock, then hooked it up to some sort of scale to measure bumpsteer through a range of motion? They compared using various combinations of idler and pitman arms-I don't think they addressed the steering arms.
Anyway, I can't find it now and I can't remembr the outcome of the test. Can someone help me out? Thanks!!

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

I glossed over it and put aside somewhere!
I think the short pitman and idler were a bit better, but can't say for sure.
I'll look for it.
David

Bret,

I think your talking about the Jeff Smith article in the October 2000 issue of CHP named TAKING TURNS The Inside Story on Early Camaro and Chevelle Steering Tricks. It begins on page 90.

I don't know if I'm busting copywrite laws here but this is what the BUMP AND RUN sidebar reads....

MAXIMUM TOE CHANGE IN INCHES
TEST 1 - Long idler/short pitman:
Passenger - Driver Passenger - Driver
31/2" susp. travel 2" susp. travel
0.075 0.150 0.050 0.085

TEST 2 - Long idler/long pitman:
0.160 0.235 0.100 0.135

TEST 3 - Short idler/long pitman:
0.165 0.225 0.100 0.140

TEST 4 - Short idler/short pitman:
0.125 0.140 0.090 0.090

The sidebar says the best combination is the long idler arm and the short pitman, with the short pitman being the best regardless of which idler arm is used. It also states that bumpsteer of more than 0.125" over 3" of suspension travel is considered excessive, and that the early Camaro exceeds this amount.

Hope this helps...



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Joe
HwyStar@Rochester.rr.com
'97 Blazer
'69 former basket-case

Darn.. it didn't come out like I had it typed... sorry!

My 67 was a lot worse than that!
Maybe there was something different about my linkage.
I would be happy with any of those readings.
I haven't tested any other Camaros other than mine, but I could FEEL mine it was so bad.
While I have warned others to be wary of bumpsteer problems, I don't have a good feel for how bad the average Camaro is.

If you turn into a corner going pretty quick, and after the initial turn in you have to add more steering wheel lock as the body rolls, to keep the car on line, I wold suspect a bumpsteer problem.
David

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

Dave,I thought you had a computer program,that would address bump steer.I've used Auto Ware's front suspension geometry pro,very good program.1st time out with computer designed front end netted a first place,against 80+ other cars.I loved it.It's a 3 D program,addresses,bumpsteer,side scrub,fore/aftmovement,camber curve,caster curve.All of these are plotted statically and dynamically.

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids

For those in the know, does anyone agree/disagree with the findings? I'm planning on running the Guldstrand mod, would these results still hold true with that modification?

Does the length of the outer arms make a difference in bumpsteer characteristics? I'm switching to quick ratio steering with the short outer arms. Thanks for the help so far guys!

[This message has been edited by bretcopsey (edited 03-18-2001).]

dale,
I have the program but need measurements from the car with all the suspension on it and aligned to 0 for a starting point.
I have the car all apart and can't get the measurements yet.
Also any measurements of steering link ball joints would be estimates of exactly where the center of pivot is on the ball joint because you can't see exactly where the pivot point is inside the joint.
I'm not confident the program would pin the bumpsteer down exactly right.
I would rather actually measure bumpsteer off the car and correct it there.
I could have done this when the subframe was out of my 67, but wasn't thinking of those things at that time.
I'm going to be doing some bump steer stuff to my 67 though, I had gone to Anti-Ackerman on it years ago and will take some of it out to make more wheel clearance for deeper wheels.

I had the long pitman, long idler, short outer arms, it couldn't have been worse than mine was. I'd hit the brakes and the car would dart left and right due to the toe out.
Another unknown is if you have factory bushings, the A frames can move and affect it.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

If anyone here is interested in measureing their bumpsteer, I'll talk you through it and we'll see how bad it is.
The car can be fully assembled, you don't need to pull the springs.
I eventually got mine down to around .050".
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-18-2001).]

Ok, I found my copy of the article. Gotta get a better filing system!!

Since I'm converting to quick ratio power steering, obviously I need a new pitman arm. Since I'll already have the linkage apart, I thought I'd preform any other possible mods at the same time.

My question is this; The article states that the best combination is the long idler (from 67) and short pitman. From the test, you can see that those numbers were the lowest.

I think maybe that is an incorrect conclusion though. The reason I say that is GM changed from that idler design to the one seen on 68-69. I'm sure there was a reason??

Secondly, even though that combination resulted the lowest numbers, it has a wide spread between 2" and 3.5" There is also a large difference between passenger and driver side measurements. If you look at the data for the short idler/short pitman combination, you see that at two inches, the passenger and driver side figures are the same. And the increase from 2" to 3.5" is not as great as in the suggested combination. This leads me to believe that the short/short combination would be the more stable one.

Any comments on this? Did I make any sense?

Bottom line is that I want to buy the best combination of parts-not just get the 68 idler arm b/c I have a 68. Know what I mean?

------------------
Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

The sidebar says the best combination is the long idler arm and the short pitman, with the short pitman being the best regardless of which idler arm is used. It also states that bumpsteer of more than 0.125" over 3" of suspension travel is considered excessive, and that the early Camaro exceeds this amount.

Hope this helps...


Here, I'm trying to fix your post so it's more readable, If this doesn't work, it is correctly viewable by clicking on the origonal post quote icon. It's the one on the upper right above the message with the arrow pointing to the right.
David

Hey, cool! it worked! I really like this bulletin board software!

[This message has been edited by davidpozzi (edited 03-18-2001).] MAXIMUM TOE CHANGE IN INCHES
TEST 1 - Long idler/short pitman:
Passenger - Driver Passenger - Driver
31/2" susp. travel 2" susp. travel
0.075 0.150 0.050 0.085

TEST 2 - Long idler/long pitman:
0.160 0.235 0.100 0.135

TEST 3 - Short idler/long pitman:
0.165 0.225 0.100 0.140

TEST 4 - Short idler/short pitman:
0.125 0.140 0.090 0.090

The sidebar says the best combination is the long idler arm and the short pitman, with the short pitman being the best regardless of which idler arm is used. It also states that bumpsteer of more than 0.125" over 3" of suspension travel is considered excessive, and that the early Camaro exceeds this amount.

Hope this helps...



------------------
Joe
HwyStar@Rochester.rr.com

I finally found the article! I gotta clean up!
I think you are right about the short/short being more stable. over the whole suspension travel. But 3.5" is almost more than avaliable on a lowered Camaro.
I would concentrate on the 2" figures. the camaro tie rods are too short and that makes the bump steer curve change at each end of the travel.
If you made them longer they would hit the oil pan when turning.
I found some old records and the really bad bump steer I had was with the manual long outer steering arms I had at first.
When I changed to the PS short arms the bump steer was between 3/16" and 1/4" per inch, per side.
I had the long pitman and 67 long idler.
The idler is easy to do something with, you can slot the holes or redrill them on the frame to move it up, but you still have the other side to contend with.
third gen Camaros are slotted on the idler arm holes with thick washers on the backside.

A couple of things I noticed in the article.
The idler they show is a Moog replacement that is square section cast or forged piece. It is longer than a stock 69 idler arm. I haven't checked the height difference.
The toe measurement can be seen in the photo. they are measuring points closer together than at the tire tread, so if you are comparing to a factory spec, or home set toe in measurement read off the tire tread you would have to increase their measurement.
The measure points appear to be from 12" to 14" apart. Tire points would be around 26" apart.
So to get a tire equivalent you would have to nearly double the toe change they give.
Maybe I'm off a bit by looking at the photo, but that's a 9.5" ID drum on the car and the points they are measuring at are just out from that by maybe a couple of inches each side.

I think converting inches to degrees works at 14"?
So at 14", 1/8" = 1 degree?
Or it's 1/16" = 1 degree, I'll have to look it up.

Also note Pg 94, the stop on the guys left side is different height from the dial indicator. This tool isn't set up exactly right. The tool hinge point at the floor also has to be exactly parallel to the car's centerline or you will get bogus readings.
It's a good idea to put a weight on the frame to keep it from moving too.

They say .125" is the limit for three inches of travel, that's .125 per side, I guess, so that's an eighth inch toe change over three inches, That's .041" per inch of travel, per side.

I once loaned my bumpsteer tool to a friend and stopped by his shop to see how it was going, he had it set up all crooked, and was allready busily machining spacers to correct the linkage!
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-18-2001).]

I agree,it is difficult to pinpoint the center of a ball joint.I've spent all day measuring my front end.And thats on a modified(no fenders,engine set back,18",radiator behind the cross member).I was as picky as is reasonable on the measurments.I felt if I were to become more exact ,I would never do it.Even if the info is wrong,at least you have a baseline.I sold my homemade bumpsteer gauge,but,how do you measure bumpsteer without pulling the springs?

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68 z28 ,68 rs 327 ,73 454 vette, 2 goofy kids

measure toe by using a trammel bar, tape, or putting a 2x4 sitting on blocks along the tire side.
pile stuff on the radiator support with the hood open. Cyl heads come in handy, the wife if she's heavy, or some friends.
The stock spring rate of 327 is only around 100 lbs per inch at the wheel, so for every 200 lbs you place on the rad support, the front end goes down 1 inch.
Check the toe every inch or whatever you like, bounce the car a little to loosen it up for each measurement.
You can put a floor jack under to get rebound toe measurements.
A several sheets of wax paper under the tire can help reduce binding due to side scrub.

I made a bump steer checker out of some angle iron and a piano hinge. Even plywood works. some guys use a garage creeper against the wheel rim.
I clamp a flat plate against an extra wheel to measure from. This is for when I have the spring removed.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-18-2001).]

David, I forgot about the comment that the short pitman was best regardless of which idler was used. I also didn't consider a lowered Camaro not being able to obtain 3.5" So if I focus on the 2" numbers-which would you go with? The long idler/short pitman has .035" difference from pass side to driver side at 2", wouldn't that create some stability problems over a match measurement with the short/short combo? I have a '68 style replacement idler now, I just need to figure out if it is the ione I want to continue to use or not. Thanks for any help.

PS. You should be getting a picture of three different length outer steering arms together in a couple days thanks to JOHNNYR.

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

Thanks, please get the numbers off them if you can, and the center to link eye length, or center of attachment hole to link hole.
I found some more arm numbers in my books and updated my steering page with them in the parts list. I also corrected the wrong manual outer arm length on the table.

I also read where the Corvair steering arms will fit Camaro, and are short!
Can anyone confirm this?

I think you should keep the short idler, after thinking more, if you have lowered the car, it will be near the end of travel, the 2" to 3.5" area more often. that's probably more important than the 2" number because you can re set the toe in for the static setting anyway.
Don't try and bend a Moog replacement idler, it is cast iron and will break. It's probably stiffer because it's heavier than a forged stock one.
Thanks, David


------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-18-2001).]

David, I'm just going to keep beating this horse!! I just had a thought, isn't the quick ratio pitman the long one? If so, what am I supposed to do about that? Apparently, if I use the long pitman I'll suffer from more bumpsteer and if I use the short pitman, it'll help correct bumpsteer but slow down my steering ratio. I would appreciate any comment you have about this as well. Too many variables-aaaaahhhhhh!!!!

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

That's why if you just bite the bullet and use the long pitman and bend down the outer steering links you will get the bump steer to near zero and have whatever steering ratio you like.

The other way is to get a fast ratio PS box 12.4 to 1 and the short pitman arm length won't be noticeable.
I don't see any bolt on way to make the bumpsteer really good.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

David, thanks for the advise. I think I'll get the long pitman (quick ratio), short idler and bend the short outer arms like you suggest. The short outer arms are on the way and I just bought a quick ratio box from a '91 Firebird. I'll be getting in touch to help walk me through the bumpsteer measurement and bending of the arms when I get everything together if you don't mind. Again, thanks!

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

Here is the steering arm diagram for bending. It's from my old notes from the 70's when I was autocrossing the 67.
when heating the steering arm heat it to a dull red in the area shown, and use a big crescent wrench to bend the arm down.
There might be a better way to do this, but this is how I did it.
It would be nice if there were a link end that had a longer stud.
You know, Rare parts would make a special one with longer stud, but they only make parts for wholesale.
David
http://ourworld.compuserve.com/homepages/David_Pozzi/67_STEERING_ARM_BEND.jpg

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

David, that's a good idea about using a tie rod with a longer stud. Have you checked into whether there is an existing part for a different application that would have the longer stud-a truck maybe? Even if it were a larger diameter where the tie rod threads into the adjusting sleeve it would be possible to make an adapter sleeve to work. The tie rod would only have to be nearly the same length as far as I can figure.

I wonder if it would be possible to contact a company like Moog or TRW to see if they would help out. Anyone have any contacts at one of these companies?? Chacane67???

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

Rare Parts is the size company that could do it. The other companies are to big to mess with us. Rare parts will even rebuild your old pitman arm, or steering link with new parts inside!

They had a booth at SEMA and CarlC and I stopped by and saw a tie rod end apart and saw a long stud that started us thinking about having them do a special tie rod end for us.

The other thing that could be done is use a Steeroids or Guldstrand bump steer adapter that converts the steering arm to a rod end and use a spherical bearing instead. That might have a longer life than a rod end, but I don't know if it would last as long as a stock type tie rod end.
You would have to fabricate a housing to put the spherical bearing into and it would be thirty or fourty bucks just for the spherical bearing with teflon lining.

I like the longer stud on a tie rod idea. Whoever would deal with Rare parts needs to have a resale license, they won't deal with retail customers. I don't have one, and I don't want the liability.
And it's not that hard to heat and bend the arms anyway.

Another option would be to weld another tie rod end socket to the center link. Put it about a half inch higher and you are set. I have seen circle track setups that have the inner mount adjustable for height.
But bending the arms is easier than doing that.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-20-2001).]

David, it seems that you're right about bending the arm being the easiest fix. I was just thinking that maybe something for another application might work-one that already has the longer stud needed. I was thinking of trying to find such a beast, not having one specially built. I know that bumpsteer correcting rod ends already exist, but I plan to run this car on the street and because of your previous comments about the bearings not holding up for very long I hesitate to use them.
In the long run it's highly likely that I'll bend the arm if needed, I just hate to make a permanent change like that-especially since I've had such a hard time finding the short arms. I'm going to see where I can get trying to find a existing replacement part and if I turn anything up I'll let everyone know.

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Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu

David,

Along the lines of my Guldstrand email to you from last week....

Dick stated that in order of preferance,

1) Guldstand mod
2) Springs, shocks, swaybars, etc.
3) Bend the steering arm using your guidelines to correct geometry.

Dick seems to like inexpensive modifications that work. I'm all for that!

His description of a dial gauge checking tool is similar to yours.

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Click here to see see my car and hear 5-speeds. http://www.geocities.com/casanoc

Carl,
Thanks, I really like Dick Guldstrand!
Get him to tell you about driving the Mulsanne straight at night with the headlights going out at 190 mph, or whatever they were going! http://www.camaros.net/forum/smile.gif
They were running an L88 Corvette.

Bret,
I don't know if I posted it here, but I reciently read that Corvair steering arms are short and will fit Camaro.
That might be another source for us. I just don't know for a fact it's true.
Your arms could allways be bent back if you wanted to later. I don't know why though.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer

[This message has been edited by davidpozzi (edited 03-20-2001).]

David, can you heat the steering arm using a regular propane torch?