Negitive Caster problem - Page 2 - Chevelle Tech
Brakes, Suspension & Steering Conversion questions & more.

 15Likes
Reply
LinkBack Thread Tools Search this Thread Display Modes
post #16 of 33 (permalink) Unread Jun 24th, 19, 5:09 PM
Senior Tech Team
Steve
 
Join Date: Sep 2015
Location: Central MA
Posts: 1,174
Re: Negitive Caster problem

Well, you've definitely got room for improvement there - they just messed up the alignment.

The fact that you are at 0 camber and have shims on all 4 bolts means you have room to adjust the caster without changing the camber. And, adding more shims to both bolts will actually move the camber the way you want (you want to have about -0.5 if you can get it) and then give you even more wiggle room to increase caster.

For example, in my car, I had to stop increasing caster once the front bolt on the passenger side was without shims. Any more shimming of the rear bolt to increase caster was also decreasing camber at that point on that side, so to keep 'em equal that was the stopping point. This is still with factory angled front control arms, and I was about to get about -0.7 camber and about 3.0 positive caster on both sides.

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
lucifershammer is offline  
Sponsored Links
Advertisement
 
post #17 of 33 (permalink) Unread Jun 24th, 19, 8:51 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: In the Shadow of GIANTS stadium,N.J.
Posts: 7,351
Garage
Re: Negitive Caster problem

You may have frame sag which effects a lot of A-body's of all makes. Chevy's, B-O-P's all can be affected by this.If those readings are accurate you may need to take it to an auto body shop with a frame rack and the knowledge of how to fix this problem.
Of course, if the alignment tech is paid flat rate he won't mess around with shims any more than he has to and you get the set the toe and get it out quickie alignment.
gnicholson likes this.

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
71350SS is offline  
post #18 of 33 (permalink) Unread Jun 25th, 19, 12:50 AM
Senior Tech Team
 
Join Date: Apr 2006
Location: OR
Posts: 1,476
Re: Negitive Caster problem

Quote:
Originally Posted by driveshaft-texas View Post
Try to find an old guy a different alignment shop. Its tricky to get the shims right ...every change affects both caster and camber. All the new stuff uses eccentrics and youngsters don't understand the shim system. Last resort , Moog makes a problem-solver offset upper shaft to add some caster but you will have to remove both upper bushings to install
Unfortunately, Moog no longer makes an offset shaft with added caster. I had a set installed and we couldn't get any more caster than before. I then called Moog and they said that the offset shaft has adjustments only for camber. My alignment guy was equally surprised. He said he remembers Mood helper shafts that were obvious to the eye in the added caster. It must have been a phased out part.

Global West and a few others do make an offset shaft to add caster, but they all claim no more than another +1.25 degrees, and that's in the best of all possible worlds. That may not be enough to fix Joel's alignment, even with the right shop doing it.

To Joel: I know you just spent a chunk of change rebuilding your front end, but consider upgrading to upper and lower tubular arms from UMI. I just did that to my daily driver of more than a decade and while spendy, it was well worth every penny. We ended up settling on +6 degrees caster, and had room for +9. When I now drive 80 mph, it feels like what 60 mph was with the factory control arms, and I had +2.5 caster on one side, and +2.75 caster on the other. The stability and drivability is tremendous with the UMI arms. Highly, highly recommend them, especially if your frame has significant sag. It may be worth it to try another shop and see if they can get better specs, but even at optimum with the factory arms, it's nowhere near as good as with tubular arms made by the right company. UMI products are high quality with very reasonable prices.

And by the way, please, please, please do not buy cheapo tubular arms off of Ebay or even Summit that are made in China. They cost 1/3 of what US-made arms do, but are probably only 1/100 as safe. Read the fourth sticky in this forum: https://www.chevelles.com/forums/16-...ntrol-arm.html The guy was very lucky that his Chinese control arm didn't fail on the highway at 70 mph. If it had, I doubt he would have survived to write that sticky.
658Chevy is offline  
 
post #19 of 33 (permalink) Unread Jun 25th, 19, 2:24 AM
Senior Tech Team
Gary
 
Join Date: Feb 2007
Location: Kansas City,Mo.
Posts: 4,306
Re: Negitive Caster problem

you could get more caster with them as well because the offset allowed more room to stack shims for a caster gain but still have enough leeway to get the camber right but they were mostly made to straighten the camber out when the frame and cross member sagged
gnicholson is offline  
post #20 of 33 (permalink) Unread Jun 25th, 19, 2:33 AM
Tech Team
Joel
 
Join Date: Feb 2006
Location: Idaho
Posts: 40
Re: Negitive Caster problem

Thanks guys this is Joel getting my user name etc.Ö straightened out. next step I will try an other shop. think I found one with an older more experienced tech.( poor guy seams to be as old as me !) the shop I went to has poor record on old cars I am learning. Will keep you posted.
joelbert62 is offline  
post #21 of 33 (permalink) Unread Jun 25th, 19, 8:29 AM
Senior Tech Team
Jeff
 
Join Date: Jun 2009
Location: Pittsburgh, Pa.
Posts: 1,826
Garage
Re: Negitive Caster problem

I would pick up a set of SPC adjustable upper control arms from SC&C with the Howe .9 tall ball joints and set the alignment as follows.. The ultimate with be the uppers and lowers with a Lee 14:1 box.. Marc at SC&C is the only one who uses the exceptional Howe ball joint..
That said, its hard to throw two grand at a toy in this economy..

Caster Positive, Drivers side 5.5, Passenger side 6.
Camber Negative, both sides 1 degree..
Toe in, both sides 1/32-1/32..

SC&C Street-Comp Stage 3 Plus GM A-body `64-`72 with greaseable delrin bushings | Savitske Classic & Custom
pannetron likes this.
hydro462 is online now  
post #22 of 33 (permalink) Unread Jun 25th, 19, 8:37 AM
Senior Tech Team
Jeff
 
Join Date: Jun 2009
Location: Pittsburgh, Pa.
Posts: 1,826
Garage
Re: Negitive Caster problem

There will be severe issues in trying to gain more then 2 degrees caster with a stock upper control arm in either direction. You can either get modern uppers like I suggested or move the upper control arm pick up bracket back two inches..

Back when I was a teen, down the alley from my house, I used to watch this master mechanic for the Port Authority busses do this on every car he bought. He would cut the bracket off and move it back 2 inches and weld it back on. We had no idea what he was doing but he was one of those kind of guys who had very few words but had the answer to any car problem we ever had.. He always owned GM A body station wagons with big engines with quiet exhaust..
hydro462 is online now  
post #23 of 33 (permalink) Unread Jun 25th, 19, 11:08 AM
Gold Founding Member
 
Join Date: Aug 1998
Location: 30.1298228, -97.9771166
Posts: 6,180
Garage
Re: Negitive Caster problem

Maybe my old eyes are misperceiving but it looks like one of those uppers is damaged. You sure they weren't swapped side to side? Take the driver's side wheel off and take a picture from the side on so we can see the upper to lower ball joint relationship.
Attached Thumbnails
Click image for larger version

Name:	CtrlArms.jpg
Views:	50
Size:	58.7 KB
ID:	596526  

People donít like to have to think in high resolution. Jordan Peterson. Thatís why we are forced in to so many binary choices.
Alan F is offline  
post #24 of 33 (permalink) Unread Jun 27th, 19, 12:50 AM
Tech Team
Joel
 
Join Date: Feb 2006
Location: Idaho
Posts: 40
Re: Negitive Caster problem

I looked again, looked close and see no damage. a couple hammer marks at most. I have compared the way everything is installed to 3 other cars . the control arms are on the right side ! I am not sure you could hook everything up if they where not correct . This car has NOT been badly abused, but it is old. it has an original 67-327 in it. why I liked and bought it. Also note even though 4 THIN shims on drivers side and two THICK shims on the pass side. The shims are the SAME thickness on both sides, the caster was 4.5 on both sides. even , makes me think no one control arm is damaged and they look fine.
I have found I have a leaky wheel cylinder and will have the drivers side wheel of Friday. I can send a photo but don't think it will tell you much but that the top ball joint is in front of the bottom/ negitive caster.
joelbert62 is offline  
post #25 of 33 (permalink) Unread Jun 27th, 19, 3:27 AM
Tech Team
Joel
 
Join Date: Feb 2006
Location: Idaho
Posts: 40
Re: Negitive Caster problem

I meant negitive (-4.5) on each side. Thanks everyone for the help
joelbert62 is offline  
post #26 of 33 (permalink) Unread Jun 29th, 19, 4:57 PM
Gold Founding Member
 
Join Date: Aug 1998
Location: the Seasonally Frozen Wastelands
Posts: 10,871
Re: Negitive Caster problem

Quote:
Originally Posted by joelbert62 View Post
The shims are the SAME thickness on both sides,
You need a different alignment shop. Having goofy caster like that, and same-thickness shim packs at all four locations means the guy doing the alignment DOES NOT KNOW WHAT HE'S DOING.


As said, the shim packs need to be adjusted to move the caster more positive, while holding the camber about the same or slightly negative.

Did you SEARCH BEFORE POSTING a new thread?
Did you post in the CORRECT FORUM?
Schurkey is offline  
post #27 of 33 (permalink) Unread Jul 9th, 19, 2:05 AM
Tech Team
Joel
 
Join Date: Feb 2006
Location: Idaho
Posts: 40
Re: Negitive Caster problem

New Update : after checking everything over well I took it to a different alignment shop. They where able to get the caster to neg 1 degree. and everything else right in the middle of spec. it drives SOOOO much better. not perfect. but I can enjoy driving it for now. Now it has a stack of shims on the rear studs and none on the front studs. this at least makes sense , I am still confused why I can not get to positive caster but eventually may put offset shafts in to help. the incompetent shop gave me my alighnment money back at least when I went back.

When you guys speak of frame sag I imagine you are talking of the cradle / crossmember sagging because of big blocks/ weight ? so the upper contol arms basically become closer together? I just am tiring to wrap my head around this. My car still has the original 275 HP 327 in it .
joelbert62 is offline  
post #28 of 33 (permalink) Unread Jul 9th, 19, 2:10 AM
Tech Team
Joel
 
Join Date: Feb 2006
Location: Idaho
Posts: 40
Re: Negitive Caster problem

Quote:
Originally Posted by Schurkey View Post
You need a different alignment shop. Having goofy caster like that, and same-thickness shim packs at all four locations means the guy doing the alignment DOES NOT KNOW WHAT HE'S DOING.


As said, the shim packs need to be adjusted to move the caster more positive, while holding the camber about the same or slightly negative.
Yes I knew that. the point I was tiring to make was the readings were even side to side with the even # of shims on both sides / front and rear studs the idiot put in. indicating to me and my little brain nothing seamed bent or different side to side.
joelbert62 is offline  
post #29 of 33 (permalink) Unread Jul 9th, 19, 10:29 AM
Senior Tech Team
jerry
 
Join Date: Dec 2006
Location: portland oregon
Posts: 6,680
Re: Negitive Caster problem

I believe these thing have been mentioned but in different posts so I'll try to clump them together as they all are very important.

The assembly manual addresses alignment specs and basic setup.
The assembly manual states that no more than 1ea 1/16" shim shall be used on the upper a arm shaft. That's just lazy to stack thin shims.
Rake front to rear, and overall frontend height can make positive caster unachievable.
Look at your front a-arms front to back. The upper is dramatically curved while the lower is somewhat straight. That relationship changes camber sharply with any compression of the front spring. You have to drive into the setup area so any adjustment is made while at operating height. Your setup area needs to be on a level plane front to back and side to side.
Torqueing your lower a-arm bushing bolts while at bushing lockup is necessary to achieve operating height and load. If your spring rates vary greatly from factory, than I recommend adjusting the factory specs slightly, meaning if the spring sets the car 1 inch higher than stock, adjust lockup procedure 1 inch higher than factory specs. Factory lockup specs should be adjusted in the rear also, as this will affect the "rake" which in turn affects caster.

This is my understanding but I hope an expert will comment if I'm incorrect.
Toe should be 1/8"-1/4" per factory specs. Factory specs are with bias ply tires and rubber bushings.
Radial tires require less toe, and I'm assuming poly bushings will probably require less toe also since deflection has been limited.

I spent the entire day setting up my frontend but it's new and all the procedures had to be addressed as above. Your alignment guy will assume all is right and just put the frontend to spec. This can be chasing your tail if you want it done right. Techs won't spend that kind of time for obvious reasons.
Alan F likes this.
cheveslakr is offline  
post #30 of 33 (permalink) Unread Jul 9th, 19, 5:25 PM
Senior Tech Team
Eric
 
Join Date: Aug 2011
Location: Poteau, Ok
Posts: 4,034
Re: Negitive Caster problem

Quote:
Originally Posted by joelbert62 View Post
New Update : after checking everything over well I took it to a different alignment shop. They where able to get the caster to neg 1 degree. and everything else right in the middle of spec. it drives SOOOO much better. not perfect. but I can enjoy driving it for now. Now it has a stack of shims on the rear studs and none on the front studs. this at least makes sense , I am still confused why I can not get to positive caster but eventually may put offset shafts in to help. the incompetent shop gave me my alighnment money back at least when I went back.

When you guys speak of frame sag I imagine you are talking of the cradle / crossmember sagging because of big blocks/ weight ? so the upper contol arms basically become closer together? I just am tiring to wrap my head around this. My car still has the original 275 HP 327 in it .
What alignment shop did you take it to? Franchised alignment shops, IE Goodyear, Firestone, Pepboys or similar in most cases have no idea how these front ends work outside of what their computer machine tell them. The other problem is that the computerized machines don't even list these old cars anymore. You should have no problem getting a bit of positive castor out of an alignment. If you think it drives good now think of how well it would drive if setup better. Just saying.

Frame sag is at the front crossmember, I personally have never witnessed a car having it, yet everyone talks about it.

Your just jealous because you can't hear the voices!

1967 Olds Cutlass 468 BBC/T400
1963 Plymouth Fury 440/Torqueflite
2007 Ford Mustang GT (momma's car)
oldcutlass is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in













Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome