I Found the Magic Button!

[BMERDOC]

Ok, so I've been messing with my trucks alignment and have a thread going about how to improve the original specs. I haven't been driving it much but now that its warm out its time to dust it off. I added power steering, shocks all the way around and a 1 1/16" bar I had laying around. I thought now would be a good time to recheck the alignment and see if anything had changed.

In my Alignment thread I have advised that it is best to remove all the shims in the front end and equalize the sides to gain the most negative camber and positive caster you can get.

Welp, this Saturday I took the truck up to work to do another alignment and discovered this little button that says "Match using cross spec". I never noticed it before. I clicked on it and it gave me the option of which side I'd like to adjust to match the other side. I couldn't de-shim an already unshimmed control arm so I had to "de-tune" the hotter side. So selecting the left side gave me the measurements required to match the left side to the right. One 1/8" shim was required in the front and two 1/8" (1/4" total) was all that was required to get the most out of the angles I could. I set the toe 1/16" per side and took it for a spin. It handles great! And it won't burn up tires. The stock specs are .8 to -.3 camber and 2.0 to 3.0 caster so the front end is still within factory spec but at the outer permissible ranges. -.3 camber is fine but I'd be happier with -.5. I will be performing the "Caster Mod" to dial in additional caster.

My truck does have 3" springs on the front so I'm curious what effect different suspension combinations would have. My machine is a Hunter, I'm not sure if other brands have this same kind of feature. I hope you guys find this useful!!

[MusicMan70]

Thanks, Sure wish I had this for reference when I took mine's in for alignment. I had just rebuilt the front end and it took me two trips before the guy got it right. This should help.

[jjzepplin]

"Castor MOD"? Is that where you switch the upper control arms and move the lowers forward?

[BMERDOC]

Originally Posted by MusicMan70

Thanks, Sure wish I had this for reference when I took mine's in for alignment. I had just rebuilt the front end and it took me two trips before the guy got it right. This should help.

Well I hope it does help and he can get it straight for you!

Originally Posted by jjzepplin

"Castor MOD"? Is that where you switch the upper control arms and move the lowers forward?

I tested switching the uppers and it gives waay too much Caster (13° to 14°). So swapping the uppers is a dream and doesn't work but you are correct about moving the lower arms forward. You would redrill for the locating pin 3/4" forward to come up with 6° to 7° of caster. I will be drilling mine at both 1/2" and 3/4" to see what the difference is. The only problem with dialing in caster this way is that it tilts the steering arm up and back and messes with bump steer so I will be testing to see what effect both 3/4" and 1/2" have on both caster and bumpsteer.

[Tinkermc]

Well I know where I'll get my next alignment.

[68gmsee]

Good info. I didn't realize it got this technical.

[jjzepplin]

Originally Posted by BMERDOC

Well I hope it does help and he can get it straight for you!



I tested switching the uppers and it gives waay too much Caster (13° to 14°). So swapping the uppers is a dream and doesn't work but you are correct about moving the lower arms forward. You would redrill for the locating pin 3/4" forward to come up with 6° to 7° of caster. I will be drilling mine at both 1/2" and 3/4" to see what the difference is. The only problem with dialing in caster this way is that it tilts the steering arm up and back and messes with bump steer so I will be testing to see what effect both 3/4" and 1/2" have on both caster and bumpsteer.

Interesting. I did both but don't have #'s yet as it is still a frame on the ground and the body is around the corner. 1973 HD disc front end. Those lowers were tough.

[BMERDOC]

Originally Posted by Tinkermc

Well I know where I'll get my next alignment.

Tink, consider your next alignment "on the house"!

Originally Posted by 68gmsee

Good info. I didn't realize it got this technical.

Lol! I'm not laughing at you but my discoverys have me scratching my head at all those shim stacks in these trucks. To the person you are paying, it shouldn't be all that "technical". As you can see I used a total of three, count them, THREE shims to get a great alignment with a stock suspension (and within factory specs) minus the three inch springs. I'm chomping at the bit to get a hold of a stock suspension truck and try this same method.

I'd have to say that after years of experience most techs aren't mathematical geniuses. I think those capable of doing alignments with the old technology they were provided just added and subtracted shims until the alignment was "good enough" and within spec. You were pretty much stuck with the end result. If they had removed all the shims and started from scratch looking at the numbers and realized what was actually happening alignments could have been better. Maybe after some time and experience aligning these trucks it'll make more sense as to why this happened.

Sorry for the semi-sorta rant. I feel better now.

[ChevLoRay]

So, when we completely disassembled the chassis, I made sure to keep each of the shim packs and associated parts in separately labeled bags. From what you wrote, it would seem that maybe it could be put back together differently, regarding the shims.

After my truck was lowered (ECE) 2.5 up front and 4.0 in back, I took it to a good friend to align. It drove great and I am hesitant to reassemble it differently, yet I know that having it completely apart and reassembling it may mean that it won't be the same. I also feel that it would need to be put back on the alignment machine, but I'm just trying to get it close enough that it could be driven w/o destroying the tires in a short distance.

[BMERDOC]

Originally Posted by jjzepplin

Interesting. I did both but don't have #'s yet as it is still a frame on the ground and the body is around the corner. 1973 HD disc front end. Those lowers were tough.

You might as well swap the uppers back to the correct sides. Its way too much. The upper limit is 9° and thats with a suspension designed for it. I'm still skeptical of 7° for a stock suspended C10. Rob McGregor addressed bumpsteer (as well as roll center among other things) in his "Make it Handle" thread. The steering arms would have to be modified to drop back down (heated and bent) or the tie rod would have to be flipped underneath the steering arm to correct Bumpsteer. A good alignment is something you can do to any truck but its only when you modify the suspension that things get hairy.

[BMERDOC]

Originally Posted by ChevLoRay

So, when we completely disassembled the chassis, I made sure to keep each of the shim packs and associated parts in separately labeled bags. From what you wrote, it would seem that maybe it could be put back together differently, regarding the shims.

After my truck was lowered (ECE) 2.5 up front and 4.0 in back, I took it to a good friend to align. It drove great and I am hesitant to reassemble it differently, yet I know that having it completely apart and reassembling it may mean that it won't be the same. I also feel that it would need to be put back on the alignment machine, but I'm just trying to get it close enough that it could be driven w/o destroying the tires in a short distance.

To put it simply I drove my truck for a while with NO shims in it until I had time to get back to it. One of the pictures I showed was with no shims. Caster is a "none wearing angle" and the camber was under -1.0° so I was confident I was not going to see abnormal wear from excessive angles. If you pull them out it should not effect it. The only thing that would effect it is the change in toe from pulling the shims before aligning it but depending on your alignment your tires should not be smoking on the way to the shop.

If you are rethinking your alignment now after seeing my thread dont fret. Don't take anything apart until you have it back at the shop. Have your Aligner pull all the shims and start from there.

[VA72C10]

Great thread! You'll get to align a bagged truck soon
Posted via Mobile Device

[BMERDOC]

I have to add this...Looking at the picture of my alignment with no shims if I could have landed at -.5° camber and 3.9° caster I might well call that good enough. Is it in spec? No, but the original specs in a word STINK! There isn't enough caster OR camber allowed. Sorry, I'm not that old, it may have had something to do with bias ply tires but I doubt it. Could it have been that a truck was made for work? I doubt that too. If I had +.5 camber dialed in and had the bed (or tongue) so loaded down that the nose was light then the camber would be even more positive making things worse. Not adding enough caster makes higher speed stability twitch and return-to-center dull and almost no exsistant. Dialing in better specs not only makes your truck handle better but it is also SAFER. Your truck will be more likely to do what you need it to do when you need to grab handfuls of steering wheel to get out of a jamb!

Originally Posted by VA72C10

Great thread! You'll get to align a bagged truck soon

Its only a matter of time! Without a doubt I'll be posting our findings when the Stepper is on the rack!

[66 C10 383]

Originally Posted by jjzepplin

"Castor MOD"? Is that where you switch the upper control arms and move the lowers forward?

The Castor Mod is where you move the lower a-arm forward, usually about 3/4". Here's a write up on how it's done:

http://67-72chevytrucks.com/vboard/s...d.php?t=501241

BMERDOC - thanks for sharing all the info you are as to how to make these trucks handle with a better alignment. I'm currently updating my suspension from the stock 66 C10 to the 73-87 spindles, steering linkage along with power steering and it will be dropped somewhere around 1.5" - 2" with a stock spring cut 1 coil and 2.5" spindle. I'll also do the castor mod while it's apart, I'm shooting for about .75" forward. So, nowhere close to a stock C10 setup.

Although I won't know what exactly to tell the guy who aligns it, I'll be able to refer back with the specs as to whether it's right, close enough, or needs more work.

Thanks for the shared knowledge.

[Koffer]

I wish I could find someone local who could do alignments on older stuff around here . I don't trust anyone as they are all $29.95 "haven't got a clue, was fired from Burger king last week master front end tech"
I need to replace the front upper control arm frame brackets soon and know finding an shop to aline it when I'm done is going to be the worst part of the job

[BMERDOC]

Originally Posted by 66 C10 383

BMERDOC - thanks for sharing all the info you are as to how to make these trucks handle with a better alignment. I'm currently updating my suspension from the stock 66 C10 to the 73-87 spindles, steering linkage along with power steering and it will be dropped somewhere around 1.5" - 2" with a stock spring cut 1 coil and 2.5" spindle. I'll also do the castor mod while it's apart, I'm shooting for about .75" forward. So, nowhere close to a stock C10 setup.

Although I won't know what exactly to tell the guy who aligns it, I'll be able to refer back with the specs as to whether it's right, close enough, or needs more work.

Thanks for the shared knowledge.

Originally Posted by Koffer

I wish I could find someone local who could do alignments on older stuff around here . I don't trust anyone as they are all $29.95 "haven't got a clue, was fired from Burger king last week master front end tech"
I need to replace the front upper control arm frame brackets soon and know finding an shop to aline it when I'm done is going to be the worst part of the job

Good luck to you guys in finding a shop that is willing to do a good job! I mean that. As much as I hate to refer them, I know a lot of Goodyears and Firestones use the same Hunter machine that I use. You'd just have to find one that is willing to work with you on your project. I will also say that you should go somewhere like Harbor Freight to buy your own shim kit to provide them with. They are $10 a kit and your Aligner will have nice, new and clearly marked shims to use instead of trying to stack some old ones out of a bucket or reusing your old crusty ones. I forgot to give credit to Jonathan (VA72C10). He donated a new HF shim kit to this project.

[toddtheodd]

Guess I'm lucky.
There's still a shop here in Fort Worth that does alignments on old vehicles.

[Hutch]

toddtheodd

Guess I'm lucky.
There's still a shop here in Fort Worth that does alignments on old vehicles.

Would you mind sharing the name of this shop?

[alsriv2]

BMERDOC - Glad to have found this thread!
My '69 C10 will be on the road by the spring and I might just come down and pay you a visit.

[BMERDOC]

Originally Posted by alsriv2

BMERDOC - Glad to have found this thread!
My '69 C10 will be on the road by the spring and I might just come down and pay you a visit.

Gotcha! Bring it! I'm just a hop, skip and a jump off I95.

[chevy-fun]

Originally Posted by toddtheodd

Guess I'm lucky.
There's still a shop here in Fort Worth that does alignments on old vehicles.

can you share.
i took mine to firestone an they spent lil over 2hrs an still not right pulls lil to the right. an tried to get them to put more caster but they kept telling me it wasnt like that from factory. i have it dropped 4.5" an all cpp front end. told them this isnt factory. no luck

[lolife99]

In your opinion,... what camber/caster/toe specs would be best for these trucks?

[BMERDOC]

Originally Posted by lolife99

In your opinion,... what camber/caster/toe specs would be best for these trucks?

Up to -2 camber is ok but I'd prefer a range of -1 o -1.5 degrees. Somewhere between +5 and +7 degrees caster is good but I have yet to get that far on mine. While my truck does feel great with +3 degrees caster I have found that the steering is still a little dead feeling and the "return to center" isn't great. I worry about +7 degrees because rolling the spindle back that far raises the steering arm and creates more bump steer. Again, I haven't had the opportunity to dial in that much caster into a truck to see what affect it would have on the steering arms. You could always heat and bend the arms or relocated the tie rod underneath the arm. Toe is easy...+1/16 per side (1/8 total)

[lolife99]

Thank you.

[litew8]

Great, just what I needed to hear Mine is at that point in the build where I'd like to get alignment done. It'd be cool if you could provide the specs and we could copy. Not sure about moving the lower control arm out though. Would they do that for alignments? I've got lots of shims in mine, so I'm guessing not so great.