Need to add Caster...How?
Thread Starter
Drifting
Joined: Dec 2015
Posts: 1,319
Likes: 221
From: Dalton, Ma
Need to add Caster...How?
I posted this on the C1-C2 board and thought I'd ask my C3 brothers for their experience on this as well.
I don't have the specs in front of me but if I remember correctly my front guy could only squeeze 2 degrees of caster last time I had the front end aligned. [after I added Borgenson Power Steering]
Recently there have been threads [C1-C2] on how to increase road feel with the new Borgenson set up.
On my car I've decided to try to add caster first as a remedy.
Question, Can anybody tell me how much caster they were able to add with the Moog offset upper control arm shafts? I've read you will only gain a degree or so and I have to wonder if that is enough. I've read where you want to have 4-6 degrees.
I'm reading that slotting the shaft may be a better way to achieve the addl Caster. How much slotting would you recommend to get an additional 3-4 degrees?
As always, Thanks for the anticipated advice.
I don't have the specs in front of me but if I remember correctly my front guy could only squeeze 2 degrees of caster last time I had the front end aligned. [after I added Borgenson Power Steering]
Recently there have been threads [C1-C2] on how to increase road feel with the new Borgenson set up.
On my car I've decided to try to add caster first as a remedy.
Question, Can anybody tell me how much caster they were able to add with the Moog offset upper control arm shafts? I've read you will only gain a degree or so and I have to wonder if that is enough. I've read where you want to have 4-6 degrees.
I'm reading that slotting the shaft may be a better way to achieve the addl Caster. How much slotting would you recommend to get an additional 3-4 degrees?
As always, Thanks for the anticipated advice.
Thread Starter
Drifting
Joined: Dec 2015
Posts: 1,319
Likes: 221
From: Dalton, Ma
I have checked them, That is were I got the 1.25 degree figure from. Moog also makes them at a lower cost. Seems like a lot of work and expense to only pick up a degree and change...
Thinking slotting the shaft may be the way to fly...
Thinking slotting the shaft may be the way to fly...
Pro
Joined: Jun 2014
Posts: 706
Likes: 294
From: New Jersey
Thread Starter
Drifting
Joined: Dec 2015
Posts: 1,319
Likes: 221
From: Dalton, Ma
Pretty trick arms but I'd rather stay kinda stock...
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Drifting
Joined: Aug 2019
Posts: 1,510
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the .125 is for Camber degrees … to get positive Caster you have to take/remove Shims from the front mounting stud and add them to the back mounting stud of the Control Arm … If you remove one front shim and add it to the back Shim you increased your Positive Castor with out losing your Camber adjustments , you generally take as many front shims as you can and add to the rear until you run out of Camber adjustment AKA no more shims to take out of the front to give to the back for more positive Caster , at this point Off Set Control Arm Shaft becomes valuable
Drifting
Joined: Aug 2019
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Melting Slicks
Joined: Oct 2012
Posts: 2,156
Likes: 273
From: Dunedin NZ.
I machined the stock ones by 1/4” which if I recall correctly is about as far as you can take them. One of the best modifications I have done JMPO. Running on modern tires increasing the caster made the steering feel a whole lot less nervous especially on the lumpy roads we have where I live. I would like to add the Borgeson kit but it wont pass certification here because of the welded bracket to enable it to line up with the holes in the frame rail.
Thread Starter
Drifting
Joined: Dec 2015
Posts: 1,319
Likes: 221
From: Dalton, Ma
To answer my own question, Th extra .050 must be to provide clearance to enable reeeeeeealy angling that 'A' frame to monkey with the camber.. I'm just concerned with caster. I took a quick look at what I have and yes, I'd think .250 is all you could realistically slot a factory shaft.
I'm going to slot it .250 and see what I have.
I'm going to slot it .250 and see what I have.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Most of the race car supply houses have slotted shafts & ovoid slugs with bolt holes in varied locations ...
... change out the slugs for whatever caster is required ... that's how all the "stock" cars do it.
-edit-
similar to these
https://keysermanufacturing.com/prod...ss-shaft-assy/
https://keysermanufacturing.com/prod...highlight=slug
http://www.ubmachine.com/upperparts.html
... change out the slugs for whatever caster is required ... that's how all the "stock" cars do it.
-edit-
similar to these
https://keysermanufacturing.com/prod...ss-shaft-assy/
https://keysermanufacturing.com/prod...highlight=slug
http://www.ubmachine.com/upperparts.html
Last edited by jackson; Sep 30, 2019 at 04:23 PM.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,076
Likes: 4,430
From: Marlton NJ
Moving the ball joint back 1/4 inch would give you the caster you want. GKull did that by moving the inside a-arm mounting point backward 1/4 inch. Very cool mod!
Less expensive and more stock looking than custom a-arms. The 0-1 degree caster was there to accommodate manual steering.With power steering you are not limited to arm strength and can use 4-6 degrees caster like you mentioned and there are great tactile handling steering wheel feedback or "feel" benefits as well as self-centering benefits. At 200MPH, or auto-cross, it is very important to be able to feel what the tire is doing regarding slip-angle. The self centering eliminates the "wander" you feel at stock speeds, it just feels more stable.
Another "must-do" mod for my car!
Less expensive and more stock looking than custom a-arms. The 0-1 degree caster was there to accommodate manual steering.With power steering you are not limited to arm strength and can use 4-6 degrees caster like you mentioned and there are great tactile handling steering wheel feedback or "feel" benefits as well as self-centering benefits. At 200MPH, or auto-cross, it is very important to be able to feel what the tire is doing regarding slip-angle. The self centering eliminates the "wander" you feel at stock speeds, it just feels more stable.
Another "must-do" mod for my car!
Last edited by leigh1322; Oct 2, 2019 at 04:23 PM.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,076
Likes: 4,430
From: Marlton NJ
You do know the bracket is not required for the borgenson? It is an extra, for racing. The box bolts to the stock rail holes without out any additional bracket, no welding required.
Tech Contributor
Joined: Jun 2004
Posts: 20,894
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I'm not a big fan of just swapping F&R shims. That method gets the desired static caster (great for driving in straight lines), but during cornering the odd angle of the UCA tends to reduce the caster and camber of the outside wheel, reducing grip.
(I've got a C4 suspension on mine, I just welded up a custom UCA mount to move the UCAs rearward to get the same benefits that your slotted shafts offer on the stock C3 mounts.)
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I just recently finished up installing some new upper control arms from Global West. The specs state over 5 degrees of positive caster. Haven't had a chance to get it properly aligned yet but the difference in feel is amazing. The swap was fairly straight forward and I had no issues.
These are the arms I installed: https://www.globalwest.net/corvette-...5-1976-19.html
DC
These are the arms I installed: https://www.globalwest.net/corvette-...5-1976-19.html
DC
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
To answer my own question, Th extra .050 must be to provide clearance to enable reeeeeeealy angling that 'A' frame to monkey with the camber.. I'm just concerned with caster. I took a quick look at what I have and yes, I'd think .250 is all you could realistically slot a factory shaft.
I'm going to slot it .250 and see what I have.
I'm going to slot it .250 and see what I have.