i have 1999 chevy silverado w/6.0 liter 4X4. i am told buy the local
dealership that in order to do an alignment on the truck they may have to
remove the knock-outs which greatly increases the price. is there any way
for me to tell if my truck still has the knock-outs or am i at the mercy of
the dealership. i have heard that the new body style trucks don't have them
but i don't know if this is true. any help would be appreciated.
My 1996 had knockouts. Since it was the first I had ever heard of this I
was at the mercy of the dealer. I bought the truck in 02. When I brought it
back for an alignment at the dealer I bought it from...(I figured what the
heck...they were cheaper than Firestone...) they "supposedly" were never
removed. Due to having to drop the truck off at my lunch hour, I was unable
to get in there and look/learn myself what these things were/are.
Get in there, find out and look for yourself. I should have, and still to
this day do not know what the knockouts are and if they were there of if I
a $35.99 alignment turned into a $169 job.
Frame knock outs (partially upset frame metal) are used to usually
adjust 'extreme' front suspension caster, Or combined caster
Upper control arm 'shims' are the first line of adjustment...
Both the shims & oval knockout pattern are located at the Upper
Front Control Arm Bolt Locations ( Two bolts per side)... under
The upper control knock out surfaces (If used), can lay
either flat with the Ground, but are usually above a vertical
Spring dome bracket, on the UCA Bracket at the Front Wheel Center
In effect... each Frame when assembled has 2 holes
pierced for the Upper Control Arm bolts (per side)... The
operation also may upset the oval knock out metal to allow
for Addition Front Suspension bolt adjustment distance, beyond
the use of shims.
The whole Upper Control arm can be slid via the knock out slots for
re-alignment circumstances.. THere are 2 knock out slots per
Using a Knock out... Trades a small adjustment hole for a
where the bolt hole lays in the middle of the knock out (upset
The newer Chevy's are EASY. They have a plastic piece that you just pop
right out and then you can do your adjustments. It's great. The older
trucks like yours is different. Basically if you look at your Upper
Control Arm Bolts, where it's mounted to the Frame, this is where the
Adjustment it made. From the Factory it just has a hole for the bolt. You
can't move the control Arm in or out on the front and back of the control
arm. Usually there will already be Cam Bolts in place from the Factory,
but it's not slotted. Usually if the Cam bolt Washer that's Offset its
either straight up or straight down then it's never been screwed with so
more then likely hasn't been slotted out.
Have you owned the truck since it was new? Have you ever had it aligned
before and if so had it been slotted before? It's a 1 time thing. Once
it's been slotted, any time after it can be aligned and you wouldn't have to
worry about it, unless you only do 1 side of the truck.
Normally the person doing the Alignment would just make the Adjustments and
then that would be it. In your case, the Upper Control arm bolts will have
to be Removed, the control arm will be moved out of the Way, and then the
Holes will have to be Slotted out, then everything put back together,
Re-Measure everything, and then make the Adjustments. This is Extra work
and time. So of course it's going to cost more. At least you can adjust
your truck. A lot of cars and trucks out there you can only do a Toe set.
No Camber or Caster Adjustments possible. Or you have to do some really
funky things to get a cars Alignment right. Possibly go with Aftermarket
Hardware to get it in Alignment. You can really get into some big bucks.
You can always just have them do a Toe set and then you get out of there
cheaper. It depends on where your Camber and Caster readings are at. If
you don't have a pull, and it's not going to cause your tires to screw up, a
Toe set may be fine. All I can say is, when I have to do one of these
trucks, I always hope it's a 4x4 and not a 2 wheel drive. A 4x4 is easier
to do. The control arms bolt to the outside of the frame. On a 2 wheel
drive they are on the TOP of the frame. It's easier to Slot out and Adjust
on a 4x4.
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