Chevrolet DB90 Series, Service Manual

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Sec. 2-21
SECTION 2
t y n a m e
A ll inform ation pertaining to fr a m e s as d escrib ed in 1970 Heavy Duty Truck
S ervice Manuals ST 135-70 and Supplement ST 332-71, FRAME (SEC. 2) is appli­
cable to m od els covered by th is supplem ent. The follow ing updated inform ation
w ill a lso apply:
GENERAL RULES
L isted below are general ru les which apply to
fram e repair and rein forcem en ts. Most of th ese
ru les are d isc u sse d in the 1970 Heavy Duty
Truck S erv ice Manual ST135-70; how ever, the
im portance of adhering to them cannot be
overem phasized.
1. Always identify the m aterial of b a se ra il.
2. Fram e straightening o r repair must be at­
tem pted only by highly qualified s p e c ia lis ts .
3. A lw ays attem pt to identify the ca u se of
failu re.
4. Fifth w heel, body, and a c c e sso r y mountings
should not be made through fram e fla n g es. (See
"Body B u ild er's B ook.”)
5. Do not d rill h o le s in the lower fla n g es.
6. U se only proper e lectro d es as sp e c ifie d fo r
b a se rail m aterial when welding is n e c e ssa r y .
7. Do not u se oxyacetylene welding equipment
on fr a m e s.
8. Do not w eld rein forcem en ts a c r o s s the
fram e fla n g es.
9. Do not w eld within %-inch of the edge of a
fram e flange.
10. R em ove a ll notches or weld build-ups
from flange edge when rep airin g a broken fram e.
11. Do not w eld c a st brackets to fram e.
12. Do not w eld the flange of cracked r e in ­
forcem en ts and b a se r a ils together.
13. Do not patch cra c k s. P rop erly repair and
rein force the area.
14. R einforcem ent should be of the sam e or
better m aterial than b a se r a il.
15. A lw ays sc a r f reinforcem ent ends to p ro ­
vide adequate s t r e s s r e lie f.
16. A lw ays stagger ends of rein forcem en ts
by a m inim um of eight inches apart.
17. B efo re w elding, disconnect negative bat­
tery cable to prevent p o ssib ility of e le c tr ic a l dam ­
age to generating sy ste m .
V ehicle load capacity is dependent upon fram e strength
and rigid ity. To a ssu r e effectiv e rep a irs in the event of
dam age, fram e s e r v ic e should be undertaken only by com ­
petent p ersonnel using proper m a teria ls and equipment.
Im proper w elding or welding methods a re a m ajor
ca u se of s t r e s s concentration poin ts, which may ultim ately
re su lt in fram e fa ilu re. (R efer to "G eneral W elding In­
stru ctio n s” in the Heavy Duty Truck S ervice Manual
ST 135-70.)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT