Dear All,
I sent a detailed list of queries on the subject of wheel alignment to
the Spitfires list yesterday (a copy appears at the end of this
message), but no-one has yet taken up the challenge of answering them.
This being the case, I thought I would consult the combined wisdom of
the Triumphs list with some more-generic questions. My deductions,
assumptions and half-remembered factoids are detailed below - please
feel free to tear them to shreds and replace them with valid
information!
OK: first principles. Each wheel can either be (a) leaning in/out at
the top; (b) pointing in/out at the front; (c) too far forward/backward;
(d) too high/low; (e) too far out from/too far in towards the central
axis of the car. Is this right? What, if anything, have I missed?
(a) is called camber. It is a good thing for front wheels to lean out
at the top, and for back wheels to lean in at the top. The amount of
camber on a left wheel should be exactly equal to the amount of camber
on the matching right wheel. Leaning in is called negative camber;
leaning out is called positive camber.
(b) is called toe. It is a good thing for front wheels to point out at
the front, and for rear wheels to point straight ahead. The amount of
toe on a left wheel should be exactly equal to the amount of toe on the
matching right wheel. Pointing out is called positive toe (or
toe-out); pointing in is called negative toe (or toe-in).
(c) is called ??? It is a good thing for each pair of wheels to be
exactly the same.
(d) is called ??? It is a good thing for each pair of wheels to be
exactly the same.
(e) is called ??? It is a good thing for each pair of wheels to be
exactly the same.
What are: (a) Caster, (b) SAI, (c) Included Angle (appears to be the sum
of Camber and SAI) and (d) Thrust Angle, and what do they tell us?
Any information on this most confusing subject would be greatly
appreciated!
On Tue, 4 Feb 2003, at around 18:14:28 local time, Michael Hargreave
Mawson <OC@46thFoot.com> wrote:
>Dear All,
>
>I've just had a four-wheel alignment done on Carly, and I have to admit
>that I haven't really got the faintest idea what I have paid for, or
>what I have achieved by doing so (except that she feels much easier to
>drive...)
>
>If anyone could answer any of the following questions, I'd be greatly
>obliged.
>
>1. Front Camber
>The readings fall within the "specified range" according to their
>computers, but the left wheel is at 2 deg 21 min, and the right wheel is
>at 1 deg 58 min. Is this an acceptable variance?
>
>2. Caster
>The readings are well below the "specified range" of 4 to 5 deg at 2
>deg 36 min (Left) and 2 deg 53 min (Right). Why might this not have
>been corrected, and what is the effect?
>
>3. Front Toe
>It's OK, I think I understand this one!
>
>4. SAI
>I don't even know what this stands for, much less its significance.
>Anyone? Again, my corrected readings fall within the specified range,
>but the Left wheel has half a degree more SAI than the right. Is this
>a problem?
>
>5. Included Angle
>Both within the range, but almost a degree difference between Left and
>Right. Problem?
>
>6. Cross Camber
>It's 24 mins. Should I be pleased?
>
>7. Cross caster
>It's minus 17 mins. Should I be pleased?
>
>8. Total Front Toe
>OK, I understand this one, and I'm happy with it. :-)
>
>9. Rear Camber
>I'm a bit concerned about this one. The specified range is -4 deg 45
>mins to -2 deg 45 min. I've got +53 mins on the Left and +5 mins on
>the right. Problem?
>
>10. Rear Toe
>This too. The specified range is zero to 8 mins. I have -12 mins on
>the left and +1 min on the right. Surely this means that my rear
>wheels are driving the car crab-wise?
>
>11. Total Rear Toe
>This should apparently be somewhere between zero and +16 mins. I've
>obviously got -11mins overall.
>
>12. Rear Thrust Angle
>No specified range for this, but they have altered it from -6 mins to -7
>mins. Is this good? Bad? Meaningless?
>
>Having paid GBP40 plus VAT for the service, I'd like to understand what
>I've got, and whether they should have done things differently.
>
>Thanks in advance for any assistance.
>
>ATB
>--
>Mike
>Ellie - 1963 White Herald 1200 Convertible GA125624 CV
>Connie - 1968 Conifer Herald 1200 Saloon GA237511 DL
>Carly - 1977 Inca Yellow Spitfire 1500 FH105671
ATB
--
Mike
Ellie - 1963 White Herald 1200 Convertible GA125624 CV
Connie - 1968 Conifer Herald 1200 Saloon GA237511 DL
Carly - 1977 Inca Yellow Spitfire 1500 FH105671
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