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Avon Rear Suspension Mountings
jcduroc - 31/3/04 at 06:26 PM

Hi all Avon builders

I've been reading (the book) H.T.B.Y.O.TigerAvonS.C. and please correct me if
I'm wrong but I got the impression that the rear suspension chassis
mountings are vertically 264.6 mm apart and the upright mountings are
255 mm apart, putting the top and bottom wishbones converging towards
the outside of the car.

Thankx for clearing this.

Joćo

gjn200 - 31/3/04 at 07:01 PM

yep.
F.Y.I. you need a new shirt

jcduroc - 31/3/04 at 10:11 PM

quote:
Originally posted by gjn200
yep.
F.Y.I. you need a new shirt


Is this forum serious???
Or shall I tell the joke of the 40 english girls - 20 blonde and 20 brunetes - inside a double-deck London bus?

That was a serious question, let's have serious replies; f..k your dressing taste.

Joćo

Mix - 1/4/04 at 07:29 AM

Joao

Yes the wishbones will converge. I'm building all metric so am working on 265mm vertical split at the chassis, (it took me a while to work out where you got 264.6mm from )
I'm still in the process of making my wishbones and as I'm no suspension guru I'm not sure of the benefiets / pitfalls of converging wishbones, what prompted you to ask the question in the first place ?
As I have yet to make the uprights I could adjust the Vertical dimension if it were desirable.

Mick

[Edited on 2/4/04 by Mix]

jcduroc - 1/4/04 at 08:12 AM

quote:
Originally posted by Mix
Joel

Yes the wishbones will converge. I'm building all metric so am working on 265mm vertical split at the chassis, (it took me a while to work out where you got 264.6mm from )
I'm still in the process of making my wishbones and as I'm no suspension guru I'm not sure of the benefiets / pitfalls of converging wishbones, what prompted you to ask the question in the first place ?
As I have yet to make the uprights I could adjust the Vertical dimension if it were desirable.

Mick

Thankx Mick
BTW my name's Joćo not Joel.
264.6=290-25.4 (1 inch)
I didn't go into the geometry of such a suspension but it is very odd indeed. Thinking as fast as I write the IC (Instant Centre) lies outside the wheel so the virtual swing arm makes the wheel gain positive camber in bump and negative camber in droop directly proportional to the wheel travel.
I'm not building an Avon but I'm going IRS with Sierra components. If I were you I'd talk to others who already built Avons to check that and how they behave.

Cheers
Joćo

gjn200 - 1/4/04 at 04:26 PM

You misserable old sod. btw yep is the answer to your question.

dblissett - 1/4/04 at 07:27 PM

hello joao
my back end is taken from the avon book its in a plus 4
i have used the avon dimentions and yes you are right i do have slight posative camber as the rear wheels rise
i cant change it without a complete redesign
cheers dave

Peteff - 1/4/04 at 07:41 PM

Not quite the same thing but I knew someone who built his car to the book and had the same problem with the trailing arms on a live axle. The Haynes book is wrong and he had the chassis mounts further apart than the axle ones. He found that it ate the bushes as it was practically a solid mounted axle and it lifted the inside wheel on corners.

jcduroc - 1/4/04 at 10:06 PM

quote:
Originally posted by gjn200
You misserable old sod. btw yep is the answer to your question.

Hi Graham

I'm sorry but I'm a bloody South European Latin.
I can reasonably read and write English but no such sense of humor!...
BTW, it's a Massimo Dutti shirt (fuc..g expensive)

Cheers to you
Joćo

jcduroc - 1/4/04 at 10:11 PM

Considering that the "wishbone odd convergence" has been confirmed by several mates what do you think about it?

Is this a Dudley error?
Do you intend to correct it?
What?

I'd like to know (if only to share my further research with whom is following the "falling leaves apart" book).

Cheers
Joćo

dblissett - 2/4/04 at 08:15 PM

hello joao
if you havent started yet i would recomend you stick to rons book and dont use the avon one
there are a lot of mistakes and some poor design in the avon book
are you sure that shirt is exspensive
only joking
dave

jcduroc - 3/4/04 at 11:52 PM

quote:
Originally posted by dblissett
hello joao
...are you sure that shirt is exspensive
only joking
dave

Yes, it is; it's a fuc.... fancy imitation of a fisherman's shirt by some "renowned stylist".

quote:
Originally posted by dblissett
if you havent started yet i would recomend you stick to rons book and dont use the avon one
there are a lot of mistakes and some poor design in the avon book
dave

I haven't started yet my IRS Locost.
I'm in the process of building a "book" Locost for a friend, taking notes and designing my own (IRS) at the same time.
I started designing a rear end based on the Avon dimensions (not the structure) and came along with that discrepancy (that I shall not follow, that's for sure).

I think it would be worthwhile questioning Mr.Dudley about this.

Cheers
Joćo

dblissett - 4/4/04 at 07:43 AM

if i was doing my back end again i would not bother with irs but i would get the dedion set up from gts because the more i learn about suspesion the more complicated it gets and you only learn from your mistakes
good luck dave

WIMMERA - 20/4/04 at 12:17 PM

Hello Joao
I've made the top inner wishbone mounting brackets 75 mm long and drilled three sets of holes at 20 mm centres, the top holes are positioned as per the book, so will have a choice of top w/bone angle, I should add that I haven't done any calculations at all on this, seemed like a good idea at the time.

Wimmera

jcduroc - 21/4/04 at 11:15 PM

quote:
Originally posted by WIMMERA
Hello Joao
I've made the top inner wishbone mounting brackets 75 mm long and drilled three sets of holes at 20 mm centres, the top holes are positioned as per the book, so will have a choice of top w/bone angle, I should add that I haven't done any calculations at all on this, seemed like a good idea at the time.

Wimmera

Got any photo of it?
Joćo

WIMMERA - 22/4/04 at 12:00 PM

Joao
I'll try
Wimmera

WIMMERA - 22/4/04 at 12:47 PM

Appears that I've failed with the photo, but the bracket is the same shape as the standard Avon item except that it is 75 mm long instead of 36 and has three sets of holes, the bracket is positioned so that the top hole is in the same position as called for in the book which leaves two alternative positions to experiment with, the holes are drilled on a line described by the wishbone length, in an attempt to minimise camber change when shifting to a different set of holes
Wimmera

Northy - 26/4/04 at 09:00 PM

Joao,

Did you get to the bottom of this?

Did you email Jim?

Cheers

jcduroc - 26/4/04 at 10:05 PM

quote:
Originally posted by Northy
Joao,

Did you get to the bottom of this?

Did you email Jim?

Cheers

Meaning? Which Jim?

[Edited on 26/4/04 by jcduroc]

JoelP - 26/4/04 at 10:21 PM

jim dudley! the man with(out) the plan!

jcduroc - 27/4/04 at 01:18 PM

Did you email Jim?

quote:
Originally posted by JoelP
jim dudley! the man with(out) the plan!


Of course not, I've no reason to do it unless for claiming back the €40 I payed for the book!...
I'm not building an Avon, even less buying anything from them. But I certainly would (e-mail or call) if I did (build or buy).

The fact is that we (members of this great forum) are amateur Locost-builders and they (those who write books) are supposed to be pros but, at the end, they are frequently amateurs (sometimes with less competencies than most of us - not speaking for myself) who own a fully equiped workshop and become "pros"!...
It wasn't like that when (back in the 70'ies) I used to buy racing car bits in UK (unfortunetly...).

Cheers
Joćo

[Edited on 27/4/04 by jcduroc]