burgessj
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| posted on 12/7/03 at 07:42 PM |
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Mistakes in Book
Hello all,
Would appreciate your advice please...
Having just spent best part of a day trying to work out why I cant get top rails
J1 and J2 to fit, have discovered that measurements are wrong in the Book,
but correct in the McSorley plans (1467 instead of 1476)..
Should I just forget the book and go from the McSorley plans ? Is there any disadvantage in doing this ?
JohnB
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David Jenkins
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| posted on 12/7/03 at 07:59 PM |
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No disadvantage at all!
Use Jim's plans for the angles and dimensions, and 'The Book' for general arrangement, build philosophy, etc.
happy building!
David
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Mark Allanson
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| posted on 12/7/03 at 09:01 PM |
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And so say all of us!
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Mark Allanson
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| posted on 12/7/03 at 09:04 PM |
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Jim's plans don't cover suspension, thats where the fun starts, front and rear
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kingr
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| posted on 12/7/03 at 11:58 PM |
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Incidentaly, while we're on the subject of suspension, I seem to recall the book suggests 14" shocks, which are way too big, and all the
suppliers seem to go for less (GTS are 12", loloquality are 10", dampertech IIRC are 12" . I couldn't find any previous
reference to this on the forum before though. What has everyone else used?
Kingr
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stephen_gusterson
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| posted on 13/7/03 at 12:04 AM |
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according to recent posts, lolo are 14 inch now....
atb
steve
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craig1410
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| posted on 13/7/03 at 09:42 PM |
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I got mine from GTS Racing and had to do some mods to the upper mounting (front susp.) arrangement to get them to fit. The lower mount goes on the
lower wishbone as you would expect but the top mount has to sit at an angle where it hits the top outer vertex of J1 and J2. This give maximum
clearance between wishbone and spring although it is still very very tight (about 2mm clearance either side of spring.)
I have standard 'book' wishbones from Loloquality and a McSorely 7+4 chassis and ended up with a 6.25 inch ride height at full rebound
which should give me around 5 inches (to bottom of chassis rails) when loaded up.
Here's a pic to explain better.
HTH,
Craig.
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blueshift
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| posted on 13/7/03 at 11:03 PM |
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That angled mounting looks rather interesting. how is that fixed on there? Just curious.
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Rorty
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| posted on 14/7/03 at 03:07 AM |
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craig10, what happens in droop, do the upper wishbones not foul the coils?
Have a look at the RHS shock mounts on the front of one of my Beetle chassis below, as an alternative mount.
 
Rescued attachment VW front end.jpg
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Hornet
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| posted on 14/7/03 at 08:45 AM |
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Craig, something not right there m8... it my humble opinion, i also have just fitted same units to chassis and have not needed to do what you have
done, also my clearance is fine. i shall try taking photo tonight, PS Im in Livingston area if its any help.
Cheers
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Peteff
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| posted on 14/7/03 at 09:41 AM |
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Mine has the old lolo shocks and they were 12" open length. They work fine. What engine are you putting in the car. Get a couple of mates to
stand in the engine bay on a plank or something and see how far your chassis drops, you might need to alter the position to the side of the rail to
get your height without preloading the spring too much.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Peteff
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| posted on 14/7/03 at 09:45 AM |
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Wrong picture format,try again.
sorry about that.
 
Rescued attachment shock mount 1.jpg
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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craig1410
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| posted on 14/7/03 at 12:23 PM |
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Rorty,
I set the clearance at full droop so it is fine and clearance improves as the wishbone rises.
One reason my clearance is more of a problem is that the Lolocost wishbones use a heavier section tubing. I can't remember exactly how big but
it is a few mm bigger for sure.
I had the option of mounting the shockers underneath J1 and J2 as shown in some designs but I didn't want my springs to be so far off the
vertical as I think I'm right in saying that this goes against best practice. It will also (I think) place additional loads on the suspension
mounts and to be honest I don't like the look of it, aesthetically. The GTS coilovers are quite pretty and I want them to be seen.
I did a number of calculations and loads of little sketches and to ensure that my desired ride height will occur at the point in the shocker stroke
which is recommended by GTS Racing (dozracing) in their PDF file. I think from memory this gives me 1.25 inches of bump and 0.75 inches of rebound wrt
ride height. I can adjust the spring seats to achieve this height once the car is at full weight.
I aimed for horizontal lower w/bone (mount to balljoint centre) and chassis parallel to the ground when setting ride height.
Have I err'd?
Craig.
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Mark Allanson
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| posted on 14/7/03 at 05:01 PM |
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We had a thread ages ago about the wushbones not giving enough castor angle, I killed 2 birds with one stone by making the upper wishbones with more
setback and made of bent tube to clear the shock.
You can see the castor angle (exagerated by the camera angle) and the crazy scrub radius which I cannot get my head around at the moment - the cortina
must have had the same!
 
Rescued attachment CastorClearance.jpg
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craig1410
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| posted on 14/7/03 at 07:41 PM |
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Cheers Mark and yes I would do it all differently second time around as I expect most of us would...
The bent tube seems to be a good way to go although I suspect (no hard facts btw) that it won't be so strong as a nice triangular wishbone. I
don't know if the difference is significant though.
As for your scrub radius, I wouldn't get overly concerned as I have what looks like the same "problem". My suspension book by Des
Hammill (ISBN 1-903706-73-4) says that as long as the KPI line intersects the ground at the inside edge of the tyre then it is
"acceptable" and only when it gets more than 1 inch inboard of the inside edge of the tyre is this "too much"
Bear in mind too that having zero scrub will give you a lifeless steering which won't load up under cornering the way that you would want.
Having too much scrub may make it twitchy and somewhere in between lies the ideal.
I'll post another image in a minute which might further help to convince you.
Cheers,
Craig.
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craig1410
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| posted on 14/7/03 at 07:47 PM |
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Here is the other pic which I took of the book by Des Hammill. Look at the geometry of the rather pretty suspensin system here. Not an ideal angle but
you can clearly see that plenty of scrub is evident. Look how far the disc sits inboard!
I have just looked through the various publications I have here and many shots of Lotus 7 esque cars show lots of apparent scrub.
I don't know about you mate but I ain't worried just yet although I may avoid buying expensive wheels just yet...
My wheels are Capri Laser (RS Style) 13inch with 185 tyres by the way.
Cheers,
Craig.
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craig1410
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| posted on 14/7/03 at 07:54 PM |
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Sorry for all the posts but I missed a couple of responses:
Blueshift, check my website for more detail but I basically tack welded the bracket where it hit before taking the shocker off to avoid heating the
rubber bushes and then welded a piece of 25x3mm bar across the back of the mount to join it to the chassis tube (J1/2). This gives a very strong
triangular structure and maximises clearance (what there is of it) to the spring coils. My website has more pics showing detail.
Hornet, I'd be interested to see what you have done to avoid this situation. I'm happy with it the way it is but come SVA time the
inspector might not like the proximity to the wishbones of the coils. They do clear but as I said, only by 2mm each side at full droop. Should be okay
as long as it doesn't foul I think (Anyone disagree based on SVA experience?) My SVA manual should get delivered any day now from Amazon so I
will check the fine print on this then. I can always hack the top brackets off and weld underneath or something if necessary.
Thanks once again for all the feedback.
Craig.
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Rorty
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| posted on 15/7/03 at 02:10 AM |
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I've always stood by my beliefs and theory on scrub radius, as it has always worked for me.
However, I'm always open to other proven results, which aparently, Hammill demonstrates with his book.
I'm going to add Hammill's book to my Book Wish-list!
Mark, are you absolutely positive you have the original wheels?
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Mark Allanson
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| posted on 15/7/03 at 06:25 AM |
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I think I will double check with ford on part numbers, I also have another set (alloys from a capri) which I will try
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Peteff
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| posted on 15/7/03 at 07:07 AM |
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You are also going to find you need to hack an ugly hole in your nosecone to fit it over the modified bracket mount, don't know if that will
bother you at all, as standard ones sit on the rail where yours is.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Spyderman
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| posted on 15/7/03 at 10:54 AM |
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I don't know if this is relevant or not, but I always found that the steering on a Cortina left a lot to be desired.
I'm not talking design just the driving and handling.
They would get through front tyres at an alarming rate, probably due to scrub radius. They would wear the inside and outside edges of the tread.
Is this just my opinion or is it a case of beggars choice when looking for appropriate uprights?
Terry
Spyderman
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craig1410
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| posted on 15/7/03 at 11:53 AM |
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Rorty,
I agree with most of what I recall from your previous posts on the subject. It is only when I started to look at other Locosts in various publications
and at my own that I started to wonder. There is even a picture in the RC book 2nd edition which shows a "racing" locost which looks like
it has lots of scrub as well!
When I say I'm not worried this is mainly because I have quite enough to worry about before we get down to this level of detail. There is an
easy fix - use different wheels - so I'll worry later, if and when I find the handling to be a problem. My uprights came from a fellow LB forum
member who I shall ask if he had any problems when they were fitted to his car.
The Des Hammill book is a good read and tends to be more "practical" than the Alan Staniforth book which I also own. Given your
"practical, use what works" approach, I think you would appreciate it Rorty. Only downside is that the book was something like 17..99GBP
IIRC.
Peteff,
I'm not too concerned about the "ugly" hole as I'd prefer to see my "pretty" shock/spring units more upright and
prominent and I can make the ugly hole look less ugly with a bit of work hopefully. I can maybe build a little cowling over it or something...
Cheers all,
Craig.
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craig1410
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| posted on 15/7/03 at 12:01 PM |
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Spyderman,
Interesting what you say on the Cortina handling, I've never driven one myself but somehow I don't find it difficult to believe that they
didn't handle well (except the Lotus variant which I suspect was better)
However, I can't believe that there can be that much difference between one type of upright and another and most potential flaws could surely be
corrected by the way the upright is mounted and which wheels are used etc. Yes you can get titanium custom made uprights which are a far cry from
Cortina steel ones but in terms of basic geometry (ignoring ackerman stuff for now) there is only really KPI to worry about isn't there?
What I am trying to say is that just because the Cortina handled like a big bulky beast (which it was) doesn't mean that the uprights will doom
all of us Locoster's to a similar fate just because we use them?
I don't want to state the obvious but can I assume that your Cortina tyres had enough air in them. Underinflation will cause excessive wear on
the tyre shoulders. Just a thought...
Cheers,
Craig.
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Simon
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| posted on 15/7/03 at 12:57 PM |
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Craig,
My top front spring mounts are similar to yours - just not quite as neat - so you aren't the only one!!
Also - with engine/box in place (nearly running weight so to speak) spring bases are set in the middle (approx) of both high/low extremes (stronger
springs will allow it to be unwound).
Did you get my email?
ATB
Simon
[Edited on 15/7/03 by Simon]
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Spyderman
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| posted on 15/7/03 at 03:34 PM |
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Craig,
I'm not knocking the Cortina uprights!
It's just that, if you are using something that is less than ideal in the handling stakes, then you should expect the results to be less than
perfect.
Obviously the Cortina uprights have a less than ideal scrub radius, but this shouldn't stop you from having a reasonably handling car, after all
yours will be a damn sight lighter than the donor.
I'm merely pointing out that the cortina uprights although useful (being one of the few suitable for double A-arms) is not necessarily
perfect.
Just trying to help! If you realise that the donor parts have limitations then you won't expect too much from them!
Terry
Spyderman
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