I am now building a book based chassis, though am considering making it IRS. I have book wishbones and trailing arms, but am in a bit of a quandry. (yes I know a beam axle would be the simplest!)

Can I buy MK Indy wishbones and fit them at the front of a book chassis to make the front upto the width of the standard sierra rear end? (Do the Indy wishbones share/fit the suspension brackets as per the book?)

Or should I keep the book wishbones up front and get the sierra driveshafts shortened as Luego do on the Velocity?

Are there advantages to handling of having the wider sierra track?
(I presume Sierra standard width rear and book front would cause a very badly handling car!)

Any replies, experience, info, suggestions appreciated.

Ned.

One thing to consider:
I think if you use MK front wishbones then you will have to use Sierra front uprights so if you were planning to use Cortina uprights then this may swing it in favour of book wishbones.

Of course you could make longer "book" wishbones to increase track but may then have trouble getting springs and shockers off the shelf to fit.

The option I took was to use a wider chassis along the lines of the McSorely 7+4 which is 4 inches wider than book and gives me a 56" track (front) with book wishbones and I have a 57.8" track at the back with the unmodified sierra shafts and diff. I am running de-dion but this shouldn't matter in terms of track widths.

Check my website for any further details or just ask.

Cheers,
Craig.

Craig,

The +4 width chassis isn't something i'd thought of, though I already have a fully tacked and part properly welded chassis!

Are there difficulties or additional expense in getting +4" bodywork?

I tihnk I'd prefer to leave the chassis as is and go down either the mk wishbones or luego shafts approach.

Anyone know how much Luego charge to shorten the driveshafts?

Ned.

I'm doing a standard width chassis with longer front wishbones (made today!), sure enough it looks like i'll have to stretch the shockers....

i'm sure it'll all be OK! The actual cockpit is 50 inch outside to outside so at least theres plenty of room, but the wheels have half an inch inside the side rails. neither here nor there i guess. i think it would have looked better with the wheels further out....

not sure about body work but can always worry about that later.

didnt realise MK bones were different sizes to the book, obvious when you think.

Ned,

GTS Tuning (dozracing) are developing +4 nosecones/scuttles, and hopefully bonnets.

He must be on holiday coz I've not had a reply to my email re progress.

I was going to make, but think cost and time wise, it'll save a packet by buying!

ATB

Simon

Ned,

A good thing about the wider track would be that the car would corner flatter. With the narrower track, you get more nimbleness. 6 of one, a half dozen of the other

Negatives of the wide wheelbase with the standard chassis are (possibly) poor coilover angles and lots of empty space in your rear fenders.

The easiest thing would be to get a Cortina axle. Besides that, if I were you, I would have the axle shafts shortened. Luego's Locost price list says GBP45, quite a bargain if they do this for walk-ins.

BoL,

Pete

Simon, you figured it was cheaper to buy ready-made bodywork than do your own fibreglassing?

I haven't looked into the prices yet but that is surprising..

Not sure what we're going to do yet about fitting the v8 under the bonnet.. different carbs, custom grp bonnet, alu bonnet with stuck-on bump (ew) or what.

Blueshift,
I think Simon (rightly) will be placing a price on his time in which case it is MUCH cheaper to buy than make fibreglass parts and the quality is likely to be MUCH better too. Making moulds is only sensible if you intend to make more than one (more than 5 IMHO) or if you want to stick rigidly to the DIY ethos. I think that even the raw materials alone (matting, resin, wood, fixings, brushes, rollers etc etc) will cost almost as much as the finished product from most of the suppliers.

Anyway, I intend to buy my stuff from GTS as well once it becomes available. As for the bonnet bulge, I hope to modify the bonnet to incorporate a removable bonnet bulge panel which can be changed to suit different sizes of bulge as I can't justify the expense of a Weber 500 setup just yet and will have to stick with SU's to begin with.

Cheers,
Craig.

The Tiger Avon has a wider rear track compared to the front.

My car is standard book chassis, standard Escort axle etc.

It has terrific turn in and excellent front grip but it is very easy to oversteer. (All 7's are anyway)

One or two guys i competed against had similar front track as myself but wider rear track and they always could hold the track better before oversteer.

With a book chassis and the standard rear wings available, the rear axle is 50mm in from both outer sides of wings unless you use a Cortina or Crapi axle.

Fitting one of the above axles with book wishbones means you have odd track anyway.

I've never actually measured a Sierra rear track but suspect it's close to a Cortina, Crapi one anyway.

Shortened driveshafts. Not sure what Luego do to them but ST cuts the driveshafts and fits sleeves which are then welded all round.

quote:

---

Originally posted by blueshift
Simon, you figured it was cheaper to buy ready-made bodywork than do your own fibreglassing?

I haven't looked into the prices yet but that is surprising..

Not sure what we're going to do yet about fitting the v8 under the bonnet.. different carbs, custom grp bonnet, alu bonnet with stuck-on bump (ew) or what.

---

Rob,
The Sierra track (rear) is 57.8" which is what I have set mine to with full length driveshafts. You can adjust it a little bit when building your IRS or De-dion setup but I thought it was best to stick with the original track width to ensure that my Lobro joints were correctly biased. My front track is 56" so hopefully I will benefit from the extra stability and resistance to oversteer that you mentioned. Of course I want some oversteer

Cheers,
Craig.

I have been offered a cortina axle for a reasonable sum, but think i'd rather do the extra work to get an IRS setup.

I also have some small offseted (ex-caterham) alloys which I think will pertrude from book rear arches and i don't fancy wide rear arches. As I have a set of front wishbones and suspension bits and the fact that luego only appear to charge £45 I think i'll go with the shortened driveshafts approach.

Though as always I may have changed my mind by the time it come down to it!

Ned.

quote:

---

Originally posted by ned
I have been offered a cortina axle for a reasonable sum, but think i'd rather do the extra work to get an IRS setup.

I also have some small offseted (ex-caterham) alloys which I think will pertrude from book rear arches and i don't fancy wide rear arches. As I have a set of front wishbones and suspension bits and the fact that luego only appear to charge £45 I think i'll go with the shortened driveshafts approach.

Though as always I may have changed my mind by the time it come down to it!

Ned.

---

James,

I've spoken to Jasper about his axle, it would be suitable gearing wise as with a type 9 and my engine would have a theoretical geared top speed of 137mph.

Having checked MK's and Luego's site's it appears you can buy the IRS wishbones for around £200-300, luego do a Conversion Kit (4 rear Wishbones, 2 Hub Carriers, Diff Carrier) for £313!

Food for thought...

Ned.

quote:

---

Originally posted by ned
James,

I've spoken to Jasper about his axle, it would be suitable gearing wise as with a type 9 and my engine would have a theoretical geared top speed of 137mph.

Having checked MK's and Luego's site's it appears you can buy the IRS wishbones for around £200-300, luego do a Conversion Kit (4 rear Wishbones, 2 Hub Carriers, Diff Carrier) for £313!

Food for thought...

Ned.

---

I don't know if IRS will be worth the bother, but it's in my opinion the way the job should be done properly. It also makes it easier to change dif ratios and drop in an LSD at a later date.

Easier to service/interchange other components if ever necessary too.

Is £313 + vat (£370) a reasonable amount for 4x rear irs wishbones, uprights and dif cage? I can't see the material costs are anywhere near as much if i was to do it myself, its just the labour and design aspects i guess.

Ned.

Ned,
Are you aware of the de-dion kit which GTS Racing are planning to release. It gives you many of the advantages of IRS with the simplicity of live axle and can be made to any width.

In particular it uses the Sierra diff for ease of ratio/LSD options and requires hardly any modifications to the "book" chassis. It should also give better straight line traction than either IRS or Live axle and will cope better on bumps than Live.

Cornering wheel geometry should be as good as Live axle (ie. perpendicular to the road) but with lower unsprung weight which should be better.

Speak to Stu16V about his own "practical" experience of de-dion as I can only talk theoretically at present. If Cateringvan use de-dion and Dax use it then it can't be bad IMHO. Check my website if you want to see some detail but remember that I built my own de-dion kit which hopefully GTS will supply in a ready to drop in state.

One other thing to point out is that most people agree that Live axle is the lightest option so if weight is a big issue for you (BEC for example) then live axle is probably best. Be aware that the Cortina axle is 4" wider than escort whilst the Capri is about 2.5" wider than the escort.

HTH,
Craig.

I haven't seen a Cortina since about 1967, so I think of it as a smaller car, didn't know it was almost as big a beastie as the Sierra.

Would an Escort axle be possible? They look very nice and light.

Yes, I think it was originally quite small but later models (the ones that I know from childhood) are much bigger and chunkier. I saw a "W" reg one yesterday in fact.

Cheers,
Craig.

We have a mk IV sitting on our drive waiting to be killed; trust me, they're big.

Thanks for the responses about grp, we'll reconsider the best way to cross that bridge a bit later, I think.

[Edited on 30/8/03 by blueshift]

One of the early posts in this thread suggested widening the chassis and using standard suspension from there outward to increase front track.

Wouldn't doing that require:
- longer tie rods (hubs farther from steering rack),
- longer swaybar/antirollbar (greater hub-to-hub distance, and
- longer or relocated brake lines (greater hub to frame distance.)?

I can't think of any other non-bodywork items that would have to be changed as a result of widening the frame - have I missed some?

The longer tie rods wouldn't change the steering geometry, would it? Maybe some at full lock?

Carcentric,
I think you mean track rods not tie-rods but yes they would have to be lengthened. More commonly it seems, people just use the Sierra rack and shorten it to suit. This is what MK do for the Indy so it's not a problem really.

An anti-roll bar would need to be lengthened but I'm not aware of many people using anti-roll bars on Locost's unless they are planning to race them. You might be able to use a standard bar and use some form of bespoke linkage to suit the extra width. It is only 2 inches either side after all.

Brake lines should not present any problems. Yes you will need a little bit more on the solid pipes but these are made to suit normally anyway. The flexible hoses will have exactly the same distance to the chassis as they would with a standard width chassis if you think about it.

The way I think about this extra width stuff is: Does the component traverse the centreline of the car? If it does then it will possibly be affected. If it doesn't (such as a front cycle wing or flexible brake hose) then it will work fine as with the standard chassis.

HTH,
Craig.

quote:

---

Originally posted by craig1410
... and I have a 57.8" track at the back with the unmodified sierra shafts and diff.

---

quote:

---

Originally posted by ned
Are there advantages to handling of having the wider sierra track?
(I presume Sierra standard width rear and book front would cause a very badly handling car!)

Any replies, experience, info, suggestions appreciated.

Ned.

---

Hi Joao,
Yes I am measuring from tyre c/l to tyre c/l using Capri Laser 13" wheels with 185 width tyres. I think these wheels have an ET18 offset.

As for brakes I am using the standard disc brakes from a Sierra with the Lobro style shafts. The suspension is off the car at present as I am triangulating the chassis but I can measure between the mounting plates onto which the hub carriers bolt if that would be useful. I don't have a backplate as such with the disc brakes. Let me know what you want, I can even take a picture to clarify what I have measured.

Cheers,
Craig.

quote:

---

Originally posted by James
There's loads of hassle in changing to IRS once you've got a built chassis: suspension mounts need to change, wishbones need mounting somehow, you need to make uprights, diff mounts... it goes on and on!

James

---

quote:

---

Originally posted by craig1410
Hi Joao,
Yes I am measuring from tyre c/l to tyre c/l using Capri Laser 13" wheels with 185 width tyres. I think these wheels have an ET18 offset.

As for brakes I am using the standard disc brakes from a Sierra with the Lobro style shafts. The suspension is off the car at present as I am triangulating the chassis but I can measure between the mounting plates onto which the hub carriers bolt if that would be useful. I don't have a backplate as such with the disc brakes. Let me know what you want, I can even take a picture to clarify what I have measured.

Cheers,
Craig.

---

Joao,
I'd have to disagree with that statement as I have a standard book chassis (actually 4 " wider as per McSorely 7+4 plans) and I have fitted de-dion with only voluntary changes made to cater for the fact that the de-dion kit was designed for a standard width chassis and hence I had to mount my trailing arms inboard instead of outboard of the chassis.

In my view you can fit de-dion to a book chassis with no changes at all although obviously it depends on the nature of the de-dion axle in question. I think GTS racing are designing a de-dion kit which is specifically designed to fit easily to a virtually standard chassis.

Let me know if you want further details.

Cheers,
Craig.

Joao,
I make 1468+18x2 to be 1504mm which doesn't quite match your 1530 figure but is closer. I guess it might depend whether the suspension was in droop or compression to get the exact figure. I set mine to 57.8" with the suspension at ride height (shafts parallel to the ground) and I have equal "plunge" each way when I grab the driveshaft and push and pull it towards and away from the diff which should avoid any bind up of the lobro joints. I didn't measure the track with pinpoint accuracy so take my figures as +/- 5mm.

Hopefully this will explain it a bit.
Cheers,
Craig.

Joao,
I've sent you an email to your hotmail address with some further information.
Cheers,
Craig.

quote:

---

Originally posted by jcduroc
I think that you must make up your mind before building the chassis: Live Axle, DeDion or IRS.
The chassis rear end is (or should be) COMPLETELY different in either case.

---

The dedion system sounds interesting but I would still prefer IRS. It's just whether I can justify the extra time/money it will take!

Ned.

ps I've now got my chassis:

Now that's a man who needs some shelves!

Also, why is your chassis made of chocolate? Will this not cause problems in the summer? Or is it filled with a cunning lattice 'honeycome' substance (Crunchy Bar) that will re-inforce it?



James

quote:

---

Originally posted by James
Also, why is your chassis made of chocolate? Will this not cause problems in the summer?
James

---

i thought james liiked like that because he left it on the garage floor that got flooded.

ps is that called the iron oxide finish and is it difficult to achive an even coating

Looks like an Al Quaeda attack

You need to make some space so you can do some serious work. Arnt single garages wondeful!

atb

steve

oh, i see! so you lot thought it was a single garage! ha harr.

its only a 6'x8' (extended to 12' shed!

I'm hoping to do the welding outside if the weather's good enough or move it to my mates lockup where I'll be renting some space shortly.

Ned.

quote:

---

Originally posted by timf
i thought james liiked like that because he left it on the garage floor that got flooded.

---

to be honest is does look a lot worse in the pic than it actually does.

Ned.

Hi

Couldn't resist asking this.

What's "Iron oxide"?
Rescued attachment chassis 037s.jpg

quote:

---

Originally posted by type 907
Hi

Couldn't resist asking this.

What's "Iron oxide"?

---

Craig, if you put de dion in an unmodified book chassis the diff will fall out, you will at least need brackets for it as it needs to be attached somewhere..

yours, Pete.

Going back to the topic of the thread, I've just got off the phone to mk who can supply me an mk indy rear wishbone set and a pair of their indy rear uprights for £200. I know the indy runs full width sierra track, but presumably all I need do is to mount the inner wishbone mounts further in? Then exchange driveshafts from luego and I have an IRS system of new parts for £250!

Lol Peteff!
I wondered why that kept happening...

Yes there's always a smart arse out there isn't there

Fair point, you do need some changes but I have had to make more changes because of my engine choice than because of the de-dion axle by far! If my axle had been designed for the +4" chassis then the only changes would have been the diff brackets and (you know I can't think of anything else to be honest)

According to the plans I have for the de-dion system, you are supposed to make a small change to make more room for the de-dion axle assembly but I didn't need to do it so I didn't. Hopefully I won't find out later that I should have done but in any event it is a minor change to RU1 and RU2 so I can retrospectively change it if necessary.

If someone out there (GTS Racing hopefully) were to start building de-dion kits then I firmly believe that you could build a car more easily and more quickly than you could with a live axle. For starters you wouldn't need to track down a suitable live axle donor and you wouldn't need to strip it in order to weld the brackets on. It should literally involve nothing more than bolting it all in place via the 5 links and fitting the drive components.

Cheers,
Craig.

Ned,

Whats wrong with Sierra width?

Cheers

Northy,

I already have a set of book front wishbones plus all joints and uprights.

If the rear track were to be that much wider (sierra) I expect it may upset the handling characteristics of the car/suspension geometry.

Ned.

a lot of cars run a narrower width at the front - like 10 - 20mm.

Dunno what the effect is if exaggerated.......but you miht look like a dragster!


atb

steve

quote:

---

Originally posted by stephen_gusterson
but you miht look like a dragster!
steve

---

Look at the Lamborghini supercars (Diablo especially) They are massively wider at the back and it doesn't seem to affect them. It might catch you out when driving through the gates into your driveway though...

THinking about it, I can think of a good number of supercars which at least appear much wider at the back.

Ned, I was once given some advice by an experienced kit car builder who told me not to compromise and if I made a mistake then fix the mistake don't try to incorporate it into the design. Maybe you should sell on the wishbones and get some MK Indy ones or something and go with Sierra uprights etc. There are many advantages in doing this so you should maybe consider it at least.

Cheers,
Craig.

craig1410:

quote:

---

Look at the Lamborghini supercars (Diablo especially) They are massively wider at the back...

---

The Avon has a wider track at the rear compared to the front.

Cheers

quote:

---

Originally posted by Northy
The Avon has a wider track at the rear compared to the front.

---

Will measure it tonight.

thanks Graham.

Ned.

Rorty,
Fair point but as I quailfied my bit about many other cars "at least appear much wider " I was aware of the optical illusion and wider tyre effect. The diablo was one which I was pretty certain was actually much wider at the back as I remember jeremy clarkson moaning about it on Top Gear. All you can see in the side mirrors is the big fat ar$e of the car! Lovely!!

Here are the figures I found on the web which show a 4 inch difference:

Wheelbase : 2650 mm (104 in)
Overall length : 4460 mm (175.6 in)
Overall width : 2040 mm (80.3 in)
Overall height : 1105 mm (43.5 in)
Front track : 1540 mm (60.6 in)
Rear track : 1640 mm (64.6 in)
Ground clear. : 115 mm (4.5 in), after 1993 127 mm (5.0 inch)
Front overhang : 930 mm (36.6 in)
Rear overhang : 880 mm (34.6 in)
Weight : 1576 kg (3474 Lbs)
Distribution : 41/59 % front / rear

Source of data: http://lamborghinicars.tripod.com/diablo.html

Cheers,
Craig.

craig1410:

quote:

---

Wheelbase : 2650 mm (104 in)
Overall length : 4460 mm (175.6 in)
Overall width : 2040 mm (80.3 in)
Overall height : 1105 mm (43.5 in)
Front track : 1540 mm (60.6 in)
Rear track : 1640 mm (64.6 in)
Ground clear. : 115 mm (4.5 in), after 1993 127 mm (5.0 inch)
Front overhang : 930 mm (36.6 in)
Rear overhang : 880 mm (34.6 in)
Weight : 1576 kg (3474 Lbs)
Distribution : 41/59 % front / rear

---

But it doesn't tell me whether it has cup holders.

or mountings for a baby seat.

(for the 'little ones' such as hippy)


atb


steve

quote:

---

Originally posted by Northy
The Avon has a wider track at the rear compared to the front.

---

i think it's 4" narrower at the front.