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Can anyone help me?
B3Saxo - 24/11/02 at 12:49 AM

Before I begin, this is my first post. so sorry if I don't know anyone.

Today I was given a sierra rear diff. I was thinking of buying a kit, but just downloaded and printed the book chassis of one of the posts on here.

Will the sierra diff fit in the chassis? Or is it way to big? Thanks for any help.


Wadders - 24/11/02 at 01:02 AM

The book chassis is designed round a live rear axle,(i.e escort mk1/2, Capri etc)rather than an independent rear suspension such as the sierra, many chassis manufacturers are now producing I.R.S based chassis, and a lot of people are also adapting the book chassis to accept I.R.S. I'm lazy and have bought an I.R.S chassis,but if you fancy making your own,i'm sure plenty of folks on this forum will be able to offer advice.

ATB

Al.


B3Saxo - 24/11/02 at 01:18 AM

Has anyone converted the book chassis to a IRS? Any pics would be handy. Thanks.


Ian Pearson - 24/11/02 at 08:54 AM

If you have a look at the following site, you should be able to get some more info on things Locost.
http://locost7.info/mirror/mirror.php


B3Saxo - 24/11/02 at 11:10 PM

Very helpfull. thanks.

Where can I get the dimensions for the location of front suspension and wishbone mountings? And the rear diff mounting locations?


James - 25/11/02 at 12:45 PM

quote:
Originally posted by B3Saxo
Very helpfull. thanks.

Where can I get the dimensions for the location of front suspension and wishbone mountings?

I guess you could try buying the Locost book?!

quote:

And the rear diff mounting locations?


Basically in the middle of the transmission tunnel. But depends on how/where you mount the engine/gearbox.

Please remember that using IRS (with a Sierra diff) is a lot of work over a standard 'book' chassis and there's a lot of things you need to take into consideration- particularly when it comes to the suspension geometry.

HTH,

James


James - 25/11/02 at 12:46 PM

quote:
Originally posted by B3Saxo
Very helpfull. thanks.

Where can I get the dimensions for the location of front suspension and wishbone mountings?

I guess you could try buying the Locost book?!


quote:

And the rear diff mounting locations?


Basically in the middle of the transmission tunnel. But depends on how/where you mount the engine/gearbox.

Please remember that using IRS (with a Sierra diff) is a lot of work over a standard 'book' chassis and there's a lot of things you need to take into consideration- particularly when it comes to the suspension geometry.

HTH,

James


B3Saxo - 25/11/02 at 10:45 PM

Given my mate the sierra diff back, and currently on the lookout for a mk2 rear.

Steel is coming this weekend so, let the fun begin!


James - 26/11/02 at 10:43 AM

quote:
Originally posted by B3Saxo
Given my mate the sierra diff back, and currently on the lookout for a mk2 rear.

Steel is coming this weekend so, let the fun begin!



Probably sensible if you want it finished in the not too distant future! My IRS is taking me ages!

I recommend you download the McSorley chassis plans from:

http://www.mcsorley.net/locost/

They give you an accurate cutting list to follow.

Good Luck,

James


B3Saxo - 2/12/02 at 02:07 PM

I've got the mc sorley drawings.

Now is £6.57 per 7.5m length ok?

it's a 2.5mm wall. How many lenghths did you lot use?


interestedparty - 2/12/02 at 03:37 PM

2.5mm wall is WRONG, send it back and get 16g, (1.6mm). 2.5 will be a lot heavier than needed and a lot more work to cut

John


Alan B - 2/12/02 at 03:52 PM

Yes, John is right...far too heavy.

It sounds like SHS, which is NOT what you want....despite what Ron says SHS does not exisit at 16g..


you need ERW square tube.

Go elsewhere if they haven't got it.

[Edited on 12/2/02 by Alan B]


B3Saxo - 2/12/02 at 08:26 PM

I was told by a local steel fabricator that 2.5 would be better.
And it would not warp when I get the chasis galvagnised. Also 2.5 is easier to weld and would give a much better joint overall! Strength is a must! You ain't seen me drive!!!!!!


Alan B - 2/12/02 at 08:42 PM

What does he make? bridges?

Serioiusly, it is YOUR choice, but you can make a MUCH stronger and stiffer frame with a few extra tubes and sheet metal, rather than the thicker wall stuff.

Personally I used mainly 16g in my build (and on many cars in the past, without problem), but good luck whatever you choose.


philgregson - 2/12/02 at 08:57 PM

2.5mm is just over 1.5 x the weight of 1.6mm tubing - a significant weight increase if you don't really need it.

This is just a guess (there are people on this group who know far more about these things) but I wouldn't have thought that the gain in stiffness was not in proportion to the weight increase.


B3Saxo - 2/12/02 at 09:14 PM

I used to work with him on weekends when i was in school. He did have a tendency to "over engineer" things!

Iv'e seen a gate wee did hit by a car in a local road rally. the car was a right off and the gate needed slight straightening!

Don't know what to do now!


Alan B - 2/12/02 at 09:14 PM

Yes indeed Phil, it would give you a very poor return in stiffness for the weight increase. There are much better ways to increase stiffness enormously for far less weight penalty, and they are well documented on here. Mr Cymtricks IIRC has done a lot FEA work on the book frame, and whilst I can't personally vouch for the improvements they do seem to make sense. Also the Aussie builders have a lot of well documented stiffness improvements that are required to pass their ADR specs.


interestedparty - 2/12/02 at 09:53 PM

quote:
Originally posted by B3Saxo

Don't know what to do now!


Actually you do, but in case you've forgotten, dump the 2.5 and get some 16g

John


Viper - 2/12/02 at 10:00 PM

quote:
Originally posted by B3Saxo
I used to work with him on weekends when i was in school. He did have a tendency to "over engineer" things!

Iv'e seen a gate wee did hit by a car in a local road rally. the car was a right off and the gate needed slight straightening!

! [/quote

I work with a bloke like that.
we call him Captain Overkill


James - 3/12/02 at 11:19 AM

quote:
Originally posted by B3Saxo
I was told by a local steel fabricator that 2.5 would be better.

Maybe coz' he's got a load he got cheap that he's desperate to shift!
quote:
And it would not warp when I get the chasis galvagnised. Also 2.5 is easier to weld and would give a much better joint overall! Strength is a must! You ain't seen me drive!!!!!!

Strength comes from clever chassis design (fully triangulating designs [in all 3 dimensions] etc.) not from using massive amounts of steel.
If the joints are what you're worried about then learn to weld better! Go on an evening class if no-one else you know can help you.

Also, do you really need to galvanise the chassis? Very heavy from what I gather for not much gain. Unless you really think you'll be driving this car in 50 years what's the point- a normal car will last 10-15 years with 20gauge painted steel.

Look at it this way- if 16gauge painted is good enough for the hundreds of other builders out there then it's probably good enough for us!

HTH,

James


bob - 3/12/02 at 12:36 PM

Yep i agree with james,is it worth galvanising if a load of holes are going to be drilled for panels and stuff.

And i've heard it adds a lot of weight too.


B3Saxo - 4/12/02 at 04:30 AM

Yay! Hit a man where it hurts! Saying his welding is crap! Thicker wall thickness would equal better penetration? Unless there's somthing i've seriously missed in the last 6 years of working with various metals.


And a galvagnised coating is'nt thick only a few thous thick. So the weight gain won't be substansial enough to matter. especially with a 2.1 powering the rear wheels!

Dylan

[Edited on 12/4/02 by B3Saxo]


interestedparty - 4/12/02 at 07:31 AM

The title of this thread is "Can anyone help me", but it sounds like you've got it sorted

John


Stu16v - 4/12/02 at 09:42 AM

More thickness doesnt equal better penetration. In fact its quite the opposite. Thinner material just takes more skill to get full penetration without blowing holes in the metal. With 2.5mm, you would be looking at 'V'ing the joints to get full penetration, especially with smaller MIG welders.
And as for galvanising, look around at similarly constucted cars, i.e. Dax, Westfield, Caterham, Tiger, MK, F27, Birkin to name but a few and ask yourself why they dont galvanise their chassis. It aint cost, as it works out cheaper than powder coating. But, its up to you.....


James - 4/12/02 at 11:03 AM

quote:
Originally posted by B3Saxo
Yay! Hit a man where it hurts! Saying his welding is crap! Thicker wall thickness would equal better penetration? Unless there's somthing i've seriously missed in the last 6 years of working with various metals.


Hi Dylan,

Apologies for casting aspertions(sp?) upon your welding skill!!
I assumed you were new to welding etc.

I was under the impression though that the thicker the material the harder to get the desired penetration (ooh Sir!) for any given current.

Cheers,

James