How good is the Haynes IRS?

[Antnicuk]

Hi All,
I have just signed up here although i have to confess i'm not building a Haynes car, well not a complete one.

I have been recommended to this site by one of the Locost builders.

I have a Stylus with an Atlas Live axle. I am considering changing to IRS and wondered how the Haynes IRS compares to other kit car's IRS in terms of performance. The car has limited road use but mainly track days.

I want to try IRS to see if it copes with the power a little better.

I will be making the diff carrier to attach to the chassis but will use the measurements, wishbones, uprights etc from a known (good) system.

Is haynes the same design as the locost or any other mainstream design.

[Talonmotorsport]

This subject will throw up all sorts of answers mainly between the use of live axle Vs IRS as both have different pros and cons. Some times the problems with driven axles is not the type of axle but how it controls it, if the spring rates are not correct or the bump and rebound are not set correctly for the type of surface it is running on then the car will no grip or handle as you want it to. The other thing to consider is the size and weight of the rims and the width or the tyres as this all adds to the unsprung weight that the suspension has to control.
I would say before you go cutting the car about for a different type of drive train I would take the car to a proper suspension company who can set it up properly, you already have a starting point that can be measured and assessed with proper equipment. Your current set up may only need different spring rates, correct damper valves or just an LSD.
Internet forums are great for getting points of view but I would spend a few quid with the people who make a living from setting up suspension systems for race cars before changing one incomplete set up for another.

[Antnicuk]

Hi, thanks for your response, i have seen several discussions about live vs IRS, i was trying to avoid it if possible, i have also had professionals tell me that the Jeremy Phillips rear end (opposing arms) that i have wont work with spring rates above 180lbs springs but i eventually got to 300lbs before i was happy, i did it in 25lb incriments to try each one.

A professional would set the car to what they think it should be but i'm not convinced it would suit me. I have played with the live axle for several years and would now like to try the IRS. I wont be removing anything from the car that will prevent me from reverting back to live if i dont like the IRS.

The other issue is not many professionals will come accross cars with the same power and torque that i have. Traction is the main problem, which is where i thought the irs would be better suited.

[fabbyglass]

A well set up live axle car will handle as well if not better than one with IRS.

[Talonmotorsport]

Unless it's running on cheap tyres, springs that are too hard, dampers that don't react quick enough and the trailing arms are pointing down instead of up and aiding weight transfer. I think I've spent far too long watching mk2 escorts going round grass tracks.

[fabbyglass]

Go and watch Mk1 and 2 Escorts that have been well and truly sorted that run on tarmac then...aaaaaaawwwwwesomeness sideywaysness and make things like TVR's look pants:D

[fabbyglass]

IRS is good too though:)

[minicountryman1961]

If trying to adapt to a chassis that was originally live axle, it might be less work to go to a deDion setup as used by Caterham on their Seven.

DeDion is really good IRS, but requires very little structural change to the live axle chassis, which is probably why Caterham went to it.

http://website.lineone.net/~dmch2/suspension.htm

Hi All,
I have just signed up here although i have to confess i'm not building a Haynes car, well not a complete one.

I have been recommended to this site by one of the Locost builders.

I have a Stylus with an Atlas Live axle. I am considering changing to IRS and wondered how the Haynes IRS compares to other kit car's IRS in terms of performance. The car has limited road use but mainly track days.

I want to try IRS to see if it copes with the power a little better.

I will be making the diff carrier to attach to the chassis but will use the measurements, wishbones, uprights etc from a known (good) system.

Is haynes the same design as the locost or any other mainstream design.

[Antnicuk]

Thanks guys but i was trying to avoid the discussion about which is better, i was looking for advice around which components to use.

Talon, what are differences between the IRS you make and the locost one or other marques like Tiger or MK etc?

[Talonmotorsport]

The parts I sell are as per the design in the book, if your looking for a better range of rear axle options I'd look at the MX5 and BMW 3 series as they have more than one set of LSD ratio's to play with.

[minicountryman1961]

Thanks guys but i was trying to avoid the discussion about which is better, i was looking for advice around which components to use.

Talon, what are differences between the IRS you make and the locost one or other marques like Tiger or MK etc?

Step one, buy the books.

http://www.amazon.co.uk/Build-Your-Own-Sports-Car/dp/1844253910/ref=pd_sim_b_6

http://www.amazon.co.uk/Modify-Sportscar-Kitcar-Suspension-Brakes/dp/1845842073/ref=sr_1_1?ie=UTF8&qid=1299446388&sr=8-1

[snapper]

Just to add a bit to the advise, the Haynes set up is simple with upper and lower wishbone mounting points on a subframe that is incorporated in the final full chassis.
I am looking at taking the specs from the book to convert my Sierra backend Robin Hood to wishbones.
The Sierra diff comes in two LSD ratios, 3.6 and 3.9, Sierra diffs also have ratios from 3.14 to 4.7, you can use any crown wheel and pinion on a LSD diff internals, the Sierra LSD is viscous and may be a bit soft for racing, there are plate diffs and ATB's available to fit the Sierra case.
A friend of mine has converted a live axle chassis to DeDion, you use the original parallel trailing links to the DeDion tube with a panard rod, the Sierra diff and driveshafts.
The Sierra rear track is a bit wider than a live axle, I think about 4" total

[Eternal]

Don't forget you can also use the granada diffs but you will need to extend the top left mount outward 17mm ( looking from the back of the diff) this will give you a few more options! Also I find the Granada LSD diffs are stronger and cost less.

[Antnicuk]

Thanks guys, i'm not too fussy about diff ratios, but it must be LSD. I started with the original 3.09 in the atlas but changed last year to a 3.77 when i fitted a bigger turbo to compensate for the increase in lag. I have over 350 ftlbs and climbing so i dont notice too much difference.

A 3.6 or a 3.9 would be fine.

A dedion wont really fit as the centre of the tube has to sit behind the diff and my fuel tank is fairly close to the live axle as it is.
I guess i will have to look at getting a book. The reason i looked at the haynes was because the parts were easily accessible on ebay.

[fabbyglass]

Is the Stylus like the Fury ie same track width? If so you are into chopping down the drive shafts as the Roadster uses them as per the sierra.

[Antnicuk]

thanks for that, i did wonder if the stock shafts would be wider, i think i can get the shafts shortened, or new ones made but its an expense i could do with out. I was wondering whether an MX5 diff and shafts would be the right size. Of course that means using MX5 based uprights. I will have to look up some measurements.