Haynes Roadster Crush Tubes

[Guest davidimurray]

Spud on the Haynes forums - he ran Saturn Sports Cars, gave me this advice for starting off :-

 

"Front:

 

Toe in 2deg, camber 3deg (will vary on driving style), castor so that it just starts to self centre

 

Rear:

 

Toe in - none, camber 1/2 deg

 

Corner weighting the car is important with the driver in the car, adjust the springs to get the car even all round then you can balance the car between the front and rear. Adjust the ride height, 100mm front / 125mm rear, to as low as you dare for speed bumps and turn up the bump / rebound to as stiff as our crappy roads will allow. If you go on a track day you can drop the car right down and damper setting as stiff as they go and it will make quite a difference."

 

And i'm running 350lb and 250lb springs although I can't remember which way around they are! Tyres on mine are T1Rs 195/50/15s.

 

How is the shock damping adjusted?

 

Stupid question but have you got any play in any of the steering UJs or the rack connection. This can make the car feel 'loose'

[Guest b3nny]

I wish I had that info last week when I took it for a geo setup although I will be having another once I've sorted out the sheer stiffness.

 

The shocks are adjusted by a small knob at the bottom of the shock, to be honest I tweeked it just now two turns down to its softest setting and it went from being rock solid to being what I'd call adequate, but with out driving I wouldn't know for certain.

 

I think I'm going to install the bushes and knock the shock setting right down and see how it feels, I'm not even sure the handling is at fault I just think it may be to hard for road use hence the reason it's being thrown around.

[Guest b3nny]

This was from my geo setup last week, I think they just adjusted it to what they thought would ideal for road use

 

 

 

 

Edited July 8, 2014 by b3nny

[Longboarder]

Interesting figures. I wonder what if anything other than toe they would understand. They won't have changed anything on the rear of the car. Figure differences are due to slight change in ride height when moving the car. At the front I would doubt they would touch any more than the toe in adjustment. Again any other changes would be down to moving the car around.

As for settings on the front I think you need more negative castor on both sides. Aim for four degrees as a start. Negative castor is added by shimming the top wishbones backwards or the lower wishbones forwards. Camber of 1-2 deg negative. Wind the top wishbone outer ball joint one turn in to the wishbone on the right. Then set toe to 0 - 0.5 toe in. That should be a fairly conservative front end. Ride height you aim for the bottom front wishbone to be parallel to the ground or outer end drooping by up to 5 degrees max. Now measure ground to floorpan at the front and set the ground to floorpan 10mm more than this at the rear by raising or lowering the rear springpans on the shocks.

Corner weighting is for dedicated and experienced drivers. Most of us are not good enough to recognise the difference. It's about diagonal balance, not side to side or front to back. The aim is to get half the total weight of the car bearing down on the front left plus the rear right wheel and the other half the weight of the car bearing on the front right plus the rear left wheel. Sure it's nice to have it done. It can be surprisingly way out due to poor manufacturing tolerances in chassis and components and it does make a difference.

Finally at the back camber shims can be made to give whatever toe and camber you choose. 0.5 toe in and 2-3 degrees neg camber should be OK.

I have to confess to destroying a top wishbone on a trackday, fitting a replacement with way out camber, castor, and setting the toe by eye, driving 200 miles home and not noticing the difference.

 

Nigel

 

What is a robin hood with a twist?

Edited July 8, 2014 by Longboarder

[Guest davidimurray]

Some interesting figures there. I am no suspension expert, but assuming the rear toe is out then there seems to be a lot of it. Assuming you are using standard roadster bits then you may want to look at getting some camber shims made to go behind the hubs.

 

You can do quite a good suspension setup at home with some axle stands and string.

 

With regard to your 'stiff' suspension - do you know what springs you are running? With rgeard to the damping, the softest setting doesn't mean a soft ride - I've learnt that with mine! Started at the mid position on my dampers (6 clicks) - backed off to 3 clicks and the ride got much 'harsher' currently back at 6 and may try adding a bit more damping yet.

[agent_zed]

just thinking of when i re-built my front end the other day. I took the shocks off so i was able to lift the suspension by hand to ensure it moved smoothly. It should move relatively easily.

[Guest b3nny]

I bought the car built so I am assuming it was built using Haynes parts as I also had the Haynes manual come with the car, the guy that done the set up did say there wasn't a lot of adjustment on the rear at all. I think once I have got the ride softer I'm gonna ng to bit the bullet and get it set up properly but somebody that knows what there doing as it isn't a strong point for me, on my gaz shocks at the moment there only 2 clicks up from there softest setting and by hand there 0 movment but when turned completely down there is quite a lot of movment, I'm going to change the bushes Saturday and see how the ride is if it's still to hard I'll set them at there softest and see how it is then, then I'll look at getting it set up properly or get another geo setup asking them to dial in the figures mentioned.

[Guest b3nny]

Got my bushes today, the bore of the crush tubes are slightly smaller than the original ones fitted, these has a 12.1 - 12.2 bore opposed to a 12.5 in the original apparently 12.5 was a error in the Haynes? My question what is now going to be the correct size bolt to use?

[Guest davidimurray]

Bolts should be m12 min 8.8 grade.

[Guest b3nny]

I have m12 not sure on grade but they won't fit in the new crush tubes which are a 12-1 to 12.2 bore, is it that I need to get new bolts are is the seller talking rubbish and really they should be a 12.5 bore so they would except m12.

 

I've read that a 7/16 bolt should fit as it's around 11.11 would this be ok if I can get them, it would just save the hassle of sending them back and I could get them fitted at the weekend.

Edited July 10, 2014 by b3nny

[agent_zed]

my bolts are 10mm on the 2B. The shock bolts were imperial and were only ~9.5mm.

 

make sure they are HT

[Guest b3nny]

What bore are your crush tubes? I'm off to the fixing place tomorrow and hopefully they have something that's a snug fit.

[Guest davidimurray]

Will any of the bolt go in, I,e, the threaded part or is it just the shank that won't go in?

 

The chassis mount holes should be m12 clearance going to m10 would be loose in them. In reality the tube is clamped by the bolt so it shouldn't really move.

 

Have you checked there are no burrs in the end of the tubes?

[Guest b3nny]

End of the tubes are all nicely machined, the starter at the end of the thread will go in but it won't allow the thread to go in, I'm starting tothink the supplier was talking rubbish about the error in the Haynes manual either that or there haven't been drilled correctly.

 

I won't be using a m10 with a 13mm bore

[agent_zed]

yep sorry didn't mean to suggest using 10mm just that 11.5mm would be more than strong enough etc.

 

but as said you don't want it to be slack in the holes. probably worth getting the correct ones or if the metal is thick enough having it drilled by engineers.

 

My prob was the other way as i went from 9.5 to 10 so i could drill the holes out in the chassis.