Suspension Set-ups

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Suspension Set-ups

Postby stevew » Wed Apr 15, 2015 2:49 pm

I'm looking into experimenting with suspension set-ups for racing my Midas Gold and am interested in any advice and experience others may have, and will be sharing my findings as I go along. My car is a Gold Coupe on what looks pretty standard Metro hydro front end, and Metro rear with coil-overs. This weekend I intend to measure the present set-up I have to baseline the work.

I’m keen for the collective experiences on aspects such as ride heights, toe-in, camber, spring rates, dampers, wheel/tyre sizes and pressures, so not much!

I appreciate that personal feel can be wide ranging, and there is no substitute for testing, but think there is great benefit of collective experience to select good starting points and for all the better understand the key variables and influences they have.

I've been looking on line for resources too, trying Metro clubs & forums, but haven't had much joy, can anyone recommend any sites for research?
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Re: Suspension Set-ups

Postby Rich » Thu Apr 16, 2015 11:18 am

There's some info for Hydragas suspension modifications >>here<<.

I use the poly bumpstops intended for Minis (eBay items 191348130874 and 191473454716) and Powerflex poly bushes throughout the front suspension, replacing the worn bushes on the ends of the ARB took a lot of the skittishness out of the handling but the biggest improvement came from fitting decent tyres. Geometry from memory is as per standard Metro.
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Re: Suspension Set-ups

Postby Hans Efde » Thu Apr 16, 2015 4:05 pm

You have these guys:
http://www.mgmetrocup.co.uk/

What helps:
- low profile tyres, I have 175/50 R13. Rather harsh, but precise. Maybe now not more available.
- full coil springs around, the Watson spring mod.
- the Polyflex bushes, check my threads, there are AR bushes around that are wrong. There must be an internal chamfer on 1 side.
- the AR clamps inside of the AR bushes, cast iron that break easily. Replace by milled steel ones.
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Re: Suspension Set-ups

Postby stevew » Thu Apr 16, 2015 9:52 pm

Cheers Guys. I've already bought some Powerflex poly bushes for the front to this weekend, so glad to hear that will be a positive start. Will also buy some poly bump stops too, as maybe that is a part of the knocking noise, though it does seem to come more from the rear. The rear is a coil-over set-up, but it does seem a tad high; wheel arch 1” above front tyre, but 2” at the rear. There isn’t any more pre-load adjustment left to lower it, so will have to live with it for now, but as the shocks are pretty worn and don't seem to be doing much damping wil be looking to replace soon.

My tyres are 185/55R13 at present, but finding it difficult to get decent rubber in this size. What tyre makes and sizes have others found good (& bad)?

I was surprised to see in the Haynes manual that the Metro runs toe-out. It states up to 3mm; I was expecting an angle, so feeling a bit stupid here, where is the 3mm measured?
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Re: Suspension Set-ups

Postby Rich » Fri Apr 17, 2015 2:06 pm

Yokohama do a decent tyre in 175/50/13. The old Metro Turbo size is near impossible to find in anything you'd want on your car.
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Re: Suspension Set-ups

Postby streetsy » Fri Apr 17, 2015 5:05 pm

I have nankang as1 tyres in 175-50/13 they seem to grip well, not noisy either.
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Re: Suspension Set-ups

Postby ACourtney » Fri Apr 17, 2015 7:52 pm

Hi Steve,

Unfortunately, the two guys who have probably done the most development work on their Golds don't come on the forum these days. I'm thinking of Peter Hill, who hill-climbed his Gold convertible and Adrian Lee who track days his. Peter Hill would probably have been the most helpful/relevant, but he sold his car some years back and I don't have any contact details for him now.

I think that fitting better bushes to keep the front alignment under tighter control is a good first step. You probably need more suspension compliance for hill-climbing than you would for circuit racing, so polyurethane bushes rather than nylon are more suitable. Having said that, the standard MG Metro ARB to subframe bushes are nylon, so I would fit a good pair of them and then use the poly bushes for the ARB to lower arm joint.

Also at the front I would fit road spec Metro adjustable dampers rather than race spec ones. I have used AVO front dampers and found that for road use the lowest settings give the best results. The standard Metro Hydragas units already have some internal damping so the telescopic unit is adding to that. The main thing to watch with fitting front dampers to a Midas Gold is to make sure that the suspension bottoms out on the top arm bump stop and not on the damper, otherwise the damper top will push its way through the wheel arch eventually.

For the front hydragas you could look at doing the Nitrogen valve mod. I am now set up to do that with a bottle of Nitrogen gas and a high pressure gas regulator that came from the US. I've modified a pair of front units, but as yet I have not fitted them to a car thanks to having too many other distractions.

At the back I would just make sure that everything is good and tight. A slightly worn rear radius arm bearing that might scrape through an MOT is going to make the back end feel loose when cornering hard.
I have also come across cars that rely purely on the mountings at the front of the subframe, which can't be too good for cornering either so I would start by checking everything over and making sure the subframes are secure too.

When we met you at Wiscombe Park last September I noticed that your competitor in the GTM was running AVON ZZR tyres in 185/55 - 13. As these are road legal track tyres they would seem a sensible start, especially as that is what your competitor is running. I found one website selling them http://bmtrracing.com/size-price-list/ - they are at the start of the last section for Road Legal Competition tyres. There are two options available so it would pay to ask the supplier what the difference is, though I would guess one has a softer compound which would be more suited to hill-climbs and sprints.

I look forward to hearing how you progress with your car and hopefully I can get along to see you in action again at some point this year.

Regards,
Alistair
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Re: Suspension Set-ups

Postby stevew » Mon Apr 20, 2015 10:53 pm

Have fitted the poly bushes and bump stops, and set the alignment up such that there is the required toe-out, rather that the toe-in, and after the first drive have fallen in love again with the Midas. :D
Must admit that it’s been a bit of a job to do with many skinned knuckle and my language matched the blue skies over the recent days :x , but it’s all been worth it and just hope the track stays dry for Saturday at Wiscombe Park as optimism is increasingly!
Thanks for the tyre link Alistair, as it’s now encouraged me to start feeding the piggy bank. All I need to do is purchase a 2nd set of alloy wheels such that I can wear out the present “Camac Aurigas” which came with the car for the commuting, and save some precious Avon rubber for the racing.
Does anyone have a set of alloys in 13”, or am also considering 12”, that they’d like to sell – ebay has been a bit baron is this area recently?
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