rear suspension

[tony archer]

First post!

Hi All im new to the site, im looking for advice on my rear suspension ? i have a fairly modded 5 which was known as the immaculate conception in Revs and all work carried out by BB tuning. I now use the car for hill climb but am really struggling with the handling at the rear as it is so twitchy and wants to step out allthe time, can anyone point me in the right direction. it currently has GAZ adjustable dampers and has been lowered some what, Could this be the problem ?

[Woznaldo]

You need to make sure you there are no underlying problems but, it sounds like you need to soften the rear (to add more grip) and/or stiffen the front (to reduce grip) as this will address the balance and stop the rear stepping out as quickly.

[Ian S]

First post!it currently has GAZ adjustable dampers and has been lowered some what, Could this be the problem ?That could be. People tend to drop the rear onto the bump stops and also some shocks just don't move much. the result is that from 'every' bump the rear gets punted up off the tarmac and also the wheels don't drop into hollows.

[Ian S]

stiffen the front (to reduce grip)The stiffer I made the front the better the front gripped. I was only up to 250lb springs though and Koni shocks. But it seemed to reduce the front roll and keep the front tyres flatter on the road. Of course I'm generalising. Dialling it all in perfectly takes some good comprehension of the specific geometries, etc, and the results on everything of what your doing to it all. I never managed it at the time. Only last month I realised a mistake I was making with the rear. The cars been off the road for maybe 5 years but I'd just thought of something; I needed to wind up the rear on it springs so as to compress the hard gas pressured rear shocks so they could go out wards over hollows. That wasn't happening, only inwards. Seems obvious now. Don't know why I didn't think of it then.

[RussellT]

Hi Tony nice to hear from a fellow hill climber. What you describe shouldnt be happening and I bet Ian is right and the rear is too low giving a lack of suspension travel. If the rear goes solid it will behave as you describe. You do want a very stiff rear end but never solid. Also check the rear dampers they could have leaked and be full of air. A really good tip to improve the handling of the car is to have nice big squashy bump tops on the dampers and then put door stops over the damper rods so that the car effectively sits on the bump stops. Then as you corner you get a rising spring rate at the wheel as the bump stop compresses which mimics an anti roll bar. However it must never go solid so it only works with big squishy bump stops.

[tony archer]

New poster! (less than 10 posts)

Cheers all thanks for your help, has anyone any experience with fitting a small coilover to the rear ?

[RussellT]

I havnt the damper is set at a disadvantagous angle. if you are competing in mod prod you can put turrets on the rear suspension and several people have done that. If you are competing in the road going classes you have to use the original suspension mounting points.

You will find that door stops are cheaper :) give it a go before paying huge money for a pair of motorsport coilovers. Spax dampers set full stiff, door stop mod and Roberts your father's brother.;)

[RussellT]

check out my rear suspension on this clip

http://www.youtube.com/watch?v=IAp5axKBHDY

[Matt@CodeRedMotorsports]

New poster! (less than 10 posts)

Cheers all thanks for your help, has anyone any experience with fitting a small coilover to the rear ?

We did on Oli's pink race car.
We have changed the rear end a bit since then though...

[Bruce - BHPerformance]

James Moore had coilovers custom made for the rear of his hillclimb car. Seemed to work well.

[tony archer]

New poster! (less than 10 posts)

Cheers Russell, Please can you explain that mod for me sorry if i sound thick, your car handles amazing what have got on the front. I am running Mod Prod so was toying with turrets but looking at that clip i dont think i need to !!!!!

[RussellT]

OK full suspension is as stated on the rear. At the front I have Leda dampers with 300lb/" springs and a reinforced antiroll bar. The car is corner weighted. All wishbones and suspension mounts are standard R5 items with poly bushes.

Re the door stop mod.
Get a solid rubber door stop drill a 1/2 inch hole through it (in the same place that the screw to fx it on the floor would go) cut verticaly so you can open it up and wrap around the damper rod cable tie in place or use a jubile clip. I found I needed to make a washer to stop it being pushed into the bunp stop over time.

[Ian S]

I think it's Powerflex who make various graduated foamed polyurethane bump stops specially for this purpose. You can select the one that best suit you needs.

http://www.powerflex.co.uk/product_listing.php?id=141 Errm, the empty page suggests they no longer do! But here are some other they do: http://www.powerflex.co.uk/products/Bumpstops-2666/1.html

As I've said before, my experience in a fast road car on bumpy B roads is that the Spax were utter garbage and I took them off as I had to drive 20mph slower due to the rear being punched up in the air on the larger bumps. They were simply very stiff and barely moved in either direction. Then there were the very long hard bump stops. And it was NOT lowered at all. For B roads you need properly working suspension that actually goes up and down, but especially upwards by a few inches.

On the smooth race stages you can evidently get away without that movement.

[tony archer]

New poster! (less than 10 posts)

Yeah i have seen James moores idea very neat i thought i was up against that car last week at gurston at the hands of matt clements 2 very helpful guys heres a link to run 3. http://youtu.be/f2I7cUn6eiM

[Matt@CodeRedMotorsports]

Blimey! What size wheels and tyres you got on that thing? I wouldn't sway away too far from a 13 or 15" wheel. You will be on bump stops if lowered too much.

[RussellT]

This is a quick R5 on the same track

http://www.oldlinkssurgery.com/Cookie_Gurston.wmv

[Woznaldo]

The stiffer I made the front the better the front gripped. I was only up to 250lb springs though and Koni shocks. But it seemed to reduce the front roll and keep the front tyres flatter on the road. Of course I'm generalising. Dialling it all in perfectly takes some good comprehension of the specific geometries, etc, and the results on everything of what your doing to it all. I never managed it at the time. Only last month I realised a mistake I was making with the rear. The cars been off the road for maybe 5 years but I'd just thought of something; I needed to wind up the rear on it springs so as to compress the hard gas pressured rear shocks so they could go out wards over hollows. That wasn't happening, only inwards. Seems obvious now. Don't know why I didn't think of it then.

Ian, I was actually referring to the adjustable damper settings but, didn't make it very clear :ashamed:. And yes, I was being very general but, as Russell has pointed out, it's probably a case of running out of travel due to excessive lowering.