Racing Ultima in Britcar
Discussion
Hi all. We have gradually been building our GTR up over the last couple of years with a view to entering it into next years Britcar Championship. We were hoping to get into the Britsports category (because of our planned power to weight), but since this has been axed we are planning to settle with a 510bhp lump which, with a car weight fo around a ton, should give us close to the highest bhp/ton allowed.
That aside, I am growing increasingly concerned about the ability of certain components on the car being up to the forces involved in racing, particularly the suspension components. We have the AP brake kit, which will have extra cooling added, and we have the full FIA rollcage, and intrax dampers. I am guessing that after some testing we will end up stiffening up the suspension with stiffer springs and/or antiroll bar.
My main concerns are surrounding the wishbones, uprights and suspension mounts. I was rather horrified to see the effects the standard cars can have on the suspension mounts under hard acceleration and braking (bending of the mounting points etc), and although the factory have been quick to address this issue with the release of their strengthening kit, it does worry me that the rest of the suspension components may not be up to the forces involved. I am concerned that the uprights (and maybe wishbones) may not be up to coping with the continued high stresses involved in highspeed cornering/braking - obviously they are designed for road use, but I believe fatigue will be an issue here since the units are cast. The problem I have is that I do not have any kind of reference point to start off any kind of stress analysis on the parts - being a mechanical engineer I am comfortable with doing anlysis like this, however with unknowns like shock loads generated when potholes/kerbs are hit etc being involved, it makes the analysis very difficult. Calculating cornering forces is realatively straight forward, its these unknown shock loads that concern me.
Have there been many Ultimas used for racing? We are aware of a couple, but they have been run in British GT, and as such have had substantial amounts of extra work done to the car at great expense (which we cannot afford!). Are my fears justified (fracturing an upright mid corner will not end up in a pretty result), or do people's experience show that the components are sufficiently over engineered for road use to be able to cope with circuit racing?
Any sugestions/help will be appreciated.
Thanks in advance, Jonny.
That aside, I am growing increasingly concerned about the ability of certain components on the car being up to the forces involved in racing, particularly the suspension components. We have the AP brake kit, which will have extra cooling added, and we have the full FIA rollcage, and intrax dampers. I am guessing that after some testing we will end up stiffening up the suspension with stiffer springs and/or antiroll bar.
My main concerns are surrounding the wishbones, uprights and suspension mounts. I was rather horrified to see the effects the standard cars can have on the suspension mounts under hard acceleration and braking (bending of the mounting points etc), and although the factory have been quick to address this issue with the release of their strengthening kit, it does worry me that the rest of the suspension components may not be up to the forces involved. I am concerned that the uprights (and maybe wishbones) may not be up to coping with the continued high stresses involved in highspeed cornering/braking - obviously they are designed for road use, but I believe fatigue will be an issue here since the units are cast. The problem I have is that I do not have any kind of reference point to start off any kind of stress analysis on the parts - being a mechanical engineer I am comfortable with doing anlysis like this, however with unknowns like shock loads generated when potholes/kerbs are hit etc being involved, it makes the analysis very difficult. Calculating cornering forces is realatively straight forward, its these unknown shock loads that concern me.
Have there been many Ultimas used for racing? We are aware of a couple, but they have been run in British GT, and as such have had substantial amounts of extra work done to the car at great expense (which we cannot afford!). Are my fears justified (fracturing an upright mid corner will not end up in a pretty result), or do people's experience show that the components are sufficiently over engineered for road use to be able to cope with circuit racing?
Any sugestions/help will be appreciated.
Thanks in advance, Jonny.
Excellent responses so far thanks. Its good to hear the voice of experience before we start stabbing away in the dark. We went for the standard (non rose jointed) suspension - purely because of cost, although I have to admit I did not realise that the rose jointed units were made of thicker walled tube than the standard stuff. Does the rose jointed suspension allow for castor changes as well as camber etc?
We met a chap at the Britcar on saturday who raced Ultima in the British GT championship - though I do not recall his name, though I have his business card at home. Could well be the same person! We are aware of the dry break issue - watching the lead Prosport car (effectively a race prepped Ultima chassis-d race car which the aforementioned chap drove) the refuelling was slightly cumbersome to say the least - but thankfully i have it all on film so that we can have a good think about how to best approach this. The cost of the dry break systems from ATL are quite staggering, especially when you have a good look at them and see how basic they really are!
Going and having a good poke round the pits and watching the race and pit stops gave us a good feel for what equipment we need on top of what we already have, as well as how many people we would need for a weekend. What kind of increase in spring rates did you go for in the end?
We met a chap at the Britcar on saturday who raced Ultima in the British GT championship - though I do not recall his name, though I have his business card at home. Could well be the same person! We are aware of the dry break issue - watching the lead Prosport car (effectively a race prepped Ultima chassis-d race car which the aforementioned chap drove) the refuelling was slightly cumbersome to say the least - but thankfully i have it all on film so that we can have a good think about how to best approach this. The cost of the dry break systems from ATL are quite staggering, especially when you have a good look at them and see how basic they really are!
Going and having a good poke round the pits and watching the race and pit stops gave us a good feel for what equipment we need on top of what we already have, as well as how many people we would need for a weekend. What kind of increase in spring rates did you go for in the end?
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