I know having IRS isnt ideal but does anyone have any tips to reduce my 60 foot times?
My TVR Chimaera has run a best of 1.85 to 60 foot on 255 mickey Thompson street ETs.
Im sure the suspension is letting me down.
I have invested in a set of 3 way adjustable shox but need some more tips
IRS and drag racing
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Hi
Just spotted this not sure why I missed it before, there is not alot you can do without chassis surgery. If you are prepared to move suspension mountings then you want to put in some anti squat into the rear suspension, to do this you want to move the front lower wishbone mounting up a couple of inches, this will obviously compromise the cornering a bit, but if you lower the rear lower mounting about half the amount you raise the front one the changes in increased camber gain will be minimal. If you are prepared to go further then you want to move the front lower suspension mounting forward and out to the side of car, this will obviously require a new lower wishbone. The final area to change is to reduce the amount of camber gain as the suspension squats, for this you need a longer upper wishbone with it's mountings further in to the centre of the car, slightly lowering (1" or so) the front upper wishbone mount and moving it forward will also help.
Best regards
Mike
Just spotted this not sure why I missed it before, there is not alot you can do without chassis surgery. If you are prepared to move suspension mountings then you want to put in some anti squat into the rear suspension, to do this you want to move the front lower wishbone mounting up a couple of inches, this will obviously compromise the cornering a bit, but if you lower the rear lower mounting about half the amount you raise the front one the changes in increased camber gain will be minimal. If you are prepared to go further then you want to move the front lower suspension mounting forward and out to the side of car, this will obviously require a new lower wishbone. The final area to change is to reduce the amount of camber gain as the suspension squats, for this you need a longer upper wishbone with it's mountings further in to the centre of the car, slightly lowering (1" or so) the front upper wishbone mount and moving it forward will also help.
Best regards
Mike
poppet valves rule!
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stevieturbo
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Re: IRS and drag racing
IRS can work fine. How are you launching ? And on what surface ?dbv8 wrote:I know having IRS isnt ideal but does anyone have any tips to reduce my 60 foot times?
My TVR Chimaera has run a best of 1.85 to 60 foot on 255 mickey Thompson street ETs.
Im sure the suspension is letting me down.
I have invested in a set of 3 way adjustable shox but need some more tips
Re: IRS and drag racing
I am on a half decent drag strip prepped surface at York.stevieturbo wrote:IRS can work fine. How are you launching ? And on what surface ?dbv8 wrote:I know having IRS isnt ideal but does anyone have any tips to reduce my 60 foot times?
My TVR Chimaera has run a best of 1.85 to 60 foot on 255 mickey Thompson street ETs.
Im sure the suspension is letting me down.
I have invested in a set of 3 way adjustable shox but need some more tips
I find i cant launch from more than 2500 rpm with a little clutch feed and my nitrous only gets blipped in 1 st gear progressively then pretty much full on in 2nd, 3rd and 4th
Not my best runs but to get an idea...
www.youtube.com/watch?v=WhGVdyoZdCs
www.youtube.com/watch?v=9u4kpZfSnPw
10.612 @ 129.77
176.5 standing mile.
176.5 standing mile.
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stevieturbo
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Something else is amiss.
Monaro's with good tyres can get traction. I was chatting to a guy at the weekend with a turbo Honda S2000. With ET streets he was able to pull 1.5x 60fts. Basically just dumping the clutch at 7000rpm.
Mind you, it only lasted 3 runs before snapping both shafts lol
That was at Santa Pod though.
IMO if you have so little traction, its down to the surface more so than your IRS.
I may have a live axle, but the 4-link is far from anywhere near optimal. And at Santa Pod I can pretty much sidestep the clutch around 5-6000rpm and it just grips.
ive done 1.8x on Nittos, 1.7x on MT DR's and 1.5x on ET streets. All circa 255/50x16 size
The former tyre types probably could go faster, but I always held back a bit on the launch, fearing it would light the tyres. But they gripped amazingly well.
By comparison. Use those same tyres on an airfield, and there is zero grip until well into 3rd gear.
Monaro's with good tyres can get traction. I was chatting to a guy at the weekend with a turbo Honda S2000. With ET streets he was able to pull 1.5x 60fts. Basically just dumping the clutch at 7000rpm.
Mind you, it only lasted 3 runs before snapping both shafts lol
That was at Santa Pod though.
IMO if you have so little traction, its down to the surface more so than your IRS.
I may have a live axle, but the 4-link is far from anywhere near optimal. And at Santa Pod I can pretty much sidestep the clutch around 5-6000rpm and it just grips.
ive done 1.8x on Nittos, 1.7x on MT DR's and 1.5x on ET streets. All circa 255/50x16 size
The former tyre types probably could go faster, but I always held back a bit on the launch, fearing it would light the tyres. But they gripped amazingly well.
By comparison. Use those same tyres on an airfield, and there is zero grip until well into 3rd gear.
I also struggled at Shakey.
I think its down to too much camber on the rear and not enough weight in the rear. I will be getting the new set up geo'd properly and i should have more weight towards the back.
The total weight of my car with me and all the nitrous bottles on board probably still weighs less thean 1200kg.
Maybe next year i will just give it the full beans and see what happens.
My new driveshafts should hold up
I think its down to too much camber on the rear and not enough weight in the rear. I will be getting the new set up geo'd properly and i should have more weight towards the back.
The total weight of my car with me and all the nitrous bottles on board probably still weighs less thean 1200kg.
Maybe next year i will just give it the full beans and see what happens.
My new driveshafts should hold up
10.612 @ 129.77
176.5 standing mile.
176.5 standing mile.
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stevieturbo
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Lack of weight could be an issue, and poor camber certainly wont help.
But if running the tyres at fairly low pressure, I think that would sort of counteract the camber.
Most times when racing, Id run the tyres down to say 12psi or so. Although obviously how low you go may depend on the profile. probably a very low profile tyre might not like such low pressures. You didnt mention what size you were using, other than tyre width ?
But if running the tyres at fairly low pressure, I think that would sort of counteract the camber.
Most times when racing, Id run the tyres down to say 12psi or so. Although obviously how low you go may depend on the profile. probably a very low profile tyre might not like such low pressures. You didnt mention what size you were using, other than tyre width ?
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stevieturbo
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stevieturbo
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Not as daft as you think.stevieturbo wrote:Full tank of fuel, or fill the boot with sand lol
I am moving the battery and 3 nitrous bottles to the boot so thats nearly 40kg shifted as far back as possible.
I will get the rear camber set with minimum camber and set the rear shocks soft.
I will ask advice from Nitron on further settings to the shockers as i havent a clue yet really. Theres 3 knobs to turn on each of the rears!
Apparently the seperate reservoir is the important 1 for drag launches as this controls the low speed damping.
I suppose i can look forward to a lot of trial and error at test and tune days
10.612 @ 129.77
176.5 standing mile.
176.5 standing mile.
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stevieturbo
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shocks soft or hard etc is debatable. Squat or anti-squat ?
Either seems to work on different cars. Hard shocks may be better as when weight transfers, the tyres may get hit harder. Or soft might be good to absorb some of the transfer so it doesnt shock the tyres.
Either way, weight over the tyres, less weight up front is always a good thing. Weight behind the tyres though, might not be.
Just so many variables. What way is the IRS on a TVR ? Is there any play with trailing arms etc ? Much like a ladder bar arrangement, I'd imagine the angle and how these arms meet the chassis could play a part in how much force is applied to the tyres on launch etc.
Either seems to work on different cars. Hard shocks may be better as when weight transfers, the tyres may get hit harder. Or soft might be good to absorb some of the transfer so it doesnt shock the tyres.
Either way, weight over the tyres, less weight up front is always a good thing. Weight behind the tyres though, might not be.
Just so many variables. What way is the IRS on a TVR ? Is there any play with trailing arms etc ? Much like a ladder bar arrangement, I'd imagine the angle and how these arms meet the chassis could play a part in how much force is applied to the tyres on launch etc.
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stevieturbo
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no idea what you could try there. I guess moving the weight, and perhaps playing with spring and shocks
Although the westfield etc type cars all seem to get very good traction, and I think they use a similar layout ?
How much lift is there available at the front end ? Do the shocks allow a lot of travel, or are they very restrictive ?
Although the westfield etc type cars all seem to get very good traction, and I think they use a similar layout ?
How much lift is there available at the front end ? Do the shocks allow a lot of travel, or are they very restrictive ?
