Diff and Gear ratios
Discussion
Think we have been here before but I still don’t have it clear in my mind.
I have two Diffs one is around 3.25:1 the other is 3.5:1
According to Steve’s book the T5 gear ratios are 2.95,1.95,1.34,1,0.79. and I assumed 24.7 rear wheels. Now if I throw those into a ratio calculator at 5000 rpm for the 3.5 I get 1st 36mph, 2nd 54mph 3rd 78 mph 4th 105mph and for the 3.25 1st 38mph, 2nd 58mph, 3rd 84mph, 4th 113mph.
I know that the concept of a standard TVR is difficult but which of these ratios would have been the standard fit for a 98 car and indeed which best suits it ? I need to decide which one to put an ATB Diff into.
I have two Diffs one is around 3.25:1 the other is 3.5:1
According to Steve’s book the T5 gear ratios are 2.95,1.95,1.34,1,0.79. and I assumed 24.7 rear wheels. Now if I throw those into a ratio calculator at 5000 rpm for the 3.5 I get 1st 36mph, 2nd 54mph 3rd 78 mph 4th 105mph and for the 3.25 1st 38mph, 2nd 58mph, 3rd 84mph, 4th 113mph.
I know that the concept of a standard TVR is difficult but which of these ratios would have been the standard fit for a 98 car and indeed which best suits it ? I need to decide which one to put an ATB Diff into.
My late '96 car had the earlier diff ratio of 3.31:1,and my later 2000 year car had the BTR ratio of 3.45:1,but i'm not sure when this changed.Prsonally i much prefer the 3.31,as it makes the motorway cruising that bit better,and i could never tell the difference in the bottom gears!
Well, i dont know, i'm still running the new differential in...i guess it depends on the tarmac and what tires you're using.
By the way, did you ever run american hoosiers dot tires for hillclimb? what's on your opinion the best full RACE (but non slick and street approved) tires for a griff?
By the way, did you ever run american hoosiers dot tires for hillclimb? what's on your opinion the best full RACE (but non slick and street approved) tires for a griff?
Don't know why you are asking me because I am not an expert, however :-
The absolute best road legal rubber by a long way that I have used is what I generally have on the car now and what I use as wets. That is a set of half worn Yokohama A032r soft compound. They offer an enormous amount more grip than any “normal” list 1a road tyre I have tried. When these need replacing I will probably try a set of Toyo R888s they seem to have a better footprint on the road and others running in my class find them very effective. If I have to use the car on the road in really wet conditions or compete “road going” I go back to an old set of SO3s.
For slicks I am currently using Hoosier DOT A6 compound rubber on 17inch rims. Have to say that when they arrived I was disappointed that they were not all that soft. Certainly compared to some of the Avon Hillclimb compounds they are rock hard. Also they are not real slicks, they are grooved like current F1 rubber, apparently this is what allows the US DOT rating. All things considered they have worked very well on the front and OK at the rear (nine trophies from nine meetings this year). The additional turn in grip over the 32rs is significant, the rears have more lateral grip allowing higher cornering speeds but they spin up with more ease than the 32s which makes getting the power down harder. They did however only start working after I upped the spring rates and got the damping right.
The absolute best road legal rubber by a long way that I have used is what I generally have on the car now and what I use as wets. That is a set of half worn Yokohama A032r soft compound. They offer an enormous amount more grip than any “normal” list 1a road tyre I have tried. When these need replacing I will probably try a set of Toyo R888s they seem to have a better footprint on the road and others running in my class find them very effective. If I have to use the car on the road in really wet conditions or compete “road going” I go back to an old set of SO3s.
For slicks I am currently using Hoosier DOT A6 compound rubber on 17inch rims. Have to say that when they arrived I was disappointed that they were not all that soft. Certainly compared to some of the Avon Hillclimb compounds they are rock hard. Also they are not real slicks, they are grooved like current F1 rubber, apparently this is what allows the US DOT rating. All things considered they have worked very well on the front and OK at the rear (nine trophies from nine meetings this year). The additional turn in grip over the 32rs is significant, the rears have more lateral grip allowing higher cornering speeds but they spin up with more ease than the 32s which makes getting the power down harder. They did however only start working after I upped the spring rates and got the damping right.
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