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hi to all, i'm running a 253 v8 with m20 4speed box with a 2.78 salisbury diff.my 253 had a full rebuild and now i have done 5000 k's on it,it pulls hard and very good on the open road. the thing is i'm not useing the full rev range. at 120 k's it siting on 2400 rev.now what is the right ratio i shoud be running. i was thinking 3.36 or 3.08 , what do you think? by the way my wheels are 225/60/15.
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For a manual box running those revs I dont think you have a 2.78 diff. If you go to 3.08 or 3.36 your revs will increase for the same speed you are doing now but youre off the line take off will improve. Taller tyres will improve top speed and smaller tyr |
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That sounds about right for a 2.78. It'd be a bugger reversing up a hill though. Is 1st gear OK? If you want to keep the low revs at highway speeds you could rebuild the box as an M22, which gives you the same 4th gear but 1st goes to 3.74:1, M20 is 3.05: |
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That sounds about right for a 2.78. Itd be a bugger reversing up a hill though. Is 1st gear OK? If you want to keep the low revs at highway speeds you could rebuild the box as an M22, which gives you the same 4th gear but 1st goes to 3.74:1, M20 is 3.05:1 |
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thanks for your input , the diff is a 2.78 as i buided it my self. frist gear all good but like you said on a hill need lot of rev to get moving , that why i was going to a lower ratio , as it will make it lot better for standing point. but not sue on 3.3
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If you are happy with 4th gear then just rebuild the box as an M22. Requires an input shaft, cluster, 3rd gear and a bearing kit. Probably easier than changing the entire diff centre. From memory I can get the input shaft and cluster NOS, not sure about 3 |
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i've done all this befor,if your going to do any towing (even a 6x4 trailer)then a 3.08 is a good all round combo. remember its only a 253 and they do need some revs to be alive. ive also done a m22 v8 box but input/counter gear teath have more stress as
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ive done all this befor,if your going to do any towing (even a 6x4 trailer)then a 3.08 is a good all round combo. remember its only a 253 and they do need some revs to be alive. ive also done a m22 v8 box but input/counter gear teath have more stress as i
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hi the 3.08 will be 10% lower and you should get 110 3000 rpm 3.36 will be 10% lower then that
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