400 SE Diff ratio

[TVRleigh_BBWR]

Hi Anyone know the Diff ratio of the 400SE.

Want to do some calc's if not I'll just look the weekend, as it should be stamped on the back of the diff.

Thanks
Leigh

[Wedg1e]

I thought most wedges had 3.54:1.

[TVRleigh_BBWR]

ummm ok.

3.31 give better results when you do the maths. as I have had my 400SE to 155 and it was not quite in the Red.
Rolling Radius was calculated from 225/50/15 Tyres.


RPM KPH/RPM Rolling Radius Final Ratio Gear Ratio KPH MPH
5th 6000 0.000 1.848 3.54 0.79 2.7966 237.889 147.817
5th 6000 0.000 1.848 3.31 0.79 2.6149 254.419 158.089

[grahamw48]

My handbook says 3.54 but as you know, all cars were open to buyer's choice.

I suppose it also depends on whether the car will pull 6,000 in top.

Don't think I'd have the balls to go flat to the boards.

[Wedg1e]

TVRleigh_BBWR said:

ummm ok.

3.31 give better results when you do the maths. as I have had my 400SE to 155 and it was not quite in the Red.
Rolling Radius was calculated from 225/50/15 Tyres.


RPM KPH/RPM Rolling Radius Final Ratio Gear Ratio KPH MPH
5th 6000 0.000 1.848 3.54 0.79 2.7966 237.889 147.817
5th 6000 0.000 1.848 3.31 0.79 2.6149 254.419 158.089

Y'see you think it'd all work out just like that wouldn't you... but a couple of years back I had Tallbloke in my car with his Satnav and on the M** at an indicated 102 mph the satnav said 100 exactly. However the rev counter said we were doing about 94.
I have had (on a race track of course) my car's speedo off the scale at 160... an impossible speed for a 390 considering they were only ever allegedly good for 146 - and mine's not a particularly fit example. The rev counter said about 130.
So either the speedo is hugely optimistic (I believe so: even in 50mph average-speed-camera zones when you know damn-well everybody IS doing 50 I get an indicated 55) or the tacho is (harder to believe; even the rev limiter does seem to cut the sparks very close to where its scale says) or the wondrous satnav is also telling porky pies... which I can also believe.
My diff's a 3.54 LS.

[grahamw48]

I use my satnav as a speedo on my Wedge, and I'm actually shocked sometimes at the (true) speed she gets up to when overtaking, etc.

On my workaday car, indicated 70 is really 66/67 when checking on satnav...probably why everyone is in my way...

[Number 7]

My tacho over reads by 2-300 rpm at the top end, compared to the computer when its hooked up to the ecu. No bad thing really.

7.