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2001 Changes

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2001 New 5 Speed Sequential Gearbox
Quaife 5 Speed Dog-Engagement Sequential Gearbox It would have been necessary to upgrade the gearbox, when we decided to build the 2.5L CIH engine, as the Quaife Sierra Pro gearbox is only rated to about 250BHP.  So, I ordered a new 5 speed Quaife Sierra Sequential Gearbox, with dog engagement.  This gearbox is rated to in excess of 300BHP.  This is another project which has been brought forward from next year.  This gearbox has now arrived and is now fitted to the car.  Gear selection is as follows:-

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Move Gear stick forwards

Reverse
Neutral
1
2
3
4
5

Move Gear stick backwards

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\/

To select neutral from 1st gear, you must lift the gate lever.  This means that you cannot select neutral or reverse accidentally, which is very useful when dropping through the gears for a hairpin.

This gearbox has dog engagement gears, therefore it is very strong and gear selection, without the use of the clutch, only requires a slight lift on the throttle.  It will also allow full throttle gear changes, should we upgrade the Engine Management System in the future.

With a differential ratio of 3.67 and 205/50 x 15" wheels, this gearbox should give the following capabilities to an Opel Manta fitted with a 2.4L CIH engine:-

Gear

Gear Ratio

Low RPM

Top RPM

Speed at TOP RPM (MPH)

1st

2.39

-

6500

52

2nd

1.54

4118

6500

81

3rd

1.21

5107

6500

102

4th

1.00

5372

6500

124

5th

0.87

5655

6500

142

Installation of the gearbox and Gear Selection Indicator was completed in March 2001.   We ran the car up on a rolling road to test the gearbox.  Moving up and down the gearbox, without the use of the clutch, is very quick and slick.  I am very impressed.
Modifird rear case for sequential selector mechanism
Gear Lever & Gear Selection Sensor
Gearbox Internals
Gear Selection Indicator on tunnel in front of lever Here is a picture of the Gear Selection Indicator.   I have not yet decided on a final location for the Indicator, so I have surrounded it with foam, and taped it onto the transmission tunnel.  It is a bit too big to put on the dash, so I am not sure what to do with it yet.
New lightweight gearbox bracket We finally got around to fitting a lightweight bracket for the new sequential gearbox.  Previous bracket made of 1/4" (or 6.35mm) thick plate, and its weight was ridiculous.

Conclusion

After some testing on the road, including some motorway driving, this gearbox is very good when used together with a high torque engine like my previous 2.4L engine, and my new 2.5L engine presently being built.  However, I would not like to try it with a 2.0L engine, as 1st gear would be much to tall.

I can't wait to try it on a track.

I have also decided that I would like to be able to do full throttle gear changes, which should be possible by upgrading my Engine Management System to a DTAfast E48 Exp or P8 Pro systems. 
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Last updated: Tuesday, 18 November 2003.