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MED S/C DROP GEAR SET - ROLLER TYPE

Name: MED S/C DROP GEAR SET - ROLLER TYPE
Brand: MED Engineering
SKU: MED-3095-RD-PLUS
Price: 395.0 GBP
Availability: InStock

Part No: MED-3095-RD-PLUS

£395.00 £329.17 EXC VAT

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Description

A must for any competition engine build, the MED roller bearing drop gear sets use a highly durable roller bearing/spindle design for the idler gear.

The idler gear roller bearing runs on the steel support shaft fitted into the gearbox casing, with a steel top hat spacer to replace the idler bearing within the flywheel housing, which encapsulates the idler gear assembly when fitted. There is no need for any idler gear shimming, as all tolerances are taken up within the gear assembly.

Straight-cut drop gears are stronger and more reliable than the standard helical design, with less side-loading effect.

MED roller bearing drop gear features

Primary gear tooth width is now 17.2mm long, an increase of 2.4mm, to give more contact area between the primary gear and idler gear to greatly reduce tooth wear.

A fully-floating primary gear bush, which is retained by a flat section circlip to help reduce primary bush failure.

The idler gear has an integral roller bearing, running on fixed axis within the gearbox and flywheel housings – probably the strongest and most reliable available for the A-Series transmission.

Extra wide input gear teeth to give greater tooth contact between both idler gear and input gear, again to help reduce tooth wear.

Gear set choice

We can supply alternative ratio sets by changing the primary gear/input gear. See the Additional Information tab for more on changing drop gear ratios. If you're happy with your current gear ratios, select the 1:1 option.

Both 1275cc and 998cc sets can be chosen from the dropdown menu above. For reference, A-plus sets have a 22mm idler gear shaft and pre-A-plus have a 19mm idler shaft.

For fast road applications we would recommend setting the primary end float between 0.004-inch to 0.006-inch. For competition, a marginally larger tolerance may be suitable - contact us if you're unsure.

Additional Information

The MED drop gear sets are available in three different ratios, which can be used to tweak the final drive ratio. Changing the effective final drive ratio will either improve acceleration or top speed potential, although one will always come at the expense of the other.

We can do this by changing the tooth count on either the idler gear or primary gear to 23 or 24 teeth. The idler gear in the middle remains at 30 teeth regardless.

The table below shows the various tooth counts and the effect on the drop gear ratio:

Drop gear set configuration
	1:1	1:1.043	1:0.958
Input gear	24 teeth	24 teeth	23 teeth
Idler gear	30 teeth	30 teeth	30 teeth
Primary gear	24 teeth	23 teeth	24 teeth

To calculate your effective final drive ratio based on the above, simply multiply your existing final drive ratio by the number of the drop gear set. So for example, a 3.47:1 final drive ratio with a 1:1.043 drop gear set then becomes 3.62:1. Remember that the higher the number, the shorter the gearing will be, so this change will result in a higher engine RPM for a given speed.

Changing the primary gear is easier than removing the differential to change the final drive ratio, so racers use this to adjust their gearing to suit different circuits. Keeping an engine in its peak powerband for longer will result in a faster lap time.

See the following table for our final drive conversions using the various drop gear sets:

Drop gear ratio adjustment
Original final drive	With 1:1.043 drop gears	With 1:0.958 drop gears
3.47:1	3.62:1	3.32:1
3.75:1	3.91:1	3.59:1
3.875:1	4.04:1	3.71:1
4.066:1	4.24:1	3.90:1
4.2:1	4.38:1	4.02:1
4.5:1	4.69:1	4.31:1

Frequently Asked Questions

What is the advantage of a roller bearing drop gear set?

This makes the ultimate drop gear upgrade, omitting the problematic standard needle roller bearings from the idler gear, in favour of a large (2.000" outside diameter) roller bearing. The strong idler spindle shaft presses into the gearbox housing and is supported by a top hat bush in the transfer gear housing. The primary gear and input gear are the same in the regular MED straight-cut drop gear set, it's only the idler gear that varies.

Why are these straight-cut?

MED straight-cut drop gears are stronger and more reliable than the standard factory helical design, with less side-loading effect, to transfer power more efficiently through to the gearbox. Combined with a straight-cut gear set and final drive, it's possible to 'free up' an extra 10bhp through to the front wheels on a powerful competition Mini.

When would you advise to upgrade to straight-cut drop gears?

As a general rule, for reliability we would highly recommend straight-cut drop gears for any A-Series engines beyond 100bhp, especially if running the smaller pre-A+ idler gear bearings. Surpassing 100bhp does place an A-Series engine into a more competition-orientated state of tune.

Can I use these on a road-going Mini?

Yes, and many do, although you should expect a louder gear noise when under load. Many of our customers enjoy this distinctive 'rally car' soundtrack.

Which ratio set should I choose?

If you are content with your current gear ratios, keep it simple and choose the 1:1 kit. If you would like to shorten the gearing slightly for better acceleration, choose 1.043:1, and to give taller gearing for better cruising, 0.958:1. To do the calculations, multiply your existing final drive ratio by the drop gear ratio, and this will show the corrected figure. If you click the 'additional information' tab above, we've listed more detail on this.

If I have a later rod change gearbox and an early transfer housing, can I still use these gears?

Yes, and vice versa. Depending on stock levels, we can usually supply an idler gear with different size spindle shaft and transfer housing top hat. Please contact us if you have a specific request on this and we can check to see if it's possible.

Do I still need to set the gear end float?

On the primary gear, yes, aim for 0.007-inch end float on a race Mini and 0.004-inch on a road car. For the idler gear, shimming is no longer required, as the gear has an integral roller bearing that simply floats on the supplied shaft.