It is apparent that both regulations have been brought into line with a single transmission specification from 2013. The paperwork which I have details the following restrictions.
- Gearbox type must be A+ 998cc
- Identification No DAM5626 (by oil filter)
- 2nd Gear ratio = 21 tooth laygear and 26 tooth gear
- Final Drive ratio 3.44:1 = 18 tooth pinion and 62 tooth crownwheel
- Crankshaft gear = 29 teeth, Idler = 27 teeth and 1st motion gear = 29 teeth
To check your current transmission you should look for the following identifying features.
- Gearbox type must be A+ 998cc & Identification No DAM5626 (by oil filter)
This is not as easy to check as you would think, the A+ gearbox case was used on all variaties of the A+ engine from 850 to 1300, but the key according to the regulations is the use of the DAM5626 casting.
This is easily identified by looking at the front of the case
Also check the size of the idler bearing
Assuming those two are correct then you have the right case.
However, this in no way relates to the inside of the case, all you have determined is that it is an A+ case with DAM5626 cast into the front, as mentioned above, these units were used on minis, metros and even some allegro's and all have different gearsets, final drive and input gear ratios.
- 2nd Gear ratio = 21 tooth laygear and 26 tooth gear
Fortunately for identification purposes there is only one combination of a 26 tooth 2nd gear and corresponding 21 tooth laygear, that is the A+ Single groove gearset.
Looking inside the transmission look at the top of the gear teeth, there should be a noticable SINGLE groove through the top of the 2nd, 3rd, 1st motion gear (4th) and the largest gear on the laygear.
If you have TWO grooves, then you have the alternate Wide ratio A+ gearset, which only has 25 teeth on the 2nd gear, or if you have NO grooves at all then an A series or early A+ gearset is fitted, and although has a 26 tooth 2nd, the tooth count on the laygear is only 20. Both these gearsets are now outwith regulation.
- Final Drive ratio 3.44:1 = 18 tooth pinion and 62 tooth crownwheel
Fairly self explanitory, the 3.44 final drive is the only one to use the 18 tooth pinion, and it's just a matter of counting the teeth to determine conformity.
- Crankshaft gear = 29 teeth, Idler = 27 teeth and 1st motion gear = 29 teeth
Only the 1st motion gear, or input or broach gear is attached to the transmission and is the bottom of the 3 transfer gears.
Apart from counting the teeth, there is another way to quickly identify the type of gear. Firstly the teeth are pointed which is indicative of an A+ gear, and secondly the shaft of the gear will either be plain or have a single groove machined into it. Those which are plain are 29 tooth, and within regultion, those which are not are the economy 28 tooth varient and are now outwith regulation.
The correct input gear 29 teeth and plain shaft.
The economy input gear with 28 teeth and the identifying groove on the shaft
For reference, all A+ idler gears have 37 teeth and does not affect the transfer gear ratio, however, the primary gear should have 29 teeth. There is a version which has 30 teeth but was only used on the 1300 engine, and is identified by a single groove through the top of the gear teeth, similar to that employed in the transmission for identifying the A+ gearset.
Parts
- 3.4 Final drive
- A+ Single groove gearset parts
- A+ 29 tooth input gear
- A+ Idler gear
- A+ 29 Tooth Primary gear
- Central Oil Pickup Pipe
- Windage Tray
- Differential Pin Upgrades
- X-pin Differential
- Rebuilt kits
Gearboxes.
These are links to example specifications and pricings for gearboxes within regulation to suite different budgets. Does not including exchange surcharge & shipping
- Budget Gearbox - A basic refurbished gearbox to regulation with steel diff pin and central oil pickup pipe
- Budget Gearbox 2 - As above but fitted with a fully rebuilt differential including new pinions, thrusts and Moly' diff pin.
- Mid-Budget Gearbox - As per the Budget gearbox but fitted with an x-pin differential for ultimate strength.
- Rebuilt Gearbox - A completely rebuilt box with high grade competition parts, new top quality branded bearings and an x-pin differential for ultimate strength.