James Cole 4844 Transmission and Driveline: manual transaxle day 2 / 3 / 4

Day 2.

The assembled transaxle.

Today, after disassembling the transmission on tuesday, we took measurements and inspected the components of the transaxle.

The first components we inspected were the bearings in the transmission.
There are a few types that are present.
Taper rollers, in which the rollers are tapered and roll around on a tapered cone. These were found on both sides of the crown wheel, part of the final drive assembly.
Another type was the normal cage supported roller which were located at the rear of the input and output shafts. This type of bearing uses rollers or balls which roll between two shells and are supported by a cage.
The needle roller bearings are are type of bearing that uses needle shaped rollers which are supported by a nylon type cage. This type of bearing are very thin and are found on certain driving and driven gears in the transmission. The fifth driving gear has this type of bearing in two pieces.

we removed the top cover.

Another type is a bush. It is fixed in place and for lubrication, the bush has grooves in it which let oil in between the bush and shaft. This type of bush was used in the transmission on the reverse idler gear, and as it sits over the shaft it needs lubrication, so the grooves allow oil to get in between.

Another measurement we had to take was the side clearance of the non fixed gears. Side clearance is the sideways movement of the gears. These clearances are measured using feeler gauges. The clearance between most of the gears was about .3mm, which is normal.
While checking the side clearances, we also checked the condition of the teeth and gears. We had to check that the hardened face wasn't worn, make sure there were no teeth chipped off. We also checked the condition of the syncro dog teeth. Everything was in good condition.

Removing the selector mechanism

The syncromesh system also needed to be inspected for damage and clearances. Cracks on the baulk ring need to be checked for, wear on the inside of the baulk ring and wear points on the teeth. We also need to check for the clearance between the baulk ring and the engagement ring. If this clearance is too small, then this will mean wear on the inside of the baulk ring. Again, this clearance is checked using a feeler gauge. The minimum clearance is about .5mm, anything less than this will mean insufficient pressure can be put on the engagement ring, and will be unable to slow the gear down. Our clearances were good, ranging from .5 to .9 mm.
Also as part of the syncromesh system, the shift plates, wire springs, syncro hubs and shift sleeves had to be inspected for wear and damage. All of these on our tranny were in good condition and no further action had to be taken.

using the gear pullers to remove
the fifth gears.

Next we had to inspect the selector mechanisms for damage. The detent systems, the interlock system, the selector forks and shafts had to be inspected. The detent springs were stiff, the selector forks had no visible signs of damage and the selector shafts were smooth, also with no damage.

Next we had to measure the diameter of the different shafts. We had to measure the input and output shafts, the reverse idler shaft and the 3 selector shafts.

We then had to check the condition of the cir-clips, splines, housings and covers, breather, seals and thread holes and bolts. All of these were in good condition and no further action was needed.

We removed the gearbox housing

The last step was to calculate the gear ratios of each individual gear. After counting the teeth on each gear, we used the formula Driven/Driving to calculate the ratio. E.g. The third driven gear had 38 teeth, and the third driving gear had 29 teeth.. We then use the formula so 38/29, which we get 1.31, therefore the ratio is 1.31:1. This means that the input shaft will turn 1.31 times, and the output shaft will turn once.

Day 3.
On day three, we reassembled the transmission. The most difficult part of this was assembling the selector forks. This was a very fiddly task but we got there in the end. Once we got the transmission assembled, all gears were selected and it was as good as new.

The selector forks and shafts.

Day 4.
Because we had finished assembling the transmission, it was unnessecary for us to be at class. I went home and worked on this blog and revised some automatic transmission material.