Transaxle re-build & upgrade 

 

 

This has been the most extensive modification made to my car thus far. In January 1998 I installed a complete, re-built transaxle from a 1987 Alfa Milano Platinum.  

 The transaxle had been perhaps the weakest and most problematic component in my car. I had experienced a lot of trouble with the syncromesh at the last Driving School at Willow Springs. Despite very careful gearchanges & double-clutching, the crunches as I shifted from 3rd to 2nd were appalling - and obviously did nothing to hasten the cars progress around the (very tight) track. I knew then that I would have to replace the syncros soon. 

 

 

The possibility of installing a Milano gearbox was appealing for a number of reasons: 

  1. Isostatic Shift Linkage - Alfa modified the shift linkage with the introduction of the Milano in 1987. The new style shifter decreases the length of the throw as well as improves the accuracy of the shift mechanism.
  2. Limited Slip Differential - the Alfa Platinum model all come equipped with a 25% LSD - highly desirable for track use!
  3. Improved Gear ratios. Alfa had by this time perfected the gear ratios - they remained the same throughout the entire production run of the 2.5 liter Milano.

I was fortunate enough to find a Milano Platinum in a local wrecking yard - I thought the gearbox was in good condition - until I got it home and removed the oil drain plug. Strangely enough, a small piece of piano-wire dropped out. Not a happy moment! This of course meant that the gearbox would have to be stripped down to find out where the broken piece of wire came from. As it turned out, the wire had come from the centering spring on the end of the gear-selector shaft.

 

Here you can see the Intermediate Flange with both mainshaft and the pinion shaft installed. Note that the long steel rod that extends to the bottom left of the picture is the gear selector shaft - this is the shaft that must be replaced with the Milano part if the new isostatic shifter is to be used. 

 

Here the gear shafts have been removed from the Intermediate Flange - and the components removed in order.  

All the parts had been removed from the pinion shaft. The differential can be seen at the bottom centre. The syncro rings can be seen at the bottom right. I decided to replace 2 of the syncro sleeves (1/2 gear, 3/4 gear), and I re-used the 5/rev gear sleeve by just turning it around. I ordered 4 new syncro rings - installed on gears 1 thru 4 - and once again just turned round the 5th gear syncro ring.

 

What actually happens when you change into second too quickly with those worn syncro's? What makes that grinding noise? Well, it's not the gears grinding, its the small teeth on the component shown in the (lower) centre of the above photo. The grinding occurs when the syncro's have been unable to synchronize the speed of the gear and the syncro sleeve as it moves over to engage. These tiny teeth eventually get worn out. How to replace these teeth is a problem (short of purchasing new gears) - unless you have access to some junked gears from another gearbox. It is possible to pull the needed component off a gear using a simple 3 leg puller shown at the top of the picture. Obviously, it is better to use the donor engagement gear rings from 4th and 5th gears since these will be the least worn. You can then press these onto your 2nd and 3rd gears - there you have it 'as-new' gears! 

Note that the component shown on the lower right is the complete 5th gear assembly - with the engagement gear ring still installed. The lower left and centre components show the 2nd gear and its engagement gear ring separated. You might be able to see the grooves machines into both these components to enable them to be pressed together. 

 

Here is a home-brewed rear trans bush driver. I used the same 36mm deep socket that I bought for removing the pinion shaft nut. On the right of the trans bush is a length of steel pipe, just large enough to allow the 36mm socket (and rear trans bush) to slide through it. A length of threaded rod with nuts & washers (shown in the picture) is then used to drive the bushing from the trans case. Easy :-) 

 

Problems 

There are of course a few issues to address in order to adapt the newer transmission to the older car.  

One has to use a Milano speedo sender unit. The reason for this is that the sender measures the speed of the vehicle by 'watching' the splines machined into the end of the pinion shaft. These splines were modified with the introduction of the Milano and so you cannot use your old GTV6 sender. The answer is to use the Milano speedo sender, the amplifier from a Milano (which usually resides under the rear seat) and the speedo unit from an '86 (or late '85) GTV6. (Or even better, also use the Milano speedo itself to guarantee compatibility between the speedo sender, amplifier and speedo ... see below ...)

 

Here you can see the Milano speedo amplifier that needs to be installed - here under the back seat. The wiring is quite straight forward.  

Just ground the unshielded cable to the chassis.  The other output wires from the Amplifier are one red and one white wire.  The red connects to the pink wire (that then leads to the '86 speedo), the white connects to the white/red wire (that then also leads to the '86 speedo).  The pink wire and the white wire I mentioned are the ones that used to hook up to your old speed sender.  It is of course necessary to re-route these wires back into the car (you can see them coming back through that rubber disk on the left of the above picture).  I did not make any more modifications. 

One of the problems associated with installing a Milano gearbox is that the speedo does not work properly with a mixture of (early) GTV6 and Milano speedo parts.  The solution I came up with is to install the innards of a Milano speedo in my GTV6 speedo housing (a late model '85 or '86 housing must be used).   Not an easy job - but can be accomplished with a dremel tool being used to modify the existing GTV6 instrument face.  The only problem I have experienced so far is that the illumination is poor at night ... this will be addresses as soon as I have time to deal with this...  Note that the actual 'guts' of the Milano speedo mechanism screws into the late style GTV6 housing - but extensive carving is needed to make space for the circuit board etc.

The isostatic shift linkage will not bolt directly in. There is not enough space between the trans mount and the body to accommodate the more complex isostatic shift linkage. It is possible though, to 'clearance' the sheet metal with a large hammer to make the requisite space. 

You will need to assemble the 'kit' needed to install the isostatic shifter. This 'kit' (running front to back), includes the Milano shift lever (with the aluminium housing), late GTV6 shift rod (shorter than the Milano rod!), complete rear isostatic assembly (can be sourced from a Milano) with all the rods & links, Milano front trans mounts and the Milano gear-selector shaft that is actually mounted in the front casing of the transmission housing. All these parts are quite easy to find, with the exception of the late model GTV6 shift rod. It is inexpensive though, and can be ordered from ARicambi (I have been waiting 4 weeks already for this part though!). They are not generally available used. 

  Send me your comments / experience / advice / suggestions.