Transaxle Gear Issue

I have a Ricardo transaxle that's running very well but I just have one intermittent issue. So the issue is when changing from 3rd to 4th I sometimes cannot engage 4th. It feels like a hard block at the selector/shifter. I can wiggle the shifter while trying to engage 4th but it will not go in. There is no synchro whine or anything. I can go down the gears and up and still get blocked. The only way to engage 4th when this happens is to engage 5th and then go back to forth. Going to 6th does not help. After getting 4th engaged the box works for a variable time (can be for many 3rd to 4th shifts) and then baulks at 4th again for no apparent reason. 

I have also observed this even with the car at standstill not running. Again exactly the same symptom and engaging 5th is the only way to get 4th. The only other thing I have noticed is an occasional small gear dog ring crunch from 2nd to 3rd as if I beat the synchro as the shift has an intermittent uncharacteristically low to no synchro resistance. I do not know if this is related. As the main issue 3rd to 4th issue is a simple non cross-gate change this is most surprising.

1) I cannot see any selector anomalies or adjustment issues with the ford short shifter or cables. Can this be some sort of cable/shifter adjustment issue? If so any ideas?
2) Is it worth pulling the selector housing assembly off the side of the transmission and looking for something on the selector assembly? With an intermittent issue this could be hard. I don’t even know if it is possible to peek in that part of the box without major disassembly.
3) Could it be an internal gear stack issue where a stack is moving in a way it’s not designed to and fouling the change?
4) Could it be oiling? I am using the OE coolant but have fitted an external cooler.

While a few people gave me some options they all involved getting the box out and pulling it down. So before I took this route I decided to have a look myself. Thinking about the issue I thought it would be best to look at the selector assembly as the issue could be there. Inspection of all the detents showed no issues. So off with the selector housing on the side of the transaxle. I could not see any issues with the selector assembly. So a peek into the box :(

And what did I find, the 3/4 selector bush had fallen out of the selector!!!!! Hoorah!!!!

You can see it highlighted in yellow below and the original image after that.

I have also attached a link to a video of the problem:

So this explained the symptoms perfectly as it jammed when the bush fell out as the bush then became a spacer and worked when it partially slid back in. Selecting 5th pushed the bush in a little and then selecting 4th was possible, I am so happy I found this.

To fix it I cleaned the bush and selector bore with brake clean while not getting it in the gearbox. I used Loctite® 620™ on the bush and tapped it securely back into the selector bore. It took a bit of tapping so its not a loose fit and should not come out again.

Thanks to all those I contacted that had ideas about the issue. None guessed this one but your support was appreciated. Now off to finishing other little things on the car.

Update : 16th January, 2016


Transaxle Mount

I wanted to have a transaxle mount from the rear cross member to the OE mounting point on the transaxle. It is probably not required (other cars just hang the transaxle off the bell housing and are running around OK) but I wanted to do it. I mocked up the part in cardboard, then to CAD and had one NC machined out of 6061T6 Aluminium. The worry when such a part turns up is that one gets a dimension wrong and a hole does not line up or something. Luckily it fit perfect first time.

While I was at it I also made a cover for the rear of the transaxle as the raw gearbox casting looks like rubbish and it can be seen at the rear of the car.

Update : 4th January, 2013

Drive Shafts

I have been through quite a lot to try and get drive shafts for this car. After obtaining the correct length (12.5") I have had to deal with the bolt circle diameter on the transaxle output shafts differing to the standard 108mm CV bolt circle.

Basically the CV's I have measured have a bolt circle diameter of 93.7mm, close to the standard of 94mm. The Ricardo output flange circle diameter's measure ~95.75mm. I will need to try to open up the holes in the CV's a little, well by 1.025mm radial to be exact!

After elongating the holes to fit the Ricardo output flanges I wanted to ensure the CV and output flange remained concentric. Elongating holes allows the bolts to bend more than normal and I did not want them to allow the CV to move out of centre. I therefore machined a step in the CV that corresponds to a small machining land on the inside of the transaxle output flange (near the bolt threads). The two parts now lock together perfectly without any movement before the bolts are inserted. All load will now be tangential on the bolts. I'm sure this has not weakened the flange and its only extended the CV length by ~3mm so that will not be a problem. I have also shortened the ball races but if they are out that far I would have to be airborne and I would have more pressing issues to deal with!

I feel a little better now about the CV's I have however if they blow I will replace them with a matched PCD unit.


Details on the CV Joint used is below (visit

Update : 17th March, 2009

Gear Shifter

With the transaxle chosen I moved to the gear selector system. An original Ford GT selector was purchased to ensure good shift quality. It is planned to use the OE bracket at the transaxle end as per below. This has also been obtained with the transaxle. The second photo shows how the Ford GT routes the cable under the supercharger, I will try to do the same. This will require a custom bracket.

The transaxle selector cables will be routed over the engine in the same manner as the Ford GT. This should provide a very similar shift quality (depending on the cables used as well). The image below shows the basic installation in the Ford GT.

Also above is the gear lever and mounting plate. This has also been purchased (normal shifter, not the aftermarket short shifter). I would like to possibly get a set of Ford GT cables to complete the OE link, however they will be the wrong length (I gather) and may be quite expensive. I would also like to get a Ford GT gear knob as well - why not, will have everything else!

Update : 7th May, 2008

The decision to buy a Ricardo Ford GT Transaxle

After numerous hours calculating the potential power developed by my engine, after fitment of a supercharger, left me with little choice. Numerous calculations and investigations left me with 3 main options.

1) Albins Sequential Transaxle

This transaxle has heaps of headroom for power but to fit in the GT40 the AGB10 sequential is the only choice. Made in Australia and very capable I strongly considered this option. One of the main issues was the sequential shifts, great for track work but a little difficult for the occasional road use the car will encounter. For a true track car I would say its an excellent choice. Cost is approx USD14,000.

2) The ZFQ is another good transaxle but it is very much an unknown quantity at this time. Its only just achieving initial deliveries and a bit too risky right for me right now. Cost is USD11,950 plus shipping to Australia.

3) The third option is a Ricardo transaxle. This was going to be difficult to purchase after Ford Racing withdrew it from their catalogue. However I was lucky and Fran Hall from RCR was able to help me out with one. He seemed to have a corner in the shop where they just sprout out of the ground!

The Ford Ricardo transaxle met my needs but was expensive and large. Fitments were required to see if it would live inside a GT40.

The space was tight but as can be seen it "should fit"

Further checks will be done in Australia when the car arrives. I expect some shortening of the engine pulleys etc.may be required! Videos of the preliminary installation check can be found here.

Update : 4th May, 2008

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