Transaxle Chapter and Verse

[Fylnn]

Got my GTV6 up and running and enjoying it immensely.  The intended use is for gravel rally.  Especially the V6 with the Haltech all tuned correctly.  It goes hard and sounds the beans.  I finally realise what everyone has been talking about since the early 80's.

Now I realise the transaxle on these has always been not to everyone's liking and was part of the charm, but just trying to establish what is reasonable.  It is not as bad as my memory of older Alfettas but still has its issues.  Note it is the original transaxle that i put straight back in untouched.  Questions for today are all about second gear:
1.  Changes from first to second are not too bad, no graunching, but not something to rush. 
2.  Main issue is on down-changing from third.  It is OK if you can give the engine a blip or double de-clutch, but if for example under hard braking you try to just put it back to second it gives the old graunch.

So what is normal?  What would you expect from a good transaxle or should I be thinking about a rebuild?

[BradGTV]

second synchro wears out as its the most used? from a good usable transaxle u shouldnt have any noises issues with shifting, it depends what level of competition you intent on competing in? if your going to push the car to its limits u will definatly need to fix it or if you just going to go for a drive every sunday you could get away with it for a couple of months but the problem wont fix itself 

you can swap 5th synchro onto 2nd or buy a new synhro (or a set, but $$$) and put the box back toghether. after doing this myself for the first time i would not pay someone else to do it! give it ago!

[aggie57]

The third to second change is the weakest one for this box.  For the use you are intending then heel and toe is a given if you want it to have any sort of life.  The syncro's will wear out very quickly (as in a few hundred or few thousand k's) if you are relying on them. 

Over the years many theories and rationales have been put forward as to why this is so, many of which are probaby fully or partly true, but in the end with this what is just is I'm afraid.  

The upside is if you look after the box, use some really good synthetic oil of the right spec, you will get many years service out of it.

[MD]

Flynn

Alfa transaxles when going back down the gears should always have the engine revs matched to the anticipated road speed for the gear you are about to get into. Just relying on the synchro assemblies to mesh the gears is the fastest way to shorten its life and ruin your gearbox. Practice good heel & toe technique which is mandatory.

The second and important issue is a misconception that you can repair the damaged "synchros" by just replacing the synchromesh ring. Actually to make a proper job of it, all three components of the synchro set need to be replaced ie.

1 Synchro ring
2 Synchro hub ring
3 Synchro dog ring

Choice of transmission oil is also important and you should look through the posts on here for that.

[aggie57]

Flynn

Alfa transaxles when going back down the gears should always have the engine revs matched to the anticipated road speed for the gear you are about to get into. Just relying on the synchro assemblies to mesh the gears is the fastest way to shorten its life and ruin your gearbox. Practice good heel & toe technique which is mandatory.

The second and important issue is a misconception that you can repair the damaged "synchros" by just replacing the synchromesh ring. Actually to make a proper job of it, all three components of the synchro set need to be replaced ie.

1 Synchro ring
2 Synchro hub ring
3 Synchro dog ring

Choice of transmission oil is also important and you should look through the posts on here for that.

Snap!

[alfagtv58]

Without wanting to wander too far off topic here, it is my understanding that heel toe technique has no effect on synchronizing gear changes (or prolonging the life of your synchromesh), heel toe technique will only stop compression lock upon release of the clutch.  Double de-clutching is the way to assist gear changing by matching the road speed to the input shaft speed.

I am happy to be corrected by those more knowledgeable than me on this topic though.

[alfagtv58]

A good conversation here about it the double declutch / heel toe debate.

http://www.alfaclubvic.org.au/forum/index.php?topic=893.0

[aggie57]

Without wanting to wander too far off topic here, it is my understanding that heel toe technique has no effect on synchronizing gear changes (or prolonging the life of your synchromesh), heel toe technique will only stop compression lock upon release of the clutch.  Double de-clutching is the way to assist gear changing by matching the road speed to the input shaft speed.

I am happy to be corrected by those more knowledgeable than me on this topic though.

Yes, fair point Phil.  Over the years I've just learnt to heel and toe and double de-clutch as one so forget to differentiate. 

[Evan Bottcher]

Phil's definitely right - I believe just heel-toeing on it's own does little to reduce wear on synchros.  Heel-toe plus a double declutch for a quick change without excessive wear.

Hmmm.  I have always heel-toed, and find it quite comfortable to do.

I have never even tried the double declutch.  Maybe I should be trying it. 

That was back in 2007.  Did you learn?

[alfagtv58]

I have tried it, and for sure it reduces the 'crunch', but it is in no way 2nd nature for me yet, I have to really concentrate on a) doing it in the firstplace and b) doing it effectively.  So I usually end up doing it in the 6 Hour or races where I'm a bit lonely.  I have found myself doing it in the road car as practice, not at high rpm changes, just normal road speeds for the practice of clutch in and out a couple of times.

The proof is in watching my in car from PI a couple of weeks back, my 2nd and 3rd gear synchros are knackered 

[MD]

Yes Phil you have it right. ( I must admit I had a chuckle about this)

I have been doing this all my life and I naturally assumed everybody else also understood that to heel and toe means you double declutch simulatneously otherwise it is a pointless exercise in terms of synchro assistance.

I appreciate that you have pointed this out to those not in the know.

[Fylnn]

Thanks for the input guys.  One thing i have in the To Do list is to move the accelerator pedal closer to the brake pedal so I can actually heel and toe.  Being 6' 2" I have trouble with the standard set up.  I also want to move the brake pedal about 50mm closer to the floor since it has a pedal box with no booster, so very little pedal movement, and plenty of room for more using some of the un-needed travel to give my long legs access. 

I am thinking of moving from Penrite to the Redline Shockproof transmission oil, just in case it helps and then  drive around it for a while.  Do a few rallies and then decide what to do with the transmission.

Having said all that it is not circuit racing and the flexible nature of the V6 helps in things like holding 3rd longer than otherwise so maybe not an issue. 

Plan B is to win Lotto, give the transaxle to someone like Vin Sharp and ask him to make it all better. 

[dehne]

flynn,
I have a spare box if you want a spare one either to rebuild or parts

[GTVeloce]

The best way to learn to double-declutch is the way I learned - the forced way! My first alfetta had the worst synchro you could imagine and I had to double-d into both second and third! Otherwise I basically couldn't shift gears. You get good at it in a hurry. Plus, it has to be the best way to pull a smile on your face - hard under brakes change down two gears then throw the car around the corner. If you get it just right the feeling is fantastic! Getting it wrong of course...

[Duk]

I am thinking of moving from Penrite to the Redline Shockproof transmission oil, just in case it helps and then  drive around it for a while.  Do a few rallies and then decide what to do with the transmission.

Redline Shockproof doesn't have a good reputation for synchro equipped 'boxes. Apparently the synchro's get glazed because Shockproof is more for dog ring engagement 'boxes.

And just for the record, you can't compression lock a petrol engine. Not unless you fill it with a liquid  .