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Twin Spark gearbox on 3ltr 75

Posted: Tue Jul 05, 2011 6:27 am
by sammbo
Hi everyone ...

There are a number of good forums for Transaxle Alfas, so forgive me if i break any rules by posting the same thing to each of them... Please let me know if it's an issue.

I recently posted this in a local Alfa Club forum and here in Australia and the ABB, but I thought I should cast the net a little winder hence I’m posting here too ….

I’m having a problem that is really causing me some grief …

Background
The gearbox on my son's 3ltr 75 was a mess - gears crunching, bearing noises, etc
His clutch went recently and given the condition of the box, we thought while the clutch was being fixed, we should drop the box and rebuild it too.
The average quote he got was $2000 to $2500 plus a few months wait for it to be done.
Given he has a new baby on the way and funds a little tight, as a short term solution, I offered him my spare Twin Spark gearbox until he gets around to rebuilding the 3LTR one.

while installing the TS box, we encountered 3 main issues.

1) The wheel hubs have larger bolts on the 3ltr, so I also gave him my spare Twin Spark A frame.
2) We could not use the TS clutch assembly because the donut flanges are smaller than the 3ltr ones, therefore we used the 3ltr clutch assembly to ensure it would bolt up to the lager donuts.
3) The 3ltr clutch is Pull type, so we had to change over the pivot pins where the thrust bearing fork pivots on.

It seems pretty much straight forward, a little bit of work, but it all seemed to go together ok.

Issue
1) We have everything bolted up and looking ok, except I can’t seem to bleed the clutch slave cylinder. I tried the usual tricks, like pushing it backward, (in case there is air towards the front of the cylinder), but it still want come hard.
I’m worried, because I can’t see air coming out of the bleeder, yet the pedal goes straight to the floor and won’t come up.
I did manage to get it working at one stage, maybe 80-90% expected pedal feel, but then while trying to get the last 100%, I played with the bleeder and it went flat again.
Is there something I’m missing with this?

2) has anyone else put a TS box on a 3 litre 75?


Thanks in advance
Sam
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Re: Twin Spark gearbox on 3ltr 75

Posted: Sat Jul 09, 2011 2:41 pm
by kevin
Hi, most chaps on this forum use the ts box on the 3.0 in their ra ce cars due to the ratios . By changing the a frame was a quick solution to your problem as you had it . Most of us just change the half shafts.
Make sure bleed nipple is on top when bleeding on slave. I use a short 7 spanner with a 24 to Hold it in position . You must undo clutch slave pipe to get bleed screw to sit naturally on top otherwise it puts tension in it. First let fluid just run through system to start then I depress fork under by hand to bleed initially until some resistance then only do I then use clutch pedal. Some times it can take you 5min sometimes 25 min and then some more ?
Just check you have the correct tension spring in clutch slave and also CHECK you transferred the guide shaft that the thrust bearing slides over from the 3.0 box to the 1.8 box other wise you find a horrible rattle about 10 seconds after you have let clutch out as thrust bearing moves around.
The guide shaft differs by 4mm from the 1.8 to the 3.0
see pic with the bigger 'tube'

Re: Twin Spark gearbox on 3ltr 75

Posted: Mon Jul 11, 2011 3:17 am
by sammbo
Hi Kevin

Thanks for your reply, I hope you can help me a bit more …..

I already had the car on the road before I received your reply. I hadn’t changed the Thrust Bearing guide, and yes it does rattle. :oops:
Hopefully it’s only in there for a couple of months while we get around to re-building the original gearbox.

I have a couple of other problems I has after you advice on too

• Sometimes when travelling over 80kph, If I push the clutch in and then let it out or sometimes when I change
from 4th to 5th, I get a vibration. Could this be related to the Thrust Bearing guide shaft too?

• The TS box is not in as good condition as I thought. Second and third syncros are shot.
Given that you race these cars, do you have any idea where I can get good quality syncros from? Also, have you
lightened your gears and is that worth considering to save syncros wear?


Thanks for you help so far, and sorry for all the questions

Sam

Re: Twin Spark gearbox on 3ltr 75

Posted: Mon Jul 11, 2011 5:08 am
by alfahaka
Well, I'd be inclined to give the local suppliers a bell, especially if you would like some advice with your parts... But looking further afield there is EB spares ( http://www.ebspares.co.uk/alfa75/gearbox.cfm ) among others.

Darryl.

Re: Twin Spark gearbox on 3ltr 75

Posted: Mon Jul 11, 2011 5:47 am
by sammbo
Hi Darryl

thanks for the link,

i'll give them a try


Sam

Re: Twin Spark gearbox on 3ltr 75

Posted: Mon Jul 11, 2011 9:33 am
by Giuliettaevo2
You could use the synchro from fith gear/reverse gear from a spare gearbox, they're all the same. :wink: And on fith gear and reverse you get the least wear. :)

Re: Twin Spark gearbox on 3ltr 75

Posted: Mon Jul 11, 2011 12:13 pm
by kevin
We also use fifth and reverse here as there is no stock of parts in deep , dark, corrupt Africa.
Put car in neutral let clutch out and wait 20 secs and you will find the rattle starts. It's a result of the thrust moving out it's central locating point then moving all over the show on the smaller shaft.
I have never lightened gears. Never needed to.

Re: Twin Spark gearbox on 3ltr 75

Posted: Tue Jul 12, 2011 2:58 am
by alfahaka
Giuliettaevo2 wrote:You could use the synchro from fith gear/reverse gear from a spare gearbox, they're all the same. :wink: And on fith gear and reverse you get the least wear. :)
Just make sure you know what a good synchro looks like - in case someone has been there before you and "fixed" the 2nd gear crunch on the donor gearbox by swapping synchros around already... Ask me how I know this :oops: .

Re: Twin Spark gearbox on 3ltr 75

Posted: Tue Jul 12, 2011 7:23 am
by sammbo
Oh no, don't tell me you swapped bad for worse?

BTW , thanks for all your help everyone. I'm thinking of pulling the clutch out and fixing the rattle, but the thought of another week end under the car in a freezing cold shed may be difficult to handle.

Maybe I will wait a couple of weeks before I do it ... hopefully it won’t do any damage in the meanwhile.


BTW - here’s another question...

is there any additive or temporary thing I can do to - even slightly - improve the 2nd & 3rd gear crunching? ….(Yeah I know ... just trying to delay the inevitable: cry:)

Sam

Re: Twin Spark gearbox on 3ltr 75

Posted: Tue Jul 12, 2011 11:50 am
by kevin
It's a thee hour job if car is on tressles excluding bleeding clutch with me and an assistant and having a few alfa tools . Eg the one to hold the dedion away from the body when you Jack dedion, and a curved bar to put between gearbox and dedion so you can pull clutch off. This is without air tools.
If weather is cold ( below 15 deg celcius) it needs an extra hour to get the motivation and then coffee breaks every 30 min. If it's below 10 deg then it's gonna stay right where it is.

What oil you using . That can also make difference.. Just blip throttle every time you change . You probable could skip 1st to 2nd due to ratios now .