Franknstein
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GTV6 box made of glass?

Post by Franknstein »

I haven't bought my GTV6 yet, but its on the cards. I have test driven two already, one with a lot of miles on it and the other with very few. In both cases I found the gearbox very awkward... in respect of gear changing speeds.

It feels like you need to double clutch when putting in first at idle, and also going into second. What are the general thoughts on this gbox? Is it a badly designed box... or is this just a case of the particular ones I drove having bad synchros or something..? Cant you snap change a GTV6? Do you have to granny shift all the time?
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Post by MALDI »

1) More than likely the synchros were shot, this is very common.
2) The gearbox oil must be warm before fast shifts can be made.
3) Lightening the gears will increase shifting speed.
4) It will never be a very fast shifting gearbox no matter what you do.
5) Enjoy how the gearbox 'talks' to you, its all part of the Alfa mystique.
6) Buy an automatic transmission 75/Milano.
'84 GTV6 3.0L
'81 X1/9
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SimonB
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Post by SimonB »

Trouble getting first from idle could be a clutch that needs a little more bleeding. Every time a garage bleeds my clutch it does this, until they bleed it "just a little more", then it works fine, if the idle is set right.
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Alfettish
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Post by Alfettish »

going into second before first almost completely eliminates the problem.
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Mats
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Post by Mats »

Never judge it by "cold oil performance", i.e. let it warm up first.

You will learn to just leave it in first at the lights, it's the way I have done it since forever.

From my logging data/videos of my races I have come to the conclusion that I can shift as fast as I can move the stick. ~0.4 seconds from accelerating to accelerating, total shift time that is.

Make sure the linkage s in order, the bushing in the lowest point of the stick usually is bad.
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Post by MALDI »

Alfettish wrote:going into second before first almost completely eliminates the problem.
I second this, it is how I routinely do things.

I also tend to double clutch on the street out of habit stemming from the time before my synchros were renewed. (On the track I typically do not double clutch but do rev match as best I can.)
'84 GTV6 3.0L
'81 X1/9
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mjr
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Post by mjr »

interesting topic, since everyone seems to have varying experiences. its weird because I have never ever had to mess with 1st on mine, it always slips in first time without any fuss, yet reverse rarely goes in without a crunch, unless I go to 2nd first.

2nd to 3rd is always slightly sticky, 3-4 perfect, 4-5 perfect, and I sometimes get the hint of a 1-2 crunch, and other times not. coming down the gears is always perfect.

I noticed more imperfections since going to a semi synthetic oil, the thicker oil I used to run, used to hide most of them. I think a good air free clutch and the right oil, and the boxes are plenty useable when warm. anyone run one with lightned gears? how does that compare?
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Post by MALDI »

I have lightened gears (all 5) and it made a noticeable difference (I also had new synchros installed at the same time so it is hard to separate these two effects). Is it the smoothest, fastest shifting gearbox I have ever used? No. But it is noticeably faster and better behaved. The gear lightening machining alone was $75/gear, so $375 total. Was it worth it? Depends on how much the stock 'box irritates you!
'84 GTV6 3.0L
'81 X1/9
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mjr
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Post by mjr »

how much did you lighten each gear by? are you using the original shifer geometry?
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Post by Alfettish »

I've driven a 75 with lightened gears (1st, 2nd, 3rd) extensively and it makes a massive difference. everything feels alot smoother and accurate. FYI I drove it also before the work on the gearbox so I have a before/after comparison.
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Post by Mats »

And I'm sure it was in mint condition before the job? :wink:
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-onemanracing.com-
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Post by Alfettish »

This is more than the feel of new synchros and linkage. I'm sure of it.
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Post by MALDI »

mjr wrote:how much did you lighten each gear by?
For example, 1st went from 1100.3 g to 932.6 g (-15.24%). I did not measure the decrease in rotational moment for each gear but, of course, this is really what you wish to reduce.

mjr wrote:are you using the original shifer geometry?
It has the stock shifter mechanism but with new bushings at the base of the shift lever.
'84 GTV6 3.0L
'81 X1/9
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killaz
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Post by killaz »

Hello everybody! (My first post & question)

Since I'm going to rebuild 4.100 gearbox & install it to mine Milano 3.0, I'm very interested in lightening... Can you please, post advice regarding to lightening 2nd and 3rd also? What is the difference between weight?

And how many miles you made with lightened gearbox (I'm asking in therms of durability)?

Thx in advance!

/Laki

Edit: I've found few topics related to lightening, I saw how ingegnere and Barry did.
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Post by MALDI »

killaz wrote:And how many miles you made with lightened gearbox (I'm asking in therms of durability)?
I do not have the specs for the other gears in front of me, but 2nd and 3rd were about the same percentages as 1st gear. Fourth and 5th were lightened less, on the order of 8% each.

As for longevity, I have 5000 miles on the gear box with no problems thus far. This includes about 6 hours of track time at driver-education events. By the way, the engine is stock so I am not putting abnormally large amounts of power through the transaxle.
'84 GTV6 3.0L
'81 X1/9
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