Alex Jupe's short shift mechanism

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SydneyJules
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Alex Jupe's short shift mechanism

Post by SydneyJules »

ANy of our UK friends tried this?

He doesn't seem to answer emails...
Fixing it bit by bit....

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Re: Alex Jupe's short shift mechanism

Post by mjr »

reduces throw by about 30%, but doesn't address gate slop at all. easily achieved by yourself on standard equipment. push ball up the shift mechanism, replace pivot bush with bronze and a little re shaping of longitudinal rod to clear chassis.

IMO this type of mod, beats ISO hands down. by the time you have shipped to Oz and sent him a whole unit as part of the purchase, doubt you will get much change from 300 odd AUS dollar! for that you could make a stonking custom one yourself

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Re: Alex Jupe's short shift mechanism

Post by SydneyJules »

Thanks MJR! Once I have her back together I'll start on this!
Fixing it bit by bit....

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Re: Alex Jupe's short shift mechanism

Post by GTV27 »

I recommend corresponding with MD on shifting mods - he wrote the book on it!

I personally wouldn't advocate a shorter shift - I think it could make timing the shifts more difficult. More accurate shifting certainly, reocation of the shift position (closer) absolutely, but I don't think the actual distance of movement is such an issue (but I did grow up with 105's, and their gearlever movement is measured in metres :P )
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Re: Alex Jupe's short shift mechanism

Post by brookstroutr »

Hey mjr,

Can you interpret your comments into Yank speak?

"push ball up the shift mechanism, replace pivot bush with bronze and a little re shaping of longitudinal rod to clear chassis."

I went back and forth on my '84 restore with an updated '85 gearbox for the better ratios which was great. I literally went back and forth probably 6 times in 4 weeks switching the iso with the standard shifting rod and finally decided the iso was monkey crap. Not worth the forecasted problems due to it's complicity. Simple was better for reliability. Jeez, I should of just used velcro on the DeDion, etc, it went up & down so much with the gearbox.

gtv27, I'm obviously somewhat familiar with md but what's the deal with his works on this issue?

You're sorta correct about the short shift application. It's better intended for track use. BMWs can be notchy and distractive on street use some depending on the model used. I thought I knew how to shift until I got my first GTV6. An '83 in '84. You've either got it in gear or crunch!!
Regards,

N. G. Brooks Robinson
'84 GTV6
'84 M635CSi

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Re: Alex Jupe's short shift mechanism

Post by GTV27 »

MD totally re-engineered the shift in his gtv6. As this involved close scrutiny of both types of alfa shift mechanisms, I'd say he is well qualified to comment on alternative modifications.

The 'move the ball up' comment is to change the ratio on the lever to give more movement at the box for a given movement by the knob (a picture here would help...).

I agree that a properly set up non-iso is fine. People are amazed how un-bad the shift in my gtv6 is given the reputation these things now have. Its no mx5, but is far from a 'screwdriver in a bucket of marbles'. I may have adapted, but I did some practice laps in a wrx with a short shift kit and it was hard for me to quickly be CERTAIN which gear I'd selected and it was easy to beat the synchro because the movement was so small - maybe with a dog box it would be worthwhile?
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Re: Alex Jupe's short shift mechanism

Post by SydneyJules »

MD was gracious enough to allow me s drive of his immaculate machine, and il say that his solution sits head and shoulders above any other.... But I want to keep it underfloor- I may still want to use my back seat. Mike has a cage!

Ive already got an iso linkage in my GTV, but think I will look at getting it modded down the track- I'm completely comfortable with my shift, but I feel a slicker shift would be better.

Having said that, I wouldn't be too fussed if the shift was left as is!
Fixing it bit by bit....

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Re: Alex Jupe's short shift mechanism

Post by brookstroutr »

Last nite after my post I found an older thread about this issue with I believe md's mutherkation to his shift lever. I couldn't get the full jist as after a long day the cervezas took over. That is quite a lot of effort for what level of mod and yes, SidneyJules, if I had a good condition iso I wouldn't bother to swap unless I had to. I went to the effort to bang the flooring to accept the iso attempt and was a royal PITA on jackstands. Guess how many times I had to check with the linkage and you can't just do it partial. I found that out.

I really didn't notice much of a difference over the iso maybe because I was so greatful to get rid of the horrible 1 - 2 gear ratios. It's bad when you almost get rear-ended leaving a stop light waiting & slowing down for the r's to drop off to not crunch 2nd. I also did some mod to the shifter but cannot remember. Maybe I used a Milano shifter because I do remember having to do some mods to the bottom bush & bolting. I did swap the bolt & nut to SS with a nylon locking nut.

GTV27, now I get the picture on the 'ball' function. The shifter's function is basic geometrics. Ratio of pivot point to leverage length.

Many BMW Club Racer's here would swap their SS kits to the Z3 1.9 ltr shifting parts as it did improve the motion. They complained about your WRX comment and would wear on the synchros. Not worth the advantage level. I'm going to do this adaption in my M635CSi. I've had others and only one manufactured SS Kit was acceptable to me which is now defunct and this kit went when I sold the car.
Regards,

N. G. Brooks Robinson
'84 GTV6
'84 M635CSi

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Re: Alex Jupe's short shift mechanism

Post by Zagato »

If you have problems with crunching between gears 1-2, alfa did adress this problem in the late Alfa 75. For first gear there is a very special syncronisation ring that is threathed for more friction, so the box works much better on quick shifts.
That ring is much more expensive than the normal ones, but worth every penny.
Do not forget to change the syncronisation drum also, otherwise it is only a half cure. If you then have an ISO linkage in perfect shape, and the correct oil in the gearbox, for example Castrol 75-90 Syntetic, you will have a gearchange that is very near any other car!

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Re: Alex Jupe's short shift mechanism

Post by brookstroutr »

Yeah, zagato. The US '81 thru '84 got the horrible 1 - 2 spread and corrected on the '85 MY which is why I went to that gearbox. I'm running Redline Syn in mine and it's light years different over the early box.
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N. G. Brooks Robinson
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'84 M635CSi

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Re: Alex Jupe's short shift mechanism

Post by mjr »

Sorry for the late reply. hopefully by now the other threads gave you a better idea. Some points.

By altering the vertical position of the ball, hence changing the pivot ratio is the simplest mod, and personally I think Alfa simply got the math wrong at the factory. changing this makes a big difference. The shift is so much more precise, assuming your box is in reasonable condition in the first place. What it does not do is shorten the gate gaps. However, I would not touch that anyway, since it would make the box nigh on impossible to use. I found that shortening the pivot ratio seems to make the gate feel more precise too. You will find that it makes the box far more notchy to use than originally. you will fell any little shifting mistakes or imperfections more, becasue you tend to shift more quickly, rather than wait an age with the old system. Hence if you havce any slight crunch between 1st and 2nd it will tend to be amplified, unless you make the effort to wait longer as before. It doesnt bother me. ISO is ok if it's all in good condition, personally I just cant be bothered to rebuild it everytime it turns to jelly. IMO the ISO system goes againts basic rules of engineering, too many moving parts involved and over complicated!! they wear out and feel like rubber bands..

The shorter pivot would also benefit from the entire shifting box being moved aft on the transmission tunnel by 2-4inches.

personally I dont think any more than that is required to make the shifting plenty ok, but each to his own..

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