Help: un1 gear changes

[Howard Jones]

Steward. When you look at the translator, is it vertical. I mean, is it 90 degrees to the horzontal plane of the cables or said another way, 90 degrees to the centerline of the main shaft of the gearbox. I have found that if it is at too much of an angle, either leaning forward or backward, then the car is hard to shift.

The translator is the thing that the cables go to and is clamped onto the shaft comming out of the gearbox.

This really makes a big difference in how well my R21 shifts, check it. I would say that at 50-60 degress or 110-120 degrees I can barely get into 2nd gear on down shifts. At 90 degrees it shifts so well that I don't think about it.

 

[stuart]

No it's not at 90 degrees to the shaft. As it comes out of the box it's at 90 then it's been cut and welded to about 30 degrees different towards the front of the box, I will get a pic of it later.
I can't see how that would make a difference but will give it a try if I can, obviously me gear cables would have to move and I don't know if I have enough slack to move it that much.
I suppose I could go 90 90 so it moves forwards then drops straight down?

How did you find that out?





Also can you go too big on a master cylinder?
I'm thinking if I have to change it I will get the biggest I can, which is a tilton 28mm, is this too big for a 22mm slave? Would I be better off with a 22 or 25mm master?

Cheers

 

[Howard Jones]

Here's a couple of pictures of what I am talking about. Not quite exactly 90 degress but you can see what works for me.

 

[stuart]

couple of things.

i have noticed that it crunches really badly with the 0.75 master and the pedal adjusted so its inline with the rest of the pedals, about 3/4 throw

if i adjust the pedal up higher so i get more throw it crunches a lot less, but still doesnt make it into gear.

so i assume i do need a bigger master
as im going to change it, i might aswell go as big as, 28mm


but i think the synchro for 2nd is now dead after all the trouble, as it now crunches all the time shifting up and down, even if i blip the throttle on the down change, at slow rpms and slow shifting speeds.

so im going to get a new master and synchro then try again.
i will try to straighten up the translator at the same time,
if all that doesnt work im stuffed. lol

 

[stuart]

i spoke to some1 today who told me the un1 box really struggles to change gear at high rpms.
the std renault 21 turbo only revs to 6000, and if you are trying to change gear at 7k+ like i am it just wont.
i was also told that chris cole of mach1 has done some work to stop this.
aparently he has some parts polished to improve high rpm gear changes.
does any1 know if this is true?
and if so, any ideas what parts have what done?

any1 got a contact for him?
ive been told he has retired but still does odd jobs for beer money?

 

[Ian Anderson]

Stuart

see
http://www.gt40s.com/forum/gt40-tec.../30552-un1-un5-release-throwout-bearings.html

IAn

 

[stuart]

I rang chris this morning and he said what I'm experiencing is a common un1 problem when trying to change gear at high rpms.
The STD engine fitted to a un1-013 rev limits at 6200, I'm revving to 7500.
Aparently the box needs some internal work for it to shift well at high revs.

I now have to strip the box again and call him once it's apart and go from there.