+1

My old box was getting quite crunchy in 1st, 2nd & 3rd & was always quite heavy to change.

The new box is very smooth and just slips into any gear-

Marton

 

This is also on my list of things to do. I don't mind the feel of my 84 and love the ratios, but the 1 second wait between high rpm shifts so you don't grind it is annoying

 

If you ever wanted to down shift to 1st @ 25, now you can!

 

There's a lot of stuff that affects gear change smoothness and the apparent function of the synchros. Operation of the clutch is a big one. If the clutch does not disengage completely, the synchronizers are overworked trying to get many more parts spinning at the same speed. Focus on the splines where the disk(s) ride and the splines in the disks themselves. If there is wear on either spline, it can easily cause the disk(s) to continue to drag on the flywheel and/or intermediate plate. The cover may pull back completely, but the trans still sees the input shaft spinning at engine speed. A worn intermediate plate may not pull back when the pressure on the cover is released.

Amother often-overlooked item is the pilot bearing. If it's grumpy with wear and maybe dirt/rust/no grease, it will try to spin the input shaft at engine speed. Synchros need to overcome that 'drag' to get the gearbox sections spinning at the same speed, or they grump and grind.

Last but not least on the list is the hydraulics and the throwout bearing release mechanism. A bit of air in the system. A master cylinder pushrod not adjusted correctly. A worn throwout bearing that doesn't push far enough. A worn or missing bushing or pivot point on the release arm. Any can keep the clutch from disengaging completely.


A majority of synchro 'problems' turn out to be synchro 'symptoms', especially if you can identify and cure the root problems before a lot of damage is done to the snynchros. It's amazing how much better the car will shift when the rest of the parts and supporting systems are set up correctly with the correct parts.

 

Yes Alan, Mark A. did this many years ago and then concluded that it really does not work very well , he modified his GTS gearbox to fit an conventional slip , not a plug and play .... The bolt method does not compensate for heat expansion and easily gets too tight making the car understeer push in tight corners. Even pushing the car in the parking lot the inner rear wheel would chirp if you tried to turn the car .... much like my old 911 with a locked (welded spider gears) diff

 

but, when 1st and 2nd are terrible, and 3rd is perfect, it kind of points to the synchros. Mechanically, the later gear boxes feel very different. its almost like the shifter is sucked into the next gear. I think i rebuilt my 84 box about 3 times over the 12 years i owned it.

mk

 

you mean oversteer?
mk

 

NOPE you turn the front wheels and you continue to go straight , the only way to turn was throttle induced oversteer , pitch it and catch it by spinning the rear wheels I would down shift and dump the clutch at 7,000 RPM or so to rotate the car shift at 8,500 leaving the "corner".