Printable View
I recently had a chance to race a Crossle 32 equiped with a Hewland MK6, this was my first time vintage racing, I found the 4th to 3rd downshift to be very tricky, was told by the crew who runs the car "Vintage gearboxes are tricky that way", I lost a lot of time on those downshifts... Can they be restored to be smooth up and down...?
Thank you for your input or suggestions....
I'd guess it's most likely due to shifter linkage adjustment, possibly internal shifter fork alignment. I've messed up the shift linkage in Swift trying to adjust things but I was able to get it back with patience.
The other thing I'd suggest is to really practice that shift. If the upshift is fine, the downshift will be smoother with the exact opposite motion.
This assumes that the issue is with any gears being used and good condition dog rings. Worn dogs can cause an issue. I guess someone put a Mk 6 in that car since it should have come with a Mk9
When I experienced a hard time going from 4th to 3rd (LH sweeper at out track) it turned out to be a broken engine mount that was on the RH side of the car. Moved enough in that corner to cause an issue but was not readily visible in the paddock.
Agreed. Very often it's a linkage issue, not the box per se. Worn apex joints, cracked motor mount (or even frame), linkage not totally free thru all four gear positions, etc. etc. Also the adjustment of the three detent springs (at right side of gear bearing carrier) is critical. If not just the right spring load, shifting can be FUBAR. Screwing one of those in just 1/4 or 1/2 turn can render a box almost un-shiftable. Best adjusted on the bench with the carrier out of the car. Also, if you have an older set of dog rings, even if in perfect shape, consider some new ones. Older dog rings have wider "lugs" and thus less open space between the lugs. Thus less space to get gears to engage. Newer dog rings (RIP Wayne Mitchell) have considerably narrower lugs and thus more space between the lugs for a gear to fall into place.
https://www.apexspeed.com/forums/att...d=114224&stc=1
The gearbox itself is not "smart enough" to do something different between an up-shift or a downshift.
It's is probably a linkage issue or driver error.(seating position, poor U-joints, loose attachment bolts, etc.).
Do not "play" with the three screws you see in the picture. There is more to it then just tension on the rods that have an effect on shifting. Have this attended to by someone who has the carrier jigs and experience.
When everything is correct, shifting a Hewland Mk6,8,9, etc. is no big deal.
What Keith said! Make sure the shifter "U" joints are tight, the bolts are a tight fit in the holes, and the threads are not in the bolt hole of the "U" joint. It also never hurts to make sure the shift forks are not badly worn, bent or loose.