Tony Martyr Posted December 1, 2003 Share Posted December 1, 2003 This is a variation on the 1800 k series crank-shaft fitting theme My new crank has a spigot bearing drilling that is too shallow by about 12 mm to take the full length of the gearbox shaft supported by the spigot bearing. I understand that some up-graders have cut length off the gearbox shaft to solve the problem but it is case hardened and not a nice solution. Looking at the original 1600 crank the hole is 47mm deep and 20mm dia. The 1800 crank I have has a hole only 27mm deep so I propose to turn up a drilling bush in pilot size and for an 18mm drill and take to hole another 18mm deep. I would welcome comments, particularly from those who have successfully done the same job Link to comment Share on other sites More sharing options...
EFA Posted December 1, 2003 Share Posted December 1, 2003 Tony, Chop the input shaft. The 1400cc K cranks with the deep spigot hole were non std - drilled by Caterham so they could use the same 6 speed gearbox spec in VX and K. Cutting the end (neatly) off the input shaft and chamfering shoulders takes about 2 mins with a decent angle grinder. You'll need someone to turn the other end of the box though. Fat Arn Visit the K2 RUM website See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Rob Walker Posted December 1, 2003 Share Posted December 1, 2003 Tony , I agree with Arnie, chopping off the input shaft is the best option. I cut mine off with an angle grinder and chamfered the end took a couple of minutes. It was only the old six speeders that had the long input shaft. I had no choice but to cut mine as I fitted a fully crossdrilled steel crank which had an oil drilling in the end journal, if I had or could have drilled deeper to accomadate the long input shaft I would have broken through into the drilling. Nitrided EN40B is pretty hard to drill is another reason. Link to comment Share on other sites More sharing options...
Rob Walker Posted December 1, 2003 Share Posted December 1, 2003 Tony , IIRC the hole is 22.15mm in diameter and the six speeder input shaft runs in the ford spigot bearing so you need the special Caterham bush to sleeve up the hole to take the ford spigot bearing which is 20.98-21.01mm OD. The depth of the 22.15mm section should be 20.3mm. I chopped 13mm offa my input shaft. Confused Yet????????/ Link to comment Share on other sites More sharing options...
Joe 90 Posted December 2, 2003 Share Posted December 2, 2003 Bear in mind that the hole in the crank has a tight tolerance as it forms the outside bearing surfaces (unless it's bushed). I will be on the road by Christmas. Photos here Link to comment Share on other sites More sharing options...
Lawrence_Z Posted December 2, 2003 Share Posted December 2, 2003 Tony I did exactly as you suggested above The main benedfit being able to swap back to the small engine if/when required. The spigot bearing kit includes a bush/sleeve Lawrence Link to comment Share on other sites More sharing options...
scooby dooby doo Posted December 2, 2003 Share Posted December 2, 2003 Angle grinder and take 13mm off the gearbox shaft is what I did. It means the gearbox will fit any crank in future as well. You need to take some time to chamfer it carefully though - having someone on hand to turn the rear wheels as you grind will make it easier. HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Tony Martyr Posted December 2, 2003 Author Share Posted December 2, 2003 Thank you Guys - what a truely wonderful system this forum is to all of us in our lonely garages faced with taking an angle grinder to an expensive gearbox or drill to a fully built engine. Angle grinder and steady hand it is them Link to comment Share on other sites More sharing options...
Paulo Posted December 2, 2003 Share Posted December 2, 2003 Mesure twice, cut once We're all behind you. Link to comment Share on other sites More sharing options...
Englishmaninwales Posted December 2, 2003 Share Posted December 2, 2003 Does shortening the input shaft (5 spd) prevent reinstallation of original 1.4 as suggested in Lawrence's posting? malcolm Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted December 3, 2003 Leadership Team Share Posted December 3, 2003 Not at all Malcolm. When you remove the 1400, check the end of the input shaft and you should be able to see where it has been running in the spigot bearing - place a new spigot bearing on the shaft if you have one. You'll find approx 13mm of shaft sticking out that spins in free space - this is the bit you need to remove. BTW, make sure you re-gring a good taper on the end of the shaft otherwise mating the engine to the gearbox will be a nightmare. Stu. Link to comment Share on other sites More sharing options...
scooby dooby doo Posted December 3, 2003 Share Posted December 3, 2003 measure about 6 times, cut once worked for me ❗ Hmm.. I wonder how much weight it saved 🤔 HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Englishmaninwales Posted December 3, 2003 Share Posted December 3, 2003 Stu Malcolm Link to comment Share on other sites More sharing options...
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