Hi. Does someone know if an overdrive from a KCN gearbox fits a JCN gearbox ? I cant find any data about the KCN gearbox. Gear ratio and what Jaguar model had the KCN gearbox Can someone help me
Regards
Jarmo
This may help , I have not read it so don’t know for sure !
http://www.jag-lovers.org/xk-lovers/library/gearbox_reilly/moss_gearbox_identification.html
If I remember correctly, there were two types of Overdrive, both had same interface to gearbox, but another was longer unit, so shorter propshaft was required.
Köpi
Thanks Ian and Köpi. I looked at the link but the gearboxes was older ones in the arthicle.
Köpi. If the interface is the same between the JCN and the KCN gearbox it means that an Overdrive from a KCN should fit to an JCN gearbox. Am i right ?
Regards
Jarmo
Jarmo, you can see from this page:
https://www.scparts.co.uk/sc_en/british-cars/jaguar/jaguar-mark-ii-and-daimler-v8-1959-1969/gearbox-and-overdrive-jaguar-mark-ii.html
that there were 2 types of OD used, A type for Moss (1st gear not synchronized) and C-type for all synchro box. I’m pretty sure (hopefully somebody on the forum can confirm) they both have same interface to gearbox, but if I remember correctly (somebody confirm again, please) they are different length, so you need different length propshaft. JCN is probably Moss, but as KCN is later one, it might be all synchro box. Speedo output can also be different, I’m not sure of that.
Köpi
When I wrote that there weren’t a whole lot of people on these forums, so its missing info on some models, but there doesn’t seem to be an easy way to update it.
I searched saloondata and xjdata and only found 1 car with a KCN box, which was a 240. Another 240 had a KC and some XJs had KFN.
What you posted is correct. Going by my 3.8S with full syncho, the overdrive is referred to as the “compact” type and that is helpful as it can be slid of the back of the gearbox adapter plate with the gearbox insitu. It is necessary to remove the tin cover to the tunnel accessible under the center console to gain access to the upper mounting nuts. Then slightly tilting the engine down at the back allows the OD to be slid off the mainshaft. Do keep in mind when replacing it remove the pump unit so it does not foul the cam that is on the mainshaft when sliding the unit back in place. And as a final note seal very well the adapter plate to OD unit gasket as it is not very wide at the very bottom where it is most likely to leak and drip oil.
Köpi. The KCN gearbox is an all syncro box and i have the c-type overdrive. As i understand there are two types of rear casings for the c-type overdrive. One shorter and one longer version. I have the longer version and shorter propshaft. I think Jaguar made the JCN gearbox if i remember correct. My MK2 had the Moss gearbox from factory but PO change it to all syncro KZN gearbox. I have difficullty getting in second gear when i go from third or fourth gear. The reverse plunger is correct adjusted so it cant be that.
I have a friend who has an rebuilt JCN gearbox and i wants to sell it. Hense my question about the OD.
Jarmo
According to this page:
https://jec.org.uk/forums/viewtopic.php?t=9110
N in gearbox name means it is with OD. So GBN (Moss), KZN, KCN and JCN were all with OD, but I do not know if OD in latter two was same, C-type. Probably yes, but I can’t guarantee.
This page:
https://www.jaguarforums.com/forum/mark-v-x-420g-58/gearbox-identification-puzzle-149675/
tells some names with models but does not say anything about OD compatibility
“From a Jaguar Service bulletin F15 dated 12/66
Mark 10 JZN
4.2E type EJ
Mark 2 JCN
S Type JBN
XJ6 KFN
420 JDN
420G KZN”
Do you have Service Manual? If not, it is here:
http://jagmanual.krissmotors.com/manual.pdf
It has a chapter of gearboxes and OD, but only original ones.
About your problem with 2nd gear, which oil you are using? Have you tried other oils? At least Moss box behaves quite differently with different oils. Paul on this forum recommended Redline MT90 and I have been happy with it.
Read thru all those pages and maybe you find your answer, I’m afraid I can’t help you more.
Köpi
http://www.elisanet.fi/kopik/jag/jagmk2.htm
The Gearbox oil i use today is Castrol EP90. I have tried Redline MT90 to but dident noticed a difference. I have the manual but could not find any answers to my questions.
Thanks for your help Köpi.
By the way. Very nice MK2 you have.
Regards
Jarmo
MTL is very good for boxes without OD.
As they share oil, it is the delicate OD which decides what to use.
I have to correct myself. I have the A-type compact overdrive. Not C-type as i wrote earlier.
I found a number on my OD. 28/61743. Is it not the same number that is on the overdrives mounted on JCN gearboxes ?
Regards
Jarmo
Hi again.
I have been told that the OD from an KCN gearbox does fit to an JCN box. The overdrive from the KCN box is from a Jag 240 2.4 and the JCN gearbox is from a Jag S-type 3.8 -65. Do i encounter problems with gear ratios and so on if i use them togheter ?
The o/d on a 3.8 has 12 springs acting on the friction cone and the o/d on a 2.4 has only 8. Should be no gear ratio issue just torque may be too much if you have 3.8 engine and o/d may slip. I am talking about the standard ‘A’ type overdrive. Assume your JCN has the o/d mainshaft already otherwise need to swap.
Thanks for your reply. The JCN box has the o/d mainshaft. My o/d is the compact A-type from a Jag mk 240 and my Engine is a 3.8. What worries me as you also pointed out is it may slip. On the other hand, i`ve been driving for 2 years with with the 240 KCN gearbox and o/d without notice any slip so i hope it works with the JCN box.
Jarmo