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MK Gearbox Conversions

Posted: Thu Sep 06, 2007 9:06 pm
by MQfishbucket
Have an '84 MK SWB, L28, 4spd manual. The clutch died today.
Wondering how to replace it, and/or if i can very easily slot in a 5spd manual MK box off a diesel or later petrol, or an auto box of the same age.
If anyone still drives these things or makes it their business to know about them, then your advice would be very much appreciated. Cheers.

Re: MK Gearbox Conversions

Posted: Thu Sep 06, 2007 11:19 pm
by macca81
MQfishbucket wrote:Have an '84 MK SWB, L28, 4spd manual. The clutch died today.
Wondering how to replace it, and/or if i can very easily slot in a 5spd manual MK box off a diesel or later petrol, or an auto box of the same age.
If anyone still drives these things or makes it their business to know about them, then your advice would be very much appreciated. Cheers.

im fairly sure lotsa ppl still drive these things.....



to the best of my knowledge, the 5spd bolts straight up with no problems. yet to do this myself to give you a definate but from all acounts you should have no probs should you go down this path. (rumor has it that marks has a 5spd that has a lower 1st and higher 5th than stock, im looking into it atm coz alower 1st would be tops, if ya can get that then do so)

Posted: Fri Sep 07, 2007 12:24 am
by RMP&O
You need the 5spd from an L28 or at least the bellhousing. But I think you need the whole thing because of the top cover, mounts, ect. 5spd is longer so it won't just bolt right in.

Marks never made a 5spd for the MQ/MK's. They made a 5spd for the G60's which was a custom cast box with Nissan Cabstar guts.

Posted: Fri Sep 07, 2007 12:42 am
by MQfishbucket
Thanks guys. So basically I'll need a wreck or something to do a 5spd conversion, as I'll need driveshafts and all if its longer than a 4spd. What about an auto swap?

Posted: Fri Sep 07, 2007 11:05 am
by pongo
MQfishbucket wrote:Thanks guys. So basically I'll need a wreck or something to do a 5spd conversion, as I'll need driveshafts and all if its longer than a 4spd. What about an auto swap?
Where abouts are you, are you near sydney ?

Posted: Fri Sep 07, 2007 2:53 pm
by Vanne
Oh, and we definiatly /STILL/ drive the old busses around :)
wouldent sell mine for quids!

Posted: Fri Sep 07, 2007 4:38 pm
by MKPatrolGuy
Marks did do an adaptor to fit a Nissan Cabstar 5 speed to the MQ/K transfercase. The Cabstar box had a very low 1st gear but the adaptor is no longer in production.

Posted: Fri Sep 07, 2007 5:07 pm
by MQfishbucket
Actually i'm in perth. Guess that explains why I have the impression not many are left- less people, less cars in general, less old patrols. I can probably remember seeing about 5 on the road since I got interested in them, and saw mine driving around before i got it out of the newspaper. Their scarcity in no way diminishes their greatness though. So can i simply bolt on an auto from a similar model, or do they need different bellhousings and driveshafts like the 5spd?

Posted: Fri Sep 07, 2007 5:31 pm
by macca81
imfrom hobart, with even less ppl, and i cant go a single day without seeing half a dozen of them...

Posted: Fri Sep 07, 2007 5:40 pm
by chabby
The L28 Cabstar 5 speed fits the MQL28 ...the only mod required is to shorten the propshaft.
check www.nissan4x4.co.za

Posted: Fri Sep 07, 2007 7:13 pm
by MKPatrolGuy
chabby wrote:The L28 Cabstar 5 speed fits the MQL28 ...the only mod required is to shorten the propshaft.
check www.nissan4x4.co.za
And get the adaptor that Marks no longer make to fit it to the transfercase.

Posted: Fri Sep 07, 2007 7:21 pm
by MQfishbucket
chabby wrote:The L28 Cabstar 5 speed fits the MQL28 ...the only mod required is to shorten the propshaft.
check www.nissan4x4.co.za
Call me stupid, I can't find a thread on the matter (great site for nissans though). Don't want to start a fight, but do I or don't I need an adaptor?

Posted: Sat Sep 08, 2007 1:24 am
by chabby
Contact these dudes they are in Auzzy anyway and have done this conversion http://www.dellowauto.com.au/main.html

Posted: Sat Sep 08, 2007 7:38 am
by David_S
I have done the conversion from 4 speed to 5 speed on a P40 engine using the 5 speed from a SD33. This is reasonably straightforward as the bell housings are the same. But issues which arose were.

1) Longer front, shorter rear drive shafts
2) Longer handbrake cable
3) Longer speedo cable
4) Transfer lever fouled floorpan and had to be "bent"
5) New or modified rear gearbox mounts
6) Possible extension to 4wd and reversing indicator light leads
7) Front driveshaft fouls chassis crossmember. Some cutting and welding required to get around this.
8) Flywheel spigot bearing had to be modified to suit the smaller diesel gearbox mainshaft. Mainshaft had to be shortened to suit P40

This conversion was relatively straightforward as the P40 and SD33 bell housings are the same. According to my Parts book the L28 bell housing is different - not sure where as I have never seen one but possibly length or bolt patterns. You would need to check this and the dia and length of the gearbox main shaft which fits into the spigot bearing. P40 and SD33T clutches are larger than the L28 and SD33 which might affect the bell housing size.

There were two 5 speed boxes fitted to MQ/MK Nissans the later one having lower first and reverse gears (1st gear 3.897 and 4.222)

Can't help with auto conversion but suspect it would be more complicated. Parts book only lists one housing for the torque converter though.

Cheers, David