Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Important Service Items Question

Hi Dave, yes, that’s what I originally thought but when I jack up the rear and spin one wheel, the other one goes in the same direction, so on that basis only, I ASSUME that it’s a LSD. The owners manual though only specifies semi synthetic 80w140 and makes no mention of additives.
Interestingly, the gearbox oil is specified as Lodexol, and actually states “fill with 1.7 litres up to the fill hole.” No mention, as often discussed on this forum of the need for 2 litres due to the 8 degree cant of the Mazda gearbox, but mine was one of the very first with the Mazda box so its possible that the manual was printed for the Ford MT 75 box!

I have heard it said before that some ordinary plus 4 models may have been fitted with LSD depending on what the factory had in stock at the time. Have you tested yours?
Regards
Doug

Plus 4"s also got the LSD. I think it's more common than you might think.

Thanks for confirming that Dave.
The worrying thing for owners though is that the owners handbooks seem to be generic so people could unwittingly change their diff oil for one without LSD additives…unless they check first!
As the additives do not appear to upset an open diff. seems that it is best for everyone to use the LSD oil to be on the safe side.

Cheers Doug, I was hoping you'd say that

TBH I've not tested Monty for an LSD yet but it is something I've been meaning to do, if it stops raining tomorrow I'll wheel him out of the garage and get the rear wheels is the air, however, from the way the car drives on the limit I'd be very surprised if Monty doesn't have a limited slip diff.


Thanks Dave, this supports my suspicions and Doug's results when he checked his, as I understand it the VVT Mazda L/Duratec Supersports was released in 2011 and clearly advertised as having an LSD, so perhaps it made sense for Morgan to standardise from that point on meaning all Duratec Plus 4s from 2011 ended up with the same LSD axle fitted to the SS?

It is a guess though, what I do know is Monty was built in late 2011 and first registered in early 2012 as such the car benefits the Mazda MX5 box which really is a delightful transmission to use. Much like the Mulfab front wishbone conversion Monty came with, I freely admit I had no idea about all this stuff when I was bidding on the car. All I knew is I wanted a galvanized chassis port injected Duratec Plus 4 as I felt it was a bit of sweet spot model, to me the direct injection, drive by wire throttle and autophoretic coated chassis of the the later GDI Plus 4 are not improvements.

If it now turns out I also have a limited slip diff as I strongly suspect I do, I'll be delighted as it fits nicely with my attempt to create my own interpretation of a Supersport. A Supersport with a better ECU, a long runner inlet/plenum instead of ITBs, wishbone front suspension….. plus the practicality of an Easy-Up hood and a spare wheel, neither of which I’ve seen on a factory Plus 4 Supersport.

An LSD would just complete the Monty SS spec nicely

Just one point of caution - a friend has a 2007 +4 and the “standard” belt supplied by a reputable Morgan dealer was too short. He was told that the spares manual only lists one belt for the Duratec +4. He eventually got a belt of the correct length. It would seem that there was a change to +4 belt dimensions at some point.

Could be worth a careful look of the belt along its full length to see if a PK number is visible . I have read somewhere online that belts should have a close inspection for wear after 60k miles and certainly be replaced at 90k. Much better than the old vee belts.

On my 4/4 there was a squeal at around 5 years old. I changed the alternator belt and the squeal vanished. I now change the belt at 4 years. They cost so little and are so easy to change, it’s not worth waiting for a failure.

The squealing auxiliary belt was a known issue with the Rover Plus 8’s. Mine did it. It was pretty new when I got the car. I took the belt off, cleaned all the pulleys, wiped the belt clean. Replaced and tensioned and squealed no more.
The belts should have their dimensions printed on them as standard. Have a look and get the identical replacement.

Sadly on a +4 there are (IIRC) two pulleys that the reverse of the belt runs over so any markings are usually long gone before the belt needs changing.

Doing an online search, I came across holley.com and their recommendation is:
with old belt removed and tensioner at rest, pass a length of string or wire round the pulleys in all the right directions, measure its length and subtract 16mm to determine the actual belt length required.
I also read somewhere else that if you cannot find the exact length, up to +/-3% is acceptable.