LT77 & R380 Morgans Speedo Gears - Plus 8s from 1977-2004, Plus 4s from 1987-2000
by Lorne Goldman

As time passes some wines and some Morgans stand out from the others. Their value increases and owners put more money into them than other models. This is true of the Classic Plus 8 line which sadly ended its 36 year run in 2004. As if it was a sign, the Plus 8 Anniversary Celebration in 2003 was the last Morgan event that Peter Morgan attended before his passing a few weeks later.

The model is infinitely flexible, giving owners more options for personalization, while maintaining its essential character, than any other Morgan. For example, bhp can be tweaked anywhere within a range of a stock 140ish to a Class A Morgan Challenge Racer at something around a race reliable 375bhp, though pleasant road car power tops out around 280 bhp.  Rob Wells is correct...with stock size tyres one cannot get the power to the ground beyond that, so why bother unless you are a hot rodder?

Like other affectionatos, I have been saddened in the last two decades to see drop in owner interaction with their Morgans. Is it a new owner demographic? Hands-off technology or an aging  population? Much of the lore of these machines seems to be disappearing. Yet with power enhancements and tweaks still going strong, the lore is still vital.

THE RIGHT SPEEDO GEAR

Driven Gear Assembly I have recently been approached with questions of how to get a speedo to match the real speed. The age of GPS has made owners more sensitive to speed anomalies. A short tale! When the Factory and I were rebuilding my Plus 8, I noticed after the 2-3 test run that the speedo was too slow. I had fit the car with a more agressive BTR ratio.. 3:45:1 (rather than the 3:23 or the 3:08) on the advice of a number of UK dealers I trust. Of course, the speedo was off....showing a faster-than-reality speed by 11%. When I reported this to a racer/dealer I most respect, he replied, "Perfect!". (GRIN!)
Despite that wise advice and being a stickler for perfection, I pressed on.

The LT77 and R380 were used in a wide variety of vehicles with a wide variety of rear ratios, and power ranges. Of course, Morgan was the lightest cars that had them, and because of that, and the lack of load, these boxes can be bullet-proof in a Morgan, especially  the S version of the LT77 (last one) and the R380s fit after February 1999. There is no need to fit a non-Morgan box in anticipation of more power. Admittedly, the stock ratios married to more power, makes the Plus 8first gear ...er...unnecessary. Indeed, the nature of the stock gearing makes my best 0-60s from a second gear start.

As for the speedo, the mentioned variety of instruments and vehicles gives the owner low cost non-onvasive options for these boxes.. No need to spend silly money on electronic fit-all adjustable senders and speedos made to look vintage.Like most other gearboxes, the LT77 and the R380 have an incorporated, easily accessible assembly consisting of a transmission turned cable that attaches to the rear of the speedo...(often interfaced on the way with a speedo transducer mid-way that gives a speed signal to the ECU). However, with the LT77 and  R380, there are five different gears offered. Each have a different number of teeth and send a different speed signal to the speedo (and/or the ECU). They each have a different number of teeth so they turn the cable at different speeds.

They come in different colours and they can be changed in minutes. Last time I checked..they cost 10£ each.


 
COLOUR TEETH
PART NUMBER
ORANGE 20 219001
GREEN 21 219002
RED 22 219003
BLACK 23 219004
YELLOW 24 219005
WHITE 25 219006

WATCHPOINTS

1. Aside from their colour, they all look the same and slip into the speedo gear assembly as shown in the images.

2. Unless you have changed your gear box from standard, the gear you need will depend on the final ratio of your rear axle. See table below.

3. In any event, your existing gear will give you a good idea of what you need as a replacement. Each extra tooth represents approximately 5% more or less speed on your speedometer.

****4. Be careful!!! The LR drive gears are different, in color/tooth match, and part number [the LR stuff begins with "FRC..."] Make SURE whatever you buy looks like the gear you have already!

5. Your speedo can malfunction if the speedo cable bind, at either end. Make sure that you replace the assembly and fit the holding clamp carefully and tightly so this does not happen.