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MG MGB GT V8 Factory Originals Technical - V8 speedo cable

Does anyone know of a outlet for a speedo cable that will fit a Rover gear box and a late MGB speedo.
Jimmy P


Contact Martyn Harvey in Waterloo, Ontario: or his web-site:

He's the Canadian distributor for Clive Wheatley-UK. I've got a lot of the parts for my V8 project from him including a speedo cable for my SD1 'box-MGB speedo.

Great guy to deal with.


Simon Austin


I have used the spedo cable from a Rover P 6, it fits the MgB speedo

I have been building the hole car & the speedo cable for the rover 5sp to ANY speedo in the M.G.s for 20 years. If you would like one E-mail me.
Glenn Towery

I purchased a speedometer cable and ratio adapter from

ACI Engineering
6728 Lovers Lane
Portage, MI 49002

Sent my original cable to ACI Engineering. They built be a new cable which allowed me to connect my original speedometer to a right angle ratio adapter and then to the transmission (GM Borg Warner T5).
Below is the cost break down of the system and a picture.

How I got started was I talked to Tom at ACT Engineering. He had me send my old MG speedometer cable to him so he could get the speedometer connection correct. The length of my original cable was perfect (about 4') so that is what he made the new cable length to. Received the new cable from ACI in about a week and installed it on the car. Went out on the highway and used the mile markers on the side of the road to check the odometer. Worked out that for every mile I traveled the odometer said I traveled about 1.35 miles. Gave this information to Tom at ACI and he worked up a right angle ratio adapter that slowed down the speedometer. I needed a right angle adapter due to the amount of space in the transmission tunnel. Received the right angle adapter in about a week. While I was taking the odometer readings I was also making speedometer observations using a GPS receiver. When the speedometer read 100 MPH the GPS receiver said I was doing 70MPH. Talked to Tom about this and he said he works off the more accurate gear driven odometer to get the ratio adapter right. After installing the ratio adapter on the car the odometer and speedometer are accurate.

Cost Detail


4' Speedometer Cable
with tax and shipping

Right Angle Ratio Adapter
with tax and shipping


Jim Miller

Jimmy, what jim miller says is ok if you wont to spend a lot of money! With the rover v-8 (not the tr-7 4 cyl.) trans. & the 3.4 to 3.0 rear gear ratio you will need no 90 deg. ratio adp. There are 4 diffrent speedo gears that go in the trans. at the end of the speedo cable that will set the 1,000 ct. speedo right on the m.p.h. If you have the tr-7 trans. you can change the speedo drive gear on the output shaft (white) to the tr-8 (black) one. V-B has them for around $10. I think
Glenn Towery

This thread was discussed between 16/02/2004 and 23/02/2004

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