Speedometer cable

[Vinman1]

Hey all,

 

Has anyone sourced a speedo cable for a Seven with Rocket box trans and Smith speedo. I am told I will need a right angle drive too? The trans has a fork type clip to hold in the large cable end, internet search shows all threaded type and adapter to go from Ford to GM.

 

Greatly appreciated,

 

V

[MV8]

There is a driven gear to engage the output shaft that comes in different tooth counts/colors to match the axle ratio and tire size to turn the cable 1000rpm at 60mph for calibration, a drive gear housing to hold the driven gear and seal the opening which needs to be an adapter with threads added to engage the angle drive, a fork to hold the housing on the trans, then a 90 degree angle drive box. The only special part is the angle box. I don't know what they normal driven gear tooth count is or if there were different ratio angle drive boxes used. The driven gears, housing adapter, and angle drive are shown on this page:

https://kelvedonlotus.co.uk/product-category/ford-2000e-gearbox/gear-box/page/8/

Domestically, angle and straight ratio changing or rotation reversing boxes are available for custom ordering but would probably require a custom driven gear housing adapter to install.  

[Vinman1]

MV8,

 

That is great! I did not know about that supplier!

 

Cheers,

 

V

 

 

[NSXguy]

you can get the angle drive and speedo cable (they have different lengths) from Burton power. The angle drive was out of stock for sometime but it is back in stock now. 

-Des. 

[Vinman1]

This is the input. Not finding any right angle adapters with this type of cable input, only threaded type. Did find an adapter to go from this Ford type to 7/8" GM. Might have to do in two pieces? Will send pics to Kelvedon..

[MV8]

Those are standard domestic ford parts (a bonus imho for adapting and calibration). I guess your speedo uses a gm cable. I've spliced different mfg cable types together (most recently suzuki cable and speedo to gm) but you won't need to do that.

Axle ratio and rear tire size? What color is the gear on the trans output? Count the teeth straight across the gear horizontally? Probably 6-7 teeth?

[MV8]

Don't buy anything yet as these parts may not be the best choice depending on a few variables.

Ford gear housing to gm cable adapter ($16):

https://www.ebay.com/itm/Ford-speedometer-sender-adapter-change-GM-to-Ford-type-/261007138948

GM 90 deg drive, 1:1 ratio ($52):

https://www.ebay.com/itm/325356595192?hash=item4bc0c3a7f8:g:TWMAAOSwtlhWFouF&amdata=enc%3AAQAHAAAAsFdvds12uqTAgGmE8W28O%2B3RjAcjNYJ79r%2Fyx8eoeuU0bxigrze%2BWUHPisOaE%2Fnrjw4ETpP75cGn%2BMD0%2FVz4bvzq41f6Nrxunaa7k57CnD52Nmu4VjwbbK4rlD49KYk2iczf5RVdYmGwurYR%2FxP1TeNun9czlMPyKdw6gHpZLUhe8aPqFlAvq0OGwKpl4MVRJzlxJtE%2B%2BFsbWnHiuh%2BilSD%2F2FzWJp3O51BKGCYNdoNn%7Ctkp%3ABk9SR5anu-bvYA

Your existing driven gear is white which indicates 17 or 23 teeth so the drive gear in the trans is probably 6 teeth. 6/17= 0.353:1. If you have a 4:1 diff and 185-60-13 tires, that ratio would be as close as you can get with a 1:1 angle drive at the limit of adjustment and reliability with oem gears (truck like axle with tiny tires) but the ratio could be adjusted in part or whole with the angle drive.

To check the cable direction of rotation, install the old drive and rotate the input shaft clockwise as viewed from the front in gear. The driven gear looks like standard rotation for a common driver's side cable output but there are reverse rotation driven and drive gears depending on application. The cortina speedometer itself may be reverse rotation. Angle drive adapters can also reverse rotation. I expect your speedo is standard cw cable rotation. You can check this with a drill and a short piece of vacuum hose to slip over the cable end or, if the cable is straight for low friction simply rotate the cable end with your fingers while observing the speedo needle direction of movement. A pic of the drive gear on the trans would help too.

[Vinman1]

MV8,

 

Great info there, appreciate the knowledge sharing!. Will count trans gear teeth, take pic, and do the calculations. Speedo is Smiths from an MGB.

 

Best,

 

V

[MV8]

The tire and axle ratios were just an example where a 23 tooth driven would work. Rereading, I don't think I was clear about that.

I'd rather have longer legs for a touring car to get on the highway; probably around 3:1 is a good compromise with no overdrive considering 13 or 14 inch tires. If you mostly stay on an island versus interstate highways where everyone is going about 70+, Consider something numerically higher for more torque multiplication. Imho, it really needs overdrive to do everything well with tiny tires and push rods.