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MG MGA - Sierra 5 speed cable

My speedometer cable broke. Where is a source for a new one. I have a hi-gear 5 speed conversion
Terry Marcus

I have a brand new one that I got with my kit last month from Hi Gear. I also got the Angle adapter and thus used the standard existing MGA cable. I have no use for the longer Hi Gear Kit cable. E-mail if interested.

jferguson at bellsouth dot net

Image is of the angle adapter and standard cable and the reverse switch

Jim


Jim Ferguson

Check with your local speedometer repair shop. They can make you a new cable. Sometimes the quality and price is better from a local shop. I have done this with very good results.
Ed Bell

Jim, is the right angle adapter really as close to the side of the tunnel as it appears in that photo? It looks like the adapter would bump against the sheet metal with any side-to-side movement of the gearbox. Is the adapter sturdy enough not to be damaged if that happened?
Andy Bounsall

Andy,

The adapter has about 1/4 inch clearance but is low on the case and does not hit the side during operation. A support of the cable is recommended by Hi Gear. I mounted a clamp to the transmission just forward of the adapter. (image attached).

Steve Gyles has posted earlier that he mounted a rubber block against the tunnel for support.

The adapter is very sturdy appearing but it is free to rotate in the connection behind the snap ring. That rotation is what the clamp helps control. The Hi Gear instructions call for a clearance on the right side of the case of less than 1/4". The new cross member limits movement effectively.

I am pleased with the installation and have had no problems with speedometer wavering or any oil leaks in the 300miles I have driven.

Jim


Jim Ferguson


Terry, I believe that the firm that makes them for Hi-Gear is www.speedograph-richfield.com in England. I have just ordered the angle drive from them and a special speedo drive cable which is 4" longer than the standard one because the take off point for the Sierra T9 is further back, although the original cable fits with a stretch. You can get an original replacement cable from them directly or even go with the angle drive. If Jim has a new one like I do I would suggest buying it directly from Jim. It that falls through I also have my original speedo cable which came with the Sierra conversion still in the bag unused.


Andy
Andy Preston

I agree that the Sierra cable connection is further back than the MGA Gearbox, but the standard MBA cable will fit without any stress or stretch. The straighter path on the side of the transmission makes up for the longer distance to the connection. It actually fit better and in a more relaxed position than with the MGA Gearbox.

There is a MGB cable that is 6 inches longer available from the usual suppliers, but it is not necessary. I am pleased with the stock MGA cable.

Image of Gearboxes attached.

Jim




Jim Ferguson

Terry

Jim has said it all about the right angle connector and using the standard MGA cable. The right angle connector is costly but, in my opinion, a very worth while mod as there is no wander in the instrument, normally attributable to the modified cable. 3 months down the line, my speedo is still rock steady.

A word of warning if you have a cable made up locally; the inner cable square ends are of different cross section. i.e. the Sierra speedo drive shaft hole is a different cross section to the instrument hole.

Steve
Steve Gyles

>> There is a MGB cable that is 6 inches longer available from the usual suppliers.

I was just looking at the info on Moss & LBCarCo web sites. The MGA cable (331-110) is listed as 66" long. There is also a 69" cable (331-190) for '62-'67 MGB w/OD, and a 72" cable (331-430) for '72-'74 MGB w/OD. Would it be safe to assume that these speedo cables all have the same threaded ends?
Andy Bounsall

Thanks to everyone for their comments regarding my spedometer cable. It appears that I have seveal options. I wouold like to install the 90 degree adapter as it appears to be a better install. If someone has the part number to order from speedograph-richfield I would appreciate it.
Terry Marcus

Terry, according to Steve Gyles, the correct part number is RGB1030/03A. See this previous thread - http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=archiveth&subject=6&subjectar=6&thread=2008082320080913463
Andy Bounsall

keep in mind that the cables hav different length for LHD and RHD MGAs

Siggi
Siggi

The cables and lengths I asked about would be for LHD. Can anybody confirm that the screw connectors on the ends of the MGB w/OD speedo cables are the same as those used on the MGA?
Andy Bounsall

Andy

This has been asked before and the answer seems to be yes. See here: http://www.mgbmga.com/tech/mga4.htm

Steve
Steve Gyles

Andy,

As Steve said, yes they are the same. I got the MGB cable thinking I would need the extra 6" length. I can confirm from testing that the connections are the same.

As it turned out with the angle adapter the origional MGA cable is a perfect fit on my LHD car. Steve had indicated it was a stretch on his RHD car, but worked.

Jim
Jim Ferguson

Steve, Jim,
Thanks for that info. I've ordered a right angle adapter from Speedograph Richfield and thought I might need a longer cable. It's a LHD car, so it sounds like the original cable should be OK. In the unlikely event that it's not, at least I now know what to get.
Andy Bounsall

Terry the angle drive part number that Andy Bounsall stated is for a 1:1 ratio for the angle drive, and so there will be no correction to the speedo. It will read slow. It's possible to calcualte the difference between the original gearbox drive shaft revolutions to the speedo drive revolutions against the Sierra T9 and order an angle drive which will correct the speedo calibration. According to my research on the origainal MGA gearbox, in fourth gear (direct drive) there are 12 driveshaft revs to 5 speedo drive revs a ratio of 2.4 driveshaft revs/speedo rev. On the T9 there are 7 driveshaft revs to 2 speedo drive revs, a ratio of 3.5 driveshaft revs/speedo drive rev. Therefore with the T9 the speedo will show a slow speed. If you divide 3.5/2.4=1.46 you should get the correc ratio for the angle drive. Speedograph Richfield make an angle drive with a 1:1.5 ratio that should work. However on my car I'm using a radial tire, 185/65R 15 which has a smaller diameter and rolling circumference than the origianl crossplys. The origianl tires were 25.5" dia and my new ones are 24.4" dia. This is a reductioin of 0.96 which changes the ratio to 1.46x0.96=1.4. Therefore I ordered an angle drive with a 1:1.4 ratio, part # RGB1030-09A 1:1.4 NR. You can find all the differnet ratios on their website. It's going to be at least 3 months before my car is back on the road so I won't know if my calcualtions are correct until then.

hope this helps,
Andy 60 Coupe almost done.
Andy Preston

Andy, your calculation sounds pretty close to me. After installing my 5 speed, I had to have my speedometer recalibrated from the original 1440 tpm to 1050 tpm. If I've done the math correctly, a 1:1.4 right angle adapter would've put the original speedo calibration back very close to the correct reading.
Andy Bounsall

I went for the 1:1 because I had already recalibrated the speedo - twice; first for the initial 5-speed conversion and then again after fitting a 3.9 diff.

Steve
Steve Gyles

I have a 1600 with the Hi Gear 5 speed conversion. My speedo has been rebuilt by Speedograph and double checked by them twice but I still get violent variations in the speedo reading - it jumps up to 20 mph. I have looked at getting some new cables made with the correct sized inner but this will be expensive. I had therefore decided to get the Speedograph angle drive and re-route the cable inside the tunnel but have not yet done this. Then a friend pointed me to this thread which I have read with interest.
My calculations estimated that the top edge of the angle drive would only just clear or possible even touch the side of the propshaft tunnel. This concerned me because as commented on already it would not be good practice to have any friction between the unit and the tunnel because of the movement of the gearbox. I had therefore decided to enlarge the existing opening in the tunnel and after completing the installation of the angle drive to cover this enlarged opening with a piece of 1/8 inch thick rubber secured in place with a metal frame and scews. The advantage of this is that the if the angle drive touches the rubber it will give and not cause any significant friction. Installation and subsequent removal of the drive, if necessary, will also be easier.The rubber cover would not show under the carpet.
I had also calculated that I would need a cable about 4 inches longer than the standard original MGA cable - do you agree with that Steve or have any comments on what I had proposed before I proceed.
Thanks for your help.
Terry



T Holden

Terry,

I see nothing wrong with your plan but it probably is not necessary to the use the rubber cover. Peter Gamble recommends cutting a larger access hole for installation of the angle adapter but with a solid cover plate. If the transmission has the clearance on the right side as he specified in the Hi Gear instructions the adapter is close but does not touch the tunnel. Cable support at the transmission is very important. (I installed the adapter without any holes in the tunnel.)

The adapter edge is below the drive line of the transmission and engine torque actually rotates it away for the side. The rear crossmember mounting also limits any excess movement.

Jim
Jim Ferguson

Terry

My memory is fading a bit about my fitting process. As I recall, I had to cut a bigger hole in the tunnel wall than that required for the normal 5-speed drive arrangement, but this was so that I could actually locate the right angle drive into the gearbox offtake. Otherwise, there is a geometric lock because of the overall small clearance between the gearbox and tunnel wall I then fixed a removable plate over the hole. It was backed with soft rubber to provide some additional support to the drive body. The angle drive body tilts down slightly. i.e. it is not parallel (vertically) to the tunnel wall. You will know this already from the way the existing cable ordinarily enters the cockpit through the tunnel wall.

If the installation is done with the tunnel wall removed, there is no need to cut any holes.

The standard RHD original cable is just long enough. If it ever breaks I will probably get a replacement that is slightly longer.

I did have some speedometer swing before the modification - about 10mph at higher speeds. It is now absolutely rock steady.

Hope this helps

Steve
Steve Gyles

Terry, my angle drive arrived today. It only took about 4 days from England to California. That's quicker than anything else I know. I have installed the angle drive and added a support through the previous gearbox support that works really well. The clearance to the side of the tunnel is probably around 1/8". I'll attach 3 pictures in the following emails. It looks great.

Andy 60 Coupe


Andy Preston

Terry, here's the one from the top of the tunnel, btw I painted the inside of the tunnel with silver paint to help reflect the heat.


Andy Preston

Terry, here's the shot from the bottom of the tunnel. Looks pretty tight.

Andy


Andy Preston

Andy,

You will be glad you got the angle drive. I installed mine along with the retrofit of the 5 speed. The clearance of my drive-to-tunnel side is slightly more than you show. I did not remove or cut any holes in the tunnel for the installation. The hardest part was getting the snap ring seated.

I would advise you to put the holes of your snap ring at the bottom. You may have to remove it after the tunnel and everything is together. No way with the holes at the top without damaging something.

Jim
Jim Ferguson

Andy

Looks good. So much easier to install with the tunnel removed.

Steve
Steve Gyles

This is a somewhat delayed thank you to all of you for your help. I am currently finishing a new engine and rebuilding another gearbox for my J2 and when this is in I will get back to sorting out the A speedo problem using the angle drive and new cable. WIll report the outcome in due course.
Terry
T Holden

This thread was discussed between 18/11/2008 and 04/12/2008

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