MGB & GT Forum
Speedometer angle drive question
Posted by GWUISTER
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Aug 16, 2017 03:14 PM
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Started today on diagnosing why the speedometer isn't working.
First thing I checked was the 90 degree angle drive and sure enough the connector cable between the drive and the trans was a twisted broken mess.
I got that all dug out and my question is:
It doesn't look like the part inside the drive gear is square to fit a square end cable. Is this short length of cable pressed in in some way?
Of course there had to be a cause for the angle drive to break...Ended up the speedometer was locked up...
Took the speedo apart and the drive shaft was stuck in the housing. I soaked it with some break free and finally got it to come loose. Cleaned it up and will lube it with something. Was thinking of silicone spray since it won't hurt the plastic gears unless someone has a better suggestion.
Thanks
First thing I checked was the 90 degree angle drive and sure enough the connector cable between the drive and the trans was a twisted broken mess.
I got that all dug out and my question is:
It doesn't look like the part inside the drive gear is square to fit a square end cable. Is this short length of cable pressed in in some way?
Of course there had to be a cause for the angle drive to break...Ended up the speedometer was locked up...
Took the speedo apart and the drive shaft was stuck in the housing. I soaked it with some break free and finally got it to come loose. Cleaned it up and will lube it with something. Was thinking of silicone spray since it won't hurt the plastic gears unless someone has a better suggestion.
Thanks
ardvark79 thanked GWUISTER for this post
mgbanthony
Anthony Henderson
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Aug 16, 2017 07:39 PM
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Topic Creator (OP)
Aug 16, 2017 07:50 PM
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In reply to # 3574625 by mgbanthony
Throw the angle drive in the garbage and buy a longer,overdrive cable. Fewer moving parts is always a good thing.
Humm, hadn't considered that. I need to crawl under it again. I suppose a longer cable would allow it to make the bend..
I appreciate the suggestion!
benhutcherson
Ben Hutcherson
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Aug 16, 2017 08:04 PM
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Aug 16, 2017 11:20 PM
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In reply to a post by mgbanthony
Throw the angle drive in the garbage and buy a longer,overdrive cable. Fewer moving parts is always a good thing.
X2 on this advice. Bought a new angle drive, and it got chewed up, too. Then went to a longer overdrive cable, and haven't looked back since. The only problem is fitting the grommet back in the firewall, which is kind of hard.
Aug 17, 2017 03:07 AM
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albeegreen1
bob tresch
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Aug 17, 2017 04:21 AM
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Boris67MGB
Richard Boris
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Aug 17, 2017 07:18 AM
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The Mk1 MGB with 3 synchro without overdrive uses plastic/nylon speedo drive gears. The angle drive s/b used because it acts as a fuse if the speedo gauge/cable seizes. The D overdrive uses metal speedo gears; but, requires an angle drive to prevent speedo cable kinking near a chassis stiffener. Note: this issue is caused by the fact that the D overdrive gearbox is approx 2 inches shorter than the non overdrive gearbox.
about 4 years and 1 week later...
Aug 23, 2021 07:50 AM
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Donthuis
Don van Riet
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Aug 23, 2021 08:58 AM
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For the 1971-1974 build years yes, after this the speedo side small angle drive disappeared again and the cable was rerouted differently
In reply to # 3574647 by benhutcherson
I will just say that I'm running an O/D cable straight into the trans and only have an angle drive on the back of the speedo.
This is a fairly common thing to do.
This is a fairly common thing to do.
Aug 23, 2021 09:38 AM
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Aug 23, 2021 09:59 AM
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Aug 27, 2021 12:30 AM
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Lyle,
Sorry for the delay to your post. When I first read it, I glossed over the part about the angle drive behind the speedo. For a few years as Don van Riet stated, the speedo cable was routed differently for a couple of years. The cable entered the cabin on the right side and traveled to the left side behind the dash to the speedo. The angle drive was needed to make a 90ยบ bend into the speedo. Without that angle drive, the bend is too sharp.
If your car has the speedo cable entering the cabin on the right side and then travels under the dash to the speedo, you have two choices. One is to use the angle drive behind the speedo.
The other option is to drill a hole on the left side of the firewall between the pedal box and the heater. In my photo, which is of a MK1, and was taken when the pedal box was removed for maintenance on the pedal box, you can see the factory hole where the speedo cable enters the firewall. The cable drapes over the bell housing before entering that hole. This gives the cable a straight shot to the speedo with no bends between the firewall and the speedo.
When you stated that the OD speedo cable snapped, I am assuming that your cable entered the cabin on the right side, under the dash to the speedo. The angle was too great, and since there is more torch at the transmission, that is where it snapped.
Sorry for the delay to your post. When I first read it, I glossed over the part about the angle drive behind the speedo. For a few years as Don van Riet stated, the speedo cable was routed differently for a couple of years. The cable entered the cabin on the right side and traveled to the left side behind the dash to the speedo. The angle drive was needed to make a 90ยบ bend into the speedo. Without that angle drive, the bend is too sharp.
If your car has the speedo cable entering the cabin on the right side and then travels under the dash to the speedo, you have two choices. One is to use the angle drive behind the speedo.
The other option is to drill a hole on the left side of the firewall between the pedal box and the heater. In my photo, which is of a MK1, and was taken when the pedal box was removed for maintenance on the pedal box, you can see the factory hole where the speedo cable enters the firewall. The cable drapes over the bell housing before entering that hole. This gives the cable a straight shot to the speedo with no bends between the firewall and the speedo.
When you stated that the OD speedo cable snapped, I am assuming that your cable entered the cabin on the right side, under the dash to the speedo. The angle was too great, and since there is more torch at the transmission, that is where it snapped.
Quote:
in reply to post # 4387554 by lagraves
I tried the OD-length cable w/out angle drive at either end (the one behind the speedo is bad). It worked for a half-mile or so and stopped. Upon examination, the new cable had twisted and had snapped at the transmission. Suggestions?
I tried the OD-length cable w/out angle drive at either end (the one behind the speedo is bad). It worked for a half-mile or so and stopped. Upon examination, the new cable had twisted and had snapped at the transmission. Suggestions?
Aug 31, 2021 07:32 PM
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I think Larry has it right in his photo. The cable should have a straight entrance into the speedo as shown in the picture. An angle drive is used at the transmission to include the required packing washer to prevent it from locking down the cable when tightened.
dickmoritz
Dick Moritz
Philly 'burbs, PA, USA
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Aug 31, 2021 07:55 PM
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