Tach Drive & Cable Issue
Thread Starter
Safety Car
Joined: Sep 2011
Posts: 4,115
Likes: 1,230
From: Madeira Beach, FL
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Tach Drive & Cable Issue
Hello,
2nd issue I encountered today.
I replaced my tach cable today in my '68 BB.
While the dash was being removed, I forgot to disconnect the tach
cable and yank the crimped ferrule off the tach side of the case.
So I purchsed a new old stock one. Length exact same.
I fished it up hooked it up to the rear of the tach. So far so good.
I go to insert the other end in the distributor.
It is a squared drive and is to large in diameter to fit into the distributor tach drive end. The PO did tell me he had to replace the tach drive.
I saved the old take off cable and case.
The cable end has been modified at the distributor end.
It had been ground down on all four sides of the squared end and smoothed out.
Were there different sizes of tach drives and cables?
I really don't want to have to drop the lower dash again.
Any ideas would be great.
Marshal
2nd issue I encountered today.
I replaced my tach cable today in my '68 BB.
While the dash was being removed, I forgot to disconnect the tach
cable and yank the crimped ferrule off the tach side of the case.
So I purchsed a new old stock one. Length exact same.
I fished it up hooked it up to the rear of the tach. So far so good.
I go to insert the other end in the distributor.
It is a squared drive and is to large in diameter to fit into the distributor tach drive end. The PO did tell me he had to replace the tach drive.
I saved the old take off cable and case.
The cable end has been modified at the distributor end.
It had been ground down on all four sides of the squared end and smoothed out.
Were there different sizes of tach drives and cables?
I really don't want to have to drop the lower dash again.
Any ideas would be great.
Marshal
Drifting
Joined: Jan 2012
Posts: 1,908
Likes: 129
From: Fredericksburg Virginia
I don't believe there are different 'size' tach drive cables.
The good news is that you CAN replace the tach cable without dropping the dash. It is a complete pain in the rear, is easier with a partner (my 7-year-old-at-the-time son did a very good job of helping me), and requires you to do the "Stingray Limbo", a very uncomfortable arched-back keg-stand sort of maneuver with your head in the footwell for an extended period of time.
So there's that glimmer of hope...
The good news is that you CAN replace the tach cable without dropping the dash. It is a complete pain in the rear, is easier with a partner (my 7-year-old-at-the-time son did a very good job of helping me), and requires you to do the "Stingray Limbo", a very uncomfortable arched-back keg-stand sort of maneuver with your head in the footwell for an extended period of time.
So there's that glimmer of hope...
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Hello,
2nd issue I encountered today.
I replaced my tach cable today in my '68 BB.
While the dash was being removed, I forgot to disconnect the tach
cable and yank the crimped ferrule off the tach side of the case.
So I purchsed a new old stock one. Length exact same.
I fished it up hooked it up to the rear of the tach. So far so good.
I go to insert the other end in the distributor.
It is a squared drive and is to large in diameter to fit into the distributor tach drive end. The PO did tell me he had to replace the tach drive.
I saved the old take off cable and case.
The cable end has been modified at the distributor end.
It had been ground down on all four sides of the squared end and smoothed out.
Were there different sizes of tach drives and cables?
I really don't want to have to drop the lower dash again.
Any ideas would be great.
Marshal
2nd issue I encountered today.
I replaced my tach cable today in my '68 BB.
While the dash was being removed, I forgot to disconnect the tach
cable and yank the crimped ferrule off the tach side of the case.
So I purchsed a new old stock one. Length exact same.
I fished it up hooked it up to the rear of the tach. So far so good.
I go to insert the other end in the distributor.
It is a squared drive and is to large in diameter to fit into the distributor tach drive end. The PO did tell me he had to replace the tach drive.
I saved the old take off cable and case.
The cable end has been modified at the distributor end.
It had been ground down on all four sides of the squared end and smoothed out.
Were there different sizes of tach drives and cables?
I really don't want to have to drop the lower dash again.
Any ideas would be great.
Marshal
Both cables are .104" diameter and use the same .104" diameter squared ends. I found its best to insert the tach drive cable into the distributor end of the housing so it can be pulled out easily and lubed without having to take the dashboard apart.
Thread Starter
Safety Car
Joined: Sep 2011
Posts: 4,115
Likes: 1,230
From: Madeira Beach, FL
2024 C8 of the Year Finalist - Unmodified
2024 C2 of the Year Finalist - Unmodified
2023 C2 of the Year Finalist - Unmodified
2020 C3 of the Year Finalist - Unmodified
TBTR,
I did not think the cable was reversable?
Thanks for the diamater. I'll mic the new one.
Keith,
Yeah, Ive been soar for two days.
I yanked the drivers seat.
Cinched my big self under the dropped steering column.
I'm dreading taking the cable out again.
Car has AC ducts so everything has to come out just to see it.
I may get my dremmel out and reduce the new square drive end
to the size of the old one.
It's been one of those weeks.
Marshal
I did not think the cable was reversable?
Thanks for the diamater. I'll mic the new one.
Keith,
Yeah, Ive been soar for two days.
I yanked the drivers seat.
Cinched my big self under the dropped steering column.
I'm dreading taking the cable out again.
Car has AC ducts so everything has to come out just to see it.
I may get my dremmel out and reduce the new square drive end
to the size of the old one.
It's been one of those weeks.
Marshal
Last edited by marshal135; Dec 8, 2015 at 04:16 AM. Reason: more typo's argh
Thread Starter
Safety Car
Joined: Sep 2011
Posts: 4,115
Likes: 1,230
From: Madeira Beach, FL
2024 C8 of the Year Finalist - Unmodified
2024 C2 of the Year Finalist - Unmodified
2023 C2 of the Year Finalist - Unmodified
2020 C3 of the Year Finalist - Unmodified
USA-OSC,
for 1968 unfortuately, the tach and speedo screws on at both ends.
The clip came later on.
Marshal
for 1968 unfortuately, the tach and speedo screws on at both ends.
The clip came later on.
Marshal
Melting Slicks
Joined: Jan 2000
Posts: 3,326
Likes: 523
From: home
Try H&R Radio on 155 York Road, Warminster. They may be able to help or find a place that repairs speedometers- if such a place still exists- and have a new cable made to go inside your original casing.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I don't think the OEM tachometer cable can be put in from the distributor end but after I made a new cable I found it can be put in either way. So I chose to put it in from the distributor end which really makes it easy to jerk out and lube.
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Thread Starter
Safety Car
Joined: Sep 2011
Posts: 4,115
Likes: 1,230
From: Madeira Beach, FL
2024 C8 of the Year Finalist - Unmodified
2024 C2 of the Year Finalist - Unmodified
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Yes, H&R radio has been there forever and remains.
I think if the cable is a standard OD then the tach drive gear maybe
wrong. Last owner told me he replaced it. The cable end I took out looks like its OD was reduced by grinding down the OD on all for sides
and then polished.
A new cable I suspect will be the same diameter as my new one.
Agh, the fun of straightening out someone elses mess.
Marshal
Thread Starter
Safety Car
Joined: Sep 2011
Posts: 4,115
Likes: 1,230
From: Madeira Beach, FL
2024 C8 of the Year Finalist - Unmodified
2024 C2 of the Year Finalist - Unmodified
2023 C2 of the Year Finalist - Unmodified
2020 C3 of the Year Finalist - Unmodified
I see your point now
Definitely easier to service from engine side.
The stock cable has a detent on the instrument side of it
that prevents it from working its way out via the case towards the tach.
I'm thinking about ordering a new 68 tach drive gear?
Marshal