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1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1966 Mustang => Topic started by: drummingrocks on January 15, 2013, 07:02:46 PM

Title: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 15, 2013, 07:02:46 PM
I was working on my 4-speed '66 fastback today, and I realized that ever since restoring the car, I've had the speedometer cable passing through the firewall in the wrong place.  I always thought the cable was a little short, guess now I know why: I had it passing through the hole for C4 and 3-speed cars.

I've got it rerouted to the correct hole transmission tunnel near the gas pedal, but now I'm wondering what originally plugged off the other speedometer cable hole in the firewall for C4 and 3-speed cars?  I wish I had taken better pictures of this area before I restored the car, but that's water under the bridge now.

This is a Dearborn '66, built December 8th, 1965.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: J_Speegle on January 15, 2013, 09:33:51 PM
Any sheet metal work/replacement during the restoration?   Or did a PO have an auto in the car?
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 15, 2013, 11:19:24 PM
Yes, the floor was replaced with a one-piece floor pan, and part of the RH toe board was replaced as well.  The firewall is still original--it hasn't had any work or repair done below the steering column on the driver's side.  The correct 4-speed speedometer cable hole is still in the transmission tunnel, to the right of the gas pedal.  As far as I know, the car has always been a 4-speed car.  According to the original data plate, it was a 4-speed car when new. 

Being a 4-speed car from the factory, would it have even received the hole in the firewall that a C4/3-speed car uses to route the speedometer cable?  I assumed that all Mustangs regardless of options received that hole, and that on 4-speed cars, an additional hole was punched to the right of the gas pedal to route the 4-speed speedometer cable.  Of course, I'm probably way off base--you know what they say about assuming!   :D
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: J_Speegle on January 16, 2013, 07:19:02 PM
Being a 4-speed car from the factory, would it have even received the hole in the firewall that a C4/3-speed car uses to route the speedometer cable?  I assumed that all Mustangs regardless of options received that hole, and that on 4-speed cars, an additional hole was punched to the right of the gas pedal to route the 4-speed speedometer cable.  Of course, I'm probably way off base--you know what they say about assuming!   :D

Not certain all cars got the automatic hole or if no used what would plug it (to keep water, fumes..... out

Need to see if I have some pictures that can provide anything to the discussion - maybe someone with an original manual 66 can check theirs and report
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 16, 2013, 08:05:35 PM
The hole would be plugged with a rubber grommet...
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: J_Speegle on January 16, 2013, 10:38:13 PM
Thanks Charles was just drawing a blank on that one :(
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 17, 2013, 12:55:04 AM
Thanks Charles was just drawing a blank on that one :(

Easy to think the hole wouldn't be there on a 4sp, but seeing it on all original floors no matter what trans.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 17, 2013, 10:43:35 AM
The hole would be plugged with a rubber grommet...

Thanks for the picture.  I feel better knowing that that 2nd hole was in the firewall originally and wasn't made by a previous owner.  Any ideas of where to find a correct rubber grommet?  I thought one of the grommets used to plug unused brake line holes in the front inner fenders might work, but it was too small.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 17, 2013, 11:05:49 AM
Thanks for the picture.  I feel better knowing that that 2nd hole was in the firewall originally and wasn't made by a previous owner.  Any ideas of where to find a correct rubber grommet?  I thought one of the grommets used to plug unused brake line holes in the front inner fenders might work, but it was too small.

Pretty sure it's the same size used in the trunk floors on top.  Pushes in from the interior of the car.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 17, 2013, 01:14:48 PM
Thanks!
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: midlife on January 17, 2013, 10:43:46 PM
Hmmm...I have a 66 that came with a 4 speed, and there's only the hole in the firewall for the speedo cable.  The center hump has not been molested and there isn't any hole there for the speedo cable.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: rockhouse66 on January 17, 2013, 11:04:44 PM
Hmmm...I have a 66 that came with a 4 speed, and there's only the hole in the firewall for the speedo cable.  The center hump has not been molested and there isn't any hole there for the speedo cable.

Ditto.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 18, 2013, 10:30:40 AM
Well, I have 2 '66 examples with the C4 hole, can anyone provide a pic of an original '66 floor without the hole?

Jan '66 Metuchen/March '66 San Jose (both factory 4 speed cars)
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: rockhouse66 on January 19, 2013, 07:19:15 PM
Hmmmm - upon further review, my 9/65 SJ car may have that hole.  Tell me if you agree please.  When I took the car apart, it had a really long speedo cable in it and it was routed through the firewall hole  :-\

Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 19, 2013, 07:31:23 PM
Hmmmm - upon further review, my 9/65 SJ car may have that hole.  Tell me if you agree please.  When I took the car apart, it had a really long speedo cable in it and it was routed through the firewall hole  :-\

The hole we're taking about is further over, right above where the parking brake cable bracket attaches.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: rockhouse66 on January 19, 2013, 08:59:48 PM
Well I'm getting lost as to the location but it sounds like if it were there, it would be seen in this picture.

Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 19, 2013, 09:52:15 PM
Yep, the hole is there in your pic, the brake line is in front of the middle of it.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: rockhouse66 on January 19, 2013, 09:55:18 PM
Thanks Charles. So the hole in the tunnel is the 4-speed speedo cable hole and the one under the brake line was for C4/3-speed cars and should be plugged?
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 20, 2013, 11:01:43 AM
Thanks Charles. So the hole in the tunnel is the 4-speed speedo cable hole and the one under the brake line was for C4/3-speed cars and should be plugged?

Yep, that's right... at least what I have seen so far.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: midlife on January 21, 2013, 10:57:11 PM
Back to the 4 speed hole in Metuchen cars...I had my Jan 6 1966 car on the lift today and examined the area in question: there definitely never was a hole for the speedo cable in that area.  My car originally (I think) came with a T-10, but now has a toploader.  I wonder...since there were two different 4 speeds in 65/66, if the hole is toploader specific or not...
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: JKWilson on January 21, 2013, 11:51:30 PM
I thought my Oct '65 Metuchen car (T10 4spd), only had the tunnel hole. While in the garage today I double checked. Whatta ya know? A plugged C4 hole!
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 21, 2013, 11:55:00 PM
Back to the 4 speed hole in Metuchen cars...I had my Jan 6 1966 car on the lift today and examined the area in question: there definitely never was a hole for the speedo cable in that area.  My car originally (I think) came with a T-10, but now has a toploader.  I wonder...since there were two different 4 speeds in 65/66, if the hole is toploader specific or not...

Randy:  Your car had quite a bit of rust repair didn't it?  I wonder if a previous repair to the toe-panel area on the driver side might have been done around where the hole would be?

Incidentally, the photo I posted previously was also of a Jan '66 Metuchen GT fastback originally with a 4 speed.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: JKWilson on January 22, 2013, 12:39:03 AM
Incidentally, the photo I posted previously was also of a Jan '66 Metuchen GT fastback originally with a 4 speed.

Charles is that the car you had mentioned sometime back about possibly doing another resto blog on?
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 01:42:43 AM
Charles is that the car you had mentioned sometime back about possibly doing another resto blog on?

Possibly, not sure!

That car is painted, awaiting assembly.  Trying to finish putting together a red '65 convertible at the present.  The '66 is next.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: midlife on January 22, 2013, 07:26:57 AM
Randy:  Your car had quite a bit of rust repair didn't it?  I wonder if a previous repair to the toe-panel area on the driver side might have been done around where the hole would be?

Incidentally, the photo I posted previously was also of a Jan '66 Metuchen GT fastback originally with a 4 speed.

Isn't the 4 speed hole in the transmission hump?  That's the area I was checking.  And all of my sheet metal replacement was via patching, not full panel replacements.  The tranny hump did not need any repairs for rust.   My speedo cable did have the foam rubber insert and when I bought the car in 1998, the speedo cable came through what every one is calling the C4 hole in the firewall.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 22, 2013, 11:06:11 AM
Isn't the 4 speed hole in the transmission hump?  That's the area I was checking.  And all of my sheet metal replacement was via patching, not full panel replacements.  The tranny hump did not need any repairs for rust.   My speedo cable did have the foam rubber insert and when I bought the car in 1998, the speedo cable came through what every one is calling the C4 hole in the firewall.

Yes, it's in the transmission hump, to the right of the gas pedal.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 11:27:25 AM
Isn't the 4 speed hole in the transmission hump?  That's the area I was checking.  And all of my sheet metal replacement was via patching, not full panel replacements.  The tranny hump did not need any repairs for rust.   My speedo cable did have the foam rubber insert and when I bought the car in 1998, the speedo cable came through what every one is calling the C4 hole in the firewall.

If you look at the post made by rockhouse with the image above, you will see a brake line running vertically in front of the firewall.  Where the firewall starts to turn down, there is a hole with the brake line sitting right in front of it, that's the hole we are referring to.  Another point of orientation... there are 2 screw holes for where the front parking brake cable bracket attaches to the firewall.  The hole is right above that.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 11:31:01 AM
Pic showing hole circled in red....
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 22, 2013, 12:01:23 PM
Sorry if I'm making this more confusing, but here's a shot of where the speedometer comes through on my 4-speed '66.  You can see the 4-speed cable coming through on the transmission tunnel, to the right of the gas pedal.

4-speed hole:
(http://img43.imageshack.us/img43/3324/photo2hhh.jpg) (http://imageshack.us/photo/my-images/43/photo2hhh.jpg/)
[/URL]

This is the C4 automatic/3-speed hole:
(http://img4.imageshack.us/img4/8920/photo3ei.jpg) (http://imageshack.us/photo/my-images/4/photo3ei.jpg/)

Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 12:15:45 PM
Sorry if I'm making this more confusing, but here's a shot of where the speedometer comes through on my 4-speed '66.  You can see the 4-speed cable coming through on the transmission tunnel, to the right of the gas pedal.


I guess you know that cable goes behind the carpet and not through it???
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: drummingrocks on January 22, 2013, 12:16:28 PM
I guess you know that cable goes behind the carpet and not through it???

Oops!  I'll need to fix that!  So the carpet lays over the cable entirely?  Is the carpet cut at all to make it easier to route the cable? 
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 02:59:29 PM
Oops!  I'll need to fix that!  So the carpet lays over the cable entirely?  Is the carpet cut at all to make it easier to route the cable?

No cuts in the carpet, the cable just rests up against the firewall pad.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: midlife on January 22, 2013, 09:55:36 PM
Pic showing hole circled in red....

Charles: just to be clear: that is the C4 hole, correct?  That's where my speedo cable enters the passenger compartment, both before and after the restoration.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 22, 2013, 10:20:42 PM
Charles: just to be clear: that is the C4 hole, correct?  That's where my speedo cable enters the passenger compartment, both before and after the restoration.

The hole I circled in red in the picture is the typical C4/3sp speedo cable hole.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: jwc66k on January 23, 2013, 08:36:42 PM
I'm still laughing. Through 14 replies did anybody mention the plug's part number, so I will - per Osborn "1966 Mustang Body Assembly Manual", pg12 "377949-S". It's dimensions are found in Osborn "Standard and Utility Parts Catalog, July 66" on pg 58 (my measurements are 0.750D HOLE, 0.100PNL, 1.312OD, 23/64T, BLK RBR). The most common use for 64-66 is the two hole plugs in the trunk over the frame rails. The plug is a common item used on all years to cover control holes.
Jim
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 24, 2013, 12:52:32 AM
Thanks Jim, but I did mention in a previous post that I thought it was the same size used on the trunk floors.
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: jwc66k on January 24, 2013, 04:02:38 PM
Charles,
 You are correct, and sorry about that. My point was that a reference to a part number gives a definitive item, right or wrong.
Jim
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on January 24, 2013, 04:55:09 PM
Charles,
 You are correct, and sorry about that. My point was that a reference to a part number gives a definitive item, right or wrong.
Jim

Absolutely, and thanks for the input as it confirmed my "guess."
Title: Re: 4-speed '66--Plugging Original C4 Speedometer Hole?
Post by: CharlesTurner on April 28, 2013, 12:21:23 AM
Has anyone else ever seen anything like this?

Haven't seen it before and it wouldn't be normal.  Not sure that I would leave it as-is since this may cause the speedo cable to be in a bind and malfunction.