Correct mounting position of 1962 Sun Tach sending unit on fender well.

Lou Small Jr.

Lou Small Jr.

Member
I'm installing the tachometer sending unit on my 62 Impala SS 409. I got Show Cars #4037 1961-2 Tachometer Installation Guide. Within the guide the copy of GM assembly drawing 3777100 has had sending unit dimension in View A for height above wire harness retainers cut off by copy machine. Anyone have a clear copy of this? Mounting is above main wire harness on fender well, .84" forward of rear harness retainer, with a 6.00" hole spacing for the sender. I estimated missing dimension from other dimensions on drawing but the sender is too high and hood hinge spring will hit sender when closing hood. In a online search of tachometer sender mounting photos almost every car has sender mounted below the main wire harness on lower fender well yet this drawing clearly shows it to be mounted above the harness. Getting car ready to attend the Car Craft Nationals in Milwaukee, Wisconsin on 7/17-18-19/2015. Any help would be appreciated.
 
62impala409

62impala409

 
Supporting Member 1
The '61 senders were mounted above the harness. For the '62 cars, the sender is mounted BELOW the harness. Phil Reed sent me the hole dimensions from an original tach car inner fender. This is where the sender is located. Personally, I don't know how consistent these boxes were mounted coming down the assembly line. I am thinking the workers were not going to measuring with a tape on every single car when they only have seconds to do their job. IMG_0430.JPG
 
Lou Small Jr.

Lou Small Jr.

Member
Thanks for the info. That sucks because I already drilled the (2) mounting holes in my pristine fender well above the harness only to discover hood springs don't clear it. I enclosed a photo of a 62 409 car showing it mounted close to what your saying I took of a guys car that seemed to have done a lot of research about it, I also scanned the Assembly drawing Show Cars sent me showing it mounted above the harness. So your sure it goes below on a 62? Too bad this info being sent out isn't accurate for the model year. I got the same assembly drawing from both Williamson Instrument who did my tach and Show Cars. Have to figure out how to hide the holes I guess! Hope the grommet hole location is correct since that one is drilled also and seems in a good location. Lots of variations of that location or wires put thru other grommets is see in researching photos also.
100_1048.JPG 409 tach sender assembly drawing.jpeg
 
Lou Small Jr.

Lou Small Jr.

Member
Does anyone else have the exact correct mounting location or assembly drawing for tachometer sending unit on a 1962 Impala SS 409 car?
 
62impala409

62impala409

 
Supporting Member 1
That drawing is interesting. Is that the ShowCars drawing? Looks to be for the '61 cars because the inner fender liner is shaped differently on top. My '62 assembly manual shows a similar drawing but does not include the transmitter box location measurements.
 
Lou Small Jr.

Lou Small Jr.

Member
Yes, same drawing sent to me by Williamson Instrument & Show Cars. I should have asked this group for help sooner! Williamson also sent a incorrect harness so I'll need to get Show Cars harness that is complete with tach light bulb & correct connectors into fuse block. I do have to say though that Williamson Instruments tach & sender are pristine restorations absolutely stunning! You just have to do your homework on the rest of the installation! Appreciate your help on this!
 
62impala409

62impala409

 
Supporting Member 1
Our own Phil Reed, an esteemed restoration shop owner in KS helps us out regularly on this forum. Phil sent me these measurements off an original tach car inner fender and I put them in my file. This is the document I scanned. sender drawing.jpeg
 
Last edited:
Lou Small Jr.

Lou Small Jr.

Member
I went on the Mecum Auction site & looked at all the 61 Chevy engine bays photos sold. Only one had a tach & sender but it matched that assembly drawing I posted exactly, mounted above the wire harness. On some of the others sold I could see the different fender wells with those dimples at the top shown on assembly drawing. So it is a fact that the drawing I posted is "ONLY" for a 1961 car.
 
tripower

tripower

Well Known Member
Supporting Member 2
62impala409 said:
I found my drawing from Phil Reed. I will attempt to scan and post it shortly.
Click to expand...
That is defiantly the 61' tach installation diagram. Didn't the 62' use the 61' shop manual with a 62 supplementary manual? Maybe that is why the 61' tach diagram is the one being sent out? Was there a tach diagram in the 62' supplementary manual?
 
pvs409

pvs409

Well Known Member
Supporting Member 11
I also have an original inner fender off a 62 factory Sun tach car. The holes are very similar to Phils drawing.
My inner fender has the factory tach holes about 1 " to the rear of the wiring holes in the inner fender at the same vertical location.

Paul
 
62impala409

62impala409

 
Supporting Member 1
tripower said:
That is defiantly the 61' tach installation diagram. Didn't the 62' use the 61' shop manual with a 62 supplementary manual? Maybe that is why the 61' tach diagram is the one being sent out? Was there a tach diagram in the 62' supplementary manual?
Click to expand...
Dan, the '62 assembly manual uses the '61 drawing of the inner fender and firewall/dash area. The difference seen in the '62 assembly instructions is that the transmitter holes in the '61 inner fender drawing have been eliminated. I scanned the only 2 pages provided in the '62 manual. No transmitter mount hole mapping provided. We are stuck with Phil's info. Scan 9.jpeg Scan 8.jpeg
 
Last edited:
62impala409

62impala409

 
Supporting Member 1
pvs409 said:
I also have an original inner fender off a 62 factory Sun tach car. The holes are very similar to Phils drawing.
My inner fender has the factory tach holes about 1 " to the rear of the wiring holes in the inner fender at the same vertical location.

Paul
Click to expand...
Paul, I mentioned before that unless there was a fixture or template of some kind used, those transmitters were probably eyeballed into position as the car came down the line. Those fellows (bless them) had a few seconds to get their task accomplished and move on to the next car. Hard to believe there was a guy running around with a tape measure being annal. That's my story and I'm stickin to it.:brow
 
pvs409

pvs409

Well Known Member
Supporting Member 11
I am sure you are right. I have seen the transmitters on 62's on the firewall and the top of the inner fender not even close to the locations we are noting.
Paul
 
You must log in or register to reply here.
Top