Need help with instrument bezel

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10-04-2009, 08:16 PM

#11

2+2GT

6th Gear Member

Join Date: May 2009

Location: PA

Posts: 5,232

A little-known fact is the gauges are usually adjustable, through small holes in the back of the gauge, using a small torx or phillips tool on the tiny gear teeth. It's just a real pain to do, because the gauge has to be connected but not in the cluster.

10-04-2009, 11:30 PM

#12

xian67

2nd Gear Member

Thread Starter

Join Date: Jul 2007

Location:

Posts: 281

Quote:

Originally Posted by kalli

when the fuel gauge doesn't show correctly it could be the sender in the tank or the connections simply corroded.
check the connection at the fuel sender first of all. this is out in the open and craps up first
. disconnect that cable at tank with ignition on. you should show either show full or totally empty.
then put that cable directly to ground on chassis or tank. it should now show the complete opposite.
If that's the case the fuel gauge is ok. if not then it's either gauge or the cable leading to it having a bad connection somwhere

a speeedo showing too much or too little can be caused by improper gearing ration for the driven and drive speedo gear in trans. maybe someone changed rear axle ration that will throw it off.
So if your speedo is too slow or too quick the problem is 99% not the speedo itself.
If it doesn't work at all make sure that the speedo cable isn't broken. drive a few meters with speedo off and look at the speedo cable. does the inside turn?

what I'm saying is. don't spend any money on speedo/tankgauge repair. I'm nearly certain they are ok. one of them is mechanical, the other electric

My uncle did what you mentioned about the sending unit and what you described is exactly what happened. So it's just a bad connection some where?

As for the speedo, the rear axle hasn't been changed. The speedo does work it's just 5-10 miles off.

10-05-2009, 12:43 AM

#13

hiboostwoody

3rd Gear Member

Join Date: Aug 2009

Location: Washington

Posts: 723

Sounds like a bad connection. They work on resistance so if you have a bad connection , the resistance will be all screwed up. As for the speedo, you likely have the wrong driven gear on the transmission end of the cable.

10-05-2009, 04:44 AM

#14

kalli

6th Gear Member

Join Date: Oct 2006

Location: Cork, Ireland

Posts: 6,417

Quote:

Originally Posted by xian67

if you did the grounded and disconnected test and the needle went all the way to full and empty I'd say the gauge and wiring is ok. problem is connection at fuel sender or the sender itself.

as for the speedo. if it's 5-10 miles off (let's say at 60mph), then the speedo is perfectly fine. You just need to match the little plastic gears at gearbox where the speedo cable connects to gearbox. a change of tyre size might have thrown it off.

There are formulas online, but there's people who have experience using and changing them (never did it, only know the theory).
There's 2 plastic gears. one is in the box, the other at the end of the speedo cable (at box end). swapping them will simpley make the speedo cable go slower or quicker. This is what you need to adjust

Kalli

10-05-2009, 10:22 AM

#15

Stepman

4th Gear Member

Join Date: Mar 2004

Location: Az

Posts: 1,090

Quote:

Originally Posted by AJ_68

Just recently I had my mechanic replace the fuel tank and sending unit on my '68 FB. I went with the more expensive stainless sending unit. He said it Ohm'd out correctly, but the fuel gauge wasn't registering properly. He tried adjusting the float but couldn't seem to get it right. It shows "empty" a lot sooner than it should. It sits at "F" when the tank si full. This might be pretty vague, but anyone know where the problem might lie?

I think everyone has thrown in all that can be said but, thought I'd add this.

I believe the problem is that these vendors are making a part that works, but sacrificing accuracy.( I guess it's cheaper that way) I bought one of the cheaper ones a while back and had the same issue...it's not accurate on the empty side. I filled up and it went almost to full but when I drove it to empty, I still had a 1/2 tank left. So, I ran out what I thought was in it, then adjusted the float arm. Then I repeated the process. I quit after like 3 attempts but I got it to where it reads just above full when full and when it hits empty, I have about 4 gals in the tank. That's close enough for me because I don't like to go below 1/4 tank before I fill anyways. I'm sure if I kept going, I could get it closer though.

BTW, with the the sender out of the car, it ohmed out correct.