Build Thread Mustang5L5's Build Thread - Stock tach calibration

JKWilson61

Active Member
Jul 27, 2018
121
137
53
Summerville, SC
@JKWilson61 sent me some hardware at one point. And once I get this rear end sorted out, I’ll have plenty of stuff to pay it forward I hope.
This site has been awesome with help, info, humor..... whatever you need, it’s here!
Thanks for the shout out Rdub. Always happy to help out if I can and I know I'm not the only one here willing to do that.

Now...back to Mustang5L5 and your regular programing!:)
 
  • Sponsors(?)


Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
Never posted this but ended up scoring a very clean servo/amp setup from a 1993. It’s mounted on the car. Just need to do tthe underdash work and I’m done.

very easy to do with no fenders on the car.

D10756FC-355A-4C21-9C2B-C9459F8EACD8.jpeg
 
  • Like
Reactions: General karthief

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
Another milestone...

T5 is in. I’m getting too old for this :poo:. Time to convince the wife it’s time to buy a house with a big eboigh garage to install a lift.

523995E0-0B7C-45CB-BBD6-A93D6DD480BF.jpeg


Stifflers X-member in, although I need to send an email on the spacer stack if using the stock exhaust hanger. Their instructions and photos don’t use it

36D529E0-79A1-4E6A-A810-8D7F2C7E46EC.jpeg
 
Last edited:

Rdub6

So while I wait to figure out my rear end issues
Dec 29, 2017
1,977
1,453
123
Long Island, NY
Another milestone...

T5 is in. I’m getting too old for this :poo:. Time to convince the wife it’s time to buy a house with a big eboigh garage to install a lift.

523995E0-0B7C-45CB-BBD6-A93D6DD480BF.jpeg


Stifflers X-member in, although I need to send an email on the spacer stack if using the stock exhaust hanger. Their instructions and photos don’t use it

36D529E0-79A1-4E6A-A810-8D7F2C7E46EC.jpeg
I used the stock hanger with my Stifflers. I’m pretty sure I set it up like you have it, and it worked out ok. I’ll take a look when I get home.
Surprised you didn’t clean and paint that hanger.;)
 

OldManRiver

Active Member
Feb 14, 2015
141
85
38
47
Central Wisconsin
I thought the instructions stated to use one spacer with the T5,but not having the instructions in front of I might be blowing smoke.That said I only used one spacer on my T5 install and measured 4 deg at the balancer.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
I thought the instructions stated to use one spacer with the T5,but not having the instructions in front of I might be blowing smoke.That said I only used one spacer on my T5 install and measured 4 deg at the balancer.

depends on what mount you use, but with poly mount and no driveshaft safety loop it says to run 2

AF275BD4-3005-4BFC-929E-3E8FAB52E965.jpeg
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
Got the rest of my Cruise parts todsy. Just need to install these and that’s it.

Column harness thanks to @General karthief

1441170F-420D-4EC4-84EF-62A2BCF44737.jpeg


This is going to be the tricky part. This slips over the brake pedal and depresses the vacuum dump plunger. Since I have the MM hydroboost pedal, it needs to be redesigned. I’ll likely have to 3D print one
C19C7695-7804-482C-AAD2-3A9A1CEA5B13.jpeg


also, I scored this NOS set of ‘86 Taurus cruise buttons. They are the same as the mustamg except they were mounted horizontal. I was thinking this might look better, but upon mock-up, the mustamg buttons look “right”. I bought these first....but USPS is slooooooow.
86376034-49EA-4246-9B3E-B6CAF2553FFD.jpeg
 
  • Like
Reactions: RaggedGT

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
So my $13 EBay frequency generator showed up. Figured I’d try calibrating the tach.

this is a spare tach I decided to play with. Here are my set values

7C5AC852-1AF6-4FDC-8C20-FBBBC09DB957.jpeg


So this tach was off initially by 400 RPM at 5k. I adjusted the pot, but the upper rpm range is waaaay off.

set point/actual

5000/5000
5500/5800
6000/6450
6500/7000

If I adjust for accuracy at the top end, it’s off at the bottom. My 88 tach only has one adjustmrnt pots. I know 90+ has two. I wonder if I can swap in just the electronics from a 90+ tach in.

2055AE44-71FC-4D93-8F5C-063F2B7CA2C9.jpeg


I have two other tachs I can check. I’m curious if they are all as bad.

at least now I know I can do it.

Here’s what I bought. Might be able to find one on Amazon. I wish I had an O-silly-scope to verify accuracy

https://rover.ebay.com/rover/1/711-...0001&campid=5335821607&icep_item=392993715816
 
  • Like
Reactions: Cheapskate207

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,693
10,858
224
Massachusetts
So, played around with this a bit. Decided to test all 4 tachs I have and see how they differ.

The 4 clusters I have are
Original to my car white face 140MPH
A good spare 140MPH original cluster
My 160MPH cluster
A junk parts cluster. This one I played around with the pot a bit to adjust

Here's how it plots out. The RED line is the standard set value for the RPM. Closer to the red line, the better.

1611682857072.png



As you can see, the junk tach that I played with last night is the closest after tweaking the pot a little. The 160MPH and 140MPH cluster were pretty even. The surprise was the white face cluster. This is the cluster that's been in my car since 1988 and the one i've been staring at for 20+ years. It's off. WAAAAY off. It's one of the reasons I installed the Autometer shift light you might have seen in earlier posts. The shift light would go off at 5400RPM and my tach would be showing almost 7K.

I've also discovered the tach in my 160MPH cluster is a late 1989 tach with 2pots for adjustment. The earlier 87-early 89 tachs only have a single pot. My next step is to get that tach (blue line) as close to the red line as i can.

Anyway, too much geek stuff i guess but i ripped the shift light out, so i want to get the stock tach as accurate as i can in the 5000-6000 range.
 
  • Like
Reactions: Boostedpimp