Jag E-Type Body and Paint Repair

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Larry Kluss
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Re: Jag E-Type Body and Paint Repair

Post by Larry Kluss »

Charged the newly upgraded A/C system today.
That completes this phase of the ongoing rolling restoration.
Ready for the Queen's English event on Sunday. :drive
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Larry Kluss
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Location: Conejo Valley

Re: Jag E-Type Rolling Restoration

Post by Larry Kluss »

Installed a new starter over the weekend as the original unit started making a bad noise right as the motor fired. Turns out the pinion gear clutch went bad, inhibiting proper overrun once the motor started.

Unfortunately I could not locate a clutch for it, let alone any other parts, save for brushes and solenoid. So my choices were a rebuilt original or a new hi-torque gear-reduction unit. The cost was virtually equal between them. I opted for the new GR part from http://britishstarters.com/Home.html. They have GR starters for most British cars.

Starter replacement in an E-type is as challenging as they come. The new unit is a fraction of the size and weight of the original which helps make it easier, though not without its challenges. The mounting flange has thru holes instead of being threaded, the main cable post was 5/16" instead of 1/4", and the auxillary spade connector is smaller than the original.

Once installed, I happy to report that the new starter works very well.
Attachments
The original starter = 23 lbs, GR starter = 8.5 lbs!
The original starter = 23 lbs, GR starter = 8.5 lbs!
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TEAM ROSBIF
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Re: Jag E-Type Body and Paint Repair

Post by TEAM ROSBIF »

Nice, thats what I fit on the twin cam, you will be very happy I am sure !

Hope to see you at the Highland games.

cheers

Mark
WORKS MGA TWIN CAM YD1
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Larry Kluss
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Location: Conejo Valley

Re: Jag E-Type Body and Paint Repair

Post by Larry Kluss »

Mark, I drove the E-type to work all last week (pressed into service) and the starter worked great.

Sorry to report I will not be at the Highland games. I have a lot of commitments and projects going right now, so no more play time. I can't complain as I had a great summer attending many events. :)
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Larry Kluss
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Joined: Wed Jul 25, 2007 12:28 pm
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Location: Conejo Valley

Re: Jag E-Type Body and Paint Repair

Post by Larry Kluss »

This may be of interest to anyone running a Smiths electronic tachometer. When I first got the Jaguar I noticed the tach was reading significantly higher than it should. Like 1200 RPM instead of 700 actual RPM at idle. I recalibrated it (as explained below) and since then it reads fine when the interior of the car is cool to cold. But when the interior is warm to hot the tach reads higher than normal, like 500+ RPM high at 60 MPH. I know this because I have calculated RPM at a few key MPH points to check it on the road.

A while back I came across a great article from a Sunbeam Tiger forum all about repairing these tachs – http://www.classictiger.com/techtips/motach.html" onclick="window.open(this.href);return false; The article talks about various maladies, but one of the common problems is temperature sensitivity or erratic readings. The remedy for this is to replace the .25 MFD capacitor in the tach that can internally deteriorate over many years. This particular component is responsible for the length of the pulse from the coil which in turn moves the needle. The longer the pulses the more the needle moves. Hence, if the capacitor is bad the pulse length will not be correct.

Since .25 MFD capacitors are not readily available, it says you can use a .22 or .27 MFD capacitor in its place since the calibrating pot should have enough range to compensate. I sourced a .22 MFD 63 volt (the voltage rating must be higher than system voltage) capacitor online from Radio Shack for $0.43. Installed it in the tach, and recalibrated the tach. I am happy to report that it is working great and is very stable now.

One good thing is that replacing the capacitor and calibrating do not require disassembling the inner workings of the tach, nor removing the needle. It can be done simply by removing the internal tach body assembly from the case. This is done by rotating the bezel relative to the case until the case notches line up with the tabs on the bezel. Then the bezel will separate from the case. Once the bezel and glass are off, two screws on the back are all that hold the tach body in the case. Try to avoid touching the actual gauge face and especially the needle.

On the tach body assembly you will see the various electronic components including the calibration pot (a small white plastic disc). The capacitors are all marked with their values. There is only one .25 MFD capacitor. Find that part and replace it.

To calibrate the unit you’ll need an auxiliary tachometer of some kind and the tach itself will need to be connected as normal to the wiring in the car, though it must be out of its case in order to access the calibration pot. I used a handheld digital multi-meter with an RPM function as my source for calibration. I cradled the exposed tach body assembly on a towel to prevent damage or accidental component grounding, and reconnected the power and pulse wires to their terminals. My tach is normally grounded through the case to the metal dash. So I simply connected a jumper wire from the frame of the tach body to a ground point in the car. My car is negative ground, so be sure to connect yours properly if you have a positive ground car.

I did the calibration at 3000 RPM which is about mid-range for my car, ran the engine at 3000 RPM on the meter and slowly rotated the pot until the tach read the same RPM. Then I compared it a idle and in between. I then proceeded to road test it to double check the calibration.

To road check the tach calibration, you need to know the exact tire diameter and differential gear ratio. There are tire diameter calculators available on line. The gear ratio you can probably look up in the technical specs for your car. You could jack up the rear end and count the number of driveshaft rotations during one wheel rotation, but I don’t think that method is accurate enough to use for an on-road calibration.

My Jaguar tire diameter is 26.25” and my differential gear ratio is 3.53:1. 4th gear in most transmissions is 1:1, so you’ll want to check your calibration in 4th gear (overdrive off). Calculate your theoretical RPM at 60 MPH as follows:

26.25 in (diameter) x pi (3.1416) = 82.47 in tire circumference.
82.47 in / 12 in = 6.87 ft per tire revolution.
5280 ft (in a mile) / 6.87 ft = 768.6 tire revolutions per mile.
768.6 x 3.53 (gear ratio) = 2713 engine revolutions per mile.
Since 60 MPH = 1 mile per minute, 2713 is my theoretical RPM at 60 MPH.
To find RPM at other speeds, simply use the ratio of that speed to 60 MPH. Example, 40 MPH / 60 MPH = .667.
2713 RPM x .667 = 1809 RPM at 40 MPH.
At 65 MPH; 65 MPH / 60 MPH = 1.083. 2713 RPM x 1.083 = 2939 RPM.
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Re: Jag E-Type Body and Paint Repair

Post by Steve Simmons »

Great write-up, Larry. I had the same problem with the tach in my '65 B some years ago after it was professionally rebuilt. They forgot to change the resistor!
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