@550 Phil posted:I have a GPS speedometer so hopefully that is accurate. Assuming I should measure the diameter of the rear tire for the calculation?
You can download a quick/free GPS app to your phone and verify your speedometer. They are usually SPOT ON, BUT when first set up you have to set the proper pulse per mile (PPM) in order for it to be accurate. It can be off slightly (or a great deal) if that number is input incorrectly.
Yes, you'll need to know your tire diameter.
@aircooled posted:If you have limited slip. Why can't you jack up the rear wheels and manually turn over the engine as many times as it takes to make the wheels turn exactly one revolution and determine the final drive ratio in 4th ?
Or with no limited slip. Jack up only one wheel and turn the engine over manually until the one wheel turns exactly two full turns and determine final drive ratio in 4th ?...........Bruce
This relates back to the other thread of TBD vs. true LSD. Although Rancho calls their Quaife an LSD it is really a TBD and will act as an open diff with both tires off the ground, so he'd need to do the latter. That said, the crank pulley side of the motor is the worst to work on in a spyder (you have access to everything else better than a rear engine application EXCEPT the face of the motor).
Correct me if I'm wrong, but Phil and I both have a GPS speedo from Speedhut. They aren't like the VDO that Carey uses. No adapter and pulses per mile are needed.
They have their own GPS antenna. Plug and play, unless it's defective.
My speedo 100% matches my phone GPS navigation speed.
Fun fact: My speedo indicates speed in reverse too. Very weird the first time I noticed that!
The speedo can also display time, direction, altitude, 0-60, 1/4 mile, and top speed reached through a scrolling menu button. All are hidden in the LCD odometer display(This is one place where technology is super cool: it's there but doesn't detract from the rest of the car's vintage appearance).
The only drawback to the GPS signal is a very slight delay when accelerating or decelerating harshly. The needle catches up within half a heartbeat.
@DannyP posted:Correct me if I'm wrong, but Phil and I both have a GPS speedo from Speedhut. They aren't like the VDO that Carey uses. No adapter and pulses per mile are needed.
They have their own GPS antenna. Plug and play, unless it's defective.
My speedo 100% matches my phone GPS navigation speed.
You are correct, I forgot he used those speedhut gauges in later spyders. I've had them make a few custom sets for me over the years (Mullis' aircraft inspired spyder gauges for example) and IIRC they were plug and play, no programming. But you can still verify they are accurate with a free app or Nav.
I’m going to check my speedo with the app first. Then I’m going to put the phone in front of my face when I check speeds in each gear at 3000 rpms. That way I’m just looking at center tach with center phone app right above it.
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@DannyP posted:....Fun fact: My speedo indicates speed in reverse too...
Handy when you swap ends halfway through a turn?
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@550 Phil posted:....I’m going to check my speedo with the app first...
Phil, if there's a big difference between expected speeds in gear and what you're actually seeing, there's always the possibility that your tach is off. Have you ever checked it against another reference tach?
I did this when my car was new and the, uh, 'budget' tach in my car turned out to be pretty close to true. I've always assumed it has stayed so over the years, but you know what happens when you assume.
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Mine was rebuilt and recreened for 8000 RPM by Harmut. It's still something short of a good estimate.
Yes the tach is the only thing that may be in question. How would I verify the validity of the tach. I’ll get the numbers and report back Saturday or Sunday after lovely Debby has passed.
@Sacto Mitch posted:.
Handy when you swap ends halfway through a turn?
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Handy for that, sure. Fast and Furious, I'm not.
First noticed backing down my 100 foot driveway.
@550 Phil posted:Yes the tach is the only thing that may be in question. How would I verify the validity of the tach. I’ll get the numbers and report back Saturday or Sunday after lovely Debby has passed.
An old fashioned tach-dwell meter.
Or a new-fashioned timing light w/tachometer display. Can be used on ANY car with spark plug wires. I believe the Suby engines used by Greg and Carey are 2006 or older based. They all have plug wires. $44.
Just talked to Greg. He said tach in my Spyder is probably programmed for V6 or V8. Just has to be changed.
And the transmission in my IM has stock gearing with a 4.12 R&P. So I just need to beef it up, switch to a 3.44 and use the stock gearing.
@550 Phil posted:Yes the tach is the only thing that may be in question. How would I verify the validity of the tach. I’ll get the numbers and report back Saturday or Sunday after lovely Debby has passed.
Do you have access to a Dwell Meter? I would guess that any competent garage/mechanic would have one or two kicking around from the days before Electronic Ignitions, just like me. A dwell meter usually has a switch setting to turn it into a tachometer for 4-6-8 cylinder cars. Attach it across your coil and Bob's your uncle, instant tach, then you can compare what it says to your dash tach and they should be the same. A dwell meter doesn't care if you're running points or an electronic module.
@Gordon Nichols Phil has a Subaru with aftermarket fuel injection and smart coil packs.
He COULD hook up a tach/dwell to maybe the tach out of the ECU, but he'd have to know how to do that and which pin it is, yes?
Which is why I suggested a timing light with tachometer display.
@DannyP Got'cha. I forgot about the Suby/ECU and coil packs.
The timing light with built-in tach makes the most sense.
I'm too old school - My timing light isn't that smaht.
I think I bought it in the 1970's 😉
Hey! You gonna be at Thompson this weekend??
My timing light isn't smart either, but it's only a few years old. At least it's inductive. My Dad's Craftsman finally died.
No, not doing the Majors race. That is for slicks only which I don't run, and there are 6 open wheel cars, 2 Formula Fords and 4 Vees. Not much of a race.
@550 Phil posted:Just talked to Greg. He said tach in my Spyder is probably programmed for V6 or V8. Just has to be changed.
And the transmission in my IM has stock gearing with a 4.12 R&P. So I just need to beef it up, switch to a 3.44 and use the stock gearing.
That's excellent news. Then there's no reason not to drive it to Wytheville next month!
@Stan Galat posted:That's excellent news. Then there's no reason not to drive it to Wytheville next month!
Question is will I have the car by then. Pat has to finish building the engine. Tranny needs to be rebuilt. Installation. There are some other minor things I want done to make the car perfect. I’ve learned that it’s alway a bad idea to rush the builder. And I’d really like to go back to LA and drive the car before it ships.
Your Spyder, man -- you have a Spyder that isn't over-revving on the highway.
@Stan Galat posted:Your Spyder, man -- you have a Spyder that isn't over-revving on the highway.
Exactly. We'll stop by and I'll drive it for you. Charlottesville is on the way.
For reference, Phil(plus I have the plug-in pushbutton to program it) here are the tach instructions:
@DannyP -- we can just do it for Phil when he has his car in Wytheville.
Yup. Michelle said she'd drive it down for you.
It’s only a 3 hour drive. I’m definitely taking the Spyder if the weather on Wednesday and Sunday are good. We’ll see.
