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#91380 11/16/2001 4:57 AM | Joined: Dec 2000 Posts: 9 Member | | Member Joined: Dec 2000 Posts: 9 | Its a 65 chevy truck street rod, has original gauges, but has 350-350 turbo, and aftermarket tach that reads 41 rpm x 1000 when I am going about 70 mph. and the speedometer goes wild bouncing around up to 100 mph. the original rear I think is 4:11, what to with the rear end and the speedometer?  | | |
#91381 11/16/2001 8:25 AM | Joined: Jul 2001 Posts: 140 Shop Shark | | Shop Shark Joined: Jul 2001 Posts: 140 | What radius tires are you running on the rear end? when the diameter is different than the origional tires, it can change the "actual" speed by a few miles. I would have your speedo checked at a shop that specializes in speedo calibration. good luck
Jonathan S. Keffer
Certified Yeti Trainer
Richard Roy Schlicht-
Good Grandfather, Veteran Wrench Turner...
"If it ain't broke, fix it 'till it is..."
Es gibt nichts, zu befürchten, aber befürchtet sich.
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#91382 11/16/2001 8:38 AM | | Anonymous Unregistered | | Anonymous Unregistered | Is your speedo original? if not, you will need to get a different gear for the end of your speedo cable that goesinto the Tranny, take your tire diameter and rear gear ratio info to a chevy dealer and they can get you the correct gear. I did some rough calculations, and if you had some 3.something gears in the rear, the speedo would be right, so I think you just need a different gear.
Rob
[ 11-16-2001: Message edited by: Rob Arends ] | | |
#91383 11/17/2001 8:43 PM | Joined: Jan 2001 Posts: 198 Member | | Member Joined: Jan 2001 Posts: 198 | Try taking the truck out on the interstate where you have mile markers, drive 10 miles according to the markers and see if that compares to the odometer, if the odometer reads 7 miles it's the tires/rear end, if it showes 10 miles the speedo needs to be calibrated.. :rolleyes: | | |
#91384 11/18/2001 1:13 AM | Joined: Apr 2000 Posts: 58 Member | | Member Joined: Apr 2000 Posts: 58 | Rob has the idea, but it doesn't matter if the speedo is OE or not you changed tranny and I assume the speedo gear in it is the one that was in there for whatever vehicle it was in. These are calibrated for rear ratio and tire size also. | | |
#91385 11/18/2001 1:30 AM | Joined: May 2001 Posts: 4 Member | | Member Joined: May 2001 Posts: 4 | My chevelle has a similar problem. At about 50 miles an hour the speedometer reads about 100 mph. So what I do when I drive the thing is take the GPS receiver with me. It tells me when to slow down for smokey... 
Everybody was born crying, most of us get over it.
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