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Speedo only goes to 85, what happens if I pass 90?

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Old Apr 16, 2019 | 10:43 PM
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From: Stevensville MT
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
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Speedo only goes to 85, what happens if I pass 90?

Driving home today, a Mopar charger wanted to play on the highway. I was willing to oblige, but I had to back off at 85 because around the 90mph mark, my speedometer needle will be touching the trip reset pin. It raised the question of what would happen if I were to go 95-100 mph. Would the needle break? Would it just float against the pin?

Obviously I need to upgrade to a higher mph speedometer, in case I ever meet Mr. Mopar again 😜. But I figured it probably would be a good idea to know what would happen with my current speedometer. Anybody have any insight? I'm genuinely curious, just not enough to risk breaking something, haha.
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Old Apr 17, 2019 | 06:23 AM
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From: Kylertown,PA
Car: 85 Berlinetta
Engine: 350
Transmission: T5
Axle/Gears: 10 bolt 3.42 with Torsen posi
Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by Venom_1138
Driving home today, a Mopar charger wanted to play on the highway. I was willing to oblige, but I had to back off at 85 because around the 90mph mark, my speedometer needle will be touching the trip reset pin. It raised the question of what would happen if I were to go 95-100 mph. Would the needle break? Would it just float against the pin?

Obviously I need to upgrade to a higher mph speedometer, in case I ever meet Mr. Mopar again 😜. But I figured it probably would be a good idea to know what would happen with my current speedometer. Anybody have any insight? I'm genuinely curious, just not enough to risk breaking something, haha.
It will not hurt anything. It will just stop moving when it hits the trip reset button.
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Old Apr 17, 2019 | 06:31 AM
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Car: 88GTA
Engine: 5.7TPI
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Re: Speedo only goes to 85, what happens if I pass 90?

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Old Apr 17, 2019 | 07:33 AM
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Car: 1992 camaro z28, 1988 camaro sc
Engine: 350 tpi, 305 tbi
Transmission: t-5, t-5
Re: Speedo only goes to 85, what happens if I pass 90?

At 88mph you go back to 1985
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Old Apr 17, 2019 | 08:02 AM
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Speedo only goes to 85, what happens if I pass 90?

https://giphy.com/explore/outatime
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Old Apr 17, 2019 | 09:02 AM
  #6  
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Car: 1989 IROC Convertible
Engine: 350 TPI L98
Transmission: WC T5
Axle/Gears: 3.42
Re: Speedo only goes to 85, what happens if I pass 90?

… It would be bad… Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

No, wait, I think it's OK. It just goes past 90. Dang, where are my notes...

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Old Apr 17, 2019 | 09:08 AM
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Car: '89 Iroc Z28-15,100 Original Miles
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: Limited Slip, 2.77 Ratio
Re: Speedo only goes to 85, what happens if I pass 90?

Do us all a favor and keep that third gen under 85 mph....
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Old Apr 17, 2019 | 11:47 AM
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Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by GASPEDDLER
Do us all a favor and keep that third gen under 85 mph....
I'm just happy to see Fez is still getting work.






So seriously... Thirdgens with speed rated tires from the factory, don't have any limiting controls. When you get into the later EFI cars without Z rated tires you see they don't have the 140mph clusters, and if you hold the WHAAAAAAAAAAAA peddle long enough, when the needle gets to 115mph or so, you'll feel the brick wall and the car slowing down suddenly. After it drops down it'll let you push it back to 115, but at that point the ECM presumably cuts fuel and forces you to stop accelerating. Getting around it, is another topic, but if you want to know what happens when you put a 140 cluster into a 85mph car...

Sorta depends on the car. The old dual needle speedo in my 83 would roll past 85, and wrap around into the KM half of the scale. No trip odometer, no ecm control, with more then 14hp maybe it would have just kept spinning?

Btw, round these parts, late model Chargers are Po Lease. Saw one this weekend, think it was Junction City PD, was hard to tell because it was all black with black windows, all the gear behind the grill or inside behind glass and the PD/Call 911 markings were all done in flat black. Ergo, watch your cornhole.
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Old Apr 17, 2019 | 01:40 PM
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Car: 91 Firebird/88 Firebird/91 Formula
Engine: V6 3.1/V8 5.0/V8 5.0
Transmission: 4L60/700R4/4L60
Axle/Gears: 3.23/2.73/2.73
Re: Speedo only goes to 85, what happens if I pass 90?

Used to have an '84 Chrvy Chevette, standard with four gears, that had a speedometer that only went to 90. Drove it on the Autobahn for about a year and half and the speedometer would peg at 90 while the accelerator would go further. I would usually keep up with traffic.
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Old Apr 17, 2019 | 02:32 PM
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From: Stevensville MT
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual
Axle/Gears: Yup, still there
Re: Speedo only goes to 85, what happens if I pass 90?

Haha, my first thought when I saw him was that he was a cop... but the cops around here don't have custom mag wheels, blue-tipped chrome dual exhaust or a big ol' Mopar logo on the front fender. They're just not that sneaky, lol.

I've always backed off around 85 mph because years ago a friend had a Ford Probe he was restoring and building to race (don't ask me why, lol). He had his gauge cluster sitting out and another friend began screwing around with it, notably the pin that connected the speedo to the cable. He cranked it all the way over to the end, where there was a little stopper peg on the speedo, and the needle broke off. Given that my Trans Am can easily hit about 90 without me even having the pedal to the floor, I kind of figured the folks at GM would have made sure that didn't happen... but I didn't want to find out I was wrong the hard "oh crap, now that's broken!" way.

And the 80's movie references... love it. You guys are my kinda people, lol. Thanks for all the input, glad to at least put that question to bed!
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Old Apr 17, 2019 | 02:38 PM
  #11  
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Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: Speedo only goes to 85, what happens if I pass 90?

Nothing happens to the speedo over 85, what happens to you is another story. How lenient are the police in your neighborhood? Next you'll be singing, "I can't drive,,, 55"
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Old Apr 18, 2019 | 08:52 AM
  #12  
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Re: Speedo only goes to 85, what happens if I pass 90?


you just go faster and faster.....
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Old Apr 18, 2019 | 10:13 AM
  #13  
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Car: 1987 iroc
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Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by 427seven

you just go faster and faster.....
Nice. How Far did it take you to get there? You must have your odometer disconnected?
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Old Apr 19, 2019 | 07:35 AM
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Re: Speedo only goes to 85, what happens if I pass 90?

PLEASEEEEE dont go over 85. once you do, itll send you into a wormhole. believe me, this happened to me!
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Old Apr 20, 2019 | 12:38 AM
  #15  
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From: Stevensville MT
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual
Axle/Gears: Yup, still there
Re: Speedo only goes to 85, what happens if I pass 90?

Dang, dude! Nice looking gauge cluster, very bright! I redid mine with LED's and chromed the inside plastic for a brighter look, but yours looks absolutely brilliant.

Originally Posted by 427seven

you just go faster and faster.....
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Old Apr 20, 2019 | 05:27 PM
  #16  
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Car: 1989 Firebird GTA
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Re: Speedo only goes to 85, what happens if I pass 90?

added extra light for the midnight run.... actually 3 a.m. run.... too bright, zeroing in on the right intensity...
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Old Apr 20, 2019 | 06:53 PM
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From: Meriden, CT 06451
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by Degweiser
At 88mph you go back to 1985
We really do need that LIKE button. Great comment!

A cable driven mechanical speedometer has a magnetic coupling. So if you "pin" the needle, nothing bad happens.
It's not like overwinding a clock or wristwatch until it goes "pop" and never works again.

Last edited by NoEmissions84TA; Apr 20, 2019 at 07:02 PM.
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Old Apr 21, 2019 | 12:28 AM
  #18  
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Car: 1989 IROC-Z 305 LB9 AT Convertible
Engine: LB9 305
Transmission: AT
Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by Degweiser
At 88mph you go back to 1985
Beat me to it!

"Back To The Future" was a great movie!
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Old Apr 27, 2019 | 05:25 PM
  #19  
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Car: 1984 Trans Am
Engine: LG4 305 4bbl
Transmission: 700R4
Axle/Gears: 3.23 LSD
Re: Speedo only goes to 85, what happens if I pass 90?

I'm forever tempted by Hawks' 160MPH speedo.......but they're bloody expensive and I'm unsure about taking the cluster out anyway.........
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Old Apr 27, 2019 | 06:08 PM
  #20  
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Car: 1984 Camaro Berlinetta
Engine: LT1
Transmission: T56 6-speed
Axle/Gears: 4.11 LS1 Rear End
Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by 427seven
...............you just go faster and faster.....
How did you calibrate that Speedo Head to be accurate to the custom face-plate ?


200MPH and not even 1/10th of a mile traveled !!


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Old Apr 27, 2019 | 06:31 PM
  #21  
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Car: 1987 GTA 350 auto
Re: Speedo only goes to 85, what happens if I pass 90?

hey 427 where did you get those white needles from for your gauges
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Old Apr 28, 2019 | 11:05 PM
  #22  
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Re: Speedo only goes to 85, what happens if I pass 90?

Originally Posted by TOM305T/A
hey 427 where did you get those white needles from for your gauges

made em
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Old Apr 28, 2019 | 11:17 PM
  #23  
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Re: Speedo only goes to 85, what happens if I pass 90?

[QUOTE=John in RI;6298231]How did you calibrate that Speedo Head to be accurate to the custom face-plate ?


Long story, but the key piece is from Dakota.

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Old Jul 19, 2019 | 03:01 PM
  #24  
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Re: Speedo only goes to 85, what happens if I pass 90?





For all those Canadians, we can only wish....
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Old Jul 20, 2019 | 12:49 PM
  #25  
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Engine: 3.1 V6
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Re: Speedo only goes to 85, what happens if I pass 90?

Nothing. You just won't know how fast you're going. If I'm wot I'll be on the bottom of 4th gear when I hit 85. I bought a gauge off eBay with a speedo for 160 just to know how fast I am going. I took it to 120 the other day.

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