16 replies to this topic

[neglectedtorana]

Earlier in the year I had the pleasure of seeing my speedo hit the 200 mark on the straight at Calder Park and I'm wondering what happens when the speed goes above 200?

 

Can the speedo be damaged?

It still worked after so I'm hoping it has some sort of built in tolerance to go above the max.

 

Anyone know?

I don't want to damage it if it goes beyond the 200 mark.

[Statler]

The needle bounces off the needle stop . Hehehehe

[rodomo]

The cable to the needle is not a direct drive 

 

https://www.gmh-tora...n-your-speedos/

[claysummers]

Got mine stuck at 110mph on the wife’s FB 8)


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[S pack]

I think I have an old LX 160kph speedo here somewhere. I'll have a look later today. 

[yel327]

That’s why the faster Holdens had 140mph/225kmh speedos!

[LJ RB30]

I’ve had the needle on my LJ pointing at the 2nd digit on the odometer 🤪
She was a bit floaty 😳
Worked fine afterwards 👍

Edited by LJ RB30, 09 October 2025 - 09:00 AM.

[neglectedtorana]

Thats interesting about the magnet driving the needle, 

I'll see if I can use a GPS speed app on the phone to see if it goes beyond the 200

[Ice]

That’s why the faster Holdens had 140mph/225kmh speedos!

Yeah touched that in my van with 3.1 ratio 9 inch diff could have kept going to but 

Way to fast 

[yel327]

Yeah touched that in my van with 3.1 ratio 9 inch diff could have kept going to but
Way to fast

I was thinking fast originally! Like GTS327 and GTS350. HT-HG 350 manuals would get damn close to 140mph especially the 3.08 rear axle examples. Far cry from the 6cyl versions, only the 186S cars could even crack 100mph.

[claysummers]

I don’t know about that Byron. My first car was a HK Kingswood wagon, stock 186 and crash box. Standard diff, I suppose would have been 3.36:1? Anyway, I saw the speedo hit 100mph several times in that car, before valve bounce set in. Dad had a 253 trimatic HQ and I could not get it past 90mph on the same stretch of road, on the way to uni. Just as well, as a cycle cop clocked me and gave me a ticket in the car park at the campus. Next week dad traded the HQ for a Lancia Beta coupe, ending his run of 5 Holdens. FX, FE, HD, HT & HQ.


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[yel327]

3.55 was the manual rear differential in almost all 6cyl manual HK-WB. I have never seen any road tests anywhere showing a standard 6cyl Holden managing 100mph except for 186S cars. One of the HD-HR X2 or 186S might have been able to do it. Normally they’d say N/A on that line of the test results.
Torana is different, XU1 of course and a few like LJ 3300 auto would just do it (2.78 rear axle) plus others.
I have seen a lot of those same tests showing massive speedo errors though! One GTS327 was reading over by 15mph at around 120.

Edited by yel327, 10 October 2025 - 05:22 AM.

[claysummers]

No doubt the speedo would have been a bit out but it sure felt like 100mph. Unfortunately didn’t have GPS back then. That was a great little motor, quiet and smooth and well run in at 90,000 miles when I got it. Scariest part was button off, when the pinion dropped and tailshaft vibration set in. Valve bounce was the limiting factor and I don’t believe 186S had heavier springs, though probably a taller diff.


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[yel327]

186S had a bigger cam and different springs to all other HK 6cyl. Only the GTS got a 3.36 as standard with manual from memory, rest were still 3.55 (would have to check). HT and HG 186 (except Trimatic) had the 186S cam in them, I don’t think they got the springs though. That is why the HT 186 has 5hp more rating than HK.
The big difference with the X2 and S engines was the exhaust and carburetion was far superior it allowed the engines to produce power at higher revs.

My 2/76 LX SL hatchback was bog standard, 3300 auto and 2.78 rear axle with N67 13” alloys. They had a 160kmh speedo. When out on unrestricted roads it couldn’t do 160kmh. When I fitted extractors and 2” system & tuned it to suitt, also had 14” wheels by that stage with speedo gears changed to dyno correct the speedo it easily ran off the speedo, by a good cm. The main difference being the exhaust let it develop a bit more hp. I think it picked up around 10hp over standard just with that exhaust.

Edited by yel327, 10 October 2025 - 09:49 AM.

[claysummers]

Even with a 3.55 drive, 175/80 tyres 25”tall, engine would be doing 4900rpm. Valve bounce would possibly come in there or a bit earlier I suppose.


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[Shiney005]

Thats interesting about the magnet driving the needle, 

I'll see if I can use a GPS speed app on the phone to see if it goes beyond the 200

Go for it.  I've seen an LH speedo hard on the wrong side of the needle and it didn't do any damage.

[RallyRed]

Phone GPS speed app...

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