Speedo Gears

[Glenn 'Stinky' Stankevicius]

I have a spreadsheet to work out the gearing and speed of my car. So far I have found that cruising at

60kmh (37mph) the car does 2000RPM and at
80kmh(50MPH) it is turning 2700RPM

according to the spreadsheet it should be
60kmh (37mph) the car does 1670RPM and at
80kmh(50MPH) it is turning 2230RPM

So I am speeding when I think I am on the limit.
The speedo gear I have in the Trimatic at the moment is the yellow one, can anyone tell me what colour I should be getting to correct the problem?
and if anyone wants a copy of the spreadsheet send me a PM with your email address.

[nicko]

ring your local GMH dealer spares dept,
they always used to have the info you need to work out colour gear,so would most likely still have it
cheers Nick

[Glenn 'Stinky' Stankevicius]

Well that did a lot of good -
"errrr, what do you need again? umm just a minute, [conversation and laughter heard in the background] yeah, they don't list a four speed auto for a HQ" etc, etc

Anyway, from the spreadsheet I worked out the speedo needs to go 85% slower and thanks to a listing of colours and teeth from an oldholden post, it would seem I need the white gear (20 teeth) and not the yellow gear (24 teeth). This will spin the speedo 83% of what it is now and hopefully be fairly accurate.

[BOVAFC]

Hope you've got it sorted out now.My gear is red and when fitted with the 15" rims the speedo reads exactly half the actual speed in km's.Was going to change it but it makes converting to k's very easy.except when theres a speed camera

[FCwagon]

Hi Stinky,
I think you'd need more teeth on the speedo gear to slow it down. All the speedo gears are the same diameter and driven by a worm, the more teeth the longer it takes for each rev.
cheers,
Leigh

[nicko]

heres a list of gear colours for different gearbox,diff and tyres size combo's
Speedo Driven gears HQ to WB

DRIVEN GEARS: Trimatic transmission

Colour Teeth
/model Ratio Tyre options Engine size Part number
Pink 19/WB 3.08:1 QCP,QRU 7430967
“ 19/HQ “ 78x14 173,202 “
“ “ 2.78:1 F78x14, 7.35x14 253,308 “
White 20/WB 3.08:1 QEA, QEU 6 cyl 7430968
“ “ 4.44:1 QFS “
“ “ 2.60:1 QCP,QFD 5.0 litre “
“ 20/HQ 3.08:1 78x14 173,203 “
“ “ 2.78:1 7.35x14,185x14,6.95x14,195x14,70x14,EB78Sx14 253,308 “
Green 21/WB 3.36:1 QCP,QEA,QEU, QRU 7430969
“ “ 2.60:1 QCJ, QCH,QEB,QFL 5.0 litre “
“ 25/WB 3.08:1 QCJ,QCH,QEB,QFL 5.0 litre 7448810
“ 21/HQ 3.36 7.35x14,78x14,195x14 173,202 7430969
“ “ 3.08:1 F78x14,7.35x14 253,308 “
Dark Blue 22/WB 3.08:1 QCP,QCN,QEA,QET,QEU,QFD,QRU V8 7430970
“ “ 3.55:1 QCP,QFS,QRU,QSD 6 cyl
“ “ 3.55:1 QEA,QEU 6 cyl 7430971
“ 22/HQ 3.36:1 6.95x14,185x14,70x14 173,202 7430970
“ “ 3.55:1 78x14,195x14 173,202 “
“ “ 3.08:1 185x14,195x14,70x14,7.35x14,EB78Sx14 253,308 “
Red 23/HQ 3.55:1 6.95x14, 185x14, 70x14, 7.35x14 7430971
“ 21/WB 3.36:1 All except QEE,QCN,QEU,QFS *******
“ “ 3.08:1 6.95x14, 253,308 “
“ “ 3.36:1 F78x14, 7.35x14 253,308 “
Yellow 24/WB 3.36:1 QSD 4.2 litre 7430969
“ 24/HQ 3.90:1 F78x14,F78Lx14,FB78Sx14 173,202 7430972
“ “ 3.36:1 185x14,195x14,70x14,7.35x14,EB78Sx14 253,308 “
Light Blue 25/WB 3.55 QCP,QEA,QEU,QFD,QET,QRU,QSD 4.2 litre
“ 25/HQ 3.90:1 6.95x14,7.35x14,70x14,185x14,EB78x14,195x14 173,202 7448810
“ “ 3.36:1 6.95x14, 253,308 “

DRIVEN GEARS: 3 Speed Manual

Colour Teeth/
model Ratio Tyre Options Part number
Pink 19/HQ 3.08:1 78x14 7430967
White 20/HQ 3.08:1 78x14 7430968
Green 21/HQ 3.36:1 7.35x14, 78x14, 195x14 7430969
Dk Blue 22/HQ 3.36:1 6.95x14, 185x14, 70x14 7430970
“ 22/HQ 3.55:1 78x14, 195x14 “
Red 23/HQ 3.55:1 6.95:1, 185x14, 70x14, 7.35:1 7430971
Yellow 24/HQ 3.90:1 F78x14, F78Lx14, F78Sx14 7430972
Lt Blue 25/HQ 3.90:1 6.95:1, 7.35:1, 70x14, 185x14, EB78x14, 195x14 7448810

DRIVEN GEARS: Turbo Hydramatic 350 transmission

Colour Teeth/
model Ratio Tyre Options Part number
Lt Green 34/HQ 2.78:1 F78x14, 7.35x14 9774413
Pink 35/HQ “ 7.35:1, EB78Sx14, 195x14 9780628
White 36/HQ “ 185x14, 70x14 1359270
“ 19/HZ/WB 3.08:1 QCP,QFD,QGA,QRU,QSK,QXZ 3987919
Blue 38/HQ 3.08:1 F78x14, 7.35x14 1359272
“ 20/HZ 3.08:1 QCS,QET,QEU,QRQ,QSC,QTX,QZT 3987920
Brown 39/HQ 3.08:1 7.35x14, EB78Sx14, 195x14 1359273
Black 40/HQ 3.08:1 185x14, 70x14, 1359274
Red 21/HZ 3.36:1 3987921

DRIVEN GEARS: 4 Speed Manual

Colour Teeth/
model Ratio Tyre Options Part number
Pink 19/HZ 3.08:1 QCP,QFQ,QFD,QGA,QRU 7430967
White 20/HZ 3.08:1 QCS, QET, QEU, QRQ, QSC,QTX 7430968
“ “ 3.36:1 QFS, QFG “
“ “ 4.44:1 QFS, QFG “
Green 21/HZ 3.36:1 QCP,QCS,QEF,QEQ,QET,QEU,QFD,QFF,QRU, QRQ 7430969
Green “ 4.44:1 QSD “
Dk Blue 22/HZ 3.55:1 QSC,QCP,QEF,QEQ,QET,QFD,QFG,QFS,QGA,QRU,QSD,QXZ 7430970
Red 23/HZ 3.55:1 QCS, QEU, QFD, QRQ, QTX 7430971
Yellow 24/HZ 3.90:1 QCP, QEQ, QFF, QRU, QXZ 7430972
Lt Blue 25/HZ 3.90:1 QCS, QET, QEU, QFD, QRQ, QTX 7448810

DRIVEN GEARS: Turbo Hydramatic 400

Colour Teeth/
model Ratio Tyre Options Rear wheel lock Part number
Dark grey 44/HZ 3.36:1 QFD, QFS, QSD, 9780470
Pink 35/HZ 2.60:1 QCP,QCS,QET,QEU, no 9780628
“ 35/HZ “ QCP,QET,QEU,QFD,QGA yes 1237980
Yellow 41/HZ 3.08:1 QCP,QCS,QET,QEU,QFD,QGA,QRQ,QRU,QXZ no 1362195
Green 42/HZ 3.08:1 QSC, QZT 1362049
Light Blue 45/HZ 3.36:1 QCP,QCS,QET,QEU,QFD,QGA,QRQ,QRU no 1372313
“ “ “ “ QCP,QET,QEU,QFD,QGA yes 1237648
Yellow 41/HZ 3.08:1 QCP,QET,QEU,QFD,QGA yes 1237644
Lt Blue

[nicko]

PART LIST TWO
as first post was too big,ALSO PLEASE NOTE HOW TYRE SIZE EFFECTS GEAR COLOUR AS FOR EXAMPLE A 65X14 BRIDGESTONE IS OVER AN INCH LOWER THAN AN OLD ER78 TYRE,SORRY FOR YELLING BUT IT DOES MAKE A BIG DIFFERENCE.
////////////////////////////////////////
QEU ER70H14 6 y y
QFD FR78S14 4 y y
QFS F78-14 10 ySpeedo Drive Gears

The drive gear (on the gearbox main shaft) is normally an 8 tooth gear, and is white in colour. 7 and 9 tooth gears are also available, but far less common.

Series Model Transmisson type Diff ratios Part Number
HQ -WB Executive Chassis & cab 3 speed manual 4.44:1 7437317
WB Chassis & cab “ 4.44:1 9928961
WB 4 speed manual 3.08:1, 3.36:1, 3.55:1 5258493
WB 6 cylinder “ 4.44:1 5258754
WB “ Trimatic 3.08:1, 3.36:1, 3.55:1 5258493
WB “ “ 4.44:1 5258754
WB 4.2 Litre “ 2.60:1 9942796
WB “ “ 3.08:1, 3.36:1, 3.55:1 5258494
WB 5.0 litre “ 3.08:1, 2.60:1 9942796
HZ/WB All models Turbo 350 Gear colour: orange 6261784
HQ “ 3 speed manual All ratios 5258493
HQ All models 4 speed manual All ratios 3978758
HQ 173, 202 Engines Trimatic “ 5258493
HQ 253, 308 “ “ “ 5258494
HQ All models Turbo 350 16 teeth,orange color 8623311
HZ “ Turbo 400 Stamped 77 EK 8623311
“ “ “ “ Stamped 78 EK 8629548
• HQ employs a speedo adaptor instead of different drive gears for transmissions;
• 3.36 and 3.55 adaptor – part number 7449654

Tyre Options

Code Tyre Option Ply rating Steel belt Tubed Tubeless Nylon poly Textile
QCN ER78S14 4 y y
QCP FR78S14 4 y y
QCS ER78S14 4 y y
QEA ER78S14 6 y y
QEB ER60H15 6 y y
QEE ER78S14 6 y y
QET ER70H14 6 y y
QRU 195SR14 4 y y
QSD 195R14LT 8 y y
QTX 185SR14 6 y y
QTY 185SR14 4 y y
QXZ
QZT.
please note,all this info taken from Old Holden.com.au, web site

[Dr_Terry]

Hi Guys.

I've found an easy method with the Holden speedo gears is to allow 5% for each tooth. In other words if the speedo is reading 105 km/h at 100 km/h actual, then fit a gear with 1 extra tooth (eg 21 to 22). If it's reading 110 km/h at 100 km/h actual, then go up 2 teeth.

The simple maths are that 1 tooth in 20 is 5%.

Dr Terry.