43 replies to this topic

[makka]

Terry, you wouldnt have the numbers for the opel 4 speeds as well by any chance?
Cheers

[Dr Terry]

Hi makka.

If by 'numbers' you mean gear ratios, AFAIK GM-H only used one version of the Opel 4-speed in Holdens. The Opel M20 was used in late HR, then HK/HT/HG & LC Torana up to 6/71, after that the existing stockpile was used in LC/LJ export cars.

The ratios are 3.43/2.16/1.37/1.00. These are rounded to 2 decimal places, some publications quote the ratios to 3 decimal places.

Dr Terry.

[antelopeslr5000]

And while you're on a roll with numbers Doc ... I don't suppose you would happen to have the numbers for this Saturday night's Lotto draw?

[LX2DR]

Hi makka.

AFAIK GM-H only used one version of the Opel 4-speed in Holdens. The Opel M20 was used in late HR, then HK/HT/HG & LC Torana up to 6/71, after that the existing stockpile was used in LC/LJ export cars.

Dr Terry.

Pretty sure i'm correct in saying their were 2 types of Opel 4 speeds.
One had a tin pan on the bottom, Usually referered to as the weekest type.
One with a cast iron pan, usually refered to as the stronger one.

May have been the same box with a different pan and the benefit of strength might have been ridgidity with the cast pan?

Didnt really make that much difference, treat either hard and you will break it.

Edited by LX2DR, 19 November 2008 - 02:56 PM.

[rodomo]

There was a difference in strength between the tin and cast bottom g/boxes.
Tin I could blow in 3rd gear, cast needed 2nd gear.

[yel327]

Just wondering, with the ratios- 3.08diff/75km/h in 1st gear....would that be a M21 or M22 ratio?? I thought I'd scored a M21 (back in '92 in a LJ 2 door S- for $550, mind you) for my old LJ GTR, only to be told later, it was probably an M22 but looking at the ratios, this now dosen't seem to be the case?? Can anyone shed some light on this??? I want to replicate the old gearbox in the LC 2door....

75km/h in 1st with 3.08?

Assuming say 205/60/13 tyres, I have your tailshaft doing 2127rpm at 75km/h.

So with an M22 your engine would be doing 7954rpm.

M20 it'd be 6487rpm.

XU-1 M20 it'd be 5402rpm.

The box will probably not have been an M21 but 1st gear is the same ratio as XU-1 anyway.

My guess is you had an XU-1 box. You can buy new input shafts and clusters to make one of these out of a normal M20 quite cheaply.

[yel327]

All you need to turn an M20 into an XU-1 box is the input shaft and cluster, then they are identical (except for original markings, date codes etc). 3rd gear is the same. You can do almost the same thing with a V8 M21 box where you only need to change the input shaft using one off an XU-1 box (and 6cyl bearing cover). The M21 just has a shorter 3rd gear (1.38:1, XU-1 is 1.25:1).
Reece at Kingswood Country has the parts you need. I have some input shafts here (Newcastle) that I bought off him in bulk but no clusters.

[Dr Terry]

Pretty sure i'm correct in saying their were 2 types of Opel 4 speeds.
One had a tin pan on the bottom, Usually referered to as the weekest type.
One with a cast iron pan, usually refered to as the stronger one.

May have been the same box with a different pan and the benefit of strength might have been ridgidity with the cast pan?

Didnt really make that much difference, treat either hard and you will break it.

There were more than two versions of the Opel 4-speed used in Holdens, but they all had the same gear ratios.

You are correct about the pressed metal & cast iron bottom lids, but there were various types of shifter used also.

HR Opel gearboxes had the shifter attached to the rear of the extension housing, whereas the HK/T/G Holdens had the shifter mounted further back & attached to the floor. LC Toranas had theirs attached HR style, but not using the same parts, it was different yet again.

Dr Terry

[yel327]

Cheers m8, cool. So, the xu-1 box just has a taller 1st and nothing else?

No, all actual ratios are different to the normal M20. The only actual different parts are the input shaft and cluster. The different ratios come about because of the teeth count on the input shaft and cluster that meshes with it. The ratio is a function of the input shaft gear, the cluster gear it meshes with, the selected gear (ie 1st to 3rd) and the corresponding gear on the cluster. If you sit down and work it all out on paper it makes sense.

[StephenSLR]

while we're at it...anyone know how to identify between a celica and a supra box?

 

Celica has a cast iron case and Supra is alloy?

 

s

[craigcn27]

Aussie 4 speed smooth case

D21 (2nd april 1971)

serial number:  T262306

[yel327]

That could be a 3 or 4 speed case. Nice find.