11 replies to this topic

[fred8601]

Hi all.... please don't mock me if this is a really silly question but here goes!

 

I'm mid way through swapping a good gearbox from a 998 onto a 1275. The problem is that I've just spotted the 998 has 29 teeth on the primary drop gear but the 1275 has 30 teeth, does this mean I can't put them together??

 

What are my options if the gears won't match?

 

Thanks in advance

[Mattl]

http://www.theminifo...ox-onto-a-1275/

[fred8601]

That's why I'm confused. They are both A+ so according to the thread above they should be fine, but surely it's a probelm the number of teeth being different?

[KernowCooper]

The standard drop gears have a 1:1 ratio and 29 teeth and the economy (E) 30 tooth set-up which gives a 0.967:1

 

The E uses a 30 tooth gear which was used on certain metros.

 

Standard Drop Gears had a 29 tooth primary and a 29 tooth input gear and therefore a 1:1 ratio

 

If you use the 30 tooth Primary and a 29 tooth input you should have 0.967:1 Ratio

 

And the way I understoood it was the standard idler gear can be used. as long as its all A+

 

so in effect you could use the above to slightly alter the final drive ratio

[fred8601]

The standard drop gears have a 1:1 ratio and 29 teeth and the economy (E) 30 tooth set-up which gives a 0.967:1

 

The E uses a 30 tooth gear which was used on certain metros.

 

Standard Drop Gears had a 29 tooth primary and a 29 tooth input gear and therefore a 1:1 ratio

 

If you use the 30 tooth Primary and a 29 tooth input you should have 0.967:1 Ratio

 

And the way I understoood it was the standard idler gear can be used. as long as its all A+

 

so in effect you could use the above to slightly alter the final drive ratio

Thanks for the help, so you're saying it should be fine to mix and match the 29 tooth primary gear with the idler from the other box (which was driven by a 30 tooth primary)?

[Cooperman]

Do a 'trial installation' with the transfer cover not fitted. If it all turns over smoothly you should be OK.

[Captain Mainwaring]

The standard drop gears have a 1:1 ratio and 29 teeth and the economy (E) 30 tooth set-up which gives a 0.967:1

 

The E uses a 30 tooth gear which was used on certain metros.

 

Standard Drop Gears had a 29 tooth primary and a 29 tooth input gear and therefore a 1:1 ratio

 

If you use the 30 tooth Primary and a 29 tooth input you should have 0.967:1 Ratio

 

And the way I understoood it was the standard idler gear can be used. as long as its all A+

 

so in effect you could use the above to slightly alter the final drive ratio

 

Is there enough clearance that you can change just the one gear? I know it's only 3% bigger but.....

 

 

Ah....I've just found it, they mumfiated the tooth profile so it would work.

[Guess-Works.com]

Yes they are perfectly compatible as they all use the same idler gear....

[Captain Mainwaring]

Yes they are perfectly compatible as they all use the same idler gear....

 

Clever old BL, modifying the tooth profile so you don't have to change all the gears.... 

[KernowCooper]

Back in the day "One Size Fits All" just buy a bottom of the range car and the top end and look at the handles and switch gear as a example. But yes it was a clever move of how to switch gears of different ratios.

[Captain Mainwaring]

It's been an education swapping running gear between a 1971 ish shell and a 1997 ish SPi - reminds me of Desmond Molins....never delete a hole.

[KernowCooper]

Comes back to "There the same but different"