Low diff ratio

[Greig Smith]

Hi Guys

In the eternal quest for a bit more grunt out of the supercharged special, does anyone have or re-make a lower crown wheel & pinion ratio for the D type diff ??

I'm running the standard 5.25, what I'm after is the Van or Nippy 5.65 or one of the '50's period special ratio's in between....

Anything like that exist on Yonder Isle ?? I've trawled through the Treasured Supplier websites but couldn't find anything...

Aye
Greig

[Mark Dymond]

5.67:1 from David at A7 Components
https://www.a7c.co.uk/cwp.php

[Greig Smith]

Thanks Mark.... I totally missed that one

Cheers
Greig

[Chris KC]

Tony Leslie's got a 5.65 crown wheel on eBay if you have a pinion to go with it....

There was a Regent 5.35(?) pair popped up at a couple of autojumbles last summer , I'm afraid I don't recall whose stall it was on - they are still out there though.

[JonE]

Foolish question, but are the pinions completely matched sets... or do they still technically fit when the crown increases by a tooth or so?

[Chris KC]

I asked a very similar question a while back Jon! 

You need the right pinion, the tooth shape is different.

(That is to say, you could only use a pinion from another 8/45 pair.
Ideally you don't mix and match parts from different pairs, but they will work - the main probable downside being noise).

[Steve Jones]

Thanks Mark.... I totally missed that one

Cheers
Greig

David Cochrane's 5.67:1 is the one to go for, Greg. The trouble with the Austin 5.65:1 sets is that the teeth are quite thin being 8:45 but in the same overall dimension CWP as the 5.25:1 with 8:42 teeth. David's 5.67:1 sets use a 7 tooth pinion which means a much more robust unit. I've used a set in my trials Chummy for many years having destroyed an Austin 5.65 set in about 18 months of trialing. I've fitted a further 5.67 to my hill climb Ulster for this season also.

Steve

[spannerman]

Can someone tell me if austin 7 diff
Is the same as big 7 I know the shafts are a different lenth I'm in the process of building
At trials car from parts and need a lower
Diff ratio sorry for butting in !

[Ruairidh Dunford]

I fitted one of David’s 5.67 : 1 ratio sets to my Pearl about 8 years ago - I am very pleased with it and would suggest it is a good modification if you want to keep going in top gear on longer hills etc.

[Rogerfrench]

Steve, you can't get 5.67 with a 7 tooth pinion. David Cochrane's website quotes 6 teeth, 6:34 to be precise.