OverDrive 4 speed manual boxes

Adrian Worman · Post by **Adrian Worman** » Thu Feb 24, 11 7:18 pm

Has any body here tried using an A833 overdrive in a street and strip car? I got one well cheap of this board a while back and thought it would make a good performance box cos of the relatively steep 1st gear and the added bonus of a 0.73 final drive. Can run a decent rear gear and still get a happy cruising speed at sensible revs. I've looked on Brewers and Passon's website and can see plenty of potential............what do you reckon?

Pete · Post by **Pete** » Thu Feb 24, 11 7:40 pm

Weaker than a standard A833, I think it could end in tears on the strip with slicks on.....

Adrian Worman · Post by **Adrian Worman** » Thu Feb 24, 11 7:57 pm

Weaker Pete? I think this iron cased one that I have came from a van or truck, would have reckoned on a bit of strength, based on application?
I know that the aluminium cased boxes used in the later A bodies have a tendancy to distort the tailshaft housings

Pete · Post by **Pete** » Thu Feb 24, 11 8:08 pm

The internals are weaker.
Blue or Duncan can advise more, but I think that the main or layshafts are weaker because of the arrangement of the gears. I think they basically replace third for the high gear and the result is a weaker solution but it was designed for low power highway cruisers.....

J Clark · Post by **J Clark** » Thu Feb 24, 11 9:27 pm

Pete wrote:The internals are weaker.
Blue or Duncan can advise more, but I think that the main or layshafts are weaker because of the arrangement of the gears. I think they basically replace third for the high gear and the result is a weaker solution but it was designed for low power highway cruisers.....

Yes it was just a fudge whereby they inverted the 3rd / 4th lever on the side of the box 180 degrees so that 4th became third with a 1:1 ratio and then they put new gears on what should be 3rd to give the 'overdrive' ratio. What this means is that top gear now goes through the lay-shaft all the time rather than directly coupled through from the input to output shaft as would normally be the case with a 1:1 top gear. The result is increased wear on all the internals as most time is spent in top gear and all the shafts are turning at different speeds.... Not as durable........