Help with torque steer

[JamesM]

Originally posted by Brookp01
Thanks for the info. I think the gearbox/cavitation plate is at the same vertical height as before just 2 inches further back, as the transom has been cut down to accomodate the lower saddle position.

If the gearbox is at the same height as when you had a 20 inch mid section the extra 2 inches of setback in the 15inch mid section won't mean that the gearbox is 2 inches further back than before with the 20 inch mid. In order for the gearbox to be at the same height as before the engine must be mounted to the transom 5 inches lower than before, due to the angle of the transom mounting it 5 inches lower will mean that the saddle brackets are approximatly two inches further forward than before. So if the 15 inch midsection didn't have that extra 2 inches of set back the whole engine including the gearbox would be 2 inches nearer to the back of the boat than with the 20 inch midsection. As I guess most boats have similar transom angles Mercury in their infinite wisdom built 2 inches more setback into the 15inch midsection to gain back the 2 inches of setback they lost buy reducing its height.

So to conlcude, your gearbox should pretty much be, as near as dam it, in the same place as when you had the 20 inch mid, not 2 inches further back.

If with your old prop fitted you drive along at the same speed and revs you used to see when flat out with with your old 2.5 200 is the steering still heavy?

[Brookp01]

Originally posted by Johnny Boat Dude
If the gearbox is at the same height as when you had a 20 inch mid section the extra 2 inches of setback in the 15inch mid section won't mean that the gearbox is 2 inches further back than before with the 20 inch mid. In order for the gearbox to be at the same height as before the engine must be mounted to the transom 5 inches lower than before, due to the angle of the transom mounting it 5 inches lower will mean that the saddle brackets are approximatly two inches further forward than before. So if the 15 inch midsection didn't have that extra 2 inches of set back the whole engine including the gearbox would be 2 inches nearer to the back of the boat than with the 20 inch midsection. As I guess most boats have similar transom angles Mercury in their infinite wisdom built 2 inches more setback into the 15inch midsection to gain back the 2 inches of setback they lost buy reducing its height.

So to conlcude, your gearbox should pretty much be, as near as dam it, in the same place as when you had the 20 inch mid, not 2 inches further back.

If with your old prop fitted you drive along at the same speed and revs you used to see when flat out with with your old 2.5 200 is the steering still heavy?

Hmm I'm finding this confusing. I dont understand how setback can be lost by reducing the height of the midsection. I thought that because the leg runs parallel to the transom (ignoring trim) the 20" mid would be a certain distance from the transom all the way from the top of the tramsom to the bottom irrespective of where the saddle sits. If the 15" mid has 2" of setback it will be an extra 2" further away from the transom than the 20" mid despite where its saddle sits. I was also under the impression that the idea of setback was to place the prop in cleaner water away from the boat and also to be able to run the motor higher due to the lip of water pushed up from the bottom of the boat which rises away from the back of the hull. Anyway Hutchy has fixed it with a 20" mid and a different gearbox, mainly I think cos the motor was set too high and my gear box had a smaller cut down skeg.