Tinkerer

Ok someone posted that they aligned their drives (toe-in) to have 1/2 inch toe in instead of perfectly aligned. ( same distance between the point on the front of the drives as the distance from center to center of the prop shafts.) This was done for speed - any truth to this? I assume he was running the shaft spacing 1/2 inch wider than the nose spacing.

formula31

Yea Ive heard that too, I dont know whether it is called toe-in or toe-out but props farther apart than front of drives sounds right for control. I had my formula 1/4" that way.

JimmyBaja

Interesting information. I thought the proper adjustment was equal measurements front to rear centerlines?

Someone else have input?

blue thunder

I read all those post and ended up setting mine 1/2" in at the propshaft tip. That's what I thought the proper toe-in setting was for speed. I thought it had to do with the the prop wash of each prop coming together at a point behind the boat and that would let the engines rev higher. Not sure now. I'll probably try all combinations.

BT

Treadwellmotorsports

most manufactures set the drive at neutral. if your looking for a speed increase you want to toe out. wich is putting the front of the drive closer together. not every boat is the same and it is painstaking to do it but there is a sweetspot for every boat.. generally nothing over a half in . in most cases the best has been 3/8". you need to to test in 1/8" incremnts most boats if you fin the sweet spot will give you frim .5 to 1 mph

Treadwellmotosports.com

Rambunctious

treadwell

can you do this with a threaded tie bar? or more to it than that?

how much tow out recommended for speed for a 24 deg conventional bottom ( ie my 272SR1)

and if I add a tiebar to do this ( I have none today) will the drag of the tiebar offset any performance gain by allignment?

formula31

I had my 311 SR1 set up with 1/4" toe out, props turning out. That is, the front cone of the drives were 1/4" closer than the end of the prop shafts. The tie bar is completely out of the water at planing speeds, or it better be at any rate. You can do it with the inner tie bar but I strongly recommend an external tie bar too.

Bill272

My tie bar was set as short as it would go and put the props about 3/4" wider than the bullets. I had a machine shop cut a small section off the ends of the bar so that I could adjust it shorter. I now have the props in 1/2" closer than the bullets and the boat runs much better. I don't know if it really affected top speed, but I had a problem with porpoising at cruising speeds and that has disappeared. I spend a lot more time at 35-55 mph and now I'm not constantly dicking around with trim and tabs to get it to run level. Your results may vary, but this is what I've seen. The boat is an 89 Formula 272 with 330's/bravo 1's.

When you make the adjustment, you need to adjust the inner tie bar as well. You can't change the spacing at the back of the drives without affecting the steering arms inside at the transom. If you want to try different set-ups, it will be easier to adjust without the external tie bar. That way you're only changing the spacing on one bar instead of both. Just make sure the jam nut is tight and the cotter pin is installed so it doesn't change after you've adjusted it.

Rambunctious

thanks bill, i have an 88 with 330's, porposes a little at low planing speeds, usually just tap the tabs,

but i'm at 64.99999mph!! and trying to tweek out to break 65, then there will be a new goal of 70 i know..... so I'll probably play around for top speed.

one question for all:

if you have an external tie bar, can you / should you remove the inner one. i see so many boats "parked" with one drive up higher than the other, or people running the drives up one at a time. it seems that with both, this would put a huge strain on the inner tie bar. do you need it if you have an external one which has better leverage?

Bill272

The inner bar that ties the drives together attaches to the steering arms. These then attach to the tops of the gimbal rings and do not move up and down with the drives. The gimbal rings pivot side to side since they are attached at the top and bottom to the transom assembly and are controlled by the steering arms. The bellhousing pivots up and down since it is attached to the gimbal rings at a pivot point on each side, and is controlled by the trim cylinders. The drives are bolted onto the bellhousing. It all works like the U-joint between the drive shaft and the drive. That's how i understand it, at least, and I could be wrong. But regardless, I'd want both tie bars installed incase one fails.

BTW, I'm at just about the same spot with WOT (64.3 GPS). I haven't experimented much though.