has anyone ever placed a tr in place of a trs? i've blown my third trs lower unit so far. i have a complete tr drive in great shape and plan to throw it on for a test ride. it is said that the tr drive is alot stronger then the trs. other than being about two inches lower in the water and having to use another prop i cant see why it wouldnt work. has anyone ever done this swap? my boat is a 1979 24' pantera with a procharged 540" bbc.

The uppers are the same.The only difference in the lower is it may have a lower gear ratio which you wouldn't want with that set up and the longer lower unit will probably slow your boat down more than you think. In the Mercruiser TR-TRS Manual it states the TRS was designed for boats that run over 45mph and TR was for slower boats like houseboats,work boats,offshore fishing boats.It can use up to a 20" prop.As far as being stronger I don't know how it could be. All the parts inside are the same except for a longer lower drive shaft and number of teeth on the gears.

The TR is a weaker drive than the TRS.

Most (possibly all) TR drives are 2:1 ratio

I got a great deal on a re-manned Konrad. Bolt it up and run.

Kurt 715-410-0735

I think a TR is a little deeper also ...

Whats blowing up on the lower?? Most probable is the lower gears. Proper setup is critical to the lowers surviving. I'm assuming your blowing up a right rotation drive? You cant just swap out lowers like with a Bravo. The top bearing on the TRS lower has shims in the upper unit to achive proper preload.

The right rotation lower has its driven/prop gear facing outward from the pinion, this puts the gear in a weaker part of the bullet. Setting up the right drive with a hard shim in the lower(instead of the crush ring) stabilizes it and increases gear life.

You can also try running a left rotation lower, these are stronger because the drive gear is behind the pinion gear and in the strongest part of the housing. You would need a new LH prop though, and it might throw off handling, because both the motor and prop will be spinning in the same direction.

Again, setup is very important to survival if your running any kind of power. But I think if you have a good set of gears, a good housing, proper setup and good driving habits, you should get some life out of a TRS lower. Being a single engine boat with some HP is going to be a big load on any outdrive. Good luck.

LE

yes the gears are blowing out of these things. the last drive i just broke was a left hand unit. i figured since the tr unit was so much larger of a lower case that it would be some what stronger. it is a 2/1 ratio though so i would end up with a really crazy prop. and it's like two inches lower like the speedmaster and takes the same prop 19 spline. i'm not gonna dump the money into it for a konrad. i'm making over the 800 horse and they say is all they can take anyways. think i'm just gonna pull my motor and put it back in my race car and throw a 400 horse 454 back in the boat with the tr drive. wont be fast anymore but it shouldnt keep blowing these drives. anyone have any good ideas as for a prop selection just to get it started?