User Tag List
Thanks: 0
Likes: 0
Results 61 to 75 of 118
Thread: Name this lower unit
-
02-10-2008, 09:54 AM #61
No, it is a Merc. If you read through the whole thread you will learn about it and its close relatives.
The visual similarity/familiarity is probably the smooth prop shaft on this Merc unit and the 75/105/120/135 Chrysler unit (that most people call the 135 Chrysler unit, 'cause that was the last Chrysler to use it). Big difference between the shafts though ... this Merc is 3/4" , the Chrysler is 7/8", so props will not interchange.
Both the Mac and Chrysler are completely different from the Mercs and each other.
The Mac and Chrysler were both white, did not use exactly 1:1 gears, used fat, reduced diameter gears, had a thrust boss cast in, the exhaust exited above the cavitation plate, were slightly larger than a Speedmaster, may be co-winners of the butt-ugly racing lower unit award and were designed by the same guys; but after that they are completely different.
I guess I should be doing a separate thread on the Mac and a separate thread on the Chryslers to go thru all the variations of each of them, too.Last edited by Mark75H; 03-30-2008 at 12:56 PM.
-
03-30-2008, 12:05 PM #62
Speedmaster & Sportsmaster gearcases ....
...were first built to bolt onto production Merc 800 downhousings in 1960. The fat, short direct reversing, low geared Mark 75, 78 and Merc 800 gearcases gave the John-Rude 75 a good chance in NOA Pleasure Craft Racing, in fact until we (and also Paul Allison) got ahold of a Sportsmaster unit (geared between the club foot and 1/1, and some what thinner than an OMC 3 cyl. looper gearcase of later years), Johnson held the unlimnited record on a 14' Allison at about 57 mph. I held the 70-80 class record with the standard gearcase Merc 800 on a heavier 14' Allison at 51 mph, and upped it to nearly 57 mph with the Sportsmaster unit (and ran over 60 mph with the same motor on my 13' Allison in unlimited class, driving on my knees from the transom--Paul ran a similar rig at over 61 mph and set that record). My Dad had complained until he turned blue in the face about Kiekhaefer 6 cyl. gearcases, the new gearcases were the result of such feedback (the Speedmaster was disallowed in pleasure craft racing).
-
03-30-2008, 12:51 PM #63
Joe, you are correct, 1960 is the first year the Speedmaster was legal. The first spec sheet I have showing them is dated Jan 1, 1960. I had the spec sheet and never looked at it. You made me go back and do thorough complete research to learn that date.
At the same time the left and right 800 Speedmasters came out, so did the one in this thread ... not an 800 but a 700. There were subtle differences between the two and that is what this thread is about. 80hp Speedmasters used 3/4" smooth propshaft with 5/16 shear pins, this one has a 1/4 hole, so it was for a 70hp.
Info on the Sportmaster lower unit is in this post: http://forums.screamandfly.com/forum...1&postcount=24Last edited by Mark75H; 04-07-2009 at 06:00 PM.
-
03-30-2008, 01:18 PM #64
-
03-30-2008, 01:44 PM #65
True, but I don't know how that relates to this???
-
04-01-2008, 02:54 AM #66
Jim Hunt was my co-driver in 1979. Financed by Fred Schoellkopf (who became a fine driver in his own right in 1983) who co0drove with George Laycock. I set up both boats, my motor came from Ireland and Jost, Kenny Shaw (who won with similar boat) and bill muncie got the other two factory motors. In 1981 I drove the 4 hours alone, really loved it although the boat (Louis Collins' winning 1980 Laser) was no longer competitive because they changed the rules at the last minute under pressure from the Cal. crowd to permit beneath gerarcase water pickups. that allowed the tunnels, which previously had zero advantage, to run upwards of 100mph. We were stick at about 85mph.
-
04-24-2008, 12:21 PM #67Junior Member
- Join Date
- Oct 2006
- Location
- Kennewick Wa.
- Posts
- 7
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
Hi 75H,.
That was a cool video. I was 13 years old in 1957 and my family had a Merc dealership in Seattle Wa. I ran lots of Merc 75's 78,s and all the other D R', AS THEY CAME ALONG. I had a pair of them on a 14' Powercat. It is fun to look back on the old days and realize just how much advance has been made in engines. I love my 20' ally w/the 280. Jerry
-
04-07-2009, 03:39 PM #68Junior Member
- Join Date
- Jan 2004
- Location
- ohio
- Posts
- 21
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
was it used on a marc 75 78 made in 1957 or so????????
-
04-07-2009, 04:13 PM #69
No, it does not fit towers made before 1960
-
04-07-2009, 05:17 PM #706000 RPM
- Join Date
- Jan 2005
- Location
- South Florida
- Posts
- 1,360
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 1
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
First SpeedMaster made. Single shaft. Single pinion. Weak unit, thats why there's few left, and the reason the twin shaft, twin pinion was developed soon after. The driven gear(pinion) snaps right off the shaft. Its so weak, I would hesitate to even use it on a historical piece(motor).
Last edited by AirRide; 04-07-2009 at 05:43 PM.
-
04-07-2009, 05:55 PM #71
I have seen quite a few of them still in use and almost as many apart, and I have never seen one with a broken pinion gear as described. These work quite well as long as you don't run them with more than 100 horsepower. About 500 were made and a surprising number of them are still around.
The main failure is gear tooth wear
Link to the next Speedmaster version
.
.Last edited by Mark75H; 04-07-2009 at 06:02 PM.
-
04-09-2009, 09:31 AM #726000 RPM
- Join Date
- Jan 2005
- Location
- South Florida
- Posts
- 1,360
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 1
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
-
11-15-2009, 09:38 PM #73
If anyone who has a single pinion Speedmaster is interested in new gears ... there is an on going project that could yield gears as a side product
In order to produce the driveshaft gear, the guys involved would need to invest an additional $700 in tooling to produce the driveshaft gear. If we don't hear anything, these will not be produced.
These will be the real deal, but they will not be inexpensive.
-
02-01-2010, 01:58 PM #74Registered User
- Join Date
- Nov 2006
- Location
- Middle East
- Posts
- 198
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
want speedmaster lower unit spacer
hi
I am looking for speedmaster spacer gaer
from where can i get it and who is made by?
thank you for early reply
john
-
02-01-2010, 05:08 PM #75