Thrust blocks

Century · Post by **Century** » Wed Jan 28, 2009 11:35 pm

Folks - My century, which is an older model, has an aluminum thrust block with a brass lever held in place by a cotter pin. This pin is removed to release the lever and tilt the engine. Both my silver century and SC Plus have nylon thrust blocks with nylon levers that function as latches, both of which are broken. Many of the engines I see pictured also have nylon thrust blocks with broken latches. Is there a source to purchase replacement latches without having to buy the entire block assembly? I understand that the nylon lever is designed to break and allow the engine to tilt if it hits an obstruction. Apart from that feature, the older aluminum thrust block seems to provide a more secure fit.

Hugz · Post by **Hugz** » Wed Jan 28, 2009 11:49 pm

Good question!

Century · Post by **Century** » Thu Jan 29, 2009 4:36 am

Hugz - Thanks for posting the photo to illustrate the question. I've got to learn how to do that some time.

chris · Post by **chris** » Thu Jan 29, 2009 6:05 am

I never use that lever thing, if the seagull is locked down and you hit something there is a good chance of breaking something, the seagulls are secure enough without them.

Waggles · Post by **Waggles** » Thu Jan 29, 2009 7:25 am

I've always thought such latches exist only to help ease starting to be honest by helping to prevent the motor 'rearing up' when you pull the cord. Many motors don't have them at all ( my 40+ for example ) so I have to hold the tank when starting. They can only increase prop damage if you hit an obstruction. I agree with Chris, don't worry about it.

40TPI · Post by **40TPI** » Thu Jan 29, 2009 12:15 pm

To answer the question Seagull did indeed sell them separately from the nylon thrust block. They were sold in pairs, shrunk wrapped on card as "Packaged accessory part number 2008CP". (Service Sheet No 30 in the Maintenance Manual usefully lists this and all the other packaged accessories and spares)

See http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=018

Item number: 280294807984

John at SOS or Sheridan Marine over at Oxford will surely be able to supply.

They may well help restrain the motor when starting and also prevent the bracket unexpectedly clanging down onto the car as you lift it into the boot but their stated purpose is to restrain the motor in the vertical after closing the throttle.

Seagull's own words : " "When the motor is used on a heavy hull of good lines it may well carry its way for some time after the throttle is closed, the engine may tilt clear of the thrust block. BE SURE THAT THE THROTTLE IS NOT REOPENED UNTIL THE MOTOR HAS DROPPED BACK INTO THE THRUST BLOCK."

It is also described as a breakable item in case of hitting obstructions and the recommendation is to run with it unlatched if at all possible.......so something akin to the human appendix in terms of design? And possibly only replaced when worrying about restoring a display motor?

Apart from the early (reversing?) Marston/102 none of the thrust blocks have solid metal locked latches as far as I am aware; the later Model 90/110 EFNR design has a hard rubber breakaway sleeve around the driveshaft, an improved design that doesn't require replacement parts after an incident. A Century with a full locking metal thrust block and latch sounds like either a much earlier bracket or a modification.

Peter

Hugz · Post by **Hugz** » Thu Jan 29, 2009 12:54 pm

I have an early sixties century with a metal clamp as described by 'Century'. In fact I had to weld it up as it had broken presumably from being in a locked position when running ground.

Cheers Hugo.

40TPI · Post by **40TPI** » Thu Jan 29, 2009 3:14 pm

Interesting........... any possibility of a pic so we can see please Hugo?

Peter

Hugz · Post by **Hugz** » Fri Jan 30, 2009 1:51 am

As luck would have it, the aforementioned thrust block is right at the back of this gaggle and my back is still recovering from an infraction with an EFNR. No pirouettes from me for a while!

I'll post a pic when I'm able.

Century · Post by **Century** » Thu Feb 05, 2009 7:43 pm

Folks - Given the interest expressed above, here' a look at the aluminum thrust block from the older model century referenced in my original post. The block currently resides on my silver century. Pardon the fuzziness, but I took the photo from an awkward position making the camera hard to hold steady. The foremost cotter pin secures the latch closed and is removed to open it. When I acquired the motor, this cotter pin was secured to the mounting bracket by a short length of flat link small brass chain not pictured here, which allowed the cotter pin to be inserted or removed without being lost. The chain was heavily corroded and I replaced it with a short wire fishing leader that seems to do the job. Because I trailer my boat, often at high speed on major highways, I need to close the latch to keep the motor securely mounted and not pivoting up and down in the wind or over dips and bumps (or road slumps as I recollect them referred to in New Zealand).
[img]http://www.mapmike.com/Century100_2657.jpg[/img]
http://www.mapmike.com/Century100_2657.jpg
[url]http://www.mapmike.com/Century100_2657.jpg[/url]

40TPI · Post by **40TPI** » Mon Feb 09, 2009 2:54 pm

Thank you for that. I suspect that it is from a much older 102. I think thrust blocks were all solid black plastic by the time of the Century introduction but that would have to be confirmed by others... or more likely the chap in Poole!

Peter

Post by **charlesp** » Mon Feb 09, 2009 3:07 pm

Well this chap in Poole has been rooting round in some adverts. Mid fifties posters showing early Centuries show them as sharing a bracket with their 102 brethren, and they have the metal thrust block. From the engravings it's impossible to tell which one it actually is. There were three versions - bronze aluminium alloy, and black plastic.

So, yes, the early Cernturies did have this feature. It's not as good as the later nylon component.

40TPI · Post by **40TPI** » Mon Feb 09, 2009 6:16 pm

Thanks for that Charles, thought you might know something about it.... I've just done what I should have done to start with and check a contemporary parts list. Your prompt of several types available at once brings up problems for the stores keeper if they aren't covered by different numbers.

And so they are. Yellow cover parts list " Simplicity itself " version 11/59 under Engine Mounting Bracket Century & Century Plus has item 1340B as "Thrust block complete with Stud and Nuts, Latch and Chain" at 7s 4d, whilst 1341B is the same item but in bronze at an extra 3s 8d.

Somewhere post November 1959 1340B changes from alloy with brass latch and chain secured pin to the white plastic block with breakaway plastic latch, still known under the same 1340B number and supplied till the end of the Silver Century/75/80 models.... (goodness knows why I had black nylon in mind since that is the 40/1340 for 64cc Forty series).

Haven't got a similar vintage 102 part list to hand to see how that matches up though.

So Seagull changed from brass latch fully locked down thrust block to breakaway plastic under the same part number...... maybe too much transom damage in shallow rocky waters! The fitting instructions for the white plastic 1340B block urge the owner to run with the latch open whenever possible. I haven't got an early Century handbook so I've no idea if there were similar exhortations in that. I suspect it was meant to be a quiet changeover from alloy to plastic so the handbook may be silent on this subject...........!

"Cogoule" back on the peg....... must have been the paint fumes.

Peter