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Pre-unit vs Unit Triton

Pre-unit vs Unit Triton

Postby Johnnymac » Mon Nov 21, 2016 5:58 pm

I read here somewhere on the forum that there are several reasons why a pre-unit Triumph Triton is better than a unit. I have searched everywhere and can't find it. I am thinking about maybe building one. The pre-units are getting rather hard to find. Aside from the desirability of the pre-unit and the fact that they more accurate to the original Tritons, why is the pre-unit better? Why would a unit Triton be technically inferior?

Thanks guys.
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Re: Pre-unit vs Unit Triton

Postby Fast Eddie » Tue Nov 22, 2016 12:18 am

The featherbed is a long frame, a pre unit fills it better. The best looking is when the long chain case is used, that really looks like it was meant to be!

There are technical bennefits too, the pre unit enables you to mount the engine a long way forward, which is good for weight distribution and handling.

It also allows the gearbox to be further back, which is good for correct alignment of the rear wheel to swinging arm to gearbox sprocket centre lines.

However, the unit engine can be mounted to perfectly negate the above issues, it also have the benefit iPod having much stronger crank cases and even stronger gearbox shell.

Dave Degans (Dresda) prefers until engines because of the above. He sells engine plates etc to make it easy to get it right.

Finally, although many components can be retro fitted to different Triumphs IF you know what you're doing, why bother? Just buy a later T140 motor and you have a 5 speed box, 750 top end, etc.

So... The easier / sensible choice for a fast motor is unit. The more aesthetically 'correct' version is pre unit... Both will work well. Its all down to personal choice really.

PS, I know someone selling a brilliant 750 pre unit Triton, squished head, belt drive, Maxton forks and shocks, lots of Dresda work, etc. PM me if interested, bike is in UK.
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Re: Pre-unit vs Unit Triton

Postby Johnnymac » Tue Nov 22, 2016 3:55 pm

Fast Eddie wrote:The featherbed is a long frame, a pre unit fills it better. The best looking is when the long chain case is used, that really looks like it was meant to be!

There are technical bennefits too, the pre unit enables you to mount the engine a long way forward, which is good for weight distribution and handling.

It also allows the gearbox to be further back, which is good for correct alignment of the rear wheel to swinging arm to gearbox sprocket centre lines.

However, the unit engine can be mounted to perfectly negate the above issues, it also have the benefit iPod having much stronger crank cases and even stronger gearbox shell.

Dave Degans (Dresda) prefers until engines because of the above. He sells engine plates etc to make it easy to get it right.

Finally, although many components can be retro fitted to different Triumphs IF you know what you're doing, why bother? Just buy a later T140 motor and you have a 5 speed box, 750 top end, etc.

So... The easier / sensible choice for a fast motor is unit. The more aesthetically 'correct' version is pre unit... Both will work well. Its all down to personal choice really.

PS, I know someone selling a brilliant 750 pre unit Triton, squished head, belt drive, Maxton forks and shocks, lots of Dresda work, etc. PM me if interested, bike is in UK.


Thanks Eddie! It's probably a good thing that your buddy's bike is not State side! I currently have 6 bikes and if I get another, my wife will kick me out. ;-)

A few months ago I picked up a very nice Atlas. I'm trying figure out what to do with it. I know some will think it's sacrilege to split it up, but I'm not worried about it. I may keep it as an Atlas, or build up a Triton if the right motor comes around.
1963 Norton Atlas
1966 Norton Atlas
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1974 Ducati 750 GT
2000 Harley Davidson FLHTPI-Police
2003 Triumph Bonneville T-100
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Re: Pre-unit vs Unit Triton

Postby Fast Eddie » Wed Nov 23, 2016 12:23 am

Johnnymac wrote:
Fast Eddie wrote:The featherbed is a long frame, a pre unit fills it better. The best looking is when the long chain case is used, that really looks like it was meant to be!

There are technical bennefits too, the pre unit enables you to mount the engine a long way forward, which is good for weight distribution and handling.

It also allows the gearbox to be further back, which is good for correct alignment of the rear wheel to swinging arm to gearbox sprocket centre lines.

However, the unit engine can be mounted to perfectly negate the above issues, it also have the benefit iPod having much stronger crank cases and even stronger gearbox shell.

Dave Degans (Dresda) prefers until engines because of the above. He sells engine plates etc to make it easy to get it right.

Finally, although many components can be retro fitted to different Triumphs IF you know what you're doing, why bother? Just buy a later T140 motor and you have a 5 speed box, 750 top end, etc.

So... The easier / sensible choice for a fast motor is unit. The more aesthetically 'correct' version is pre unit... Both will work well. Its all down to personal choice really.

PS, I know someone selling a brilliant 750 pre unit Triton, squished head, belt drive, Maxton forks and shocks, lots of Dresda work, etc. PM me if interested, bike is in UK.


Thanks Eddie! It's probably a good thing that your buddy's bike is not State side! I currently have 6 bikes and if I get another, my wife will kick me out. ;-)

A few months ago I picked up a very nice Atlas. I'm trying figure out what to do with it. I know some will think it's sacrilege to split it up, but I'm not worried about it. I may keep it as an Atlas, or build up a Triton if the right motor comes around.


Wow. You'd be crazy to break up a good Atlas IMHO. Both financially and technically! Spend your money on nice cam / pistons / head work and the Atlas will be at least as fast as any Triton you're likely to build!
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Re: Pre-unit vs Unit Triton

Postby grandpaul » Tue Nov 29, 2016 2:10 pm

Nothing wrong with proportions or weight distribution on a good UNIT Triton.

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Re: Pre-unit vs Unit Triton

Postby ashman » Thu Dec 01, 2016 3:11 pm

Keep the Atlas motor gearbox and engine mounts, get what ever motor you want to fit with its own engine mounts, I have set my Featherbed 850 Commando motor up where I can pull the motor gearbox and mounts out in one hit, just undoing the engine mount bolts from the frame mounts (4 bolts and 6 small bolt from the head stay) all up about 30 minutes work to lift my motor out of the frame in one lot, so you could have another motor gearbox and engine mounts set up ready to drop straight into the Featherbed frame all you need to have is another motor and you still keep the Atlas gear for returning it back to stock set up.

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Re: Pre-unit vs Unit Triton

Postby Matt Spencer » Sat Dec 10, 2016 8:56 pm

A UNIT Vibrates more Harshly ! :P :lol: :!:

Centuries ago there were plenty of Triumphs that had ' met ' the sceneary , and plenty of blown up Nortons , in Olde Blighty .

Nowadays it isnt neccesary for a Norton to Blow Up , of a Triumph to go through hedges uninvited , so a Tritons a bit supurflous .

A Pre Unit Widelines a ' period piece ' that was better than ' over the shelf ' trash bar a black lightning , tho the Frame was better .

Preserving in Oil your standard discarded pieces & bulletproofing your 750 Norton , INEXPENSIVELY would make sense .
A Sorta Dunstall THING would be the way to go , maybe .

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And Dont Forget to Slow down for Bumps . :)
The Japanese response to ' styling ' , was to add more .
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Re: Pre-unit vs Unit Triton

Postby Matt Spencer » Sat Dec 10, 2016 9:07 pm

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SEE where it says PERFORMANCE , Just Above .
Youd need a exceptional Bonnie Motor to beat that .

Sticka witha the Norton Man . :idea:

Got This Mag , but THIS is flogged from HERE : http://www.ebay.ie/itm/1966-Motor-Cycle ... 1849878476

click to blow it up . :lol: :oops: . :mrgreen: . One needs a degree of finesse to operate a Norton , as they are pre User Friendly . :D
The Japanese response to ' styling ' , was to add more .
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Re: Pre-unit vs Unit Triton

Postby Matt Spencer » Sat Dec 10, 2016 9:38 pm

Pahh, founda nutha one. Some tecno whizz might wanna lift em 7 post to ' other nortons or somesuch .

http://www.ebay.com/itm/1965-Motor-Cycl ... 1887638427

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Of course , if youve blown up your Norton , and your Triumph has ' left the road ' , it could be a differant story . :P

Weight Distribution and Chain Alignments favour Ridgid Pre Unit Chaincase setup .

$$$$$$$$$$$$$$$$$$$$$$$$$$$ & itd be a Manx Norvin , of Course . But its gotta end SOMEWHERE . A Classic Period Piece is perhaps the Art Deco Answer .
The Japanese response to ' styling ' , was to add more .
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Re: Pre-unit vs Unit Triton

Postby auldblue » Mon Dec 26, 2016 3:54 pm

I did have most of the components to build a Triton, the bike was basically a model 50 but was registered on the V5 as Triton M reg 1974. The frame number was illegible which put me off somewhat as the idea of owning a stolen bike kinda gave me the hebegeebees . I rode it home from the MOT station in the frost with not the warmest of kit . I just couldn't take to the wee bike after that but it did look like a Triton and if I was ever to get another it would be pre unit.


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Re: Pre-unit vs Unit Triton

Postby Frankie17 » Thu Jan 12, 2017 9:27 am

Pre unit motor with unit top half would be my choice , best of both worlds old school looks with the benefit of the 9 stud top end

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Re: Pre-unit vs Unit Triton

Postby Triton Thrasher » Thu Jan 12, 2017 11:07 am

grandpaul wrote:Nothing wrong with proportions or weight distribution on a good UNIT Triton.

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Is there a chain on that?
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Re: Pre-unit vs Unit Triton

Postby grandpaul » Thu Jan 12, 2017 12:00 pm

Triton Thrasher wrote:
grandpaul wrote:Nothing wrong with proportions or weight distribution on a good UNIT Triton.

Image



Is there a chain on that?


There is NOW.

...and primary cover plugs & timing cap, and a nice polished alloy fuel tank, and a few other odd bits.
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Re: Pre-unit vs Unit Triton

Postby Triton Thrasher » Fri Jan 13, 2017 11:31 am

grandpaul wrote:
Triton Thrasher wrote:
grandpaul wrote:Nothing wrong with proportions or weight distribution on a good UNIT Triton.

Image



Is there a chain on that?


There is NOW.

...and primary cover plugs & timing cap, and a nice polished alloy fuel tank, and a few other odd bits.


Have you got rid of that huge alloy footrest plate?
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Re: Pre-unit vs Unit Triton

Postby Fast Eddie » Fri Jan 13, 2017 11:46 am

That "huge footrest plate" looks to me like a copy of the Dresda plates.

But on Dresda's, the extended plate is there as the silencer mount, with the silencers upswept to match the angle (and which are mounted on rubber bobbins).

GPs are just hanging out there looking rather superfluous though ...
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