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#285850 - 11/25/09 7:53 pm Preunit 4 speed to 5 speed  
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Triton1974 Offline
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Hi All

I have recently seen on eBay preunit gear boxes converted to 5 speed.

I have a 4 speed slick shift(I think), not sure of year but its the one that has the oval inspection / adjustment cover held on with two screws.

Anyone have any thoughts on what you have to do to convert and what gear box inners are compatible? Are there any suppliers that do replacement kits (I have looked but found nothing).

Cheers.

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#285899 - 11/26/09 2:52 am Re: Preunit 4 speed to 5 speed [Re: Triton1974]  
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Jon W. Whitley Online content
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I haven't seen any kits, but not ruling that out.

The big part of the conversion is finding the 5 speed complete. Not hard really, but can be expensive if patience isn't a virtue.

You can use the later needle roller bearings in place of the bronze bushings and there are a few tech articles on the web for doing it yourself.

Cheers


Jon W.


1957 6T Thunderbird 650
1971 TR6R Tiger 650
1955 Tiger 100 - Project
1970 BSA A65F 650 - Project

#285909 - 11/26/09 4:50 am Re: Preunit 4 speed to 5 speed [Re: Triton1974]  
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Pete R - R.I.P. Offline
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You've got the correct outer slickshift cover,check that all the parts and linkage are still in there.Its one of the best things Triumph ever did,but it was largely wasted on the ignorant masses at the time.Properly set up,you don't need a clutch cable:but you can use it if you want to.
All the 5-speed parts come from a T140.
You need the 5-speed final drive sprocket (different spline),drive-side mainshaft bearing and seal.Some grinding of the bearing shoulder in the case,to enlarge the hole.
Get all shafts ,gears,shift-forks;and bronze layshaft thrust washers(in case you fit needle rollers)
Get the camplate and plunger (some minor fitting may be required on the plunger),and the quadrant that drives the camplate.
Ratchet-plungers in the outer case are different(ground back more on the tooth).Splined shaft that the gear-lever connects to has less travel,but you could build yours up or weld up the stops in the outer case.

If you can get the parts at the right price,its an easy conversion and more fun to ride.4-speed boxes seem to be a little tougher.3rd gear is likely to fail,or have failed on a 5-speed,so check for bent shafts.(Depends how hard it was ridden).

#285913 - 11/26/09 5:35 am Re: Preunit 4 speed to 5 speed [Re: Pete R - R.I.P.]  
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Quaife do a gear set conversion for unit 650s. Price on application. They also make a complete five or six speed gearbox for Nortons but that costs around 2500 pounds sterling.

http://www.quaife.co.uk/


"Live the life you love, find a god you trust and don't take it all too seriously"

Pre-units rule!

Mid fifties Triumph T100
#285932 - 11/26/09 11:53 am Re: Preunit 4 speed to 5 speed [Re: Tasman]  
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Bodger Offline
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Jon Whitley: what articles on the web? Links please?..other than Victory Library's articles (have to be purchased).

Does anyone actually have Victory Library's articles, and are they good?

Pete R: aren't there more than one set of 5 speed internals? I read that late in the production cycle there were changes, and if so, are there years that work better than others? Thanks.

The Gold Star forum has mentioned this as being done by some there...maybe Dave in NV can say more about it.Maybe, heh, good one bodge.

#285934 - 11/26/09 11:54 am Re: Preunit 4 speed to 5 speed [Re: Triton1974]  
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Triton, do you have the links to the eBay boxes, and how much did they go for? Thanks, Ken

#285973 - 11/26/09 4:22 pm Re: Preunit 4 speed to 5 speed [Re: Bodger]  
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Triton -

My question is: why convert?

If you're looking for taller gearing, you'd be better served by installing a larger gearbox sprocket.

Just my 2c...

Happy Thanksgiving!

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#285981 - 11/26/09 5:18 pm Re: Preunit 4 speed to 5 speed [Re: JubeePrince]  
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John Healy Online content
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"Pete R: aren't there more than one set of 5 speed internals? I read that late in the production cycle there were changes, and if so, are there years that work better than others? Thanks."

There are about 4 iterations of the 5 speed gear set for Triumphs. The reliability improved with each iteration. The last change was made to the layshaft when they added a circlip keep the layshaft high gear from binding-up the layshaft 4th gear.

The conversion from a 4 speed includes opening the castings on BOTH ends of the mainshaft which can be done easily with a die grinder. This is the area directly behind each of the mainshaft bearings to provide clearance for the gears.

The first 5 speeds offered were a disaster and were subject to catastrophic failure. Often they would take the crankcase when they failed.

You can determine if you are looking a an early gear set by looking at the part numbers on the gears.

The rest of the changes were made to the layshaft. First high gear was widened (2nd iteration). This still let the pressed on high gear slide against the freely rotating 4th gear and lock it to high gear. A circlip was added which kept the high gear from moving against the 4th gear.

Also there is a difference in quality between the Taiwan 5 speed gears and the o.e.m. ones. This is especially true for the Taiwanese mainshaft which can break if used hard. The Taiwan teeth seldom break, but they do bend. Used on the street they hold up, but if you combine a road race tire and some power the mainshaft tends to break between the area where the needle bearings in the high gear run. (They are not gun drilled for the clutch rod, but drilled in from each end. The break appears where the bores meet.) If I am setting up a 5 speed to race with I always look for donor o.e.m. gears.



Last edited by John Healy; 11/26/09 5:19 pm.

#285985 - 11/26/09 5:29 pm Re: Preunit 4 speed to 5 speed [Re: JubeePrince]  
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Originally Posted By: JubeePrince
Triton -

My question is: why convert?

If you're looking for taller gearing, you'd be better served by installing a larger gearbox sprocket.



Steve


Because the five speed can be higher in top (if wanted, using your bigger sprocket), lower in first and all ratios closer than the four speed.

Last edited by triton thrasher; 11/26/09 5:33 pm.

Amateur Loctite enthusiast.
#286094 - 11/27/09 12:20 pm Re: Preunit 4 speed to 5 speed [Re: triton thrasher]  
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Why convert? is to get 5 speeds, and that's more than four, so that must be better. I'm an American, that's how we roll.

Actually, if what I think this does is get you a 5 speed with a 1.14 fourth gear instead of the GS 1.2 or even 1.3 third in the most available Gold Star boxes.(Gold Stars are BSA's, also made in England.)
The GS RRT2 box is 1.1 in third with a high first gear, so this would be better for track and street than the hard to find and expensive and collected RRT2. First gear would be more like the standard GS first..the RRT2 is I think 1.9, and altho I'm such a great rider I have no problem with it stalling and smoking, heh,..I'm really after the 4th to 5th spread.
It's cooler.
(not having a gear chart for the 5 speed handy ...)
The cost would be for the Triumph late 58-62 gear box and a set of (thank you John Healy! Once again!) oem internals from the best version of the Tri 5 speed boxes. Maybe the slickshift would still work? Even cooler if so.

Or I could win the lottery and buy a 5 or 6 speed magnesium Norton box for 2-3K$.

I'm going to spring this thread on the GS forum, they're funny over there, they may not read the Tri forum, heh....and they have talked about this 5 speed possibility... I needs more details.

Hey Triton1974, what were these selling for on Fleabay?

Last edited by Bodger; 11/27/09 1:04 pm.
#286127 - 11/27/09 3:48 pm Re: Preunit 4 speed to 5 speed [Re: Bodger]  
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Ron - in California R.I.P. Offline
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Hi Guys... I was "nudged" to chime in here... FYI, I use the Triumph 5 speed parts and put them in BSA (pre-unit) boxes.

John is correct, the last of the 5 speeds gears are the best.. There is repop stuff out there, so use the typical quality caviats. I found the 3rd gear pair of re-pop gears I got are too tight and bound up. Sadly I have no way to identify what is what, as there are no numbers or identifying marks on those gears.

On a different issue on broken main shafts, there also are two different part number main shafts. The difference is in the size of the threads, the later larger threads are considered stronger (57-7077). This is unrelated from what John mentioned on poorly made repops. I do source all my parts from England, but that does not mean they are made in England..

The reason for 5 speeds all depends on what you are doing.. Most of the aftermarket (5 or 6 speed) gear sets are very close ratio for road racing, and not great on the street (first gear is very tall).

So, what I and others notice is that with the 4 speed, pulling a steep hill or at altitude while accellerating you end up with to big a jump in between some gears, and actually slow up when you shift.. That extra gear solves that, big time..! This can be exagerated when you go to a larger tranny sprocket to try and reduce the revs at cruise.. Go find someone willing to let you ride a stock(ish) street Triumph with the 5 speed, and you will see the differences.. bet you love it.! It is so nice to just "snick" through the gears and the engine just purrs.....

OK I do not know the Tri 4 speed ratios, but I have "mapped out" all the Triumph ratios that I could find, along with the BSA ratios for comparison. NOTE, that I have what I call a "semi" close ratio gear set listed for the Triumphs. These were made for road racing, and work awesome.. however I do not know if they are still available.. this is what I use on my racer. I will try to upload my gear chart, then add a link, as I think it would all go funny if I tried to copy a spread sheet here.

Let me add some info. On the street, 2.45 to 2.65 makes for a decent first gear. (But this also depends on the weight and torque of the bike. A 500 to 750 cc bike is what I will use as reference, as this is what most here are talking about..) Go down to a 2.31 or less and first gear requires more clutch slippage to get it going, and two up makes it darn lousy in town. Again, it depends on your useage, if you plan to ride two up or with luggage, then try to keep around 2.60 for the first gear ratio. Stock road gearing on many BSA's and Triumphs is around 2.58 and 2.585 respectively.

Let's see how I do attaching the spread sheet...

http://goldstarron.com/Ratios.xls

Ron

Last edited by Ron - in California; 11/27/09 4:26 pm.
#286154 - 11/27/09 7:39 pm Re: Preunit 4 speed to 5 speed [Re: Ron - in California R.I.P.]  
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John Healy Online content
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The only 57-7077 available is made in Taiwan. While the diameter is larger, the root of the thread has is cut deeper and the kick starter end, which is drilled for the bronze bushing, is more prone to break than the earlier, smaller thread. It is very common to have people break the kick starter end of the mainshaft, while tightening the nut.

There have been two commercial sources for standard 5 speed gear sets-clusters/parts. One UK supplier that sources from Taiwan and the other that has them made/makes them in the UK/Coventry. Because there is no law in the UK that requires country of origin marking, like we do in the USA, knowing where things come from is a matter of knowing the supplier, experience and a bit of detective work. Seeing them made in a UK workshop is always a good sign when someone tells you they are made in England.

Or as the US Customs people ask, "Did you see any signs of machining chips?" While it is the responsibility of the importer to know where parts are made, UK suppliers never believed it was any of our business. We have found many of the parts sold by UK suppliers have just visited the England. Remember, England has been trading with the World long before we were a country and have very different views about these things than we do!

One of the prime movers for close ratio gears (1st, 2nd, and 3,rd) is/was Phil Pick - Triple Cycles. Richard Peckett (P&M) was also involved in this project. The gears they supplied were made in Coventry. They were also very active in supplying 5 speed mainshafts for triples utilizing belt drives.

While one should examine available gear ratios with a print out of the motorcycle dyno sheet/power curve, there are other factors. The days where you ran 200 mikes at Daytona, where any loss time at the start could be made up, our short 6 or 8 lap races are better described as a sprint.

For example: In the years where AHRMA flourished It was especially important if you were not a regular with AHRMA and wer stuck in the back - they gridded Daytona by previous season's points. Given that the bike has a reasonably wide power curve, using the stock, rather than a wide ratio gear set gives you a better chance in the drag race to get up to the front going into turn one.

Time spent thinking about gear ratios, and adjusting them to your power curve and what kind of racing you are doing, is just as an important factor as the camshaft, valve size, etc.


#286155 - 11/27/09 7:51 pm Re: Preunit 4 speed to 5 speed [Re: John Healy]  
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Thanks for the edjumication guys! I asked the question only because I hadn't seen it asked....

While I knew the 5-speed would provide close(r) gear ratios, I was under the impression that the high gear in a four-speed and high gear in a five-speed were both 1:1.

All of your $5 contributions allow us 2c to learn more everyday grin

Cheers,

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#286168 - 11/27/09 9:21 pm Re: Preunit 4 speed to 5 speed [Re: JubeePrince]  
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John Healy Online content
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I find this link helpful when considering gearing changes:
Gear calculator

If you think something that would be usefull select download from the top of the page. You will get a interactive excel program.

Last edited by John Healy; 11/27/09 9:24 pm.

#286193 - 11/28/09 12:07 am Re: Preunit 4 speed to 5 speed [Re: John Healy]  
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Ron - in California R.I.P. Offline
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J.P. Most Brit Bike top gear ratios are 1:1. I was very surprized to see the Quaife 6 speed having 6th gear at 1.19:1. Pehaps that is a mistake from the spec sheet I got it from.

One of the best ideas of the Brit Bike gear boxes is that in top gear the mainshft and output "sleeve gear" are locked together, this eliminating any wear on the bushes or needles in the sleeve gear, plus this is the most efficient method of power transmission through a gear box. Modern bikes and other makes use two full shafts so power is always transmitted through both shafts and adds to the power loss. How much I have no idea.

Ron

#286228 - 11/28/09 9:48 am Re: Preunit 4 speed to 5 speed [Re: Bodger]  
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Thanks all

The reason I was thinking of changing was to give a slightly easier crusing speed with lower revs (this I assumed as I haven't really started comparing ratios etc), as the old girl does vibrate (suppose I should just get the engine balanced) different topic!!!

What started me looking was an advert, about 6 weeks ago, for a preunit slickshift box converted by the seller to 5 speed. It went for about 250.00 wheras the 4 speed standards seem to go for between 100 - 200.

Last week there was another advert for just the five speed clusters which apparently had come out of a pre unit box (assumed modified) which went for 260.00 ish. The chap had quoted in his ad that Triumph enthusiasts would know they cost hundreds new hence my initial question can you buy these clusters or kits.

Thanks for the responses. I think I will look at the ratios and look about for a bargain T140 cluster and compare to see if its a mod that I fancy.

Cheers

#286237 - 11/28/09 12:08 pm Re: Preunit 4 speed to 5 speed [Re: JubeePrince]  
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Originally Posted By: JubeePrince
I was under the impression that the high gear in a four-speed and high gear in a five-speed were both 1:1.



You were right. They are both 1:1.


Amateur Loctite enthusiast.
#286238 - 11/28/09 12:13 pm Re: Preunit 4 speed to 5 speed [Re: Ron - in California R.I.P.]  
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Originally Posted By: Ron - in California


One of the best ideas of the Brit Bike gear boxes is that in top gear the mainshft and output "sleeve gear" are locked together, this eliminating any wear on the bushes or needles in the sleeve gear, plus this is the most efficient method of power transmission through a gear box. Modern bikes and other makes use two full shafts so power is always transmitted through both shafts and adds to the power loss. How much I have no idea.
Ron


Yes but.....

The Brit boxes are doubly indirect in the lower gears, which is far from the most efficient method of power transmission.


Amateur Loctite enthusiast.
#286239 - 11/28/09 12:15 pm Re: Preunit 4 speed to 5 speed [Re: triton thrasher]  
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Maybe it's worth saying that as road four-speeders go, the Triumph ratios aren't bad.

Try a Royal Enfield if you want to sample a bad set of ratios. Huge jump from third to top.


Amateur Loctite enthusiast.
#286247 - 11/28/09 3:27 pm Re: Preunit 4 speed to 5 speed [Re: triton thrasher]  
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Triton1974 Offline
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OK

If the high gear ratio is the same on a four and five speed there would be little point in me doing the mod if all I wanted was a slower revving engine at crusing speeds.

I have also noticed that there are wide and close ration clusters available? Were these fitted as standard or as optional OEM's for race bikes / hill climbers etc?

#286271 - 11/28/09 6:31 pm Re: Preunit 4 speed to 5 speed [Re: Triton1974]  
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Originally Posted By: Triton1974
OK

If the high gear ratio is the same on a four and five speed there would be little point in me doing the mod if all I wanted was a slower revving engine at crusing speeds.


Except- because of the five speed's greater difference in ratio between first and fifth, you can gear up by sprocket change and still have a low enough first gear.


Quote:

I have also noticed that there are wide and close ration clusters available? Were these fitted as standard or as optional OEM's for race bikes / hill climbers etc?


I think wide ratio was for trials (trying to cross obstacles without putting your foot down); close ratio for road racing (pavement). Standard ratios are almost bound to more suitable for your road use.


Amateur Loctite enthusiast.
#286375 - 11/29/09 4:19 pm Re: Preunit 4 speed to 5 speed [Re: triton thrasher]  
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Ron - in California R.I.P. Offline
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I just noticed, that Triton 1974 and Triton Thrasher are "over there'.. in the land of flatness and low altitudes.. The need for a 5 speed is less under those circumstances, so you can go on one maybe two teeth on the tranny sprocket and get away with it...

But for those of us that have big hills and altitude, and pack double, the 5 speed does exactly what is desired, gets the bike going easily from a stop (less clutch slippage needed) and really accelerates the bike with a lot less throttle as the engine revs drop a lot less in between every shift. It does not matter in the scheme of things that top gear is still 1:1. just gear (overall) for 4th gear like you have now, and then 5th becomes the overdrive. If you look at the gearing chart you will see that 4th to 5th is close enough to actually be useful, unless you go really nuts on gearing (22 tooth sprocket).

Last word, for those that are on the fence, go find a buddy's bike with a 5 speed and ride it... that will answer any questions you have...

Now for the racers, gosh what a debate they have on whether to use a 5 speed or a 6 speed... geesh now that gets complicated..! And do not even talk about the Tiddler Racers from way back then with like 11 or 13 or more gears..!!

Cheers..!!

Ron

#286384 - 11/29/09 4:59 pm Re: Preunit 4 speed to 5 speed [Re: Ron - in California R.I.P.]  
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Originally Posted By: Ron - in California
the land of flatness


I've heard Scotland called many a thing but that's a new one.

Quote:
just gear (overall) for 4th gear like you have now, and then 5th becomes the overdrive.

I'd call that overgeared, but it's a matter of preference.

Quote:
Last word, for those that are on the fence, go find a buddy's bike with a 5 speed and ride it... that will answer any questions you have...
Ron


I've ridden them and they are better than 4 speed, for the reasons previously stated and for the quicker easier changes you get with closer ratios. I've just fitted an as-new late 4 speed cluster to my Pre-unit because it was available cheaply, which good 5 speed clusters are not.

As BSA M20 owner George Orwell might have said, if he'd written Motorbike Garage instead of Animal Farm: four speeds good; five speeds better!


Amateur Loctite enthusiast.
#286501 - 11/30/09 3:05 am Re: Preunit 4 speed to 5 speed [Re: Triton1974]  
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Triton -
Lots of good tidbits floating around here, so allow me to put it together for you...

All Triumph gearboxes (4-speed and 5-speed) are 1:1 (internally) in high gear.
Installing a 5-speed raises your final drive ratio because the stock 5-speed has more teeth on the countershaft sprocket than a 4-speed. And only for that reason.
If cost or ease of installation are important to you, then you can simply install a 20 or 21T sprocket on your existing 4-speed gearbox. 20T was stock on the Thunderbird, Triumph's touring bike.
It's important to realize that raising the number of sprocket teeth will raise the entire ratio. That is, cruising may become easier, but pulling off in 1st will become more difficult.
What a 5-speed will do is retain the low first gear, while allowing you to have a "taller" high gear at the same time.


May I suggest you try a 20 tooth countershaft sprocket first and see how that does. It's a very inexpensive way to see if you'd like the gear ratio change. If you're not drag racing or needing "jack rabbit" starts, then I know you'll appreciate the cost savings.

bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#286648 - 12/01/09 12:55 am Re: Preunit 4 speed to 5 speed [Re: RF Whatley]  
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John Healy Online content
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Boston, Massachusetts
Unless you are well sponsored the question most people face with this gear setup is not which shall I use, 5 or 6 speed, but 5 speed close or standard ratios.

Oddly, the US Market 6T came with 19 teeth. It was the UK, that listed 20.

When you are doing all this remember increasing the size of the transmission sprocket will change how your charging system works.



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