To rebuild or not to rebuild-dang transmission (Rebuilding)

I may have brought this up earlier but my transmission fluid has turned gold from when I drained and put new fluid in last year. Barely put 1000 miles on the bike and I figure the bushings are wearing. Bike has just over 13000 on her and was wondering what the guys in the know could tell me.

If I need to tear down I want to get the Mick Hemmings DVD to make sure to do it right, will order off the INOA site.

I was noticing a good bit of fluid on my floor in the garage over the winter. Found out all my brake fluid drained out of my Lockheed caliper so I will be taking that down and finding out what is going on.

Engine is good, oil out of the tach hole but other than that good and I do not want to open it up with no problems. If I take the tranny apart am looking at the Norvil belt primary to replace the triplex chain.

I have taken off the exhaust and decided to go with a non crossover set of exhaust tubes. Commando Specialties has a good looking set of pipes and peashooters that caught my eye the other day.

Just sold my Mustang so I have a little play money to get into the bike but have to get a bigger compressor so there goes a little over $400 that could be used on the bike. Just have to see what you guys have to say on the transmission.

Sorry about the unjointed post, two weeks no days off and I am totally useless today. Hope to be off tomorrow for a few days to catch up.


Thanks!

Re: To rebuild or not to rebuild-dang transmission

Not sure what your asking about here :shock: - but rebuilding a gearbox is really pretty easy (and if your seeing evidence of the bushing going it would be a good idea if for nothing else than the knowing it's one less problem - esp.if you are unaware if the dreaded Portugese made main shaft bearing has been replaced)

plus relatively cheap provided all your doing is bushing/bearings etc

if you have a shop manual and follow the old britts guide - with a bit of patience you'll find the hardest part is removing it and replacing it from/in the bike!

http://www.oldbritts.com/gearbox_d.html

Re: To rebuild or not to rebuild-dang transmission

If the mileage is really that low and the transmission performs well I wouldn't worry overmuch about a little gold in the oil--most of the bushings are a little over- and under-sized as built and will throw off a little gilt as the transmission beds in


Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850

Re: To rebuild or not to rebuild-dang transmission

Didn't think about the tranny still running in, especially after sitting after several years. May go ahead and check bearing since I want to put belt drive on bike. Could save me enough to put on some of JSs carbs!

Re: To rebuild or not to rebuild-dang transmission

unless you have owned the bike since new , you have no clue what the gearbox is like so mileage means nothing ( could of been ran dry by PO etc etc)

ask yourself this - (IF YOU ACTUALLY RIDE YOUR BIKE MORE THAN A FEW BLOCKS) - is a couple of hundred bucks and 12hrs (given you've never done it before) of your time getting dirty and swearing more hassle than worrying about a gearbox locking up and leaving you (at best) stranded somewhere?

then sir, you have your answer................

Re: To rebuild or not to rebuild-dang transmission

mikegray660 said:

unless you have owned the bike since new , you have no clue what the gearbox is like so mileage means nothing ( could of been ran dry by PO etc etc)

ask yourself this - (IF YOU ACTUALLY RIDE YOUR BIKE MORE THAN A FEW BLOCKS) - is a couple of hundred bucks and 12hrs (given you've never done it before) of your time getting dirty and swearing more hassle than worrying about a gearbox locking up and leaving you (at best) stranded somewhere?

then sir, you have your answer................

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+1----yes indeed---don't take the chance---cheaper now than later after the trans locks up at 60 mph in the worst place at the worst time---not to mention what could happen
to you and a passenger.

Re: To rebuild or not to rebuild-dang transmission

(IF YOU ACTUALLY RIDE YOUR BIKE MORE THAN A FEW BLOCKS)

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2+. Digging in getting dirty and spending more than intended is the ticket price to have a reliable ride adventure of the good kind. Besides sudden lock up I can tell ya putting off a simple repair took me down twice in one day when going extra slow cautious into leans and it popped out of gear just as engine and tranny loads nullified, ie: no thrust no drag, SPAT!
Hell half the reason I bother posting on routine chores, is to get my own pep talk to do some upkeep too soon again.
Trickest tedium to me is getting the cam pawl gears indexed, next is the pawl spring spread just right, 3rd getting some back up in the KS oil ring groove and RTV to seal w/o no machined seal upgrade.

Re: To rebuild or not to rebuild-dang transmission

Then Sirs, a rebuild it is! Guess I need to order the Mick Hemmings DVD. who would you recommend purcha sing the layshaft bearing from?

Re: To rebuild or not to rebuild-dang transmission

Unless the tranny was acting funny I'd probably think twice about rebuilding it. Does it still shift smoothly and otherwise behave normally?

Re:

swooshdave said:

Unless the tranny was acting funny I'd probably think twice about rebuilding it. Does it still shift smoothly and otherwise behave normally?

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I have to laugh at this one. There you were, right on the verge of being convinced to rebuild it and Bam! "You better think twice." Great advice from both corners and its exactly what you asked for, "To rebuild or not to rebuild-dang transmission "
I'll be awaiting the outcome, keep posting!

Re: To rebuild or not to rebuild-dang transmission

Just for a benchmark.. I just went through the gearbox on my '74 with only 11,990 miles, after reading all about layshaft bearing failures. As it turns out the existing layshaft bearing inspected OK, but the pattern failure described and the potential to kill me with a lock-up made the decision for me. Also, not knowing if the PO was hard rider or not made another wild card. My local brit bike repair shop/parts dealer (Gate City Cycle, Nashua, NH, selling brits for 45 years) sternly councilled.. "be sure and replace the layshaft bearing, I've got a pile of broken commando gearbox housings out back." Sooo...... in I went. :mrgreen: Found some other low grade time bombs as well..

Re: To rebuild or not to rebuild-dang transmission

swooshdave said:

Unless the tranny was acting funny I'd probably think twice about rebuilding it. Does it still shift smoothly and otherwise behave normally?

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but what if he promises to post a few pictures of the rebuild process? :shock:

Re: To rebuild or not to rebuild-dang transmission

Damn you, damn you all to the lower bowles.of hades¡ Just fer mud in yer eye I am gonna rebuild it and post really bad close ups while I talk about my literature class. That will teach ya, hahahahahaaha!
:twisted:

Re: To rebuild or not to rebuild-dang transmission

warpedscout said:

Damn you, damn you all to the lower bowles.of hades¡ Just fer mud in yer eye I am gonna rebuild it and post really bad close ups while I talk about my literature class. That will teach ya, hahahahahaaha!
:twisted:

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i been to Mississippi a lot (sunflower blues fest in clarksdale, juke joint crawl, Leland blues fest , camped many a time in Rosedale etc etc) - the only literature in miss. worth reading is the back of a bug spray bottle to try and keep never ending squadron of blood suckers from draining you every night :mrgreen:

Re: To rebuild or not to rebuild-dang transmission

Hi All

Just do it, it's not a hard job, I had to replace my bearing when it blew up 34 years ago I was young and never pulled a gearbox apart in my whole life, just make sure you have whitworth sockets, take your time and lay all the parts out in order so that it's easyer to put together in reverse, since replacing the bearing and a few bushes I have been back into the box to only replace the kickstarter pawl 3 times now and a kickstart sharf ( only because a meckanic at a shop that was turning my carbis decicde to put some weld on my loose kickstarter, it broke a week later, wasn't happy, that was the last time my bike went to a shop), once the bearing has been replace you should have no more troubles with the gear box if you change the oil once a year, my bike has done over 120,000 miles now and the box is still going good.

Ashley

PS you only need a good workshop manual to pull it a part, the workings are pretty straight forward.

:mrgreen:

Re: To rebuild or not to rebuild-dang transmission

I can't remember who wrote this but someone said once recently, "What you have is a 30 HP gear box in a 50 Hp bike."
That was enough to make me go through the entire box.
I have replaced 2 broken lay shafts in my day from doing wheelies and being stupid.
I'm old and wiser now.
Old Brits web site is great for the rebuild tutorials.

Re: To rebuild or not to rebuild-dang transmission

Guido, I have seen that saying too. I will start pulling the tranny out soon as I can. Sold my mustang today so I can get a set of whitworths and a vise to attach to my workbench. Probably pick up a new compressor for my blast cabinet, want to clean everything up while I am going in. May take some time but better not to rush things! Too many things I want to do but don't want to over do it, but then can you over do it!?

Re: To rebuild or not to rebuild-dang transmission

Right in the middle of going through the gearbox and checking the layshaft bearing myself. Doing it in frame . So far the biggest difficulty was getting the layshaft bearing out of the case. Lots of heat and patience required. I found a standard $10 steel cage 6203 bearing that someone replaced the original Portuguese brass cage bearing with sometime during its life.

Researching the threads and the internet, it looks like there are two suitable choices for layshaft bearing replacement:

- FAG 6203 TB.P63 - a quality ball bearing with a strong phenolic cage that doesn't require shimming. Mick Hemming recommended, along with many forum members.

- NJ203E C3 Roller bearing, also a quality bearing with polymid cage that requires shimming, factory recommended, along with many forum members, see Old Britts and the Norton workshop companion for installation details. As the inner race floats, axial loads are reduced on the cage.

I took my the bearing removed from the gearbox down to the local bearing supplier - Canadian Bearing

FAG 6203 TB.P63 - $69.99 but special order that takes 6 weeks to arrive
FAG NJ203E C3 - $56.07 which I ordered - 4 days
SKB NJ203E C3 - $70.52 in stock

Not having a Dial Indicator, I would have gone with the FAG 6203 TB.P63 to save shimming but too long to receive, and I could use a Dial indicator anyway... I checked prices from various Norton parts suppliers, they can be ordered for more $. It pays to cut out one of the middle men.

Now to get the sucker back together, spring has come early this year, 18c and sunny, 20c and sunny forecast for next week, normal is 4c. We usually get a snow storm around St. Patrick's day...

Re: To rebuild or not to rebuild-dang transmission

I just did my box yesterday. New shafts and bushings. Did the roller bearing and shimming is a snap.
Had .042 endfloat, took it up with .030 of rear iso shims, done.
The bearing was about $25