Parts List for Transmission Rebuild

My 1974 850MkII has started dropping out of first gear on hard uphill pulls and I am taking this as a signal that it is time to finally open the gearbox to refresh the bearings & bushings. I have wanted to do this for some time, in part to assuage my concern about a Portugeese layshaft bearing, but mostly because the gearbox clearly has not been opened since it was built. While I am in there, I also plan to replace the rear isos with the same SS adjustables that I have on the front motor mount.

My question is simply, what do I need? I can think of the following for sure: (1) complete bearing set; (2) complete bushing set; (3) seals. Is there anything else? I was going to order the lot from Phil soon, and I would like to do this as a single order. Do I need to get the ringnut tool, or do most people just work around this?

Thanks!

A good punch to prevent mangling will work , some make the tool from a piece of pipe and cutting it too. Sleeve gear bushes yes. 1 st. gear bush yes. Layshaft roller conversion yes. Inspect everything and new seals/ gaskets. Print out the Old Britts step by step.

Hey Nomad,

I just recieved my order from Old Britts a few weeks ago with everyting I needed.

They sell them in rebuild kit form, One set has all the bushings, another the springs, another the bearings, etc, etc.

Ran me around $500 tax and all.

I take it the ringnut tool is for the nut around the clutch rod? I just used a drift and tapped mine loose.

Old Britts has a lot of good information on this.

Later

**EDIT** By the way, I got the Mick Hemmings DVD from INOA and it is a great tool in case your not totally sure of the tranny workings!

You may need some iso shims to set your shaft freeplay. I did.
Jaydee

All set on spare iso shims.

Warpedscout, which rebuild kit did you get from Old Britts? I think this is probably the best route for me to take. Also have the Hemmings video, so I should be ready to tackle this. Just need to mount my vise onto the workbench!

Speaking from experience, I won't use the roller bearing layshaft conversion any more.
Shimming the layshaft results in the kickstart shaft being pushed further into the casing, and in my case meant I could no longer use my RGM kickstarter after I'd re-shimmed it the second time, and I'm struggling to get the original kickstart back where it should be, so it's permanently wobbling around on half the splines - not healthy ;(

I had a very informative discussion with Mick Hemmings on the subject, and his solution is to use a special layshaft bearing which costs upwards of £30.



It positively locates the layshaft as per the original design, but the cage doesn't fall to pieces like the original, which can't deal with the shaft flex.

The real fix is an outrigger bearing behind the clutch, but not an easy fix!

I've ordered similar kits from UK RGM and US Baxter's to find both set of bushes needed most the bushes reamed to fit shafts, so study up on how that is done w/o being told you've ruined the bush lube feature. The lock ring around the cable gizmo does not have to be very tight and a place i use anti-seize do a blunt drift don't bugger much to notice. I made knife edge mark to help tap it home. The factory only supplied two short sleeve shaft bushes which can move together loosen a good bit of shaft support so stick and old one in the middle - if the new kit don't have the two longer bushes to take up the big gap. After seeing how this area don't ever get lubed but when runing in N, as it sits below oil level and when spinning it throws oil out and won't let much if any splash lube back in, so not a bad id to oil groove these bushes just short of the the end one to leak to outside of shell, which wise Norton didn't have to make a seal for as so so little oil actually ever exists there to leak of be forced out, so to extend next re do, keep in mind the amount of time spun up while not in 4th. If lay shaft too loose so needing shims, might consider leaving out a gasket of two like I do. Wish you well indexing the cam knuckle and the pawl spring.

Hobot's got it nailed. You'll need to ream some bushes. Yes fill the space on mainshaft with bushings. Oil groove good idea. I didn't do all that and wish I did. Hemmings layshaft bearing is cat's meow. Get a grade 8 bolt and good flat washer for the KS clamp bolt. Crank that honey down. Drift is good for layshaft nut.

If you're talking about shims for the isos, forget it and spend the loot and get Hemmings adjusters, get a life.

Dave
69S

Abybody care to offer some instruction on how to ream the bushes and cut oil grooves?

Sometimes you get lucky and reaming not so necessary. Just did my mainshaft bushes and the new type were longer and improved and after freezing them after sucking up some gear oil they drifted /knocked in nicely to home and the mainshaft slipped right into place with no griefage. Nice tight sliding fit ,so I got lucky. The 1 st. gear bush I was way carefull with ,freezing it good after letting it soak up a bit of gear oil then carefully choosing a socket that would knock it into place without breaking up the bush end which happens if ham fisted , its an extremely thin delicate bush. Nice tight sliding fit, no reaming tool needed as well , so lucky again. My 2 cents.

I'd buy Mick Hemmings' Gearbox Rebuild DVD and take notes!

Russ

I used a small ball end dermal bit to score a crude fairly swallow groove that made one turn in length of bush and not worrying about going outside the coloring lines too much. Chased with a file in case of high spots. Shouldn't use abrasives which embed then release. Good point about the tender loving care with the thin skinned 1st cog bush, which if you plan to use Cdo much, like 10K m yr best have them send two of that one. Pawl spring trick is just get legs parallel to pawl swing area and don't worry about the distance the manual lists or best wishes getting the leg parallel after tweaking toward manual optimism. If using Cdo a lot best snag a 2nd one of those two. Notice the rusted parts in behind outter cover, above oil level and no splash there, I clear coat so rust don't eventually eat the threads or pivots to dust. Really snug down the TS end of main shaft nut or might drive you bonkers as me trying to get clutch cable working with everything on main shaft shifting. Amend to grade 8 kS bolt but the KS metal is not man enough to take the torque needed to drill through than and back up with grade 8 nut. Grind bolt head to trap at back side of KS. File of 3 splines either side of the gap and open gap up at least two hack saw blades wide, and only hand start or will begin its wobble slow destruction of the splines that can trap the bugger on. It I'd been smarter I'd made some proviso to put a puller on instead of the tedious levering and creative swearing. I put oil groove in the big ole KS end bush too. My trick to get the cam teeth and lever indexed is assembling so just barely clears to allow covers to close. Marking for it never worked well for me so go by feeling trial error.
If ya pay attention ya can feel the difference between thick gear lube that has trouble getting into some bush spaces vs Dextron ATF w/o friction band additives of Type F that's used in primary. DO NOT OVER TENSION PRIMARY or can tweak tranny shafts and vastly increase its need of servicing.

Ok someone else turn to fill em in on all the options of the KS drool seal from cig foil to send out for machining.

Bruce Chessell machined my kicker and shifter to take modern seals instead of O rings. Dry as a bone.

I had that done too -- very happy with it, but I am leaking a bit of oil out of the bolt on the bottom of the main gearbox now -- have to address that too.

warpedscout said:

Hey Nomad,

I just recieved my order from Old Britts a few weeks ago with everyting I needed.

They sell them in rebuild kit form, One set has all the bushings, another the springs, another the bearings, etc, etc.

Ran me around $500 tax and all.

I take it the ringnut tool is for the nut around the clutch rod? I just used a drift and tapped mine loose.

Old Britts has a lot of good information on this.

Later

**EDIT** By the way, I got the Mick Hemmings DVD from INOA and it is a great tool in case your not totally sure of the tranny workings!

Click to expand...

I used the RGM kit, current cost is only $175. The Superblend roller went in without issue, on checking endfloat no shimming was required. The kit had everything needed in it including a nice peg wrench. The kit was very complete, bearings, bushings, springs, o rings, bushings and the peg tool, which may or may not be in the current kit.
I cant think of a way to get the price up to $500 unless you put some new gears /shafts in?

Glen

I used the RGM kit, current cost is only $175. The Superblend roller went in without issue, on checking endfloat no shimming was required. The kit had everything needed in it including a nice peg wrench. The kit was very complete, bearings, bushings, springs, o rings, bushings and the peg tool, which may or may not be in the current kit.
I cant think of a way to get the price up to $500 unless you put some new gears /shafts in?

Glen[/quote]
that might be the $271 bushing kit, plus the $134 bearing kit, still only $400, but getting closer, from Oldbritts website;
12-200001 Bearing Kit, Gearbox Commando 1 6 - 134.05 Yes
12-200003 NOR ILL Bushing Kit, Gearbox Commando, Pre-MK3 1 2 - 271.92 Yes

but RGM do seem to list an overhaul kit for GBP114 - I guess either it is not as complete, or it proves it pays to shop around.

RGM kit is listed as item 229 here:

http://www.rgmmotors.co.uk/items.asp

It includes the pictured parts:



Anything missing from what you see here?

Yep, that is the kit, all good stuff. The only additional item my kit had (bought it four years ago) is the peg socket, which is easy to make from an old socket. It can likely be purchased elsewhere on the rgm site.
I suppose it makes good competitive sense to take the wrench out of the kit, it appears others dont include it.
Also, for people with more than one amc gearbox, once you have the tool, no use getting a new one with each new kit purchased.

Glen

Here is everything I ordered from Old Britts:

06-7243 Gearbox Gasket and Seal Kit, Pre-MK3 $9.99
12-500001 Commando Gearbox Spring Kit $32.03
12-200003 Bushing Kit, Gearbox Commando, Pre-MK3 $271.92
12-200001 Bearing Kit, Gearbox Commando $134.05
04-0442 Spring, Detent Plunger $4.10
06-2015 Pawl, Kickstart $21.00
04-0044 Spring, Kickstart Pawl $2.82

Totals $475.91 then add taxes and shipping

If I had known about RGM I would have ordered their kit :cry: !!! The only thing missing from the picture are my last three items.