How to install oil seal disc and felt seal in inner primary? (2008)

How to install oil seal disc and felt seal in inner primary

Hi Brian I had a problem finding some one to spot weld my discs and asked my brother to mig weld them. He was concerned that they would distort due to the heat from the mig and gave me some small rivets from his model steam train. I just clamped them together in the case with two spacers I machined up in the lathe and drilled the 4 holes in the same location as the original spot welds and riveted them over. Just check that your clutch hub clears the heads on the inside as I have not refitted my hub as I aquired another project (69 Fastback) and started to remove some of the new bits I had fitted to the Roadster for the Fastback.
Ian

Any sheet metal shop (furnace pipe maker) will have a spot welder. These can be found nearly anywhere. Ask your heating and air conditioning man who makes his ducts. Many of these have the facility to do this in-house.

Thanks all.

I'm increasingly drawn to the idea of using small machine screw/bolts. The spot welds are close to the center of the discs, so clamping force is not great near the edges - my old one would easily slide around. If I used screws/bolts nearer to the circumference of the discs, I could get better clamping force. (I realize it probably doesn't have to be all that tight, but still....). Use some teflon tape and maybe a bit of silicone seal for added oil-tightness, and might actually be better than welding. Sure easier to replace that seal from time to time.

Thoughts?

Thanks again for all your help folks. I appreciate it. - Brian

I may be wrong, but isn't the disk supposed to be loose enough to be able to slide around? Otherwise you're basically locking in the distance between the crank and tranny shafts which would ultimately prevent you from adjusting primary chain tension since the transmission shaft can't move.

Good point - I won't crank it down too hard.

The denouement, for those who've followed our story so far:

Gathered up my parts and headed to the local welding shop this morning, where I found that, as I had half-expected, it was closed for the (long) weekend. My job is such that it'd be a long time before I could back there during normal working hours, so, Plan B.

Headed to the local hardware store, bought six small (technically, "eentsy") machine bolts and nuts, went home and carefully drilled the oil seals. Installed the bolts with a little blue locktite, then ground down the protruding bolt length almost to the nuts.

Installed, and so far so good. Clutch back on, with DynoDave clutch rod seal (hey, I'm already in there....) and now wrestling with the rotor Woodruff key so I can reinstall that (or actually, a new Sparx 3-phase (hey, I'm already in there, redux).

enough for now, I'm making a cup of tea and scrapin' a bit of grease off my hands....

thanks again to all who offered advice. It is much appreciated.

Although this is an old post I am so glad i did a quick search before i rebuilt my 750 primary. I went down the rivetting option, hope the final result is good....

I drilled 4 holes 90 degrees apart in the discs, inserted the felt seal, and used 4-40 screws and nuts to hold the assembly together on the inner primary cover. Use red Loctite and tighten just enough to give a snug sliding fit.

While you are at it, you can add a seal to help keep oil from escaping thru the transmission shaft gap. The following link is specific to Atlas - Dommie primary cases, but the concept is good for Commandos as well.

Slick

Asked the same question in April. Following is summary of recommendations Worked well:

Firstly, thank you all – great information – and very quickly.

I think I have a plan –

Oil felt seal, compress between wood plates and clamp - let set 8 to 12 hours. With dental probes (I have), gently pry-apart and wedge seal area on assembly to provide additional axial clearance to insert compressed seal. Install seal by working with small screw driver and probes. If successful, selectively peen plates to approximate original axial dimension.

If that does not work I will revert to removing current plates. I have a pair of new plate and will align and drill to accept small machine screws and use thin smear of epoxy to secure assembly.

BTW – I have some Loctite specifically used for sealing hydraulic threads so will use on the three fixing screws for the primary to crankcase attach – great suggestion. When I replaced gearbox seal I re-torqued to 50 ft-lbs with Loctite.

Again – thanks all and stay safe.

I fitted a new seal without taking the plates apart. Not too difficult.

Dereck

I equally spaced and drilled my discs and inserted M3 set screw to hold then together, I applied a smear of Wellseal to the surfaces before assembly
I know loads of folks get the felts in without having them apart. I had mine oil soaked & compressed between plated for a week.... but either damaged them, or just couldn't get them in
No more fighting to get the felts in for me

myron1950 said:

Asked the same question in April. Following is summary of recommendations Worked well:


BTW – I have some Loctite specifically used for sealing hydraulic threads so will use on the three fixing screws for the primary to crankcase attach – great suggestion. When I replaced gearbox seal I re-torqued to 50 ft-lbs with Loctite.

Again – thanks all and stay safe.

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I'm a little concerned that you may confuse some people. I assume you mean tighten the clutch nut to 50 ft-lbs NOT the three screws that hold the inner case to the crankcase. Those 1/4 screws are going to rip the threads out of the crankcase long before you get to 50 ft-lbs.

Nortoniggy said:

I'm a little concerned that you may confuse some people. I assume you mean tighten the clutch nut to 50 ft-lbs NOT the three screws that hold the inner case to the crankcase. Those 1/4 screws are going to rip the threads out of the crankcase long before you get to 50 ft-lbs.

Click to expand...

Good catch - when I wrote originally post it was in context of string that proceeded it. 50 ft-lb was clutch nut (even though "spec" say 70 ft-lbs, excessive for that small circlip). Inner crankcase fasteners (3) were torqued to 15 ft-lbs as I recall and that was where the "hydraulic loctite" was applied. My bad.