BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: johncarter on 21 May, 2022, 08:29:49

Title: Fork Oil
Post by: johncarter on 21 May, 2022, 08:29:49
The amount of fork leg oil for my 1953 plunger A7 is stated as 212cc per leg in one source I have and 100cc per leg in the Haynes manual I have. I've been running with 212cc per leg as per the BSA documentation and it seems fine (I tend to ignore Haynes when I find conflicts) but I would appreciate confirmation. Also the fork drain plug weeps. Is PTFE tape oil resistant?
Thanks
John
Title: Re: Fork Oil
Post by: DAVE BRADY on 21 May, 2022, 08:45:15
Hi John,

It is always wise to defer to BSA over Haynes and PTFE is oil resistant.  Sometimes the little fibre washers can be a hard with a bit of TPFE tape your should be able to get a good seal.

Dave.
Title: Re: Fork Oil
Post by: Spaceman on 21 May, 2022, 09:41:52
The fork design changed in 1954 and it looks as though at this point the oil capacity increased to 213 cc. According to the BSA data I have, the oil capacity for the 1950 model was 1/4 pint or 5 fl oz or 142 cc.

Haynes possibly has the changeover year wrong (1955 vs 1954) and has also wrongly stated the capacity at 4 rather than 5 fl ozs and then wrongly converted 4 fl oz to 100 cc rather than the correct figure of 112 cc.

Title: Re: Fork Oil
Post by: AdrianS on 21 May, 2022, 10:31:56
The drain plug can be a little bu**er to seal. I use a new washer and usually put some blue hylomar on it to seal. Not tried PTFE tape myself but a new washer and a bit of blue hylomar seems to work.
Title: Re: Fork Oil
Post by: JulianS on 21 May, 2022, 12:11:42
Below from BSA service sheet 706 giving fork oil capacity. It was changed for 1952 season when new shafts and top bushes were introduced.
Title: Re: Fork Oil
Post by: chaz on 21 May, 2022, 18:02:08
left hand leg of our B40 still dripping, new screw, new washer, filed off face around thread and its still managing to find a way out.

possibilities are.
2ba screw may have been a M5 supplied so thread not sealing.
ptfe or loctite will be next try, which of course means draining or losing fluid again.

RH leg hasnt been a problem!!
Title: Re: Fork Oil
Post by: cdsdorset on 21 May, 2022, 18:55:39
Use liquid ptfe from screwfix etc.
Title: Re: Fork Oil
Post by: johncarter on 22 May, 2022, 21:31:07
Thanks all for your responses. I'm going with the BSA Data Sheet for 1953 for an A7 at 212cc or 3/8th pint per leg... The drain plug has a good wrapping of PTFE tape and we'll see how it goes..