Small block dipstick thread specs.

After my recent “unscrewing dipstick” event I’m keen to ensure it doesn’t happen again and I’m getting my son to make me a modified dipstick which doesn’t need to be “nipped up” with any tools. To do this I need to confirm that the threaded hole in crankcase is 24 x 1.5 thread, can anybody confirm this please? The only places I’ve been able to get this info is on the Stein Dinse and Guzzibits site but SD says 24 x 1.5 and Guzzibits says 25mm. Using a caliper guage I think it’s 24 but any engineer types on here who could measure their small block dipstick would be doing me a big favour.Thanks in advance,Regards,Johnps for info here are some pics of the quick and dirty mod I did straight after the event using an R clip in a drilled hole.This is the position it started in after tightening as tight as I could by hand.This is where it moved to after 12 miles of brisk ridingThis is how much more I could tighten it by hand after this run, whilst still hot. It stayed in this position for the home run.

Scousus maximus2013-03-19 15:40:26

The incident is described here: http://www.motoguzziclub.co.uk/forum/forum_posts.asp?TID=16879&PID=212114#212114 Just to confirm, the standard style is hexagon head for a spanner? Like in my case, hexagon head, I would never rely on just finger tight, but always nip it up with the MG toolkit ‘special’ double-ended ring spanner, even give an extra tap with e.g. a screwdriver handle to make sure it’s properly done up and stays done up.

when i first got me 850 i had the dipstick come all the way out when riding .

Not sure if you’re asking me about the standard style? Anyway, on the small block it’s a multi pointed thing, as in the photo. A slip-joint pliers seems to be the weapon of choice to nip it up. I just want it to be a hand tighten job to avoid going too tight and knackering it completely.Regards,John

Yeh the big hex head ones are on the big block bikes it is a wierd thing on the smaller bikes BUT there are alternatives

Unfortunately the small blocks have a larger thread otherwise the push pull dipsticks Corsa sell are brilliant.

Well, I did a bit of checking today and discovered that it’s not 24 x 1.5, (by trying a nut on it), it’s close to 24.5 x 1.5 as measured by two different nut and bolt suppliers and I was quoted “about eighty quid mate” to get a dipstick made to that spec er, no thanks old chap.So, I’m still chasing it but a bit circular at the moment.Can a lathe be set to make any thread pitch or are they fixed to certain norms? I wish I could get info from the factory on what the thread actually is,hm.Any suggestions from you engineering artisans out there?Regards,John

Mike, the guzzi sb stick also has an o ring shown here :http://www.stein-dinse.biz/eliste/index.phpA thread adapter so you can use a BB stick sounds like a good idea but is there enough meat between the two sizes ?Plus you then get into the dreaded level marking biz again-the factory has several variations according to the time of manufacturing!!!

[Anyone got one for me to measure and yes a lathe can cut a thread to whatever dimension you like
Guzzi in my experiance would never use a non standard thread with the associated extra costs

quote=Scousus maximus]Well, I did a bit of checking today and discovered that it’s not 24 x 1.5, (by trying a nut on it), it’s close to 24.5 x 1.5 as measured by two different nut and bolt suppliers and I was quoted “about eighty quid mate” to get a dipstick made to that spec er, no thanks old chap.
So, I’m still chasing it but a bit circular at the moment.
Can a lathe be set to make any thread pitch or are they fixed to certain norms?
I wish I could get info from the factory on what the thread actually is,hm.
Any suggestions from you engineering artisans out there?
Regards,
John
[/quote] Ex smokingbiker2013-03-20 20:55:36

Well, why re-invent the wheel?Put a D-ring in the cap, and wire it into place. I use soft copper wire so I can check the oil level easy enough. And it’s not walking out on me.I know, putting in a huge bolt might be another way. And actually I’m eager to see those results too.Just post it with a picture, because I’ve got a simple mind.

Well isn’t that just typical, BMW ones stay put, Moto Guzzi ones unscrew themselves Yep 28 - 29 here: http://www.stein-dinse.biz/eliste/eliste_bild.php?sid=9797g312c06g2b3ceb9g&lg=en

I agree with you ex smoking biker, it would be bizarre for any manufacturer to make a special thread but all the facts point that way unless I’m missing something obvious.Here are the readings I got today showing the top and bottom of the threads. The high reading shows why it wouldn’t even start to go into a 24 mm nut. If you were a bit closer I’d gladly come over and get you to measure it but it’s just too far.I’m not actually desperate as my R clip mod is working ok but I’d just like to understand it all a bit better.Regards,JohnEdit: sorry, my photobucket is playing up.Measurements are 23.42, bottom of thread and 24.42 top of thread. I’ll sort the pics later. Done now.

Scousus maximus2013-03-21 21:09:22

The thread will almost certainly be 25mm 1.5mm pitch. The big block is 20mm x 1.5mm pitch.Both standard sizes according to this chart.http://www.mdmetric.com/tech/tict.htm

Just measured mine from the V50 and the OD of the threads is 24.85mm so I would put that at 25x1.5.By the way, the plastic dipstick does incorporate a 20x3mm O ring, which both seals and grips. If yours is worn flat, or missing, then the dip stick will as likely as not, unscrew itself.Mine grips, I had to use long pliers to undo it.
Brian UK2013-03-22 14:16:19

Re the o ring, the one that went AWOL was on a 7 month old bike and the one that’s currently fitted is from a new stock bike at the dealers so both should have plenty of give. The one in the sequence at the start of the thread is the new one.I’d like to find a torque setting to put my mind at rest over using pliers for it but nothing has come up so far.Thanks for doing the measurement, I think I’ll go ahead at 25 x 1.5 and see what it brings. Probably a few weeks before I get it done now but I’ll update when I’ve got some feedback.Thanks to all for all the help/sympathy/suggestions.Regards,John

I think this isn’t designed to be done up with pliers, but by fingers. I’d make a guess the plastic skirt is slipping on the O-ring, not the O-ring is slipping on the crankcase. Looks unusually thick to me too (the O-ring) Maybe roughing up the groove in the skirt might help? Just a wild surmise…

I’m late in here but WHAT HE SAID

I was looking for some metric thread info at work and came across Metric Conduit threads that I’d never heard of before.

They’re all 1.5 pitch and is sizes 16, 20, 25, 32 & 40 mm

Re O Rings. Measure the thickness and that will give you the default diameter.

ie a 2.4mm section diameter ring will be xxx .6 mm ID

Go here http://www.jameswalker.biz/system/pdf_docs/fichiers/3/original_2011_update.pdf?1352815186 Page 22 (Chart 72) for more info.

Another thing I’ve been researching at work tris2013-03-27 14:50:34

Well I’ve never used pliers to do up the dipstick, but have needed them to undo it.Same thing applies to the rubber seal on oil filters, do up by hand only if you want to stand any chance of undoing them. Never lost one yet.

if you go to airsupplies.co.uk they stock a nut m24 x x1.5 for £2.21 buy one and test it with your dipstick. as an alternative try butler fasteners ltd they list a 24 x 1.5 set screw. try it then fit a spigot to it to the right length. you now have a dip stick witha hex head. then use alloy/copper washers not rubber for a good seal.

if it is 25mmx1.5 i have tap and die