• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Bellhousing Blues

Share this page

G

Guy Marshall

Member
Country flag
Offline
Hi all,

Reinstalling a rebuilt BN6 side change gearbox I discovered the PO had replaced the slave cylindar mounting bolts with 20mm M10 metric bolts which have now stripped out.

There seems to be plenty of space to re-tap with longer (1½"?) 3/8" unf bolts but has anyone had any experience/recommendations?
 
20mm seems short (roughly 3/4"). Maybe there are still good threads in the hole. You can make a chasing tap out of a 3/8-24 bolt. This one's 1-1/4" long:

screenshot.1557.jpg

Otherwise you might be able to loctite studs in the holes, or install helicoils.
 
Score 1 for the good guys!

A thread clean, then two longer 1[SUP]3/8[/SUP]" screws to replace the metric ones that had been forced in and a little loctite and the slave cylinder is working.
IMG_20181229_110525805.jpg

I'll get some helicoils too...

Thanks all!
 
Do it once. Do it right.

Every Healey I get the opportunity to, I put Heli-Coil/Re-Coil inserts into the slave mounting holes. I once had the slave cylinder fall completely off my car in Lafayette, Louisiana (a LOT easier to deal with than the time I had a clutch hose burst on an MGB in San Francisco).

IMG_7425.jpg




IMG_7427.jpg


IMG_7428.jpg


IMG_7431.jpg


IMG_7440.jpg
 
Randy Forbes said:
Do it once. Do it right.

Every Healey I get the opportunity to, I put Heli-Coil/Re-Coil inserts into the slave mounting holes. I once had the slave cylinder fall completely off my car in Lafayette, Louisiana (a LOT easier to deal with than the time I had a clutch hose burst on an MGB in San Francisco).

IMG_7425.jpg




IMG_7427.jpg


IMG_7428.jpg


IMG_7431.jpg


IMG_7440.jpg
Click to expand...
My bellhousing for my Toyota trans only has one bolt to attach the slave cylinder to it. There’s a stud for the other mounting point. Simplies removal and replacement.
 
Interesting there are multiple cases of stripping these holes in aluminum. Guess there are few aluminum bolt threads on a Healey. The only other ones I can think of offhand are on the steering idler.

Are folks using "cast iron" torque on these aluminum threads and stripping them out? Or are the slave cyl bolts at such an awkward angle as to promote cross-threading?

Enquiring minds...
 
I think that a fine thread into aluminium was kind of frowned upon in engineering circles and even BMC/BL changed to UNC later.

Could it be worsened with the ageing of the ali.

Danny
 
Dandare said:
I think that a fine thread into aluminium was kind of frowned upon in engineering circles and even BMC/BL changed to UNC later.

Could it be worsened with the ageing of the ali.

Danny
Click to expand...

Interesting. Sounds logical. I believe the Smitty bellhousing uses coarse threads for the slave attachment.

Addendum: So the optimum setup would be to tap the holes for a coarse helicoil.
 
Nothing wrong with the insert being fine and you can still use your original bolts if they're good.

Danny
 
steveg said:
Interesting there are multiple cases of stripping these holes in aluminum. Guess there are few aluminum bolt threads on a Healey. The only other ones I can think of offhand are on the steering idler.

Are folks using "cast iron" torque on these aluminum threads and stripping them out? Or are the slave cyl bolts at such an awkward angle as to promote cross-threading?

Enquiring minds...
Click to expand...


Must be I never had any problem like these. //
 
Maybe dissimilar metals corrosion contributes? IIRC, mine stripped really easily, and I'm not THAT ham-fisted. That, or trying to get the slave off and on in situ, with all the hassle that entails. I never use split lockwashers on aluminum, BTW; the washers dig into the soft metal and release tension on the bolts. I use Grade 8 flatwashers under the bolts, with blue threadlocker.
 
@steveg - mine had a pair of bastard 25mm M10 metric thread bolts forced in which is why they stripped. Happily the M10s were very short so I could clean up and extend the thread and replace with 1 3/4 3/8 UNF bolts which is now "better than new". For what thats worth!
 
Back
Top