loose Bearing housing studs

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Rod 2500S
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loose Bearing housing studs

#1 Post by Rod 2500S » Sat Feb 26, 2022 12:31 am

Hi All
When I removed the bearing housing and half shaft as a unit to replace the UJ's (see other post) I found some loose nuts, at the time I wasn't too concerned as I thought I would rectify this upon reassembly..
Hmmn big mistake, the alarm bells should have gone off then and there and I should have checked all the bolts.
It turns out that (I surmise) someone has overtightened the bolts doing a previous UJ replacement.
I found two stripped studs which simply pulled out when tightened. See the pic, the top bolt is pulled out by 3mm and the thread is stripped. Curiously,one on each side at the top.
Ok don't panic, off to the internet and a helicoil kit, 5/16, 24 UNF, readily available thankfully at about 45$AUD. This gives you 25 coils.
So I removed all the remaining studs, checked the threads and then threadlocked the good ones back in as a precaution.
The helicoils went in very nicely with the following method:
1 - drill the old threads out 2mm deeper than original to make room for the coil to seat deeper in the thread to allow the stud to screw in properly
2 - Tap the thread using plenty of lubricant and clean out with a blast of air
3 - fit the coil and wind in 1-2 threads deeper than the lip of the hole to allow the stud to seat properly
4 - fit the stud using threadlock and wait 24 hrs to set.
When tightening the bearing housing nuts to the studs be very careful and use a good tension wrench, I found mine to be unreliable at the low setting required (18-20 ftlbs from the book) So I will acquire a smaller wrench to do my reassembly
HTH
cheers all
Rod
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Loose rear axle bolt.JPG

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Re: loose Bearing housing studs

#2 Post by johnnydog » Sat Feb 26, 2022 1:15 am

Rod 2500S wrote:
Sat Feb 26, 2022 12:31 am
When tightening the bearing housing nuts to the studs be very careful and use a good tension wrench, I found mine to be unreliable at the low setting required (18-20 ftlbs from the book) So I will acquire a smaller wrench to do my reassembly
HTH
cheers all
Rod
Whenever I have replaced the hub and drive shaft assembly, I have never used a torque wrench on the 6 nyloc nuts. I think the main problem is that the nuts are sometimes used to pull the hub flange tight against the back plate and swinging arm, instead of firstly ensuring that it is correctly seated before then lightly nipping the nylocs up in a rotational sequence. Sometimes newly applied grease on the male splines results in an airpocket within the female splines which causes resistance, and tightening the nylocs to try and overcome the resistance is likely to result in stripped threads.....
I only ever use a 1/4" drive ratchet to 'tighten' them, and then using 'feel' to gently 'nip' them up. I have never had much confidence with torque wrenches for very low torque figures - I'd much rather use my own judgement and 'feel', and in over 40 years of 2000 ownership have never stripped the thread of a swinging arm (found several on newly acquired vehicles though :roll: ).
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Re: loose Bearing housing studs

#3 Post by Rod 2500S » Sat Feb 26, 2022 2:27 am

Hi Johnny
You are exactly correct, I wonder how many of us are driving around with less than six nuts holding the wheel on? Apart from the one nut holding the steering wheel.
And yes If I can't borrow (not buying one) a small tension wrench then "use the force"
Cheers
Rod

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Re: loose Bearing housing studs

#4 Post by Alec » Sat Feb 26, 2022 8:21 am

Hello Rod\Johnny,

it is unusual for fine threads to be used in aluminium, i.e. UNF when UNC is much more common.
However I remember reading someone who explained why UNF was used but unfortunately I don't remember the details as to why?

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Re: loose Bearing housing studs

#5 Post by johnnydog » Sat Feb 26, 2022 8:24 pm

Is it not due to the short depth of aluminium available for the studs in the swinging arm? A UNF thread would have more strength in the available area with there being multiple threads to retain the stud than a UNC thread?
UNF is more commonly used in aluminium components in the automotive and aircraft industries apparantly....
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20220226_200920.jpg
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: loose Bearing housing studs

#6 Post by johnnydog » Sat Feb 26, 2022 8:43 pm

I've also found this which may help to understand the principles for the use of UNF studs in the swinging arms....


Screenshot_20220226-203859_Drive.jpg
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: loose Bearing housing studs

#7 Post by johnnydog » Sat Feb 26, 2022 8:52 pm

Or this....
Screenshot_20220226-203455_Drive.jpg
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: loose Bearing housing studs

#8 Post by Rod 2500S » Mon Feb 28, 2022 2:39 am

Hi All
Thanks for the very useful info Johnny
Cheers mate

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Re: loose Bearing housing studs

#9 Post by Rod 2500S » Tue Mar 01, 2022 12:47 am

gday all
two pics of the stripped stud and hole
The attachment stripped bearing housing stud 1.JPG is no longer available
The attachment stripped bearing housing stud 1.JPG is no longer available
The stud has been loctited in by some previous master mechanic, loctite is good stuff but when there is literally no thread left ??????????
Let this be a lesson to us all
Cheers
Rod
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stripped bearing housing stud 1.JPG

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Re: loose Bearing housing studs

#10 Post by Rod 2500S » Tue Mar 01, 2022 12:50 am

As per usual the other pic has dropped out ???????????????
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stripped bearing housing stud 2.JPG

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