Rear Damper lower bolt query

[chris75]

Just fitted a pair of rear dampers and have a query . The bottom bolts are torqued up very tight to 114 lbs.ft and have a large diameter washer between bolt head and damper . Having managed to finally achieve that torque whilst reaching in under the car I am concerned that I got up to 110 and the big washer was still free to turn . Only with the last nip did the washer get clamped .
Shouldn't that washer have been clamped before that at a lower torque, or is it not meant to be clamped up tight ?
I am worried that the bolt , which is a dog bolt with a guide pin end, has bottomed-out before the clamping force was achieved :shrug:
I used new bolts from Rimmers . Could always try the old bolts again or fit another washer under the head .

[marinabrian]

Just fitted a pair of rear dampers and have a query . The bottom bolts are torqued up very tight to 114 lbs.ft and have a large diameter washer between bolt head and damper . Having managed to finally achieve that torque whilst reaching in under the car I am concerned that I got up to 110 and the big washer was still free to turn . Only with the last nip did the washer get clamped .
Shouldn't that washer have been clamped before that at a lower torque, or is it not meant to be clamped up tight ?
I am worried that the bolt , which is a dog bolt with a guide pin end, has bottomed-out before the clamping force was achieved :shrug:
I used new bolts from Rimmers . Could always try the old bolts again or fit another washer under the head .

It won't have bottomed out as the threaded section in the rear hub is open ended.
If the harmonic damper is not rotating, and your torque wrench is accurate, then it'll be fine ;)

Brian :D

[chris75]

Thanks for that Brian , but two things :} The threaded section on mine is not quite open -ended ; it steps down to the thread root diameter into which the plain nose of the "dog bolt" protrudes ( see picture) - sort of a guide arrangement , so it could bottom out .
30361
Secondly , my dampers do not have the harmonic "damper weight" on the bottom mount , just the large failsafe washer ( item 11 on here http://www.rimmerbros.co.uk/Item--i-GRID001548.) :shrug: I have had the car since it was very low mileage so I am pretty sure they have never been removed . Was this an alternative arrangement ? Rimmer's listing suggests they were used on 16 and 17" wheels .My copy of Haynes shows the "Damper Weight" but my copy of Rave doesn't !

[Mike Noc]

The harmonic dampers were added during Project Drive.

[T-Cut]

The PD Guide indicates 75 diesels and all MGs got the damper. Presumably petrol 75s don't apply according to this (Item 27): http://www.the75andztclub.co.uk/forum/showthread.php?t=34369

TC

[chris75]

The harmonic dampers were added during Project Drive.

The PD Guide indicates 75 diesels and all MGs got the damper. Presumably petrol 75s don't apply according to this (Item 27): http://www.the75andztclub.co.uk/forum/showthread.php?t=34369

TC

Thank you both for that ; happier now I know nothing is missing ! :}
Still not sure that I have adequately "clamped" the shock ; think I may need to add an extra washer under the bolt head .

[Bolin]

Odd - from my personal experience, I am sure that the washer would have been tight before 110lbs.ft.:shrug:

I would personally take it apart and check everything:( - did you have the washer dished away from the damper mounting? It is supposed to be dished away, not towards.

I had the problem that the bolt wouldn't undo, I just about managed to get it undone but it destroyed the thread as it came out:mad:

[chris75]

Odd - from my personal experience, I am sure that the washer would have been tight before 110lbs.ft.:shrug:

I would personally take it apart and check everything:( - did you have the washer dished away from the damper mounting? It is supposed to be dished away, not towards.

I had the problem that the bolt wouldn't undo, I just about managed to get it undone but it destroyed the thread as it came out:mad:

Thanks for that :} My concern is indeed that the washer should have been tight long before that . The washer is dished facing away from the damper :}
They did undo relatively easily , with a 30" breaker bar !!!

[Bolin]

Yep, I think I used something similar.... maybe I should have tried some heat, that stripped thread cost me £90:duh:

I would be tempted to remove the bolt and then compare the old and new bolts and the old and new dampers, and check the hub attachment point to see if it has been 'skimmed' or something like that.

This might all be totally unneccessary and pointless, but that's what I would do just for peace of mind:o

[chris75]

I would be tempted to remove the bolt and then compare the old and new bolts and the old and new dampers, and check the hub attachment point to see if it has been 'skimmed' or something like that.



Agreed , that is what I will do :} It has occurred to me that perhaps the new shocks ( Sachs) might have a slightly narrower mounting at the bottom :shrug:

[Billy1mate]

They damper bolts should be thread locked in, regarding your washer, could it be rust in the bolt hole?

[BigRuss]

The PD Guide indicates 75 diesels and all MGs got the damper. Presumably petrol 75s don't apply according to this (Item 27): http://www.the75andztclub.co.uk/forum/showthread.php?t=34369

TC

Post PD petrol models did have the harmonic weights fitted I have some that I removed from an 04 plate Rover 75 1.8T saloon ;)

Russ

[chris75]

They damper bolts should be thread locked in, regarding your washer, could it be rust in the bolt hole?

The "guide pin" end of the old bolts was indeed rusty ; the threads were quite clean and did have thread lock on them , as do the new bolts. I am wondering if there is a small variation in the width of the new shocker lower mounting to allow for the addition of the later harmonic damper :shrug:
If that proves to be so , an extra washer should solve it . We will see :}

[Bolin]

I fitted a new Genuine shock and it seemed the same as the one that came off - not made by Delphi now though.

[chris75]

Just to finish this tale off , I have stripped the lower ends out again and compared old and new . The problem is with the new bolts from Rimmers , which are not OE stock as those are NLA . The "nose " on the bolt is about 2mm shorter , leaving the thread about 2mm longer and this means the bolt bottoms out in the trailing arm hole before the damper is properly clamped . options are another washer under the bolt head , or reuse the old bolts . I reused the old ones :}
Piccy for comparison showing old and new ( oddly, the threads look rounded off in the pic ; they are normal in real life ! ) :

[Bolin]

Interesting. I had a new bolt fitted in one side last September and no problems:shrug:

[David Lawrence]

Agreed , that is what I will do :} It has occurred to me that perhaps the new shocks ( Sachs) might have a slightly narrower mounting at the bottom :shrug:

I bought new bolts from Rimmers as well and it wouldn't tighten up on the washer, so resorted to putting the old bolt back in. That tightened up fine.

Maybe Rimmers have the wrong size listed.

[Typhoon190]

Unfortunately while tightening the rear damper to trailing arm bolt, the thread has stripped. :getmecoat: Will have to helicoil. Hoping it will handle the required torque.
:o

[macafee2]

Unfortunately while tightening the rear damper to trailing arm bolt, the thread has stripped. :getmecoat: Will have to helicoil. Hoping it will handle the required torque.
:o

The only way I can think of that happening is if the bolt was cross threaded, was it cross threaded? I found getting it in line took quite a few attempts. A google search shows that it should

macafee2

[Mike Noc]

Unfortunately while tightening the rear damper to trailing arm bolt, the thread has stripped. :getmecoat: Will have to helicoil. Hoping it will handle the required torque.
:o

If you use a decent Helicoil it should be stronger than the original thread.
I had one bolt pick up and damage the thread whilst removing it but luckily I had a tap the right size (bought in error a few years ago!) that cleaned the thread up. :}

[Typhoon190]

The only way I can think of that happening is if the bolt was cross threaded, was it cross threaded? I found getting it in line took quite a few attempts. A google search shows that it should

macafee2

Unfortunately the old bolt was heavily corroded in the trailing arm when it was removed the first time, despite treating with oil as best as I could. The bolt threaded without issue and nearly made the correct torque . . . . . nearly.

If you use a decent Helicoil it should be stronger than the original thread.
I had one bolt pick up and damage the thread whilst removing it but luckily I had a tap the right size (bought in error a few years ago!) that cleaned the thread up. :}

I believe thread inserts are stainless steel, so stronger in aluminium etc, but not necessarily steel.

The old thread failed just before I reached the correct torque. :getmecoat:

[Mike Noc]

I believe thread inserts are stainless steel, so stronger in aluminium etc, but not necessarily steel.

The old thread failed just before I reached the correct torque. :getmecoat:


Yes commonly stainless steel but they do come in a variety of materials depending on the application. I've come across Stainless, High Tensile Stainless, Bronze, Inconel and Aluminium Alloy inserts.

As the OD thread on the insert is greater than the ID thread, as long as the material of the insert is hard enough it will always be stronger, but yes the effect in steel may not be much.

The important thing is the end result won't be any weaker than the original.

Could be you were lucky that the thread failed just before you reached the correct torque - far better than getting there but have it fail going down the road afterwards. :}

[Typhoon190]

Yes agreed, thanks Mike. The insert needs to be 1.5D by the looks of it.