TF lower suspension bolts

Hi all

I’ve recently changed my suspension to the soft ride shocks using new bolts. I had doubts about the accuracy of my torque wrench that I used on the lower bolts so a few days later I tested it with weights and it was clicking at 75nm instead of 100nm. 

So I bought some of rimmer bros updated bolts and a new digital torque wrench and changed the four bolts.

I was on the Mike Satur site the other day and he’s released his version of these bolts saying that the rimmer updated bolts are not the way to go. Basically he’s saying they will still snap. I don’t like the look of his version I must say.

So now I’m bricking it, I’ve not even tested the car yet, too scared something is going to snap.

Help me put my mind to rest please, I should’ve left everything alone.

Pete.
 

Pete, From what I have read regarding replacing bolts with higher strength ones is that they are too strong !! In that in the event of excess stress, say in the event of hitting a kerb, the bolt will not bend but part of your suspension will, this could make a more expensive repair if the damage is noticed. The bolts specified at new should still be good enought now, replacing old with new bolts is a good practice

Mike

Mike, the new updated bolts from rimmers are the same strength, ie 10.9, but the unthreaded part is thicker, to take up all slack in the bush, they are now a tight fit, and the last parts of the thread have been treated so that it grips as it’s tightened which they say prevent torque relaxation and the bolt loosening itself. 

Pete
That makes sense, may try those at my next rebuild. Certainly nothing to worry about. Did Mike elaborate why they are not suitable ?
Mike

These are the rimmer ones with a description of how they are updated 

https://rimmerbros.com/Item--i-RYG000400UR

these are the mike satur ones

https://www.mikesatur.co.uk/-MGTF-Lower-Shock-Bolt
 

Pete
Since the bolts are subject to shear forces, the thicker the shank the less chance of a break, I think I would go with the Rimmer bolts in this case.

 What Mike Satur has said,

These innocuous looking bolts have a big job to do!It is recommended that the lower bolt is always replaced after use. It must be torqued to the correct figure making sure the threads are cleaned before fitting the bolt using the correct tap so the bolt can be screwed in by hand.
There are two types, the standard MG one or a higher tensile cap head bolt.
Because these have a habit of snapping  I recommend they are changed for the socket cap head ones.
The main issues with these bolts snapping is, the threads are not cleaned (use a M12 tap and wash out any debris) so the bolts can be screwed in by hand (NOT a hammer/impact wrench) then correctly torqued to 110N/m. The alignment of the bolt/thread /bearing rebate in the arm are out of alignment.These must be checked before hand for alignment. DO NOT use a hammer to assemble as I have seen reported by one Guy on a MG forum.That is one way of modifying your MG but not the correct way!!
Check the old bolts when removed, if they have witness marks on them and bent this could be a sign that you need to investigate further as the bolt could be binding on the inner bearing surface and the alignment of the mating part is out. This will require another arm fitting.( I have seen the rebate in the arm out of concentricity with the threaded section by 1mm so the bolt will bind and snap eventually!)The bolt can 'relax' as the correct torque is not reached causing the characteristic failure.
In my opinion the failure of the stock bolt is not because there is a large tolerance fit between the bolt and bore of the bearing but because of the parts not being in alignment/the bolt stretches beyond design limits causing it to relax. Using a tighter fitting bolt is not a way I would recommend as it reduces the tolerances between the bearing/arm rebate and the threaded part of the arm and the internal finish of the bottom bearing is not a true machined fit,fitting a tighter stronger bolt is a recipe for future problems! Imagine removing a high strength bolt that had to be forced into place and is now immovable ..yes it's going to snap off in the arm!!
The standard factory one is no longer  stocked.

Old thread resurrection time. Im in the middle of replacing my o/s lower wishbone and cannot remove the pinch bolt. Both ends rounded off despite the bolt being marinated with Plus gas a day in advance and then an hour before i started. In my (lack of ) wisdom i then cut off the nut and thread on the basis i could then knock out the remaining shaft of the bolt with a drift and club hammer. Its not shifting though. Any advice from those who have been up against this.

Is the hub itself threaded, have i missed something obvious like that or am just not hitting it hard enough ?

Oh yes I’ve been there & resorted to the big drill, having being sat in a pile of rust, blood, plusgas & cutting oil. I drilled a pilot hole, then successively larger holes until it let go, it then popped out as if to say what’s all the fuss about. As far as I can recall & this goes a long way back, it might even have been on the tf , there’s a groove machined at the bottom of the kingpin to allow a shouldered bolt to engage, this helps index the pin to lower control arm. If a fully threaded bolt is used the thread rapidly wares due to it allowing movement. Ensure you use the correct bolt I’ve a drawing of it amongst my scribbles to remind me of the size & tensile strength.

That gave me the encouragement i needed to have another go at it yesterday evening after work. I drilled it with 3mm first and then 6mm. Not sure whether it was the rotation or vibration that helped it or the fact the length of the bolt was now hollow but out it then came. I luckily ordered a replacement pinch bolt with the wishbone. Now waiting for a replacement drop link nut and bolt to arrive, the old one could just about be reused but the head is so rounded it's worth the wait.

As soon as the new wishbone is in i need to move the car round to work on drilling and extracting the subframe rear mounting bolts on the opposite side that sheared rather than undid the other day when trying to lower the subframe. Its odd as everyone seems to say there are 3 bolts each site but i count 4 on the TF, one of them also holds the X cross brace.

Remember you are standing in the footprints of many a mechanic, you are meeting nothing that hadn’t been seen before & all you have to do is do it properly. My advice for drilling out, based on much blood, bruising, rust some puss, swarf & words better known to Cobber.
Mark the bolt centre with a small centre punch, then when your happy it as close as you could get use a big punch & make sure it knows it’s been hit. Centre drill with a dumpy drill, a new WS 4 or better still a 5 is a good investment & Keep going until there’s no chance of the main drill wandering. Don’t use a battery drill unless it’s a real professional bugger, a corded drill won’t go flat, if it goes up in smoke that’s indicative of you need a better drill when you replace it. Use tungsten carbide drills made in the north of the northern hemisphere, although the last Dormer drills I bought were made in Brazil, the same with taps which you’ll need to retap the thread. Don’t break a drill, their really hard, even grotty ones.I broke a tap in part of a locomotive I was building & had to take the frames to another town to have the broken bit spark eroded, you can’t do that if you brake a drill in a mounting point. And there’s always tomorrow.

I’ve pretty well made a career outa removing broken bolts, before you try and centre punch the broken bolt, you need to get the un even broken end of the bolt smooth or you’ll never get your drill to start in the centre
To do this I use a pneumatic die grinder with a ball end carbide burr to carefully grind the bolt end smooth with a slight bowl depression ….. be careful and get a good grip, these things spin up over 30,000 rpm, and wear eye protection
Now you can get your punch dead centre
To dill out the bolt I use left handed cobalt drill bits start with a 3mm pilot hole and work your way up in stages to the size you would use to tap a thread into that size hole, I use a pneumatic drill spinning pretty slow.
By using left hand drill bits running slow. The drill bit will bite and when it does it may unwind the bolt outta the hole for you.
If it doesn’t you can keep going up a size until you get to the size the you would use to tap a thread for that size bolt. If then it hasn’t unwound the bolt you can pick out some of the remaining bits of thread from the bolt hole and run the thread tap through
This only works if you started your pilot hole dead centre…. You did centre punch your hole dead centre didn’t you! If you fail to punch it in the centre use the die grinder to smooth away your punch mark and punch it again in the bloody centre this time!
Use a good cutting lubricant whist drilling and tapping
I use Treflex HD cutting fluid