I have the front hubs stripped down at the moment for some brake work and I’ve discovered a small DPO problem. It appears that at some point one of the upper bolts that mount the calliper brackets to the upright has sheared off and someone has tried to drill it out. However they were unsuccessful in drilling it centrally and now there is a sliver of the original bolt sticking out around the top of the original hole and a smaller diameter hole going through. This was bolted together with a smaller that standard bolt and, because there is now no thread in the hole, a nut on the the back of the vertical link (Similar to the bolt that goes through the steering arm lower down).
I am going to try and remove this bit of excess drilled-out bolt and make the hole big enough for a standard size (5/16") bolt to go through but my question is - as the hole is going to be too big to re-thread, is it ok to have a nut on the back or do I really need a new upright?
Regarding having a nut on the back, I don’t think that would bother me too much as long as it was seated squarely.
Before that, if my interpretation of the situation is right, I think I’d try an extractor on the remaining portion of the original bolt. Maybe with a bit of heat beforehand to try and remove it then depending on where the smaller hole is positioned, you might be able to revive the original thread with a tap.
If the smaller hole has gone off centre and destroyed part of the original thread then again I would try to remove the original bolt, probably by hitting it with a dot punch if the extractor fails. At that point I’d probably use a helicoil to recover the original bolt size/thread.
It’s hard to comment without pictures of the situation but it’s a brake component. Removing metal by drilling a bigger hole makes it weaker. If you can’t remove the broken bolt without leaving the existing threads entirely intact throw it away and install a replacement. I usually find in these situations do not persist if the bolt doesn’t come out easily. Take it to a professional machine shop who will remove it without damage to surrounding parts in a couple of minutes what might take you a whole day only to end up the part being reduced to something useless or damaged. Don’t end up as DPO number 2.
Thank you both. I wasn’t going to attempt drilling as I have no way of keeping the drill on course and will just end up with a bigger hole in the wrong place. The original thread has been destroyed by the off-centre drilling bodge. Trying to remove the remains of the bolt was going to be the plan - thanks for the tips Brian.
I do have a photo but technology failure has prevented me from uploading it - I should be able to put one up later today. Probably with the results of my efforts too.
Before you go down the extractor route Robbie, if you are thinking about using the type that you have to drill a hole in the bolt first, then try and twist a reverse thread extractor into the hole, I have never had sucess with those and they usually break off, creating a worse situation. When I have posted about that before, several folk agreed.
If I did not think that I could drill sucessively larger holes in the bolt to eventually collapse it and then clean up the original hole, I would take it to some engineers who have better equipment that me, and there aren’t many, to carry out the job.
Failing that, I can probably help you with a replacement part.
Robbie
I concur with others as this is a safety issue.
Is your car a baby Elan or a +2?
There appears to be two options, first a replacement part (worth an advert on here to see if someone has a spare they will part with), or to take the part to a local machine sop/engineering company that will have all the equipment necessary to do a proper repair, which may involve welding up the existing hole and redrilling and tapping the new hole. This may not cost too much.
I have assumed that the damage is to the hub and not the caliper mounting bracket
Tony
I did try one of those windy out stud extractors but the hole was too big for the one I have so I went ahead and did a bit of tapping with a dot punch. The shard of bolt sticking out broke off flush with the face of the upright and this enabled me to get a better view of the damage done. Turns out the DPO drilled hole is way off centre and I would never have been able to wind or drill out the remains of the bolt. How the bolt managed to go through the calliper bracket I have no idea as it is undamaged.
So I suppose I will need an new upright… Pictures are attached of before and after.
Robbie
Now we can see the damage and all is not lost, as I suggested you could take this to a good engineering firm and get them to weld up the hole and redrill and tap a new hole. Take along your caliper mounting plate so they can use it to mark out the exact centre needed. Lokely to be cheaper than a new upright. Have you thought about placing a wanted ad on here for a good second hand unit?
Tony
As the steering arm is held via nut & bolt then this form of fixing must be suitable in this application.
Repair by refitting a High tensile nut and bolt as before. BTW what side upright LH/RH, may have a near new S/H with trunnion.
Robbie,
If you decide to go for a new link please be aware that there are instances of trunnions being either too tight or too loose on the new link. It has been reported on here, and also on various Triumph forums. I have read that some people have gone back and forth to suppliers to get trunnions and links that match.
If the link’s thread, and the trunnion, are in good condition I would be inclined to go for a well engineered repair. If I had to buy a new link I would probably also ask for a correctly fitting trunnion from the same supplier at the same time.
Alan
As I understand it from Robbie’s description, the damaged hole was drilled by the PO off centre which means a helicoil is likely to follow the line of the damaged hole, hence my previous reply about having it done correctly at a good engineering business, who can weld up and create a new hole in the correct place.
Tony
Ok but for me i would use the part that bolts to it as a drilling Jig. Or make a drilling Jig from steel plate to guide the Tapping size Twist Drill for the Helicoil Insert. I would not try to free hand drill the hole.
Sorry but it seems normal practice to make a drilling Jig.
Best to take to a machine shop otherwise.
Alan
An original Stanpart vertical link with nos Stanpart trunnion winging it way up to Robbie as we speak. The threads are in lovely unworn condition and the trunnion fitted like a glove, no slop. The EP90 must have been changed pretty regularly
