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Exhaust Studs


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Replacing some exhaust studs.  I'm thinking a pack of these is better value than spending about £5 each for Porsche ones.  The only difference I can see is a plus point that they're stainless but they're fully threaded and the Porsche ones have the blank bit in the middle.  Do I need to concern myself about that?

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https://www.ebay.co.uk/itm/M8-x-50-Manifold-Studs-Hex-Nuts-Washers-A2-STAINLESS-STEEL-Inlet-Exhaust/262939682768?hash=item3d386d27d0:m:mrDUQ74Y89tM2xARJGKuC2Q:rk:5:pf:0&var=561943494377

 

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I could grind the blank bit in anyway?

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Was more the bonus that they're stainless rather than cost saving, although every penny does help.  I can seem to find stainless ones in a similar spec.  They're all too short on the flange side.

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The problem with SS is it  has a low tensile rating, as do the cheap studs on eBay (usually only 5.8). Genuine ones are better quality at 8.8.

You can not grind a saddle on threaded stud, the saddle has the same diameter as the top of the thread as it is the unthreaded bar. The saddle also acts as a positive locator of the correct diameter for the manifold.

Corrosion is not the main problem with old exhaust studs, it is heat cycling making them brittle.

Mark

 

Mark

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4 minutes ago, SilverWT said:

The problem with SS is it  has a low tensile rating, as do the cheap studs on eBay (usually only 5.8). Genuine ones are better quality at 8.8.

You can not grind a saddle on threaded stud, the saddle has the same diameter as the top of the thread as it is the unthreaded bar. The saddle also acts as a positive locator of the correct diameter for the manifold.

Corrosion is not the main problem with old exhaust studs, it is heat cycling making them brittle.

Mark

 

Mark

Sorted that one then. Nice work. Love learning on here. 

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There is a chap on 911uk.com selling Titanium studs - I think that’s what Neil uses too.  

Can’t recall the benefits of Ti aside from corrosion resistance?

Are you using copper nuts too?

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I'm only changing 3-4 at the moment.  It'll need at least a top end in 2-3 years so the rest can hang on until then.  Was more about a if an off the shelf alternative was available, whilst saving money as a bonus.

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Don't know where they are, but the do get very good reviews. I seem to recall someone mention about them supplying a lightweight 915 flywheel, so will likely contact them when I'm ready to do my clutch 😁

 

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Spent the day yesterday underneath my car with David's jig, good quality cobalt drills, M8 tap and new studs.

Pleased to report the 3 snapped studs have been drill, cleaned and replaced with new studs.  The jig turns a major pain in the butt job into something more palatable, though still a pain in the butt and nerve racking.

I also tried freeze spray on the last two barrel nuts but they still snapped.  The outer hex nuts came off OK, though it was 3 inner barrel nut studs that gave up on one bank.  Is there a pattern/reason for this, is it always the barrel nut studs that cause problems?

Having said that all the hex nuts where stainless with the barrel nuts being steel.  I''ve ordered stainless barrel nuts this time round.

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There was a couple of studs left intact that I could have replaced as they were a little twiglety but I thought that might be pushing my luck.  It's going to need at least some head work in 2-3 years so they can wait until then.

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Nice work Nige - I did this myself - but only one stud and I had the benefit of the engine on a stand and set sideways. Didn't have a jig though (well maybe a small celebratory moonwalk when I got the thing out).

Don't envy you doing it on your back - even with a jig.

In relation to the original question, Mike Bainbridge gave me small fully threaded bar to replace the ones I had that weren't too clever. 

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Was tempted but thought stainless would be just as effective.  Unfortunately I was up to my neck in it to take photos and was wanting to get them done in the day so was on a deadline, my car is at Turbo Thomas'.  I'll ask Rich to send some "after" photos for me to post.

 

The jig is worth it's weight in gold, only one I can see available to buy is the https://www.stomskiracing.com/products/exhaust-head-stud-repair-kit though the one I borrowed is different but works in the same way.

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  • 4 months later...

Started with a cracked cross-over pipe and has now degenerated to a full exhaust replacement / refurbishment! Have successfullly removed the whole exhaust system, and was very carefull with the Dremel which proved very useful on both the hex nuts and the barrel nuts. Only managed to break off the tip on one of the studs, the rest are intact. I need not have bothered as I unrealistically hoped that the original sruds would clean up....wrong! They are corroded and need to be replaced as they seem to have been in situ since the Lord left Ireland! Need advice from the Brotherhood on :- Removing the corroded / necked / knackered studs, would Ice-off be of any use plus oxy / acyt. heat? Any advice on jigs should the likelihood of snapped studs rear their ugly head? Thought in advance of making a jig from the removed exhaust pipe flanges? Would appreciate any warnings, advice (other than head in gas oven)! Have shot-blasted and painted with high temp paint the waste-gate, waste-gate silencer and turbo exhaust pipe and was pretty chuffed with the result. Turns out that the couple of used heat exchangers that I had previously bought and been on the shelf for years are for a 3.2 I think, despite having the deep flange, and the same depth of head insert, the actual pipe ID is wider than the Turbo so I need to contact Matt on bended knees for replacements! I’ll photo the heat exchangers that I have and put them on sale here soon (at cost) in case they are of any use to someone, they are in really good condition. Any thoughts on replacement studs before I order from Matt, as I’m veering away from stainless due to tensile strength?  The original studs are I assume of the Iron Age? and have lasted since Jesus visited Dublin!

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I have a set of titanium studs that I bought from Fenn Lane. Unfortunately I can't use them - well, have decide not to use them.

My exhaust was removed by a local classic car specialist. All of the exhaust studs refused to move - since they are in very good condition I decided to leave well alone and let them be.

So, I have a set of lovely titanium studs that are surplus to requirements.

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