Hex bolts insert rounded - help
08-09-2015, 06:15 AM
#1
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I'm dropping my engine and gearbox for the first time. So far so good with fasteners until now 
The right hand half shaft has an awkward placement and I could see some of the hex insert holes were rounded. Probably because someone didn't take enough care and/or fitted already rounded bolts. Anyway, I managed to get four of the six loose but two won't shift and are definitely too rounded to use the hex tool. I can't cut the head off or use heat. What do the old hands suggest? Maybe file flats on the head and use a spanner? Or cut slots and try a screwdriver. They are well torqued so I'm not sure which of the web methods will work.
The right hand half shaft has an awkward placement and I could see some of the hex insert holes were rounded. Probably because someone didn't take enough care and/or fitted already rounded bolts. Anyway, I managed to get four of the six loose but two won't shift and are definitely too rounded to use the hex tool. I can't cut the head off or use heat. What do the old hands suggest? Maybe file flats on the head and use a spanner? Or cut slots and try a screwdriver. They are well torqued so I'm not sure which of the web methods will work.
08-09-2015, 06:29 AM
#2
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I'm dropping my engine and gearbox for the first time. So far so good with fasteners until now The right hand half shaft has an awkward placement and I could see some of the hex insert holes were rounded. Probably because someone didn't take enough care and/or fitted already rounded bolts. Anyway, I managed to get four of the six loose but two won't shift and are definitely too rounded to use the hex tool. I can't cut the head off or use heat. What do the old hands suggest? Maybe file flats on the head and use a spanner? Or cut slots and try a screwdriver. They are well torqued so I'm not sure which of the web methods will work.
The right hand half shaft has an awkward placement and I could see some of the hex insert holes were rounded. Probably because someone didn't take enough care and/or fitted already rounded bolts. Anyway, I managed to get four of the six loose but two won't shift and are definitely too rounded to use the hex tool. I can't cut the head off or use heat. What do the old hands suggest? Maybe file flats on the head and use a spanner? Or cut slots and try a screwdriver. They are well torqued so I'm not sure which of the web methods will work.
08-09-2015, 07:01 AM
#4
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Depending on how bad the Allen head is stripped, this may work. Dip the head of the Allen wrench in some motor oil, then roll in some fine sand. The sand takes up the space, and gives some purchase. Worked for me on some steering rack bolts.
08-09-2015, 07:09 AM
#5
I had the same issue, cut the heads off the bolts with a dremel, then wound out the remainder of the bolts once the driveshaft was moved away from the flange enough to grab the bolt. replaced mine with these spline bolts - miles better and will never round out, exactly the right size -
http://www.ebay.co.uk/itm/200806579563
http://www.ebay.co.uk/itm/200806579563
08-09-2015, 10:07 AM
#6
Race Car
Hex bolts insert rounded - help
Originally Posted by tdiquattro
I had the same issue, cut the heads off the bolts with a dremel, then wound out the remainder of the bolts once the driveshaft was moved away from the flange enough to grab the bolt. replaced mine with these spline bolts - miles better and will never round out, exactly the right size -
http://www.ebay.co.uk/itm/200806579563
http://www.ebay.co.uk/itm/200806579563
Your bolts from the factory should have been triple square xzn heads....so are the bolts you are removing a later replacement?
McMaster Carr will be you're friend if you are in the states. Not sure abroad where to buy good hard replacement Allen head bolts. Be sure to coat the heads with something water repellent after replacing them. It'll help with future rust.
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08-09-2015, 11:24 AM
#8
sorry:- to clarify, mine is a C4 and it was the fronts, originals are allen/hex head bolts as in OPs pic.
I replaced them with m8 12 spline.
eta - (C4 front and rear are all M8x50 as in VAG cars) (C2 are M10 ) so my replacement selection works for all 4 inner CV joints on C4s, the reason is the M8 hex bolts strip easily.
I replaced them with m8 12 spline.
eta - (C4 front and rear are all M8x50 as in VAG cars) (C2 are M10 ) so my replacement selection works for all 4 inner CV joints on C4s, the reason is the M8 hex bolts strip easily.
Last edited by tdiquattro; 08-09-2015 at 04:17 PM.
08-09-2015, 04:08 PM
#9
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Thanks for the suggestions. I removed the CV boot, which had a well hidden tear - (win!) and the actuator so I have more room to work. I will try all of the suggestions until one works. Nothing else so far has been an issue, I'm just slow. Sure I could have given this drop to a shop, but based on this type of fastener issue I'm more thorough than some and this is about long term ownership.
08-09-2015, 07:34 PM
#10
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FWIW I've had success with vice grips (good ones, ViceGrip brand) and also beating int the next-size-up tool.
My replacements came from McMaster-Carr; way cheaper.
My replacements came from McMaster-Carr; way cheaper.
08-09-2015, 08:12 PM
#11
Find a 12 point socket that will just fit over the head of the bolt. Using the next size down on an extension, hammer the socket onto the head until it seats. The socket will bite into the bolt and you should be able to break it loose. I've been doing this on damaged allen bolts for years and it's never failed me.
08-11-2015, 05:30 PM
#15
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Swings and roundabouts with the engine drop; the 36mm rear oil line connection was a walk in the park. 32mm and 36mm spanners and a modest amount of muscle and it unfastened. I think I'm in the relative clear now.