Conrod Bolt "re-use" question
 

If you torqued your new bolts to 20nm + 90degrees.. and then UNDID them.. do you assume that they are already stretched and are a throw away item?

Or would it be safe to use them still?

If they are factory bolts, they are trash after you torque them. One time use, my friend.

ARP and other such aftermarket bolts can generally be reused within the boundaries of the MFG's guidelines.

Does Porsche say they are 1 time stretch only? How are you supposed to rebuild the rods?

When we rebuild rods and use any bolt including the factory bolt (new)with new nuts, we measure the bolt length. Then we stretch the bolt and resize the BE. Then the nut is loosened and the bolt is remeasured to see that it returned to its relaxed length. I have never seen a factory bolt not return to its relaxed length if stretched or tighten using the torque + 90° method. Then on assembly the same bolt is re tighten (stretched to the same length) to fit the rods to the Crank.

Yes, they do. Just about every WSM I have says that. Here is the excerpt from the 997 GT3 one:

Also, my machine shop and most others I know of rebuild rods using the OLD bolts, stretched like you are saying. Then they ship with the old bolts hand tight just to hold the rods together. You, the end user, are supposed to replace the bolts when you actually build the motor.

The bigger question is what kind of false economy is it to try and save rod bolts that aren't ARP in an expensive Porsche motor.

This debate keeps going around and there a simple answers to most of the issues raised.

The conservative approach is to simply throw the bolts and the nuts away and buy new parts and to assume that the bolts have become useless but I find this approach bit wasteful.

In the first Volume of the 911 Workshop Manual Porsche described the conrod bolt as 'malleable' and recommended replacement during a major overhaul.

This comment was not made in the 1970 revision when the rod bolt length was changed to 73mm.

It did, however, re-appear in 1984 when the tightening method was changed from 50Nm to 20 Nm + 90degrees.

In simple terms this new method of tightening would be similar to a stretch of around 12.5 thou which is greater than that recommended by ARP for their ARP 2000 bolts.

If the cross-sectional area of the ARP bolt is the same as the factory bolt this reduced stretch would result in a lower preload which is an interesting approach.

The job of a rod bolt is to ensure that the con-rod is correctly clamped but the preload use in rod bolts is always greater than any fatigue loading that occurs whilst the engine is running and providing this is the case there shouldn't be any real issues.

If the Porsche supplied bolts do yield slightly when they are first tightened they will still maintain the designed preload and the material will have work hardened slightly.

Providing the stress in the bolt is below the material's Ultimate Tensile Strength (UTS) it will still support the required preload.

Once the bolt is undone there may be a small permanent offset but in itself this is not a very serious issue.

For example, many Aluminium Alloys are supplied in a mechanically yielded condition to improve their properties and specifically their fatigue lives.

Work hardening, which occurs during the yielding process, is a simple and well understood, the vast majority of metals exhibiting this type of behaviour.

It is most easily described using a parabolic relationship where the rate of work hardening with respect to strain is a material property.

If you load a typical steel beyond it's yield point its strength will increase even though its deformation behaviour becomes non-linear.

If you then unload the material it will not yield again until it has reached the new 'elastic' limit that was caused by the work hardening.

The material will also behave in a linear-elastic manner up to this new yield point.

Whilst the material is increasing in strength due to work hardening it is also reducing in cross-section and there comes a point when the rear reduces more rapidly than the material can strengthen. This is the point at which a bolt will no longer maintain a torque and we experience that dreadful experience of the load on the wrench falling and the bolt snapping.

So where does that take us? :)

I would generally agree with Neil Harvey and have re-used rod bolts for years without problems.

I have never seen a used Factory Rod Bolt that didn't return to its original length after tightening to either 50Nm or to 20Nm + 90 degrees.

To me this clearly indicates that the bolt is elastic and therefore fit for purpose.

The Metallurgy that supports this idea is very basic and fundamental. The elastic behaviour of materials is an invariant property and IMHO is impossible to mess with.

We can change strength with chemistry and heat treatment but Elastic Properties don't change.

There are clearly issues with re-using Torque To Yield (TTY) or 'Stretch Bolts as they are commonly known but this is more to do with lack of knowledge of their condition after tightening.

If we tighten a bolt to a simple 'torque' we know that it will generally hold load and that we have not exceeded the material's UTS even if it is has slightly exceeded its elastic limit.

If we tighten to torque + angle we have no idea about the condition of the fastener material after tightening.

If we measure stretch we have to assume that the fastener has been correctly heat treated or it may not generate the correct preload and we do hear stories of bad bolts.

It really is a dilemma as the scatter in preload is greatest with simple torque measurement but the other methods also have issues.

We always check rod bolts and ensure that after the second time they have been tightened they always return to their original length and we are then confident that we have no issues.

The 993 Workshop Manual suggests tightening rod bolts to 30Nm + 90 degrees and then a final check at 60Nm.

Does anyone have an ARP 204-6001 Rod Bolt and could they measure the cross-sectional area of the shank? as I would like to understand more about the pre-load when using these bolts.

There is so much fear and mythology connected to rebuilding these engines, it is always good when good sound engineering discussion puts a lot of it to rest.

Thanks Chris for your great explanation. I too learnt something.

It's not fear and mythology in my opinion. I even acknowledged that the bolts would re-stretch to their original length. The science here is irrelevant.

What is relevant is the avaricious cheapness at work by the same crowd of people who want to reuse flywheel bolts, rod bolts, and axle nuts. So much time is spent testing around the fact that the factory generally states these are one time use parts, but there are still people who are too cheap to heed the warning.

It is not hard to make a 911 motor 60 grand or more, yet the same group of people will trip over a hundred bucks worth of rod bolts, making themselves feel better with their own empirical tests sprinkled with words like "should" and "possibly".

Reused rod bolts will likely not fail, even used multiple times.

But that's not the point.

Wow.
That explains a lot. So Porsche isn't really supplying weaker bolts. Porsche is just being cautious in not reusing these highly stressed bolts. Makes sense.

I always thought the FW bolts were discarded due to the shallow drive, not due to elongating?

I was planning on reusing mine.

I'm not sure of what the reason is for not reusing the flywheel bolts but the consensus is to ditch them if they have been on the car for a while.

Perhaps someone could elaborate further.

The Porsche WSM is geared towards the Porsche repair facility, not the home mechanic. In the Porsche repair environment, there is no time or equipment to determine whether a used con rod bolt is properly elongated upon reuse. Therefore, in the effort of expediency, it is discarded and replaced with a new one.

You will not find a stretch gauge in a repair department at your dealer because no spec exists from the factory on that.

While I agree with discarding used con rod bolts, much of what the WSM says is based upon warranty repairs and other considerations.

I don't know why Porsche suggest discarding these bolts.

It is possible that in 1965 when the statement concerning 'malleable bolts' was first made it is quite likely that process control was not so good in virtually all areas of manufacture.

Tensile Testing machines were relatively inaccurate and batch control of heat treatment was quite poor compared to today.

Basic metallurgical education was also quite limited and you only have to look back at the text books used in the Fifties and early Sixties to see this point.

Put this together and there may have been evidence of yielding from time to time and Porsche decided that changing bolts was the conservative approach.


We now know, however, that even if a bolt yields the first time it is torqued as long as it stabilises when re-torqued it will be good to use. and the statement about discarding the bolts can be considered to be redundant.

The only caveat is that the bolt must be capable of holding the torque applied during tightening.

We always use dial indicating toque wrenches so we can easily determine that torque continues to increase in a monotonic fashion during tightening.



Sadly we don't see many customers that want to spend $60k on an engine re-build :( and we have to make do with re-building standard engines at much lower costs.

I am convinced that the 'chuck it all away and buy new' is stopping many owners from re-building engines that aren't performing well.

Here in the UK we recently saw an invoice for re-building a completely stock 2.2T engine for $32.5k, they didn't rebuild either the carbs or dizzy for this price.

Many UK 'specialists' now refuse to rebuild mag engines unless they shuffle pin and some even insist on fitting new oil pumps.

The latest 'fad' is to line hone engine cases to improve alignment and to hell with the impact this has on Main Bearing Crush.

People with early standard engines are being told they 'have' to uprate their oil pumps, that they must fit piston squirters or their rebuild will be catastrophic, despite that fact that the engine seems to have run successfully for 150k miles without all of the expensive add-ons.


If you add up all of the 'must-dos' the costs of rebuilding 911 motors is simply escalating in an out of control manner.

The answer must be to carry out the work relevant to the specific engine duty in a pragmatic manner.

I find it difficult to understand why some very basic engineering knowledge is irrelevant and why we shouldn't share this information and try to save a little money when appropriate.

Many people reading these threads are re-building their own engines, have invested in some measuring equipment and have the time and patience to make the appropriate measurements.

I fail to understand why a bolt that continues to behave in an elastic manner needs to be discarded.

I am not too 'cheap' to hear the warning, I just don't understand the issue and the measurements we have made confirm my doubts.

It is interesting that the 993 manual now provides a measurement for the elongation of 3 ring Rod Bolt to quantify it's fitness for purpose.

Flywheel bolts are a similar issue and I can't find anything in the manuals that suggests that these bolts need to be replaced.

Once again if they remain elastic and are undamaged they must be fit for purpose.

There are issues with some of the larger capacity engines using 6 - Bolt 70.4mm stroke cranks.

These engines are not the most torsionally stable engines Porsche produced.

The 2.7 with relatively heavy pistons can become quite 'lively' at high engine speeds and this can cause the flywheel to shuffle and eventually it can work loose.

When this happens it is common practice to blame the bolts but this is generally not the real problem.

The real issue is the mismatch of the inertia of the flywheel and the crank. When the amplitude of the torsional vibration becomes high enough the flywheel tries to stand still and the crank boss moves as the relative forces are greater than the clamp loads can withstand.

When this relative movement occurs it is common to find evidence of fretting on the two faces and this is often accompanied by a brown dust.

There are two possible solutions:

The first is to use a torsional damper on the crank but these are heavy and increase inertia.

There is a UK Company making these devices but the cost is around $1250 each. This component reduces the amplitude of the vibrations.

The second solution is to use stronger flywheel bolts such as a Grade 14.9 or maybe even a 16,9 and increasing the preload to eliminate the shuffling.

The early flywheel bolts used on the 2.0 litre engine were equivalent to Grade 14.9 but later bolts were Grade 12.9.

If there is evidence that the flywheel has been moving I would discard the bolts.

We have never seen a 9 Bolt flywheel suffer from this problem and again we always check and re-use flywheel bolts when re-building standard engines.

For interest ARP High Performance Flywheel bolts are equivalent to Grade 12.9 and the Pro Series are approaching a Grade 14.9 and can be torqued more tightly than the stock fastener.

We are currently looking to make the M12 x 1.25 bolts in a 220 ksi material fro high revving 2.8 liter engines.

Chris, thank you for your insight with actual data. I've probably been more vocal than others about my head scratching of the "chuck everything" mentality.

I've reused my CV joint bolts many times without issue and I plan on doing the same with the FW bolts.

Hold the phone a minute, Chris. I am sorry I threw flywheel bolts into the mix, let's focus back on the rod bolts for a minute.

Tippy, you don;t have skin in the game here because you have ARP bolts, and they are designed to be reused.

Chris, I am assuming you are a shop of some sort. I am a parts manufacturer as well. We both have similar considerations, namely, customers.

I logged into my SSF account, and I saw that my wholesale cost on Porsche rod bolts for an SC (I picked SC at random because it is a common car) were $9.90 each.

So in total, the bolts cost me $118.80 for the whole motor, again, wholesale.

You mean to tell me that your shop breaks a motor all the way down to rods coming off, and the $118.80 it would take to replace them per factory recommendations is somehow too much? I am assuming you buy wholesale as well.

My angle is this - I get all your science and compound sentences, honest, I really do, but you're going to tell me that instead of just paying the $120 you're going to throw a bunch of science calculations at the motor and send your customer packing with old rod bolts?

What's your angle here? I am trying to understand how any of this benefits you as an engine builder. It seems to only create liability in the event of a failure.

Oh, and it's not as if Porsche recommends that a lot of it's bolts be trashed - I can only think of a couple that it explicitly states not to reuse, con rod bolts being one of them.

So what gives? Honest question.

Love the info in your posts, just after the business side of this decision is all.

Last 2.7 I took the flywheel off of had one bolt break at the head. It was like glass almost it was so work hardened. Who knows if it was properly torqued, was 44 years old or what? Just not worth it. Same with rod bolts for my customers.

Thank you^

Have you ever thought about the fact that a used rod bolt has proven it's performance during operation...and a new one hasn't.

When you introduce a new one to your motor, you don't know, but just hope and assume it does not have any kind of defects from the manufacturing process??

I KNOW the chance for defects is minor, but it's there :p

By that logic you'd never put any new parts into your motor. Where does the line cross between "proven performance" and "worn out" on an engine component?

As soon as you remove your rod to do new bearings, and unbolt that con rod, you are upon the horns of a dilemma. You can either do math problems, throw a science lecture that talks about bolt stretch and post calculations, or you can pay 9 bucks and put a new bolt in there.

I am being facetious but you catch my drift I bet.

People contemplate the usage of used parts, simply because the cost of parts is ridiculous. Sure, for 1 part it makes little difference. But multiply by 20 parts, and whooooaaa.

I am refreshing my motor now as other threads attest. And spending $5k is awefully easy. I can see how hitting $10k by the home mechanic can be done. Or 30k at a shop.

Its only money, and we should all enjoy the process :).

That's said... I see track ready Porsche 944 turbos for sale for 10k... That's an entire car. Rod bearings, rod bolts, pistons, oil, rings, gaskets sets all included... Not to mention ITS A FULL CAR.

I understand that Porsche parts are low volume, hence the cost. But if you take a deep breath, and look at it logically, the costs are awefully silly for what you get. It is what it is, though.

If one wants to feel better, price out Ferrari parts. For the testarossa, no one makes an oil filter. NO ONE. What was a $40 part (outrageous) is now a $300 part, while supplies last. Try to buy tires. There is one brand/size that fits, and its available whenever a production run is done. Otheriwise, need to get from Europe at $4000 a set.

See...

Feel better ;)

The thing I don't like about reusing the factory bolts is that you didn't install them so you don't have the un-stretched length. Though if I understand the analysis above, it seems that if they take torque again, then they were likely ok.. maybe an over simplification.

I always get nervous thinking about re using a bolt when the factory manual says to toss it. The flywheel bolts specifically seem like they could be reused, but I'd hate to risk it, and I HAVE had a 944 turbo flywheel come loose. those cars use the same bolt as the 9 bolt 911 crank. But they're relatively cheap, so it seems like a no brainer to get new ones.

For my 964 engine refresh I opted for new rod bolts, and the price difference between the ARP and stock equivalent didn't seem very high, especially since you can re use the arp bolts. In this case going for ARP also seemed like the right thing to do.

Unfortunately with older cars, eventually used OEM parts almost always become better than the reproduction parts available. This has been my experience with other non German vintage cars. We are already seeing this in the 911 with the Glyco rod bearing problems recently. In theory if you could find a barn fresh carrera engine that had 30k miles on it, and had been mothballed there would be many nice parts inside that would probably exceed current quality metrics. I'm thinking the rockers, rod bearings, and main bearings right off the bat. I have a friend who races a 1970s triumph, and he was the first person that pointed this phenomenon out to me. We're lucky in some ways that Porsche is still in business, and make porsche branded replacement parts with good quality, but the trade off is astronomical pricing. As a community we are less lucky than my friend in that these cars get driven for hundreds of thousands of miles, and the cars / engines have value as a whole... so low mileage part outs are less common.

It's certainly a complicated problem. I bet I spent $5k on my refresh, and I only rebuilt the heads, replaced the head studs, ARP rod bolts, rod bearings, crank thrust bearing, intermediate shaft bearings, and I did all the work myself. I left everything in place that seemed like it could reasonably be reused.

Someone else mentioned that it was impossible to determine when parts were "worn out" when you start trying to reuse everything.... That's not quite true. "worn out" literally is short for worn out of spec or tolerance. Pistons, ring gaps, bearing clearances, etc can all be measured and have a spec in the manual. You still must apply a judgement call on condition of bearing surfaces, and rocker / cam lobe condition. but that comes with experience, and some risk that one might not be willing to take as a shop with their reputation on the line. If you were rebuilding a 350 chevy, it would be dumb to reuse any bearings, because aftermarket parts are good, and you can probably get every bearing in the engine for $150. There are almost $2,000 of bearings in a 911 engine if you get porsche branded parts. For me that's a lot of money to throw away if parts are still in spec.

All parts in an Porsche engine has well documented toleranses, and it is quite easy to find out if any part is beyond use...

The discussion about rod bolts is technically interesting and I have never found any justification as to why a bolt that behaves elastically needs to be thrown away.

When questions were first asked about this subject many years ago we started measuring rod bolts to see if we could learn more about the basic reasons for this advice.

If you tighten to 20Nm + 90 degrees I believe that a 911 rod bolts remains elastic and we have never found one that has yielded.

It really comes down to 'belief' and as we don't see a problem why throw them away?

If rod bolts were subjected to fatigue loading I could see the point and would throw them away.

We would never 'send one of our customers packing' and fail to take responsibility for our decisions.

I don't know why the head would shear off a flywheel bolt and it clearly can't support the torque needed to make it release.

The real question is how it supported the load during tightening. It seems reasonable to assume that the torque needed to move the bolt has increased and to try to find out why this is the case.

Work hardened materials rarely exhibit the classic signs of brittle fracture as work hardening implies some degree of ductility which will dominate the failure mode.

I would expect a Grade 12.9 fastener to have a reduction on area at failure of at least 12% so it should noticeably deform before it breaks.

Using threadlockers on bolts which are highly stressed can be a problem as the increase in prevailing torque can be quite significant and could cause an overload when the bolts have to be released.

We don't generally thread lock flywheel bolts but I would tend to use a low strength material for this duty.

I guess my logic is that if we have the engineering capacity to make sound decisions we should use this and pass on the savings.

If I felt we were taking any risks I wouldn't take this approach.

This right here answered my question. While I don't agree with it, I respect your decision and of all people I have spoke to on here, you seem to be the one that has been able to articulate your position best. Hat's off to you.

I know this is way off subject, and I apologize, but we do put out a lot of fear regarding our rodbolts failing. When I rebuilt old American V8's, I reused the original rodbolts several times knowing zero history without issue turning over 6K RPM when I was young and dumb. Never once a failure after beating those poor engines to death. Second, I've never seen a rod bolt failure in any engine. It seems the rod caps tear open right around the rod bolt flanges more than anything. Seen that dozens of times with the rodbolts there doing their job.

Another thing I've heard, is that you must replace crank pulley bolts once used. I've reused those on several vehicles too without issue. Even supercharged ones where there's added stress from the blower pulley.

Point is, I'm not surprised by Chris' findings. As an engineer I used to work with used to say when he read something over the top, "maybe this engineer had his pocket protector on too tight?"..... 😂 😂 😂

I, too, reuse my 6 bolt flywheel bolts, despite torqueing them to 150 lbs/ft. Removing them, despite the red Loctite, doesn't require heat or anything special - the impact wrench just buzzes them off.

But I have had a stock rod bolt fail, with disastrous results as you would expect. Back when you couldn't get aftermarket high strength bolts for the 66mm crank rods. I spun the engine to 8,000 RPM on the track for a couple of years when blammo. The rod bolt showed the classic necking down above and below the failure point. The crank was OK - the stretch apparently didn't last long enough to drop the oil pressure on that journal - stuff wasn't all blue or black.

I like the aftermarket rod bolts, use a stretch gauge, and write things down.

^ Actual usage, love it.... 😍

Totally off topic, but how about pressure fed chain tensioners? That is the one part I could not find any info on when I rebuilt my 375,000 mile motor. How and when do you rebuild or replace them?

Well if you search this forum alone you see some pictures of broken flywheel bolts. Reviewing one thread it seemed to have no real conclusion but that it might be a bad run from a subcontractor. So maybe hanging on to old bolts is a good idea. Sure hope it wasn't the same maker with regards to rod bolts!

For many years the information on Porsche engines and components was grossly incomplete and I am sure if we attempted repairs and improvements on the current models we would find it has not improved much. 40 years ago we were on our own and it took the consultation of people exactly like Chris who reason and investigate test and verify and economize our projects so that we do not have to major in the minors of engine building and if we are lucky move on to improvements that could maybe move the torque needle up if you know what I mean.
regards

Graham, no idea about how to check them :-/ ...but quite sure there is info elsewhere in this forum.

On thing I just started and plan to do on all my future builds is rod bolt stretch vs torque settings. So far I've only done this to a 2.7-3.0 10mm ARP rod bolt (stock rod), what I did was measure both the recommended stretch and recommended torque values and on the ARP 10mm bolt found they came out exactly the same.

I will be repeating this on a Carrillo (996) rod bolt (Carrillo rod) very shortly and plan on checking all future rod bolts that come across my bench.

Not saying I'll replace stretch with torque, or that my methods are very scientific, really only doing this for my own knowledge.
I found the results on the 10mm ARP interesting and now want to see how it compares to other fasteners.

Mark - the major benefit of using the stretch method is accuracy, since thread friction is simply not part of the clamping force equation - you are, in essence, measuring clamping force directly by measuring bolt stretch.

As you have seen from ARP's information, you need specified burnishing of threads, and a specified lubricant, to use torque in the manner they feel is adequate if you don't measure stretch. Any variation in this, or discrepancy in your torque wrench's accuracy, will leave you with more or less than the specified clamping pressure (which you would have to calculate, since that term is not used, but it is what makes things hold together).

Porsche maybe sort of uses a method half way in between - torque to a value, and then turn X more degrees.

All these methods have to have a suitable engineering safety factor built in. Maybe in an F1 motor lightness considerations mean leaving the slimmest margin between the forces of the running engine and the clamping force, but that can't be so in a street car motor.

I'm sure that for a street motor, torque is perfectly adequate. If building a higher performance motor than Porsche intended, it only makes sense to use stretch. The tool is cheap, and doesn't really take appreciably more time than torqueing. It's only draw back is that you can't use the stretch method if you don't have the crank out on the work bench.

This situation isn't quite as simple as it sounds.

Stretch only works for a bolt that is elastic and it fails to provide the assumed preload as soon as the stress exceeds its tensile strength. This is the point at which the bolt will begin to neck.

As I suggested in an earlier post for the ARP method to work correctly the bolt must be capable of maintain the applied load throughout the tightening sequence.

For example - if the bolt were incorrectly heat treated - which I would accept is quite rare - and it was simply tightened to stretch then you have no idea on the stress/strain condition of the material. This is the reason that ARP suggest that of their bolt deforms permanently by more than 0.001" it should be rejected.

I have to say that I would question this value as being a bit too low and as the 'uncertainty' of measurment of their stretch gauge is likely to be in the order of 0.003-0.004" I would think 0.0025" would be more realistic.

I would also not make the decision to reject the bolt until I had taken it to the stretch length 2-3 times.

If you have sufficient experience then you would be able to 'feel' that the bolt was still maintaining load but otherwise you have some uncertainty.

Torque + angle is really only a stretch method without the need for a gauge.

The assumption is that the initial torque value just makes the bolt 'snug' which is to say it is sufficient torque to eliminate thread and underhead friction and does not stretch the bolt.

The stretch is then determined by the thread helix and angle of rotation.

The same problem exists as with using a stretch gauge as you have no real way of determining the stress/strain condition after the final rotation.

The best method must be to use a dial indicating or digital wrench and to ensure that load continues to increase right up to the point at which the bolt is either sufficiently stretched or rotated through the specified angle.

The use of burnished threads and consistent lubrication has been well established for many years and simply follows the concept of being able to establish a repeatable 'nut factor' which is commonly used by the Aero Industry.

If established correctly using these concepts torque tightening does become a sensible option as the causes of scatter can be eliminated and using torque becomes a viable method.

Burnishing bolts does, however, contradict the 'use once' and throw away concept.

A good explanation can be found in John Bickford's Text Book 'An Introduction to the Design and Behaviour of Bolted Joints' which is summarised here:

Dissecting the Nut Factor | Archetype Joint

I'm not so sure about the tool being "cheap". My stretch gauge is an ARP one that is $200. It is cheaper than my $600 a piece Snap On digital torque and angle wrenches, but still an expensive tool.

I like the ARP gauge, but quite honestly with the Snap On, you torque the bolt to it's initial torque, and the wrench is within 2 percent accuracy at this value. Then, while still on the bolt, you press a button and the wrench goes into angle mode, and you spin to angle. Done. To me, much simpler, but it takes a pricy tool to do it.

I made my own, a hexbar off an old HF adjustable wood circle cutter, bit of lathe time to make some bits and an old starrett dial indicator I had kicking around.

^Yep, not a complicated tool at all. In the past couple years however, after turning semi-pro, I slowly got rid of all my homemade tools and harbor freight stuff. It just doesn't inspire credibility when people are watching.

I had lots of frankenstein stuff too. Worked fine, most of them, like you, were made on my mill or lathe.

Summit racing has a stretch gauge for 50$ I couldnt find one here on pelican so I'm assuming they dont carry one.

Most of my stuff looks good as well, I made my own 996 engine stand, I've held the $600 ($1000 Canadian) unit in my hands, mine is better thought out and equal in build quality.
Some of my stuff looks hacky, but most of my tools even a mechanic would be hard pressed to figure out which one is the pro tool.
But then there's tools I just can't make, those I buy.

Catorce - I've got a Summit stretch gauge. I have difficulty seeing how the $200 ARP gauge is going to do a better job in any way, so ~$50 is cheap compared to the ARP - or a fair number of other special tools.