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Learning how to build Lotus Seven replicas...together!
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PostPosted: March 26, 2015, 8:16 am 
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But JD did the same on his SBF engine. Yes he had some teething issues but ended up OK in the end.

Very diplomatic, Chuck, thank you...

What Chuck means is that I screwed up the first time. A) By not putting enough chamfer on the ends of the shaft itself and B) The original iteration was not sleeved as Chuck did.

When I went for round 2, the ends of the axle at the weld got tapered down to almost a point. Then we fitted a drilled-out sleeve over it as Chuck suggested. Weld up the joint, grind it smooth, slide the sleeve over it and plug weld the holes then weld the ends.

A couple of years of hard launches (on 14" wide slicks, even) later, no worries!
We might have broken a few (dozen) other things since then, but that axle is solid!

:cheers:
JDK

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PostPosted: March 26, 2015, 6:35 pm 
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There needs to be clarity about the problem. No one suggests that axle steel cant be welded, the trouble is that this induces a tendency for the weld area to progressively crack[ over time] and eventually this defect will propagate right through the axle . When[ if] this happens the axle wont necessarily break on extreme loadings but will simply come apart because the crack has progressed through a large proportion of the welded area. So, its quite possible that the axle will separate at high speed under low torque. Having said that please feel free to weld axles! My only point is that you need to understand the nature of the problem. Cheers P


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PostPosted: December 5, 2017, 7:14 pm 
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Old thread, but came up in a search.

Dutchman has always looked reasonable for services, and this was what they had listed for CV stuff:

"Shorten and respline your CV half shafts.

Please note the following:
CV axle shafts MUST be completely disassembled (we do not disassemble or re-assemble).
ALL we need is the shaft(s) and the sample gear that fits the end we will be machining. $75 single
$135pr."


https://www.dutchmanaxles.com/services

I should be having them do a ford set of some sort for me in the next month.


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PostPosted: December 5, 2017, 8:11 pm 
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Faster7, my original problem was that the RX-7 donor axles had a reduced diameter immediately inboard of the splines. There was no metal there to cut new splines. I had to cut 2" out of each shaft. Shortening and re-splining was not an option for me. Maybe I should have built a +4 chassis? If you can get yours done for 135, that is a no-brainer. Go for it. :cheers:

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PostPosted: December 10, 2017, 6:32 pm 
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well to shorten an axle shaft, if you cut the end off and bore a hole through it then turn down the shaft to suit, push the two halves together, bevel and weld at the mating joint and the outside end of the splined section, this leaves the total length in one piece so it can twist.

alternatively, cut the shaft in the middle, shorten the shaft by halve off each piece so the join is still in the middle, sleeve the whole shaft with some thick wall dom tube not chrome moly as its too hard it must have some "tortionality", weld at each end and no plug welds.

do not use welded tube as the weld will cause the shaft to buckle when it wants to twist.

should the welds fail, you will only loose drive at that wheel, in the first senario it would be like stripping the splines off the hub, in the second senario the tube would retain the shaft which would spin in the tube, all providing you are not using the shaft as the upper "a" arm.

having said that, jaguar used shafts made just like a drive shaft for many years as the top link (tube with welded in ends)

the problem in a sleeved shaft that has a short sleeve is the welded joints or rather just either side of the welded joints, if i had to guess where it would break, i would say the sleeve just inboard of the welds, if you additionally plug weld the sleeve to the shaft halves this will remove the ability of the center part of the shaft to twist moving the failure point to the middle of the sleeve between the plug welds or out to the original shaft sections which are now shorter and less likely to absorb twist

summers bros. drilled the middle out of their shafts so they would twist in a spiral motion and not shear but wind up and release.

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PostPosted: December 10, 2017, 10:49 pm 
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John, a lot has to depend on the application. I know of 2 who have cut the middle, beveled welded, sleeved and had no issues for several years of operation. Gonzo (JD) eventually got his design done right and runs a 5.0L V8. his car runs exclusively , autocross, when his car is running. And then there is me with a low torque rotary engine. I have run thousands of street miles. My design I cut an angle on the ends of the sleeve to eliminate a single circular weld around the original axle. I measured the run out on my axle around 0.020" after the process. Would I do it again? Sure, but not on a 300+ lb-ft torque engine with a 4.11 rear end and super sticky wide track tires. Application has a lot to do with success.

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PostPosted: December 11, 2017, 11:34 am 
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Chuck,
if it works for you and JD doing it the way you have or any other method that stays together is fine by me, just saying with the knowledge i have i would do it as i have described especially if doing it at home with limited tools and equipment.

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PostPosted: December 27, 2017, 7:59 pm 
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rx7locost wrote:
Faster7, my original problem was that the RX-7 donor axles had a reduced diameter immediately inboard of the splines. There was no metal there to cut new splines.


In my experience, most axles are like that. <sigh>


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