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Will strengthening help???
http://ozdat.com.au/forum/viewtopic.php?t=32157		 Page 2 of 2
Author:  chimp [ Sat Mar 01, 2014 10:09 pm ]
Post subject:  Re: Will strengthening help???
I agree Nick and SR20, All the cracks I have seen on 1600's in this area are from the lead loosing adhesion at the thinnest part. I reckon the repairer has thought that the primer would cover the problem. I have just done a lead wiping course so I don'r have to use filler in a join area.
Author:  chimp [ Sun Sep 25, 2016 10:33 pm ]
Post subject:  Re: Will strengthening help???
Just an update on this topic. I presently have 3 1600's in my workshop. Two I believe to be 70 - 71 model 4 doors, and one is a 510 SSS Coupe. The Coupe doe's not have any lead in this corner. The two 4 doors are different. One has lead covering the entire corner, the other only levels the corner to the boot lid (join exposed). The join under the lead is "NOT" fully welded. It has 3 spot welds. This means the join flexes causing the lead to crack. The lead is only 1- 2 mm thick. The only reason I can see for the difference is panel fit and maybe which assembly line or factory the car was built in. I have photos if needed to show what I am talking about.
Author:  SR20Datsun [ Tue Sep 27, 2016 10:29 am ]
Post subject:  Re: Will strengthening help???
It would be great to see some photos!
Author:  chimp [ Tue Sep 27, 2016 10:26 pm ]
Post subject:  Re: Will strengthening help???
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File comment: SSS Coupe with only paint removed
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File comment: 4 Door with only paint removed
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File comment: 4 Door with lead & quarter panel removed
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File comment: 4 Door with paint removed
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Author:  DatsEZ+ [ Sun Jul 02, 2017 7:00 pm ]
Post subject:  Re: Will strengthening help???
Yeah the lead thing has always been common but my wife's new car powered by an SR 20 DE has cracks in the X bracing at the rear seat parcel shelf area.It has been previously welded but as per my picture has cracked again.I intend to fabricate a new patch piece and repair the shelf as it was butchered to fit 6" x9" speakers too.Once I do that a decent cross brace as per the earlier picture posted is getting installed.This car was previously a registered engineered certificated car?How that passed I don't know?I am thinking metal fatigue may be part of the cause but you folk may know more than me .All I know I am fixing it before my wife gets it registered again.
DatsEZ

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Author:  SR20Datsun [ Mon Jul 03, 2017 11:13 am ]
Post subject:  Re: Will strengthening help???
There's a fair amount of force going through that X-brace to the parcel shelf. If you look at early rally cars without the decent cages we have today, this was one of the areas that got a fair bit of 'movement'.
Now that everyone is running 1100lbs/in springs in the rear of their 'street' cars, the transfer of force through the spring mount and shocks increases. Harmonics change, loading increases with 3-4 times the power the factory envisaged.
My suggestion is to cut the section out and bust out the oxy torch and weld a new section in and anneal it. Too much Heat Affected Zone will be too brittle and will crack again.
Author:  DatsEZ+ [ Fri Jul 14, 2017 7:34 am ]
Post subject:  Re: Will strengthening help???
Yeah I totally agree with your analysis .I have the skill to fabricate a whole new X section and parcel shelf but for the moment repair sections will do.My friend who has raced 1600 's for 40 odd years has a truely magnificent extra X brace from tower to tower.He is fortunate as his fuel cell is where the spare wheel would normally be.There is enormous HP running through his car ,far more than any street car and it doesn't let go.That was probably one of the best braces I have seen to date.He had an engineering student design and build it.As my fuel tank would be in the way I am thinking of moving it to the rear a bit to install a race proven brace design.I may need to invest in some oxy as I only have mig.Mig does tend to be hard and brittle and I don't have a clue as to how well you could aneal the weld with just a propane torch.Would that be sufficient and what grade of wire would recommend.Do you think the oxy wire fusing method would be a better weld than mig.My main focus is a safe car first and performance and cosmetics later.Can't thank you enough for your input.I may be a bit of a dummy but I am not shy in comming forward to ask questions.Thank you.
Richard AKA DatsEZ
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