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Front & Rear Bumpers - Same?


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#1 Poppet2

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Posted 23 March 2017 - 11:57 AM

Sorry, put this in wrong thread previously.

Can I fit my front bumper to the rear?
Anyone any experience of this, any problems?
1984 mini, both front and rear look the same, round curve etc.
Also, which is best stainless steel or chrome and why?

#2 mab01uk

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Posted 23 March 2017 - 12:10 PM

Front and rear are same, modern chrome is not as good as original 1960/70's chrome, so most now choose stainless steel, although it tends not to look as good as chrome it is much more rust resistant.

 

Minispares bumper below is best for fit.......some other non-genuine don't fit well:-

"Genuine minispares manufactured bumper that fits perfectly as per original ROVER bumpers. Better than the last genuine bumpers produced for Rover - BEWARE - most others on the market made in stainless are poor fitting--Although many look the correct shape they will only fit the front with manipulation, but are very difficult to fit on the rear as they are kinked.
This has rolled over ends for safety critical homologation(1996)and also allows extra clearance on fitment to the sportspack arches.The rolled over ends were never clean and always sligtly rippled. Made in Automotive stainless steel to a polished chrome like finish it still requires washing and cleaning regularly owing to the positions where they are fitted. Fitted with fixing bolts but no nuts as per rover.
Better than the last Genuine stainless steel originals these are to the quality Pianoforte reached when first supplying Rover with the open ended bumper DPB10165 which replaced the steel chromed version.
Pianoforte then had tooling problems making GENUINE bumpers difficult to fit so Minispares have come to the rescue again taking 2 years to get it perfect in looks and fitting with the curled end edges made less dangerous than the originals.
Please note that most car parts are made in automotive 430 stainless which is magnetic as opposed to pure stainless which is not magnetic.
The same bumper with holes for the deluxe corner bars and overiders is available as 14A9871
Best finished bumper in the market place."

http://www.minispare...c/DPB10166.aspx


Edited by mab01uk, 23 March 2017 - 12:12 PM.


#3 tiger99

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Posted 23 March 2017 - 02:36 PM

Please note that most car parts are made in automotive 430 stainless which is magnetic as opposed to pure stainless which is not magnetic.

 

A bit confused! 430 is actually a stainless, albeit magnetic. What makes a "pure stainless"? What they probably should have said is that it has poor weldability.

 

But thanks for posting that information. I needed to know what the grade of the steel was. My future project will now need to use black painted bumpers, which I marginally prefer as regards appearance. Each to his own.



#4 MRA

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Posted 23 March 2017 - 08:07 PM

There is nothing different about old chrome and new chrome unless the chemical constituents are different, the reason "new" chrome goes rusty is because people want it cheap so they miss off the expensive brass plating of yesteryear....

 

Chrome plate is porous, so will rust fairly quickly.

 

To be a true stainless it requires 18% nickel content I machine grades of ST ST that are both as strong as alloy steels in some cases stronger and will never rust..... but they are not cheap



#5 MRA

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Posted 23 March 2017 - 08:08 PM

There is nothing different about old chrome and new chrome unless the chemical constituents are different, the reason "new" chrome goes rusty is because people want it cheap so they miss off the expensive brass plating of yesteryear....

 

Chrome plate is porous, so will rust fairly quickly.

 

To be a true stainless it requires 18% chromium content I machine grades of ST ST that are both as strong as alloy steels in some cases stronger and will never rust..... but they are not cheap

 

NOTE!  Chrome does not rust or corrode, its the steel substrate that does that


Edited by MRA, 23 March 2017 - 08:10 PM.


#6 1314cc

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Posted 23 March 2017 - 08:13 PM

I bought stainless from wood and picket via eBay. Front and rear fitted perfectly

#7 MRA

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Posted 23 March 2017 - 08:13 PM

 

Please note that most car parts are made in automotive 430 stainless which is magnetic as opposed to pure stainless which is not magnetic.

 

A bit confused! 430 is actually a stainless, albeit magnetic. What makes a "pure stainless"? What they probably should have said is that it has poor weldability.

 

But thanks for posting that information. I needed to know what the grade of the steel was. My future project will now need to use black painted bumpers, which I marginally prefer as regards appearance. Each to his own.

 

Weldability

Grade 430 can be readily welded by all fusion methods but preheating to 150-200°C is recommended. Annealing at 790-815°C can relieve embrittlement of the heat-affected zone.

Depending on the application, recommended filler rods or electrodes are grades 430, 308L, 309 310, or 312 stainless steels.



#8 tiger99

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Posted 25 March 2017 - 12:38 AM

All true, but many suppliers do not recommend it for welding, and certainly not for impact loads, because there are better alternatives (which, being cynical, we might think will earn them more profit). In fairness to them, very few people are set up to do the annealing correctly.

 

As for the rusting, it is of course the steel, but there should be an intervening plated layer of copper or similar. When scratched, the steel has a greater electropotential than copper and will form the anode in a corrosion cell, resulting in deep pitting quite rapidly. Copper plated steel should never be used for anything. Tin has the same problem but its virtue is that it is safe in contact with food, but no use for car bodies. Zinc and aluminium are more positive than steel and will corrode sacrificially to protect the steel. But I assume you can't use ali or zinc under chrome.

 

The main reason for the copper is said to be that it can be polished to a very fine finish before the chrome is laid on top/ A bit like a primer-filler under a single top coat which can not itself be significantly flatted to finish it off.

 

As to old and new chrome, I suspect that they take less care with the copper underlay, and also use a different chrome solution. Hexavalent chromium compounds are banned under recent regulations s they are very carcinogenic. I presume they have to use a trivalent chromium compound now. That "should" not affect the finished chrome layer, but maybe it does?

 

Or is it all just the result of people not bothering about quality control any more? If the backstreet Chinese factories don't, why should we? That sort of thinking is typical of a dying business, and quite a few in the mini business deserve to die due to their miserable attitude to quality.

 

Anyone who is having difficulties getting decent chrome can always buy painted bumpers, strip the paint and send them off to a reliable platers, of which there are more than a few.






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