Suspension bolts specification

Technical Area Steering & Suspension
2

Renovating my suspension at the moment, removing all the items, de-rusting, rust proofing and then applying suitable long lasting coatings.

However I’m trying to find out what the specification is on the various bolts and nuts. It’s easy enough to identify respective sizes but the materials specification is another matter. presumably they are high tensile bolts with nyloc nuts but I’d appreciate any suggestions.

I managed to identify similar items for my Jag and saved a fortune by buying comparable even superior specced items, rather than part numbers.

So does anybody know the specification of these bolts please?

Thanks

3

I cant help with any tensile strengths I’m afraid, some bolts do have their strength cast onto their head (8T etc). Mazda don’t use Nyloc on any suspension nuts that I can think of. They are usually serrated nuts, castellated nuts with split pins, standard nuts with spring washers or oval holed type locking nuts. 

4

Do not use stainless steel here it is very difficult to get a spec that suits all the mechanical properties required.

The easiest high tensile carbon steel bolts to get hold of are grade 8.8.

Grade 12.5 being higher strenghts but harder to get from stock.

So go for 8.8.

Autolink sell secondhand suspension bolts

eddie

5

Thanks guys,
So pleased you’re not condemning me for not using official Mazda part nos. like I said I found alternatives for my Jaguar S Type (because my friendly parts guy at the dealership was so embarrassed at the cost of a single bolt @ £29.95 without the nut!!)
I really don’t want to use second hand, and even those are extortionate probably as the secondhand price is determined by cost of new.
Robbie, can you think of a good reason not to substitute a standard nut with a nyloc?

Thanks again

6

Nuts have also to be the correct spec, have you checked the spec of the nyloc nuts your supplier is selling.

If the bolts are high tensile the nuts have to be high tensile as well.

I will leave it to you to do your research on nut specs and not to buy nuts because they are cheaper than from Mazda.

7

Drumtochty
If you check my original post you will see I most definitely do NOT sacrifice quality and specification for price.
Some years ago, when I was a director of an engineering supplies company I had to supply bearings, filters, o rings and seals as well as a multitude of nuts and bolts for use on mechanical, agricultural and even heavy civil construction equipment (draglines, excavators etc)
When the parts came in from the O.E. companies. they invariably had the original manufacturers name on, e.g. SKF for bearings, Crosslands for filters, etc. I found that by going direct I could obtain the exact item, minus the equipment providers labels, for often a fraction of the cost.
This is what I am trying to do here and in the case of my Jaguar nuts and bolts I took an original to a specialist fastenings supplier and he provided me with all I needed at a fraction of the cost for one from jaguar!
I don’t compromise on safety and reliability but I don’t believe in paying inflated prices.

Rant over…and r e l a x …

8

Have you considered having yours re finished/plated?

If the threads are undamaged and the bolts are not stretched then technically you dont need to replace. 

Be aware of the bolt spec though as some plating processes can cause embrittlement. 

Steve.

9

Thanks Steve, but as these are the originals, most of them have had to be cut off or filed down to remove

10

Aye, that was a fine rant, so you can now go and research the spec of nuts you need to suit the 8.8 bolts.

Not that difficult.

11

Unless you are specifically after saving cost for low end use, it is pretty hard to buy below 8.8 spec anyway. Most Nyloc will be that or above. From memory, DIN 982. Not sure I have ever seen a low tensile fine threaded bolt or nut either.

It is not exactly aircraft grade titanium you are looking at here, Hydrogen embrittlement is not going to be an issue.

Your main issue, if you want direct replacements is most are not standard fasters but have specific head, shank and thread lengths and are fine thread. There is nothing stopping you replacing most through ones with standard Cap Heads though.

12

Thanks NickD
By the way…I’ve got a new recommendation, perhaps an unsung hero (?) for parts AND help which I will post in the appropriate section. Paul Grainger @ DavidManners Group in Oldbury West Midlands has sorted out my bushings (and I didn’t feel a thing!!_

13

Some of the bolts, such as the long upper wishbone bolt, are going to be effectively Mazda only. I’ve used David Manners before, for Jag parts and MX5 parts. They’re probably better sticking to Jag parts. They’ve been hopeless since buying up SFTMX5parts, and don’t seem to know the car that well, despite having been selling the parts for nearly 10 years now.

Unlike a Jag (I’ve overhauled the rear end of a XJ-S many years ago), there aren’t that many bolts to replace on the MX5, so the savings aren’t likely going to be that much. On my 1.6, it came with FM anti rollbars, and some American sourced bolts for the drop links. Compared to the Mazda originals, they’re not in the best of condition.