Need bolt size & pitch for small flange rear end
 

Hey guys,

I swapped a small flange LSD into my rear end and don't have the bolts that go with it. I tried using a regular old 12mm bolt, but it wouldn't thread into the rear end right.

1) Can someone tell me what the proper bolt size and thread pitch for these things is? Are they special bolts? I was thinking that they would just be regular old 12mm jobs, but apparently not.

2) Also, are there supposed to be any lockwashers in there anywhere? I realize that the small flange differentials are threaded so there aren't any nuts, but what about some lock washers? Does anyone use thread lock on these bolts?

Thanks in advance,
Jamie

I can check tomorrow and of course, I always lock tite that bitch

That would be awesome. Let me know the bolt size, thread, & length. Also let me know if there are any lockwashers in there. I was planning on just using some locktite, but didn't know if there were supposed to be any lockwashers anywhere.

Thanks Wacky,
Jamie

Ok, I was able to find a little bit of info. It would appear that there is supposed to be a lockwasher on there. However, the parts fiche doesn't say what the bolt size is. It just calls it "Bolt." So that didn't help much....

https://www.rx7club.com/attachment.p...1&d=1207827008

8mm x 1.25 but there is an unthreaded section and they're grade 12. Best to get a set from a fellow forum member rather than buying some aftermarket ones as most of those will have 13mm heads and not fit without some grinding or other mods. There is a head gripper on the pinion flange which holds 12mm heads. Or maybe I'm thinking of the large flange rears? Well, good luck with it.

So the threads are smaller and then they step up to a 12mm? Is that what you mean by grade? You know anybody that would sell me four of those bolts?

Jamie

There is a number cast into the bolt head that will show what grade or hardness it is. I don't know of anybody. I know I don't have any spares. I had a heck of a time coming up with enough bolts for the S model which happens to have a large flange LSD rear that somebody swapped in.

Hmm, you know what? As a temp solution you could use some stationary gear bolts (grade 6) or door bolts (grade 8). Anything that is the correct length and thread pitch with a lock washer could work. This will allow time to get a correct set.

Just wanted to follow up on this. I ended up using my metric 8x1.25 tap to clean out the threads on the differential flange. Turns out that is the reason I couldn't get my bolts to go in the other night. They were all full of rust, dirst, and paint. I got quite a bit of crud out of the threads with my tap. So, if anyone is wondering in the future, Jeff was dead on with his information. The bolts are 8mm X 1.25. I think the ones that I used for about 3/4" long and were a class 8.8. I realize they aren't quite up to spec but hopefully they'll do the job for now. I also put some lockwashers on them and used a good amount of thread locker so they don't work loose.

Jamie

Glad it worked out in the end.

I think I heard or read somewhere that Mazda grade six bolts are the same hardness as parts store 8.8 bolts and Mazda grade 8 are like 10.9 parts store bolts. Can anyone confirm this?