Transmission synchro hub trivia - help me understand
#1
We got this...
Thread Starter
iTrader: (1)
Join Date: Nov 2001
Location: North Augusta, SC
Posts: 215
Likes: 0
Received 0 Likes
on
0 Posts
Transmission synchro hub trivia - help me understand
I'm working through a transmission rebuild for a SA and have noticed some differences in machining of the replacement synchro hubs vs the original. The original hubs are machined flat at the same height in the valley between the cogs, the replacement hub is machined in a way where it is flat for 1/3 of the way, and then is tapered down about .005" for the rest of the width with a transition point in between. This is for the 1-2 hub, but I've seen the same for the 3-4 hub. Is this taper machining beneficial? Is this an improvement/updated design?
See pictures below. Look out for optical illusion in the pictures, the arrows point to the valley between the cogs.
Old hub part number 0437-17-261
New part 0820-17-261B. Replacement per Mazda Competition.
See pictures below. Look out for optical illusion in the pictures, the arrows point to the valley between the cogs.
Old hub part number 0437-17-261
New part 0820-17-261B. Replacement per Mazda Competition.
#4
Smells like 2 stroke.
I'm going to start off by saying I don't know for sure, however I have some insight into what you're looking at from a machinist's standpoint.
The surface finish at the root of that spline on the replacement part looks like absolute crap compared to the part it's replacing. It's quite possible you may be measuring a "peak" on one side and a "valley" on the other.
Does the major outside diameter have any taper?
The surface finish at the root of that spline on the replacement part looks like absolute crap compared to the part it's replacing. It's quite possible you may be measuring a "peak" on one side and a "valley" on the other.
Does the major outside diameter have any taper?
#5
Old [Sch|F]ool
Given that these parts are made in low volume, vs literally hundreds of thousands per year when the car was new, I am going to assume that it's simply inaccurate machining/looser tolerancing, and not look for any deeper meaning.
You ought to have seen the new GSL-SE rotor housings that I bought in 2021. They had numerous casting bubbles that were filled with epoxy as a repair, and one of them had the exhaust insert clocked wrong. I had to extract the insert from an old rotor housing in order to make it work. Very much something that would have not passed inspection for the production line!
(They were definitely not new old stock, they also had rougher looking casting on the outside, and they had QR codes on them)
You ought to have seen the new GSL-SE rotor housings that I bought in 2021. They had numerous casting bubbles that were filled with epoxy as a repair, and one of them had the exhaust insert clocked wrong. I had to extract the insert from an old rotor housing in order to make it work. Very much something that would have not passed inspection for the production line!
(They were definitely not new old stock, they also had rougher looking casting on the outside, and they had QR codes on them)
Last edited by peejay; 07-26-24 at 07:57 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Makenzie71
2nd Generation Specific (1986-1992)
11
05-07-04 11:28 AM