Mysterious Second Gear Wear, Any Ideas ??? Wrench is Stumped

[DRACO A5OG]

Has anyone ever experienced this type of wear on only 1 gear? Wrench does not know how this could happen.

This a pic of my second Sides have Blue & Brown Discoloration






Synchros look good, no chips or breakage of teeth but there is evidence of wear in the inner edge, it is shiny

85 915

[slodave]

Stop leaning on your shifter while in stop and go traffic.

Looks like divots in the metal?

[DRACO A5OG]

Thanks Dave,

Actually I do leave the shifter alone because it was very sensitive, but leaning on it will cause "Divots" like that?

[rusnak]

well you can look at it this way: everything else looks nice and tidy.

[slodave]

I was kidding.

But it does look like dirt/grit was stuck in the gear to me. I really have no clue...

[SP2]

I don't think leaning on the shifter would do that. Leaning would only push the slider towards the synchro ring, wouldn't it? My guess is just a poorly manufactured 2nd gear.

[DRACO A5OG]

Thanks Rusnak,

Wrench recommends that I replace the Synchros and all Bearings while they are in there.

I am torn, I know that is the right thing to do but I wonder if it ain't broken why should I replace them. He stated the shavings could have damaged them but with PAG's tendency to over engineer it may be OK not to replace them but it will cost more if I do have to go back in. CRAP, I'm confused!!!

Jim

[DRACO A5OG]

Originally Posted by SP2

I don't think leaning on the shifter would do that. Leaning would only push the slider towards the synchro ring, wouldn't it? My guess is just a poorly manufactured 2nd gear.

Hey James,

That is what I was thinking that the POs did a cheapo and placed some inferior aftermarket.

Jim

[rusnak]

Try PM ing Dentist90 (I think that's what he goes by) I THINK he may have had his transmission apart. You can also try Randy Webb. I'd get their input right quick.

[DRACO A5OG]

Oh Man Rusnak,

Thanks again Brother! Will Do Right Now!

[SP2]

I had my tranny apart last year. IMO you don't need to replace any bearings unless there is a problem with them. How many miles are on the tranny? If there is alot, then you probably should replace all the synchros and the 1/2 and 3/4 sliders (shift sleeves). None of my gears needed replacing. You need to replace all four brake bands that are located inside each gear assembly. And you need to replace the syncho hubs (dogteeth) if they are broken or chipped. I only had to replace dogteeth for 1 and 2 gear, which was why I was grinding those gears.

I posted this last year on Rennlist. Good luck!

http://forums.rennlist.com/rennforums/showthread.php?t=330474&highlight=915&page=2

[DRACO A5OG]

She has 175K but the wrench did say someone worked on it before and stated the other synchros looked good.

Thanks for the link, James!

[DRACO A5OG]

Whoa James!

You the man, I can't believe you DIY! Wow very impressive.

This part looked like the one on the right but the edge was a bit shiny, does it need to be replaced?

[SP2]

Yes, you probably should replace it. That is the synchro ring. The one on the right is brand new. It looks rough because it provides friction. When you start to shift into a gear, you are pushing the slider towards the synchro ring. The friction causes the gear and the associated dogteeth to spin. So when you push on the shifter a little more, the slider comes in contact with the dogteeth and they are now spinning at the same speed (i.e. synchronized).

If your synchro is shiny, it will not have enough friction and you will start banging the slider into the dogteeth. That is what causes the grinding. Or worse yet is when you start chipping the pointy ends off of the dogteeth.

At least, that is my understanding of the tranny. Thanks for the kind words. I had never done anything mechanical before.

[DRACO A5OG]

Originally Posted by SP2

I had never done anything mechanical before.

No Freakin Way Damn, I am humbled.

About the rings, that's all I needed to hear. Will replace, crap I have to replace my clutch too. It was a hair from touching the rivots.

Damn, New Brakes, Suspension, now Tranny & Clutch. Does this mean I will have a new P-car?

I guess AC is on the back burner for awhile

[Peter Zimmermann]

Make sure that every new synchro ring gets a new slider. If you mate an old slider to a new synchro you will often get engagement/shifting problems, and even if it "breaks in" you will have premature wear from the slider teeth cutting away friction material from the new synchro, reducing its effective life. In other words, if you replace 3rd synchro ring, replace the 3/4 slider and 4th synchro ring.

[rusnak]

wow, I'm going to read this tonight when I have more time. James that is like skipping the Wright flyer and going straight to a moonshot.

[DRACO A5OG]

Originally Posted by Peter Zimmermann

Make sure that every new synchro ring gets a new slider. If you mate an old slider to a new synchro you will often get engagement/shifting problems, and even if it "breaks in" you will have premature wear from the slider teeth cutting away friction material from the new synchro, reducing its effective life. In other words, if you replace 3rd synchro ring, replace the 3/4 slider and 4th synchro ring.

Dr. PZ,

Thanks for chiming in, I agree with you about the rings and synchros. How do you feel about the all the bearings except for the the throw out. I am leaning towards keeping them.

[Peter Zimmermann]

Originally Posted by DRACO A5OG

Dr. PZ,

Thanks for chiming in, I agree with you about the rings and synchros. How do you feel about the all the bearings except for the the throw out. I am leaning towards keeping them.

How many miles on the trans, and what's been its primary use?

[DRACO A5OG]

Originally Posted by Peter Zimmermann

How many miles on the trans, and what's been its primary use?

175K (not sure when it was worked on, but definetly worked on maybe at 135K)

Daily

Novice Track maybe 1-2 times a year

I got a quote from $1700 to $2700 plus $1000 Core for OEM Rebuilt 915, I am now thinking going that route, since it looks like all items need replacing anyways.