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View Full Version : New car, grinds 3rd on downshift.



Subliminal
12-18-2005, 08:35 AM
Hey guys,

The new car i'm bringing home seems to grind 3rd on the downshift. Goes in fine on upshift and no problems while in gear, but coming back down it grinds for a second. Only 3rd gear.

It's an 86, so I assume its a 525.

Is there any adjustments I can look at, or does it just mean the tranny needs internal work?

Thanks!

Frank
12-18-2005, 08:50 AM
I would change the oil in it first. Give it non synthetic proper weight oil and see what happens. Then maybe change out the shifter bushings.


Frank

Subliminal
12-18-2005, 08:52 AM
Cool. That's the kind of advice I'm looking for!

d

GLHSKEN
12-18-2005, 09:28 AM
If that doesn't solve it, only other options are shifter adjustment (more than liklely not since it goes up throught he gears) or a synchro going bad.

Subliminal
12-18-2005, 09:29 AM
Yeah, I was thinking syncro too. That would probably mean just find a new tranny to stick in, I guess.

d

Aries_Turbo
12-19-2005, 02:41 AM
555 here we come..... or at least a 520 ;)

Brian

Subliminal
12-19-2005, 09:42 AM
At this point I don't even know what kind of tranny the dang thing has in it! It's a mystery machine!;)

ludwig340
12-20-2005, 03:40 PM
But such a deal! Yeah, don't let anybody put gear oil in it like a shop tried to do to my 555...:eek:

Subliminal
12-20-2005, 03:41 PM
I think that's my mission after work. Drain it and fill with 10w30. Who knows what and how much is in it right now.

d

3Bar_Mopar
12-20-2005, 06:31 PM
The trans don't have a tag?



FWIW, it sounds like a synchro to me.

Turbodave
12-20-2005, 07:03 PM
The trans don't have a tag?


The 525's don't have a tag on top of the bellhousings like the later trannies do.

Subliminal
12-20-2005, 07:35 PM
Is that true? Man. I was going to go looking for that tag soon. It's under all the airbox crapola, and with work and cold weather, I haven't had time to go through it. Actually, that isn't true. I have had time. Like today when I drained the ATF out of it and put 5w30 in it. But, i thought that was more important than looking for the tag.

Now, here's a question:

Do many of the different manuals have rings you pull up to be able to shift past 1st into revers, or is that for only a few models?

Still grinds the gear on the downshift to third, after the fluid change, but it sure sounds better all the other times.

d

8valves
12-20-2005, 07:54 PM
Try this... in a situation where you KNOW it will grind, so downshifting at a certain rpm to thrid, be at that spot, step in the clutch and raise the rpms to where they should be when third is now engaged. SLOWLY release the clutch pedal very gradually. If the grind is now gone or much reduced I would say it's time for some new blocker rings. If it's been doing it for a long time the synchro assembly itself might be too far damaged and need to be replaced.

Either or the tranny would need to be pulled and dissasembled, which in the case of the 525 in my opinon you' dbe better off taking some time and upgrading instead. Dissasemble the 525 and make a sweet lamp or small coffee table out of the parts! :p

Aaron Miller

3Bar_Mopar
12-20-2005, 09:20 PM
If it were a bad synchro....wouldn't the grinding noise "spin down" kinda until the gear slots in?

8valves
12-21-2005, 02:54 PM
It depends on what part of the synchro assembly is bad. The blocker rings are what are supposed to take the beating from the synchronization... as they go bad the quick zing is the gears mathching speed. Sometimes the rings are fine and the dog teeth on the synchro itself are torn up and when they try and mesh it's a hard long grind where the teeth aren't fully contacting.

It's pretty hard to explain in text really, sorry.

Aaron Miller

Subliminal
12-21-2005, 03:01 PM
Well, I couldn't quite follow what you said (hard to visualize) above in post # 13, but I did this:

If I go in or out of 3rd at about 3k, or about 35-39 MPH, there's no grinding whatsoever. Lower or higher RPM on the downshift is a quick grind (like 1/2 second or so) and upshifting past 3500 rpm will grind quickly too.

That's about all I know right now. Well, that and I changed the fluid with the correct stuff in the correct amount.

d

cordes
12-21-2005, 03:05 PM
Is that true? Man. I was going to go looking for that tag soon. It's under all the airbox crapola, and with work and cold weather, I haven't had time to go through it. Actually, that isn't true. I have had time. Like today when I drained the ATF out of it and put 5w30 in it. But, i thought that was more important than looking for the tag.

Now, here's a question:

Do many of the different manuals have rings you pull up to be able to shift past 1st into revers, or is that for only a few models?

Still grinds the gear on the downshift to third, after the fluid change, but it sure sounds better all the other times.

d

I know the 555/520 have the ring for R, and I believe the 525 does too.

I know that the 523, and the 568 do not have the ring.

Subliminal
12-21-2005, 03:06 PM
Is the 525 the only one without a tag on the housing?

cordes
12-21-2005, 03:10 PM
Is the 525 the only one without a tag on the housing?

I have personally seen tags on 523s, a 568, and a 555. I would assume the 520 has them too.

If your trans is still rod shifted without the selector arms on the trans being modified, I have got to believe you have a 525.

Subliminal
12-21-2005, 03:12 PM
Roger that. I'll check it out.

3Bar_Mopar
12-21-2005, 05:30 PM
It depends on what part of the synchro assembly is bad. The blocker rings are what are supposed to take the beating from the synchronization... as they go bad the quick zing is the gears mathching speed. Sometimes the rings are fine and the dog teeth on the synchro itself are torn up and when they try and mesh it's a hard long grind where the teeth aren't fully contacting.

It's pretty hard to explain in text really, sorry.

Aaron Miller


I gotcha!:thumb:

84turbozxt
12-21-2005, 07:34 PM
double clutch!

Subliminal
12-21-2005, 09:41 PM
double clutch!


Tried that. Doesn't matter. If I'm at the right RPM, it doesn't do that. Anytime outside of a 300 RPM range, it will grind.

Thanks for the suggestion, though!

86Shelby
12-24-2005, 03:05 AM
Here's some easy ways to tell a 525 vs the 555/520 externally, without looking at a tag.
All 3 of those trans have the stamped steel end cover by the wheel. Since the 568/523 has an aluminum end cover that rules them out.

The 525's generally have a threaded plug to check the fluid level. The 555/520 have a rubber plug

The 525 has a stamped steel cover on the differential. A 555/520 has a cast aluminum cover for the differential.

I have the same downshifting issue in the R/T(rebuilt with ~15k on it) and plan to replace the 3rd gear syncro assembly while it's out. Not even going to try simply replacing the blocker ring, the whole assembly is getting tossed.