Why Do You Think My Transmission Is Grinding Going Into 2nd?
 

Now that I'm getting more familiar with my car, I'm driving it a little more aggressively which includes raising my gear change shift (rpm) points.

In doing so, one thing that is occurring is I'm getting grinding going into second gear. Keep in mind that I'm well aware of the idiosyncrasies of the 915 transmission and have been working hard at trying to develop my driving skills to work around them. This includes a pretty long pause when shifting between 1st and 2nd and shifting to neutral and letting the clutch out when coming to a stop before putting the transmission in 1st.

The problem I'm having now is that if I wind 1st gear out to anything over about 2,500rpm before shifting to 2nd, even with a fairly long pause, the transmission grinds going into second. So, I'm trying to determine what this is telling me.

I've read numerous threads on this site about the 915 but none so far have talked specifically about the characteristic I'm now describing.

Other than the normal bulkiness between first and second and second and first gears, the transmission shifts fine.

Anybody have any thoughts on what might be the most likely cause of this grinding?

Thanks

Depending on mileage, it could be the gears are worn enough to not engage properly.

Before assuming the worse case check the clutch cable adjustment as well as the shifter bushings. If the bushings are worn, you will have a hard time finding gears.
Adjusting the clutch could make everything all better, too.

Without opening the trans up, you really don't have a definitive way to prove the problem is in the case.

I'm afraid that it's time to replace synchros, at least for first and second. Every transmission has different wear because of the loads it's been subjected to throughout its life, and, of course, the mileage on the unit, but until you can drain the trans oil and check what pieces (usually dog teeth are a tip-off) are stuck to the drain plug magnet, you should make every effort to; (1) shift without grinding - bypass second and go from 1st to 3rd if you can, or (2) park the car pending diagnosis. Cost to repair is mostly determined by mileage, which can be a good indicator of what will probably need to be replaced.

No, not the clutch cable. Synchros and dogteeth are probably bad on 2nd.

After checking clutch cable and shift linkage adjustment & shift bushing condition (keep yer fingers crossed, these are all very cheap & easy fixes), it is down to transmission internals. This is classic synchro wear indicator, though, esp. on #2. If it has been worn for a significant period of time, or shifted very aggressively in the past, you can also expect to replace the dogteeth and even the slider on #2 as well. These parts add up to major $ very quickly. I just spent $1k+ doing synchros, one dog, and misc. bits, and that was all my own labor. Expect $2k+ if you have a shop do it.

Incidentally, this trans exhibited absolutely identical symptoms as yours.

I should have mentioned that my car has 77,000 miles and the previous owner had the transmission rebuilt at about 50,000 miles. The PO told me when I bought the car second gear did grind once in a while which surprised him as well because of the rebuild only 25,000 miles ago.

By the way, there's no grinding going into reverse.

Reverse is not synchromesh, so grinding would only occur with a clutch problem or driver error.

With the trans already having been apart, at very low mileage, I would have to guess that the mechanic made a mistake, or the PO abused (and I don't mean intentionally) 2nd gear with poor driving habits.

With the exception of reverse gear, most modern gearboxes have constant-mesh gears. That is, the gears are in mesh all the time. The synchromesh mechanisms lock and unlock the selected gears to their respective shafts, and these are the items that wear. The clashing you feel/hear are the little engagement teeth bits that are the final link joining gear and shaft. As is typical of most gearbox wear, first and second are the most used for upshifts and downshifts and thus the first to wear to the threshold.

Learn how to double-clutch too. Everyone.

Sherwood

my 1st and 2nd gear synchros were replaced at 93K miles, along with related parts. cost was about $1,600 but the PO had it done and got a discount according to the invoice..but thats an accurate ballpark figure from what ive read

could new swepco gear lube help this fella out? perhaps someone can advise. im new to these cars too

A rebuild means different things to different people. Without a buildsheet you don't really know what went into the rebuild. There are a lot of shops out there that don't provide buildsheets with their rebuilds, especially if they are doing an "assembly line" core exchange program boxes like you see advertised in the magazines for $1500. You get what you pay for. Even when working with a local reputible mechanic, many times car owners are looking to do the build as inexpensively as possible. This can lead to marginal parts being left in the gearbox and only the most essential parts being replaced. Some well meaning mechanics will leave stuff in the gearbox that should be tossed in the trash in an attempt to hit a pricepoint for their customer.

My suspicion is that once you get inside of this box you will find a syncrhonizer that is well within spec and virtually brand new. But you will also likely find a 1/2 operating sleeve that wasn't replaced when it should have been. You may also have dog teeth that are rounded off and need to be replaced on second gear.

The silver lining is that at the mileage currently on the box it probably doesn't need any bearings replaced as long as you do the work sooner rather than later. You are probably looking at $300-500 in parts plus whatever labor is charged depending on if you pull your own tranny, rebuilt it yourself, etc.

If you decide to do it yourself, post up pictures once it's apart and we'll guide you.

What about the pedal set? I am firm believer after rebuilding mine. It solved all the problems I was going to get the transaxle rebuilt for. Saved me a lot of money and was easy to boot. I would recommend it to anyone as a complimentary repair to a trans rebuild also. Good luck, I hope you find the problem.

Subscribing. I have almost exactly the same problem from first to second. At any RPM above about 4000 the gears will grind, no matter how much I delay the shift. I also have problems getting into reverse after having moved in a forward gear.

How Many Of These Pieces Does It Take To Make My 915 Grind
 

I'm trying to keep this thread I started alive now that I am working to pull my engine and transmission in hopes of eliminating my second gear grinding.

Today, I started unhooking things and draining the engine and transmission oil.

I screened the transmission oil and found two pieces of metal attached to the magnetic drain plug. A picture should be attached.

I wasn't sure what to expect when I drained the transmission but thought there would be more debris than these two pieces.

So I have two questions for the transmission experts on here:

1. Are these two broken pieces likely to be indicative of why I get grinding going
into second?

2. Once I disassemble my transmission, will I really be able to see where the
source of my problem is so I can fix it? I'm a bit concerned that my untrained
eye may have difficulty finding the problem. I'd like to be able to find and fix
the problem myself. It will save me some money and boost my confidence. I
just want to be realistic.


Comments and thoughts are appreciated.

Thank you.



http://forums.pelicanparts.com/uploa...1226104092.jpg

Yep, those look like dogteeth. Good thing you decided to stop driving it.

If not dogteeth, it sure is something in there. I would plan on doing a rebuild or repair, at the very least.