Gearbox Good & Bad

[sail]

Good: I got the rebuilt gear box in with the A Type OD. It works and shifts with the nice feel of a TR box.
Really good, the OD works! I haven't wired it yet but it is going to be great. No leaks, at least not yet.

Bad, really bad: I get grinding downshifting to second except at low speed, rpm. All other gears seem good.

So the first question is what is the likely cause? I was careful to measure but must have missed something. I assume it is going to have to come back out.

Second question is will I hurt anything driving it carefully till the roads go bad?

Thanks

 

[TR3driver]

Check to be sure the clutch isn't dragging. If not, just double-clutch when you want to downshift to 2nd, and drive it.

If you didn't replace the 2nd gear synchro ring, it may be worn. If you did replace it, you may have gotten one of the bad rings that were floating around a few years ago (reputedly one of the Big 3 had 100,000 of them made and most of them didn't work right; no one knows why). But I would also carefully check the tension on the 1-2 shift hub. It is what supplies the force onto the synchro ring, and they almost always get weak with age.

 

[sail]

New synchro rings from Quantum. New springs from Moss in shift hubs. They felt good, I did not measure since new springs. Rats. Even if I took off the top cover with it in the car I don't see how I could tell much. Thanks

 

[DrEntropy]

Likely you're a victim of "white box" second gear baulk ring. Do as Randall suggests and double-clutch to match speed/RPM on downshift. No sense lookin' or diggin' into it unless/until you're in a situation to pull the unit back out and replace the stoopid thing *again*...

...I really hate this kind of circumstance.

 

[Gliderman8]

If misery likes company, I can join you. I replaced all the synchros when rebuilding my gearbox on my TR6. Doc has it right... I probably got one of the bad synchros.
I just intend to live with it until I swap my gearbox for a five-speed toyota. I already have the W58 toyota box; it will just have to wait until I get the install kit.

 

[martx-5]

...I already have the W58 toyota box; it will just have to wait until I get the install kit.

You know, when I was restoring my TR3, I completely rebuilt the gearbox. Then I got this wild idea to put in a Toyota W58...well, the redone TR box sits in the basement and I'm absolutely thrilled with how well the Toyota works in the TR. I bought the Toyota trans off of ebay and never even opened it up...just went through Hermann's check list and replaced the front and rear seals...lovely transmission.

 

[prb51]

If misery likes company, I can join you. I replaced all the synchros when rebuilding my gearbox on my TR6. Doc has it right... I probably got one of the bad synchros.
I just intend to live with it until I swap my gearbox for a five-speed toyota. I already have the W58 toyota box; it will just have to wait until I get the install kit.

These bad synchros made the rounds when? Looks like some are still running into them if that is the problem here. What a pita after all of that work.
Elliot you won't look back after you get the 5 speed in.

 

[Gliderman8]

These bad synchros made the rounds when?

I'm guessing that I bought my synchros about 4-5 years ago. After all that work....

 

[sail]

These bad synchros made the rounds when?

I'm guessing that I bought my synchros about 4-5 years ago. After all that work....

I got mine about a year ago. I had heard of the bad ones but didn't figure where I got them would have that problem. I will give a call tomorrow for what it's worth. Don't know if I am glad it wasn't my fault or not. Either way no easy fix but much easier now that I have done it once. First time thru was kinda scary.

I am sure the Supra set up is a good one. I just couldn't bring myself to put a Japanese box in there. And the OD was less $.

Today was the first drive, I'll see if I can live with it. If not winter is on the way and I have time on my hands although next was going to be the rear end. And then the front end.

By the way, I was getting fuel this am and a cop pulled up to look and tell his TR story. I told him not to follow as I had a new OD that I wanted to check out. He said take hwy 100, we don't patrol there.

 

[TR3driver]

Just a thought, you might try putting Redline MT-90 oil in. It seems to improve synchro operation somewhat; might be enough.

Or check their website, ISTR they had something that was supposed to make synchro action even more aggressive than the MT-90.

 

[71MKIV]

Over at the North American Spitfire Squadron, one of the big cheeses has documented that at least in the spitfire gearboxes, the dimensions of the pieces the synchro's ride on is as critical as the synchro's themselves. If the tolerances of the synchro goes to one extreme, and the tolerance of it's carrier goes the other, the synchro will grind on shift.

I can't find the exact page on his website right at the moment.

Dunno if the issue crosses into the TR series.

 

[sail]

Just a thought, you might try putting Redline MT-90 oil in.

I emailed Redline with a quick response and yep, MT-90 was their choice for the TR given my description of problem. Their comment was the Valvoline (I apologized) motor oil may be too slick. They suggested same for the diff. Ebay $9.75 plus ship, not available in town.

Will just draining both plugs be good enough changing to synthetic?

Is their some nifty way or tool for the od notched plug other than screw driver and hammer? I have a bicycle with a smaller but similar attachment that I don't want to bugger up either.

Just got an additional comment from them:
A motor oil won't generally have the ideal frictional characteristics for the synchros but it shouldn't be too far off.
The MT-90 provides the ideal frictional characteristics for synchros so should improve your shiftability.

 

[71MKIV]

I use a pair of needle nose pliers in the notch and a screwdriver to turn it.

 

[TR3driver]

Draining both plugs should be fine.

Someone sells purpose-made tools for those plugs on eBay. Sorry I don't have a link handy, but one was posted to BCF just a few days ago.

IMO the diff wants a slick oil; I use Valvoline full synthetic GL5 in mine.

$9.75 is a reasonable price for MT-90; the local store wanted $17. After haunting eBay for a few weeks, I found some locally (so no shipping charges) for $8.

 

[sail]

Just a thought, you might try putting Redline MT-90 oil in.

Surprise surprise surprise. I really didn't think the MT-90 would make any difference but just got back from a 100 mile drive and it did. At moderate slow speeds downshifts to 2nd felt good without my help. Faster downshifts still want a double clutch or at least matching the rpm's. The other gears are fine. So thanks Randall the gearbox stays where it is for now and I work on something else this winter.
Made one stop for a photo.

 

[Don Elliott]

There was abad batch of about 10,000 synchro-rings made about 10 - 12 years ago and they were too short in one dimension. They caused a lot of "knashing of teeth", both in the gearbox and for all those TR owners who had them installed.

Here is what I still have in my files written about 8 - 10 years ago by Brent Kiser.

 

[toysrrus]

Hi Ray,

I was just driving thru the neighborhood here & see a pic of your TR. It reminded me of my `66TR4A-IRS I had just a couple of yrs. ago.

I just wanted to say how "PURRITY" She looks.

Regards, Russ