improving syncro life
 

Any tips for getting longer life out of syncros? specifically in the 82-85 gearbox. I put brand new syncro's in about 7-8 races ago and my 4th gear syncro is way below the wear limit already. I'm running Redline MT-90, not sure what else there is to do. Any ideas?

Not sure if NEO has a good GL-4 transmission oil available, but their 75w-90RHD (Racing Heavy Duty) is absolutely phenomenal, worth the cost, and definitely a secret among transmission and differential builders in professional racing. No hype, no slick advertising, just works. The one thing I would worry about with the RHD is that it is a GL-5 gear oil, and may chemically accellerate wear on the synchros....if NEO makes a GL-4 with less sulfer and etc, that would be great. Otherwise the RedLine MT-90 is probably the best readily-available "boutique" oil. Not enough experience with Motul's gearbox fluids, chime in?

Are you matching revs and going clutchless or are you using the clutch? I've got the original trannies in both my cars and they're both still going strong. Running Amzoil, 75W (I think).

I shift clutchless on the 4-3 downshift most of the time in my car, BTW. Rarely get it into 2nd or 5th around here.

It's just those mad skills of yours Chris.;) I did enjoy you thrashing everyone in my E car.

back on topic, Amsoil has a new GL-4 lubricant made for manual trannies. I'm replacing my MT-90 with that. I have heard great things about NEO but never tried it. In the ITA car I bought a few years ago the tranny had never hardly been serviced and is still going strong after (i'm guessing here) 6 seasons, 6-7 schools, wow, I never thought about that before....and when I first changed the tranny fluid it was nasty.

Funny how so many of us burn up trannies and for others they last a long time. Now this ITA car has put 5 drivers thru SCCA schools, so lots of different drivers on the one tranny.

I'm not sure about the NEO, I've never heard about anyone using it in a syncro box.

I always rev match downshift with the clutch. Use the clutch on upshifts too. I'm sure it's the 3rd-4th shift that's wearing them out, that's usually a pretty hard shift...

Russ- kill the Redline unless you are fgetting for free... I'd try some Swepco (Southwestern peroleum Company) Its popular amongst the porsche crowd, but our mazda gearboxes love it. I normally order from specmiatawest.com, casue they are local...

Marcus

I like the Mobil 1 synthetic better than the Redline oil.

Marcus is that the stuff that Susko recommends?

You could try cyro treating them. Make sure the shop has a hardness tester, and have them 'prove' it first with an old synchro. It should come out harder and last longer, but it may make shifting harsher.

Dave

How would one know if the GL-5 composition is damaging the tranny? Simply accelerated wear of the synchro, or pitting, or ??

(I have another car that claims GL-5 is bad, GL-4 is good, but no proof either way)

Dave

I thought about that, I may try it next time if I have the same problem again. The synchros work's because they're soft, so I'm not sure that making it harder is the right solution.

I've heard mobil one 75w-90 is supposed to be pretty gentle on the synchros too, anyone tried it?

Keep on trucking!

Sorry, couldn't keep myself from writing this post. :)

The point is that cryo could result in a harder brass that isn't quite as soft but still soft enough to do its job. I don't have the details handy to confirm, but I'm fairly certain that fully hardened brass is much softer than the hardened steel cones they rub against. The risk (aside from possibly harsher engagement) is they might break.

I would hope the cryo'd brass ends up becoming a medium-hardness brass, but only an experiment will prove or deny it.

Dave

shift slower? double check all of the links in the chain (forks, hub, sleeve, shift fingers etc).

Not to sound mean but seeings how the majority are not having any premature synchro wear problems then the real factor must be either in the lube (highly doubtful) or in how the box is treated. I wouldn't even bother with experimenting with cryo treating as it's already proven by all the others that the box doesn't need it.

If the synchros are wearing at an accelerated pace it has to be because of how the box is shifted. That's the only time the synchros ever do any work. If you're having problems with 4th gear constantly then either the 3-4 upshift or 5-4 downshift is what's hurting it.

There's no sense in shifting faster at the expense of gearbox reliability. Shifting a few hundreths of a second faster does not equate to the same gain in laptime because the car is not at a standstill when it's shifted.

There is no doubt in my mind that the wear is coming from upshifting quickly. I'm ok with this and don't plan to shift slower. It's not a few hundreths that makes the difference, to go easy on the synchros (like to not grind 4th now in my box) you have to shift 1/4 to 1/2 second slower (according to data, I'm not making this up) which is very significant over a lap, even moreso in a car with 110hp. At the beginning of the straight (which is where I'm shifting into 4th) the time lost hurts you all the way down the straight. Rebuilding the gearbox is not that hard and synchro's are cheap, I don't have a problem doing it once a year.

Thanks for sharing your data with me before!

Are these trannies really that balky about upshifting? Are you using stock gears?

If it really does take that long to shift the thing smoothly I'd just let the synchros get eaten too. As long as the gears themselves hold up fine.

The box is 100% stock, the gears are a little worn as they came out of a street car with whatever thousands of miles on them, but they are not bad.

When I tore the box down I expected it to be a little trashed, but there was virtually no wear on the gears or anything. I expected another broken synchro, but the cone was just severly worn.

The strange part is that 5th gear is hardly worn at all, and according to data the 3-4 shift and 4-5 shift both take the same amount of time (4/10ths). I upshift to 5th more then I do to 4th and the 5th gear synchro is smaller. 4/10ths could just be as fast as I can push the clutch pedal in and out (assuming the upshift to 4th has to be a little faster then to 5th), so maybe I'm doing the 4th gear shift faster then I need to be.

guess I'll work on my clutching :)

Yeah crazy how gearboxes and rearends are. I had an 85 that leaked gear oil like crazy I ran that car so low it would not go into reverse and the 1-2 shift would grind I would get home top it off and it would be fine did that for a year then I threw a 6 port 13b at it and it cratered still shifts but you have to be extra gentle. Sorry had to chime in. I have heard good things about Neo and amsoil not so much about mobil one.

we ran a ps1 fc last year, and with the stock 4.10's the 3rd gear synchro would last about 6-12hours of track time. our guy's are hard on the trans though

I'm not sure what Susko recommends, this was a recommendation of Barry Hartzel here on the west coast. I got tired of dealing with the synchro's on gearboxes running redline, so I gave up and listened to hi.m :) Been 14 months and the gear box is good. This would include the 25 hours of Thunderhill , 7 other hours of enduros, and about 25 regular track hours for sprint races. That's about 2 seasons for most people, if I did my math- hours right.

Just saw the runoffs EP race... That was a nasty crash. Very glad you are okay!


Marcus

West Coast? Who's Ps1 car?

Marcus

the k2rd car, black fc, ugly. when i say last year i mean 2004 too. even though it did run a couple of races in 05