Can an E-series gearbox synchro's be made stronger?

[PrettyCoolWagon]

Hi,
I own 3 corolla AE95 4WD wagons Also know as sprinter caribs in Japan or alltrac wagons in th US.
One's getting a full strip down in my shed currently undertaking a 7AGZE build for it.
This weekend me and a friend are dropping the 4AFE engine and E57F5 gearbox out.

I was really enjoying my other wagon had really good interior trim and had spent $$ on suspension roadworthy brakes etc. ..with a mind to put 4agze into it - then the synchro's went! ..and eventually the clutch started slipping and burning. It's currently parked on the street as I already have the first project on the go in my very small shed and the narrow driveway gets used a lot.
So I can only really work on one project at a time.

My 3rd wagon still runs as a tired but reliable weekender only.. and gets occasional use by the girlfriend, as I also have a company car as a daily.

After doing a bit of research I found out it's quite common in these old corollas 4wd wagons for the synchro's to go:
Ae95 Manual Transmission - rollaclub.com

I was impressed by this write up highlighting the build strength of E-series internals:
The Toyota gearbox thread. - Mazda MX6 Forums: MX6 Forum

Which convinced me that it's most probable that my gears are ok (Haven't done too much grinding ) and that it's more likely my synchromesh's need re-building.
Was going to by a whole 2nd hand replacement box but then realised I could just be refitting a box that's synchro's were about to go again

So..
My thoughts are:
I could just order the new synchro parts from toyodiy but if this is a common weakness (especially at high revs) then I should probably investigate possible ways of re-building the synchromesh's stronger.

I know toyota made some upgrades to their E-series boxes along the way... and just brushing on the topic it seems some E-series box's have interchangeable parts but not all.

Can some one who's been down this path before, shed any light on the possibility of interchanging parts from other E-series to rebuild mine stronger?

Thanks for your help - Jed

[dnegative]

Whats wrong with putting new synchros in, driving it nicely and with any luck by the time they go bad (150k?) you will have moved on?

[jonathan yee]

dunno how similar they are to the E boxes in mr2/gt4's. but the syncros were changed from late 93on, i think double syncro's or something.

having said that i've also heard that new syncro's for older 86-93 E boxes have a revised design and should be OK. tho i don't know if that for all E boxes.

[PrettyCoolWagon]

^^^ Thanks JY ^^^ little bits of info like that are what I'm looking for. Anything that will help me narrow down my research.

Dneg' - I've thought of replacing with stockparts, but the cars a full personal re-build inside and out, new paint job, the lot.
I intend to keep it for a long time.
I have pieced together forged rods and pistons, hardened steel dowel pins in the crank to the flywheel, oil squirters in the 7A block, strut braces etc. Basically where ever I can I'm trying to over engineer it and create a toyota tough build that will last as a virtue of it's build strength and not depend wholely & soley on my driving it nicely..

No doubt there'll be times when I take it well up into the high revs.
High revs is where the AE95's synchro's have trouble.

If I can make small helpful improvements to the synchro's like the other improvements I've just mentioned then that's what I intend to do.

Hope that paints a picture.

[sbfoot]

Don't forget to take the shine off the gears where the syncro runs (use the old syncro with valve grinding paste).and use the best oil you can find.
Scott

[PrettyCoolWagon]

Yeah, I've read about how the synchro's eventually polish themselves smooth and loose their traction..
I've never taken one of these apart before.. So you're saying - just use the original synchro's and re-etch the the surface using valve grinding paste?

[sbfoot]

yeah just take the shine off don't go nuts with it or it'll wear the new syncros down.

[PrettyCoolWagon]

I think I'll take jonathon yee's advice and at least do some more research on the MR2 and GT4 boxes to see what upgrades were made and if they're a compatible fit or if they can fit with some sensible modding.

[oldeskewltoy]

7AGZE... not likely going to be that high reving... well not if you intend to run the SC12, or SC14. Figure peak rpm @ about 7500. Now that shouldn't be a problem... for a well built 7AGZE running an SC14 should be able to plant about 190 #/ft @ about 2500, with a peak torque of about 230#s. With that kind of torque from your "A" based engine you have no need to rediculously twist the gearbox.

[mullett]

I rebuilt my E51 (AW11) with E58 synchros, all went together like factory, and shifted beautifully from then on. Not hard with the AW11 manual to follow!

[Talasas]

Were the synchros still available from Toyota and were they expensive?

What special tools did you need?

[Q-Authority]

2nd and 3rd gear synchros were definitely a noted problem in the original E-51 gearbox, and were eventually redesigned (not sure exactly when). Actually all the E-51 synchros got modded. I rebuilt my '89 MKI MR2 E51 tranny last year, which had a 2nd and 3rd gear issue, with an oem spec synchro/bearing kit, and all of the new synchros had an added material to their inner surfaces (sort of looked like some sort of grit). Funny thing is that I have still had a bit of a slight shifting balk issue in both 2nd and 3rd gear since the rebuild, bit I still have less than 2k on the rebuild, and the shifting has been getting better and better. It actually isn't even a problem after about 20-30 minutes of non-stop driving. Just needs to get warmed up a bit I guess, and then it is very smooth. Hopefully the cold balk issue will completely go away before too long. I also had a Quaife lsd installed and don't know if that has any effect of the issue, or not. I use 75-90w Redline synthetic in it.

[Shifty]

Just get a good working one and/or rebuild one to factory condition, and it will be like new.

Worn synchros = abused gearbox. Yes some are better suited than others but at the end of the day if you allow them to do what they are supposed to, they will (practically) last forever no matter how 'crap' they are.

[Shifty]

Were the synchros still available from Toyota and were they expensive?

What special tools did you need?

Try ebay item number: 180587603102 which is for a camry transmission rebuild. Contact them and they should be able to supply parts for your box - although bear in mind they will almost certainly not know "E51" etc. They will just know it as a gearbox from X car with X engine in X year so you'll need to make sure you pick something in their market. Alternatively often odd parts are available from Toyota here and there - bear in mind if parts have been upgraded you might be able to get the parts from a later box, as an upgrade, if they have not actually superceded the part number on the toyota catalogue.

In most cases will basically need a press, various pullers/attachments, circlip pliers, and reverse circlip pliers.

[PrettyCoolWagon]

Thanks for all the replies guys.

OST - As you probably know... The AE95's redline is around 6300rpm's
This common problem in old AE95's from my own experience seems to happen from 5000rpm's upwards. I agree with 'Shifty' "worn synchros = abused gearbox.
My original wagon hasn't suffered from this problem but there has been occasional sticky shifts that have resulted in minor grinding. The gear shifts in these old cars are definitely sloppy compared to some other makes & models of a similar era

It's hard to comment on the 7AGZE as I'm halfway through building it, so it's really an unknown factor but I take the AE95's I've owned up to redline or there abouts a number of times, so I can't say that with a full load to pull or just getting the most out of each gear, I wouldn't rev the 7AGZE up near 7200rpm's, especially since I'm using forged rods and forged ceramic pistons. I'm also planning a compression ratio around 9.3:1 with low boost and a magnetically clutched pulley to switch off the sc14, leaving the rest of the grunt up to high revs...

SHIFTY - Thanks for the ebay info - (have to move house - set up garage again) Once I'm back on track with the wagon project, I'll look into it..
But as for rebuilding like factory.. I'm not so sure.. If there is a way to build it stronger, then I'll seriously consider doing it. There's enough evidence out there to suggest that these boxes weren't perfect to begin with as Q-Authority has mentioned.

Mullet - thanks for the info - I have both the AE95 and the MR2 manual to help out with the 7AGZE build... This is definitely starting to sound more doable.