80's old school

iTrader: (7)

About 3 weeks ago I put a 5 speed in my 1980 RX-7. My previous transmission was just a 4 speed.

The 5 speed was a used unit I bought off craigslist.

When I installed the trans, everything appeared to work OK... the only issue I had was when you shifted FROM 1st or FROM 2nd gear I heard this slight whine that (I guess) sounded like Synchros winding up.

It was a subtle sound and I figured I could live with it.

Yesterday I was driving and all of a sudden, everytime I downshifted to 2nd gear....grind!!!

Upshifts were still OK.

I am running Royal Purple gear oil in the trans. I read some old posts that Kentetsu wrote about using half ATF and half gear oil to help with trans synchros and shifting.

I changed the gear oil to the 50:50 mix and took her for a drive... I thought it was a miracle because it upshifted and downshifted perfect!

I then went for a long afternoon cruise (about 175 miles)... She shifted perfect and I even had to emergency slam her in 2nd gear...she still downshifted perfect!!

I thought now I am going to have to personally thank Kentetsu for the advice....then.....

Coming home from the trip....back to grinding going into 2nd and it even grinded a couple of times upshifting.. If you are slow with the shifts, it works OK.

This morning took the car for about 25 miles of errand running.... shifted up and down great and then...back to grinding again..

Seems worse when it is fully warmed up....

Ideas???

DivinDriver

iTrader: (15)

Sounds like you need a little thicker oil after warmup... or else maybe you are leaking some? Did you check levels before the swap?

80's old school

iTrader: (7)

I changed the oil to Royal Purple when I first did the swap. I then tried the 50:50 mix of ATF and gear oil like several folks on the forum suggested.

Seems to work fine when 1st started. After driving a while is when the grinding starts.

Does seem like I possibly need a thicker viscosity..

Starfox07

If it's just 2nd gear, wouldn't the real problem be the synchro?

j9fd3s

iTrader: (3)

yep, sounds like a hub/synchro problem... either be gentle, or plan on rebuilding

80's old school

iTrader: (7)

Sounds like a rebuild coming.... I can't be gentle... the tranny is what connects the soul of the car to the soul of the driver!!

Has anyone here actually had a Mazda tranny rebuilt? I have found 3 SA 5 speeds here locally. Thing is...will those be shot also!!??

7aull

iTrader: (2)

Old school - unless your a good wrench, swapping in another might be cheaper than a rebuild? we're talking 30 yr old trannys so yes they could be shot, but then, consider all of use here on the forum running same 30 yr olds with no probs

I'd be curious to know if the synchros and other needed bits are even available TO rebuild - maybe THAT will dictate what your solution might be. BTW if you DO go the rebuild route, I have a factory SA rebuild guide for the tranny (tho the FSM might detail this too). PM me about getting a copy.

Stu Aull
80GS
Alaska

80's old school

iTrader: (7)

I know... I have located some SA trans in Houston and they come with a 90 day warranty... They are $150 each. Might be worth a try..

The FSM does show overhaul of the trans, but maybe not as much detail as the guide you have.. Thanks, and I might be interested in getting a copy.

I am going to try Redline MT90 first.... I have read MANY testimonies saying that it cured the grinding synchros.. Mine does not grind upshifting and downshifts fine when the tranny is cold.

It seems to get crunchy when the tranny gets hot.

Kentetsu

Sounds like the ATF cleaned the crap out of your synchros, only to find that your synchros are shot. Can't fix that with an addative, unfortunately. Grab a used tranny and beat it til it dies.

Keeble

iTrader: (3)

well 80's if you weren't so far away i would tell you to just pick up one of my spares, offer is still open but, its quite a drive

80's old school

iTrader: (7)

Thanks for the offer...yeah a little farther than I want to drive... appreciate it...

I am still gonna try the redline...only because it shifts fine when the tranny is cool.. I talked to our oil expert here at Dow (where I work) and he mentioned that the viscosity of the ATF and gear oil is too low at higher temps and not doing it's job correctly.

One thing I noticed, the ATF and gear oil mixture is definitely thinner... now my seal is leaking slightly where before the gear oil would not leak!

wankelbug

i have a 85 5 speed from a gslse for sale cheap if your interested im in austin and make frequent trips to houston ill throw in a like new re man starter $110

j9fd3s

iTrader: (3)

ive rebuilt a few of em, its harder than the engine, and takes a couple of weird tools.

mazda has plenty of normal wear parts, also you can get synchro's and stuff aftermarket. the pieces that are hard to get are things like gears, which were really expensive anyways

DivinDriver

iTrader: (15)

Tranny and Diff are the only parts I've never dissected, outside of changing seals and bushings and such, or swapping complete innards.

I tackled an automatic trans rebuild for my 73 satellite once (the car before my -7). Lasted almost 6 months; I just didn't have the tools needed to get it righter.

80's old school

iTrader: (7)

Thanks for the offer....I have two extra 85 transmissions myself...unfortunately they do not fit the SA22's...

Keeble

iTrader: (3)

Is it possible to swap the tailshafts of the transmissions?

80's old school

iTrader: (7)

Dunno about the tailshafts...

I tried swapping to Redline MT90.... same thing... Grinding on 2nd gear.

I am going to pickup a SA22 5 speed from Mazmax this Friday. Will give that a try. I don't feel like farting around with rebuilding one. Hopefully the one I gets works good. He is giving a 30 day warranty which at least lets me know if it will work right...

j9fd3s

iTrader: (3)

you can on the late 80 ones. peejay has the post with the infoz on that

80's old school

iTrader: (7)

Well my 5 speed (the one thats acting up) is a 1979 Trans.... My 4 speed is a 1980.

Will the tailshaft of the 4 speed fit my FB spare trans??

80's old school

iTrader: (7)

Well today I added lucas oil stabilizer to the transmission and wow..... it is doing so much better. No crunching at all upshifting...none... Not near as much crunching down shifting and none if I am just a "little" patient with it....

So.... time will tell.. I am going to give it a little more driving time before I decide to dump money into rebuilding or replacing it...

Kentetsu

Good to know, man. Lucas makes some very nice products!

j9fd3s

iTrader: (3)

it might? sometime in late 1980 MY they switched the guts of the SA trans over to the FB guts but kept the SA case, so you can take a late SA trans and put the FB tailhousing on it, without having to do anything else. PJ's post has the vin split, actually its in the parts catalog too

hmm i think if you wanted to go the other way, FB trans with SA tailhousing that always works? maybe you swap the shift rod?

but putting an FB tail housing on an early SA box, can be done, but you need to change the shift fingers, doable, but more work than its worth, unless you were gonna take it apart anyways

80's old school

iTrader: (7)

Well it's been about 15 days since I added Lucas with Redline MT-90...... she has been shifting just fine!!!

A little side not about Lucas products... I have been running Lucas Engine Oil Stop Leak to my engine... It has the same basic stock as Lucas Oil Stabilizer but also has some additive to soften and swell the seals.... It has been looking good so far.... Used to every morning start belched out tons of smoke... now i can start with no smoke.

I am still a little on edge about bragging about the oil reduction.... This car was using a quart every 200 miles before!!

7aull

iTrader: (2)

OS let us know if the mileage on oil consumption improves - and by how much - with the Stop Leak
OK?
Stu Aull
80GS
Alaska

Willy92

Do you heel and toe on downshifts?...That is, as you approach a corner or slow down, put the trnamission into neutral raise the rpm's to approximately what they would be in the lower gear at that speed, then shift to 2nd gear, while all the time braking with your right foot, yes, while your left foot is doing the clutch work, and using your heel(realisticly just rolling your foot over to operate the gas as I previously described). You may have to bend the gas pedal closer to the brake pedal as I have had to do on all of my stick shift cars, or install one of those pedal kits, wich will widen the brake pedal and/or extend the gas pedal to the left a little bit. With practice, it's not as hard as it sounds. What is does is GREATLY reduce the load on the syncros and it WILL stop the grinding or at least reduce it greatly.