33 replies to this topic

[mhiggins10]

I'm planning to follow the steps from the Miata Garage (http://www.miata.net/garage/maint.html) and have 2 quarts of Redline Shockproof Lightweight gear oil for the diff and 3 quarts of MTL for the trans.

 

Do you guys know of any gotchas or tips for this?  Anything Spec Miata-related that the garage link doesn't cover?

[pat slattery]

I'm planning to follow the steps from the Miata Garage (http://www.miata.net/garage/maint.html) and have 2 quarts of Redline Shockproof Lightweight gear oil for the diff and 3 quarts of MTL for the trans.

 

Do you guys know of any gotchas or tips for this?  Anything Spec Miata-related that the garage link doesn't cover?

Don't know what car, but a 1.6 doesn't take but about 1/2 of a quart for the dif

[mhiggins10]

It is indeed a 1.6.  Figured having some spare fluid never hurts...

 

Do you guys use fresh crush washers every time?

[trimless]

It is indeed a 1.6.  Figured having some spare fluid never hurts...

 

Do you guys use fresh crush washers every time?

 

Are you running a Mazdacomp diff in the car? If so, change the diff fluid after each weekend.  I don't know if anyone using the Redline lightweight oil in the 1.6 diff. I use Motul gear oil in my car. The 1.6 Mazdacomp diff is fragile and requires a high quality oil and frequent changes to keep it happy.

 

Crush washers? Never changed one and the diff still isn't leaking so don't waste your money until you see a sign of leakage or if you have money to burn.

[pat slattery]

Diff is precision piece, unless you know what your doing leave it to a pro. 

[AW33COM]

Figured having some spare fluid never hurts...

It very well could.  It does not take 2 quarters, but 0.63 I think    

Transmission takes 2.1.  Use Redline MTL for it.                                                                                                                         

 

I have a Mazdacomp and I run Redline 75W90 Gear Lube.  That's what Mazda told me to use anyway.  Because of the nature of the differential you'll need to swap the fluid every race weekend at least.  Tilt the car to drain everything.  Like trimless said, if the washers are holding, no need to change them. 

[DES4]

As above; heavy viscosity fluids won't require a new washer unless the washer is truly trashed.

 

As per John at 5X's recommendation, I use Redline 75W90 in the factory viscous diff, and MTL in the gearbox (just 2 quarts; car doesn't miss the 0.1 quart, as it comes right up to the sight hole). The car gets driven to and from the track (250 mile round trip) with no issues.

[mhiggins10]

Thanks guys- it's a factory vlsd as far as I can tell. I'll try the shockproof in the diff and worst-case it becomes Torsen time if something goes wrong...

Sorry I wasn't more clear schabi- what I meant was for the next change. Obviously overfilling is a bad idea.

[LarryKing]

Because of the nature of the differential you'll need to swap the fluid every race weekend at least.

 

What nature is that? At least? Do you change it each day?

 

I change the oil in my MazdaComp diff twice per season. Last few years I only run 6-7 events per year. Been running the same diff since 2006 with no issues. What am I missing?

 

I've always raised the rear of the car a little when filling to slightly increase capacity.

 

Of course I just jinxed myself - probably blow-up next race.

[AW33COM]

Well, since I finished the car I'm out driving at least once a week.  At SCCA events I do 2 or 3 groups.  That can be 8-12 sessions per weekend.  If you race in one group and do 6 events per year you change your fluid more than me

 

The MazdaComp is weaker relatively speaking, and it uses clutches.  On top of that it's expensive, so that's why I try to keep it as happy as possible.  Btw, I change all fluids like that. 

[marcusmazza]

I have a few thoughts on this issue after I blew up the rear end on my 1.6 early last season.

 

1) It's not the diff that is fragile, it's the ring and pinnion. I don't think I've ever heard of the diff itself failing.

 

2) I'm pretty sure the fluid doesn't degrade after one race weekend. I don't know how much protection you're really buying by changing it that often.

 

3) After I shreaded the ring and pinion in mine, I had it rebuilt with new bearings and seals (same diff). No issues a full season later.

 

4) I use the redline lightweight shockproof oil and change it every 3-4 weekends. The key is to use the shockproof stuff, not just regular redline diff fluid. This was the recommendation from the guy who rebuilt my diff. I know of a few people who run the redline medium shockproof oil. The stuff is opaque and light blue in color for the lightweight. I believe red in color for the medium.

 

5) My faliure only occured after an incident on track where a guy punted me while I was at full throttle. I believe the unloading then reloading of the driveline chipped a tooth, because I picked up a vibration after the hit. Three turns later and I was done.

 

-Marc

[marcusmazza]

Oh, my diff is a MazdaComp. The guy who rebuilt it has done at least a dozen of them, always the ring and pinion that fail. A few pics of the pinion out of mine.

 

 

 

-Marc

[LarryKing]

My faliure only occured after an incident on track where a guy punted me while I was at full throttle. I believe the unloading then reloading of the driveline chipped a tooth, because I picked up a vibration after the hit. Three turns later and I was done.

 

Good observation.

 

My only diff failure occured at Grattan when I applied the brakes before the car completely landed after the "jump". AIM Tuning rebuilt mine and I was told that MazdaSpeed upgraded the R&P to more durable pieces. No problems since.

[svvs]

I have a few thoughts on this issue after I blew up the rear end on my 1.6 early last season.

 

1) It's not the diff that is fragile, it's the ring and pinnion. I don't think I've ever heard of the diff itself failing.

 

2) I'm pretty sure the fluid doesn't degrade after one race weekend. I don't know how much protection you're really buying by changing it that often.

 

3) After I shreaded the ring and pinion in mine, I had it rebuilt with new bearings and seals (same diff). No issues a full season later.

 

4) I use the redline lightweight shockproof oil and change it every 3-4 weekends. The key is to use the shockproof stuff, not just regular redline diff fluid. This was the recommendation from the guy who rebuilt my diff. I know of a few people who run the redline medium shockproof oil. The stuff is opaque and light blue in color for the lightweight. I believe red in color for the medium.

 

5) My faliure only occured after an incident on track where a guy punted me while I was at full throttle. I believe the unloading then reloading of the driveline chipped a tooth, because I picked up a vibration after the hit. Three turns later and I was done.

 

-Marc

Marc, how much was it to rebuild it?  I did mine in a while ago, and still have the parts.

[marcusmazza]

Vicktor,

 

I opted for a used ring and pinion. Didn't realize that MazdaSpeed had better ones available (Thanks for the tip M&S). The guy who rebuilt it for me (fellow Miata racer in the Mid-Atlantic area) stocked a bunch of used ones. He did the rebuild with new bearings and seals from Mazda. Total cost (parts and labor) was right around $500.

 

-Marc

[Cy Peake]

Lightweight shockproof is blue.

Heavyweight shockproof is red.

 

To my knowledge, there is no medium.  Both don't play well with brass synchros so don't use it in a transmission.

[marcusmazza]

Sorry, you are correct. I knew there were three weights, so I assumed one of them was medium. It is actually super lightweight and appears to be yellow.

 

-Marc

[mhiggins10]

Lightweight shockproof is blue.

Heavyweight shockproof is red.

 

To my knowledge, there is no medium.  Both don't play well with brass synchros so don't use it in a transmission.

 

It is indeed blue- really goopy, and kinda nasty looking.  

 

Thanks for the help guys.  I was able to get this all changed out and fresh- man that old diff fluid was nasty, smelly stuff...

[Doug007]

Just make sure you get the "shockproof" stuff and not their regular gear oil.  As it says on their page, the "shockproof" stuff is good for "problem gearboxes"

 

http://www.redlineoi...cts.aspx?pcid=8

[SaulSpeedwell]

I have a few thoughts on this issue after I blew up the rear end on my 1.6 early last season.

 

1) It's not the diff that is fragile, it's the ring and pinnion. I don't think I've ever heard of the diff itself failing.

 

2) I'm pretty sure the fluid doesn't degrade after one race weekend. I don't know how much protection you're really buying by changing it that often.

 

3) After I shreaded the ring and pinion in mine, I had it rebuilt with new bearings and seals (same diff). No issues a full season later.

 

4) I use the redline lightweight shockproof oil and change it every 3-4 weekends. The key is to use the shockproof stuff, not just regular redline diff fluid. This was the recommendation from the guy who rebuilt my diff. I know of a few people who run the redline medium shockproof oil. The stuff is opaque and light blue in color for the lightweight. I believe red in color for the medium.

 

5) My faliure only occured after an incident on track where a guy punted me while I was at full throttle. I believe the unloading then reloading of the driveline chipped a tooth, because I picked up a vibration after the hit. Three turns later and I was done.

 

-Marc

 

With 20+ 1.6 diffs out there and only two failures in 10+ years, I surely agree with your 1, 2, and 5.  For your #3, you don't mention how the carrier was "rebuilt".  New ring/pinion?  All new carrier?  Low mile carrier?  Frankly, I don't know if #4 matters, but I feel that with proper setup, it falls out of the equation.  I tell my friends/customers to run Redline 75W-90NS (NS!  NS!) so they can add LSD slickifier to suit.  Once the clutches are too slick, it is hard to get them grabbing again without fairly dramatic measures.  Nothing to do with the clutches at all, I've yet to seen any clutches "wear" beyond 0.001" or so.

 

The ring and pinion are where the failure manifests, BUT the true root cause (when it is the "fault" of the diff setup and not a situation like your #5) most often starts with a loss of preload on the side bearings.  The side bearing housings "creep" over time, and if you simply set the diff up per the FSM, you will mostly likely fail the R/P unless you are using an all-new carrier.

 

With or without a new carrier, I recommend a teardown 6-12 weekends after the rebuilt/setup, inspect the preload and compare to the initial numbers, and do not let the preload fall near zero.  I cannot stress enough that the FSM specs are not only worthless for a used carrier, but will lead you astray.

 

Look at that old pinion, and you may be able to see whether the faracture started on the coast or drive side.  One of my "dead soldiers" was my own 60+ weekend 1.6 diff.  I came off the grass backwards with the engine stalled and in gear and hit pavement.  The diff failed in the next session, and showed obvious signs of the fracture beginning on the COAST side of the pinion.  The 1.6 diff just can't live through that kind of abuse. 

 

But - with proper setup, a 1.6 can last longer than most of the car, and it is still the "fastest" 1.6 diff, in my opinion.

 

The other 1.6 diff issue we can't fix without "cheating" is the crush sleeve.  If the diff fails because the pinion starts to "wobble", it isn't the diff builder's fault - most likely the driver is one who does a lot of braking with the clutch ENGAGED, and the constant corkscrewing has collapsed the crush sleeve.

 

If you find pinion wobble at the input shaft, TAKE THE DIFF OUT.  Or, if you must, retorque it, although this is NOT a good idea or a permanent fix.