24 replies to this topic

[PNW Novice Racer]

I purchase a car last year with a stock differential that was upgraded using the Mazdacomp differential speced for SM. That differential broke at the last race and I want to know what would be the best choice for a replacement.

From what I have been reading through the forums, it souds like a 1999 Torsen may be a good choice. Any help is appreciated

Thanks,

Bret...

[Jim Drago]

Bret
We sell torsen swaps.. So I will put that out there first...

If your intention is to run at the front and compete for wins.. I think the Mazdacomp is the best choice. If your goal is to run competitively and have a good time without spending $1800 on a diff once or twice a year, the torsen is by far the better choice. ( our Torsen swaps are warranted for 6 months)

[PNW Novice Racer]

Jim,

Thanks....I just finished my novice season last year and only have a handful of races under my belt. If the car was a front running car, as I driver, I'm not there yet and probably wouldn't benefit from the added cost anyway until I improve my skills. I have a limited race schedule agian this year and probably the next.

I am thinking that the 99 Torsen swap would be a good choice to keep my costs down while I improve as a driver. Maybe in a couple of years move back into the Mazdacomp when I can appreciate the difference.

I live in the Seattle, WA area. What is the cost of your 99 torsen swap?

Thanks,

Bret...

[William Bonsell]

Hey Brett...definitely a torsen. My son and I installed them in our cars last winter and definitely is the right choice. We're in Poulsbo if you need any help with the install. And we do keep the fluids pretty fresh.

Bill-

[davew]

Jim is correct. It is not a matter of IF your MazdaComp will break, but WHEN. And how often. Get a Torsen and have fun.

Dave

[Kevin B]

Hi Brett,
The MazdaComp Diff failure in my brother's car took us out of the class lead at this year's 13-hour. I have the Drago-swap Torsen in my 1.6 and couldn't be happier. It's one less thing to worry about now.

Good luck in the new season.

-Kevin

[NV Racer]

Jim is correct. It is not a matter of IF your MazdaComp will break, but WHEN. And how often. Get a Torsen and have fun.

Dave

Is that with the new Mazdacomp diff? I have the original in my car since 2006. should I be getting worried?

Dennis

[LarryKing]

My Mazdacomp diff was rebuilt in 2005 and has worked fine ever since. FWIW, failure typically involves the ring and pinion. MazdaSpeed superceded the original R&P with beefier parts

[Charlie Hayes]

Has anyone tried the new MazdaComp?

[Qik Nip]

Jim is correct. It is not a matter of IF your MazdaComp will break, but WHEN. And how often. Get a Torsen and have fun.

Dave

Dave speaks the truth. I run a Mazdacomp and am on ring and pinion number five (over ten seasons).Similarly Jim is correct that the Mazdacomp is faster. As the old gambler's saying goes, "You takes your cards and you takes your chances".
Rick

[SaulSpeedwell]

Has anyone tried the new MazdaComp?

The diff isn't the problem - the "problem" is the ring and pinion setup, and specifically the strength of the pinion and the crush sleeve.

If you set it up per the FSM, it is more likely to blow up. Some tracks blow them up more than others.

[Qik Nip]

The diff isn't the problem - the "problem" is the ring and pinion setup, and specifically the strength of the pinion and the crush sleeve.

If you set it up per the FSM, it is more likely to blow up. Some tracks blow them up more than others.

What values do you suggest be changed from the FSM? .. And to what new ones?
Rick

[SaulSpeedwell]

What values do you suggest be changed from the FSM? .. And to what new ones?
Rick

Ack, the formula for Coke! The carriers "creep" over time, so used diffs and crate diffs are different animals, and eventually they stop creeping, but new bearings need more preload than reusing bearings, etc.

I'm not going to puke out the whole database and algorithm here, but if your diff builder guy is using the FSM specs on used carriers, there is a good chance you have zero preload on the side bearings. Then the lash gets big under high loads, the pinion gets shocked more than it should and higher on the tooth than it should, and the pinion teeth start to fatigue or the crush sleeve overcrushes and the pinion starts wobbling. You'd be better off with a diff guy with an eyepatch and a wooden leg that sets everything up "by feel".


Knowing how and why your previous units failed (analysing what you noticed and when versus what the failed parts look like) can lead us to a solution - my 1.6 pinion broke on the coast side, which is rare, but that was during a crash after 60 weekends of time.

[Jonathan Davis]

I've got a similar problem with my '90 and could use some advice from the experts. Near the end of last season I found a few chunks of metal debris when I changed the fluid in my diff. It was right before a race weekend so I took the gamble and ran it as is. I never felt any problems and there was no new debris afterwards, but I assume my diff is living on borrowed time. I'm guessing the debris is from a chipped tooth. I haven't dared take it apart to look yet, but obviously something needs to be done before next season starts.

It's several seasons old at this point, so I can't complain. Just wondering what's the best way to go. I've been happy with the performance of the Mazdacomp, but there are plenty of people faster than me with Torsens. Does it sound like a ring and pinion failure on mine? If so, does it make sense to replace them? Would doing so cost more than a Torsen swap? I've done all my own work up to this point, so I'm not even sure who to talk to about rebuilding a diff...

[LarryKing]

Jonathan, You have an expert rebuilder right in your area, but first he has to finish my transmission rebuild. Dead give away - if you can wiggle the yoke on the front of the diff (where the u-joint bolts on) and feel any lateral play then it's gonna blow.

[William Keeling]

Rng and pinion failure is also driver/driving related -- the other issue with the comp is rebuild kits for the clutch pack or no longer available

[SaulSpeedwell]

I've got a similar problem with my '90 and could use some advice from the experts. Near the end of last season I found a few chunks of metal debris when I changed the fluid in my diff. It was right before a race weekend so I took the gamble and ran it as is. I never felt any problems and there was no new debris afterwards, but I assume my diff is living on borrowed time. I'm guessing the debris is from a chipped tooth. I haven't dared take it apart to look yet, but obviously something needs to be done before next season starts.

It's several seasons old at this point, so I can't complain. Just wondering what's the best way to go. I've been happy with the performance of the Mazdacomp, but there are plenty of people faster than me with Torsens. Does it sound like a ring and pinion failure on mine? If so, does it make sense to replace them? Would doing so cost more than a Torsen swap? I've done all my own work up to this point, so I'm not even sure who to talk to about rebuilding a diff...

Jonathan, On a diff, it is quite abnormal to see significant "debris" on the drain plug. The only debris that is acceptable should look like tiny "filings" or a gray-colored "paste" similar to the consisitency of "Never-Seez". If you see anything that looks like a very thin fingernail clipping or larger, then you need to be very concerned about imminent failure.

As Qik Nip said, it is fairly well-established that the MazdaComp 1.6 diff is "faster" than the heavier 99+ Torsen. BUT - quite frankly - for many hobbyists/Regional guys/enduro guys, the 99+ Torsen is a better choice simply because it will NEVER blow up.

Having said that, by necessity, I spent years coming up with a system for making the 1.6 diff live for many years and many dozens of weekends. I'd be happy to look at your diff and give you some recommendations - all I ask is that you drain it, take off the antler case, and get it to me. Since you are local, "recommendations" cost 2 beers, or 3 beers if I'm in the middle of a great story.

[SaulSpeedwell]

Rng and pinion failure is also driver/driving related -- the other issue with the comp is rebuild kits for the clutch pack or no longer available

I agree re: the driver!

As for the rebuild kit, I've yet to see a MazdaComp that needed "rebuilt". My personal MazdaComp unit, after 60 weekends and having suffering a fatigued pinion and resulting "shrapnel", measured within 0.001"-0.002" of clutch thickness compared to the rebuilt kit. Thus, I sold the rebuild kit years ago to someone on here . . .

The key to getting desired "lockup" from the MazdaComp is to NOT overdose it on LSD additive. Start with a non-LSD gear oil (e.g. Redline 75W90NS) and only add LSD additive as you feel is necessary.

5-7 ft-lbs pf breakaway torque (hot) is your target. More than that will cause chatter and reduced straightaway speed. Less than that runs the risk of reduced "squirt" out of corners, especially during curb-hopping.

If your MazdaComp is below 5-7 ft-lbs and/or you are experiencing excessive wheelspin, "wash" the diff and LSD clutches with your favorite solvent, and I promise it will be good as new.

PM me if you are confused!

[Bench Racer]

Thanks Saul, I do appreciate your competition proven knowledge/experience.

[Jonathan Davis]

Jonathan, On a diff, it is quite abnormal to see significant "debris" on the drain plug. The only debris that is acceptable should look like tiny "filings" or a gray-colored "paste" similar to the consisitency of "Never-Seez". If you see anything that looks like a very thin fingernail clipping or larger, then you need to be very concerned about imminent failure.

Yeah, I figured it was unusual when I searched the forums and didn't find anybody mentioning it happening to them. There were several thin "clippings", plus a couple chunks about the size of grains of rice.

As Qik Nip said, it is fairly well-established that the MazdaComp 1.6 diff is "faster" than the heavier 99+ Torsen. BUT - quite frankly - for many hobbyists/Regional guys/enduro guys, the 99+ Torsen is a better choice simply because it will NEVER blow up.

Having said that, by necessity, I spent years coming up with a system for making the 1.6 diff live for many years and many dozens of weekends. I'd be happy to look at your diff and give you some recommendations - all I ask is that you drain it, take off the antler case, and get it to me. Since you are local, "recommendations" cost 2 beers, or 3 beers if I'm in the middle of a great story.

I understand the reliability angle, but spending money to make the car slower just seems wrong to me
I greatly appreciate the offer and will be in touch when I get the thing apart. Thanks.