I have just put in my new engine but noticed this problem before. Since this engine red lines at over ten thousand the transmision is limiting it to only 8. But at seven when I shift into or down shift into second gear at over 20 mph, the transmision grinds. Its getting worse and I have been told that it is the syncro in second gear. If thats the case, Is it very hard to replace the syncro myself. I am kinda tight on money at the moment.
Thanks

 

I am not sure how hard it is to replace a syncro. It might be cheaper to just get a new boneyard tranny.

Although I have to ask..

WHY WOULD YOU REV TO 10,000 RPM?

That is Seriously NOT GOOD for your Engine. You will leave chattermarks all over your housings. Even Full Blown peripheral race engines don't go that high for any real length of time.

What kind of engine (12A,13B) do you have, and what mods have you done? Usually 7,000 RPM is fine on 1st Gen motors.

 

@10g's sounds like you want to buy another motor

 

The engine is from pineapple racing. It is street ported pretty much all the way, and has allot of oil mods for when I put on a turbo in a few years. Its a 12a by the way. Rob golden the owner and the person who built it has been racing rx7s for like 20 years. And when I talked to him he said the engine can go well over 10,000 rpms. I would never take it that high but thats what he said. Lets see what else. It has littened rotors, carbon apex seals and a fly wheel from an 83-85 rx7.

Anyway, I was thinking about that yesterday. Going to pick n pull and pulling one of those transmisons off. I have heard its not that easy to replace the sincro so I dont know what I will do. Im tight on money right now so I cant get a new transmison. I have to get another one when I put a turbo on, but I just need something to get me by for awhile.

 

baby the tranny until u can afford a new one ... try double de clutching it to make it last (no hardcore racing for a while)

 

yea I know. I just got my new engine in and am loving driving it. But I guess I cant race for awhile. noooo.

 

Do yourself a favor. Do not rev that engine to 10,000 RPM. There is really no benefit to it. It's not like a bridgeport that makes more power the higher you rev. A Streetport's power does plateu nicely. I doubt you will ever need to go past 8,000 RPM. If you get an extra 5 hp by revving to 10K, you will cutting the lifespan of that engine unnecessarily. Also, the 12A flywheels are heavy at 25 lbs(and need to be), so lightening the rotors but keeping a stock flywheel doesn't do much for lowering the intertia of that rotating mass. Even if it was balanced and blueprinted, all you'd benefit is the confidence that it was done right.

I am not Pineapple racing, and I don't know nearly as much as them, but I doubt you'd hear from anybody here that 10K is the shift point for a street port even with those mods.

Just my 02 cents.

P.S. - This is an exerpt from Racing Beat's site:

WARNING: None of the Flywheel or Clutch components shown in this catalog should ever be allowed to exceed 10,500 RPM under any condition. This same RPM limit applies to stock components. You must use an engine RPM-limiter to prevent excessive RPM. If your engine is capable of exceeding 8,500 RPM you must install a transmission scatter shield, or ballistic blanket. Failure to implement the above may result in serious injury or even death.

 

I am not saying that I would ever rev it to 10,000. I would never even take it past 8. Rob, the owner of pinapple racing said that the engine could go well over 10,000 but he said the engine will make peek power at about 7,500. And about the fly wheel. It is from a 83-85 rx7. It will be better for when I put a turbo on.

 

Buy a tranny from a junk yard and use your old one for a learning tool. It can only be but so difficult to rebuild one. And when it screams and hollers when you shift into second at some ungodly amount of RPM(10,000 ) back off some, or your will know what is making the noise cause it will come flying through the tranny pan. They lightweight steel and aluminum flywheels are lighter than stock. (Steel 17lbs, aluminum 9lbs, stock 27-30lbs) They make aftermarket flywheel for turbos. The aluminum ones have a removeable friction surface. Put that with a centerforce racing clutch and you should be good to go one would think. Aluminum flywheels make starting off in 1st gear kinda jerky, this is just my thinking after researching all this and a little trial and error. Nobody here is saying they are pineapple racing, but take it easy on that red-lining thing

 

Glad to hear it! Common sense prevails!
Another Seven is safe.
BTW, 81-85 Flywheels are the same weight.

 

If that engine was actually built to exceed 8500 RPMs, you would've mentioned the pinned rotors. The fact that they are lightened in conjunction with the use of the lightest stock flywheel would make no difference in the redline of your engine.
I also find it highly unlikely that you would've spent the money on such an engine apparently not having researched properly beforehand at least enough to know what's entailed in the modification as well as what's to be gained. I find it as unlikely that you would've spent that money on an engine of such magnitude only to have it mated with such a heavy flywheel and a weak transmission.

 

Back on the subject, replacing a synchro isn't impossible, but I think it'd be pretty difficult without the right tools. I tore down a '79 tranny and replaced the bearings, which required a HUGE press and some custom made plates to do. Replacing the synchro would require not only replacing the bearings, but also finding some way to get the huge (50mm?) nut that holds the gears on the mainshaft. I don't know how you'd do that outside of the special tool from Mazda.

Another option might be taking it out and paying a local tranny shop to do the work, at least then you aren't wondering about your junkyard tranny behind that fancy motor. Local tranny shops around here quoted around $250-$350 for parts and labor to do bearings and synchros if I brought the tranny in already removed from the car. Just buying the bearings cost me like $175. Food for thought...

Armen

 

Ok I did research the engine. what you dont understand is that the engine and everything that has been done to it was so that it would be able to handle a turbo when I put one on in a few years. I didnt have the money to replace the trani and everything at once. You know how expensive that would be. I will probably get a good flywheel and for sure a transmison when I put a turbo on. The first step was the engine. I have allready put over $12,000 dollars into my rx7 and am no where near even close to being done. I dont have that much money so thats why I am doing things in steps, not all at once.

 

I think I will just take it easy for awhile on the trani. Untill I have enough for a new one.

 

Dude...What the hell did you spend $12,000 on? Gold plating?

For 12k, I could have bought a 10 Sec Widebody GSL-SE with a 95 Turbo Drivetrain. AND I thought that was too much!

 

Do turbo chargers usually run above 10,000 RPMs? The warning on all the aftermarket clutches and flywheels (even those intended for racing) warn you not to go over 10,500. You got pics of your car? We would all like to see what $12,000 will get for you. Maybe in 3yrs I will be able to go down the street @10,000rpms and downshift into 2nd gear and wonder why my stock tranny is bitch'n and moanin'

 

10,000rpm? Ah, ok, you have a perpheral ported engine?(sarcasism) Unless you do, your power peak is well below this unless your running a monster j-port in which case your engine would last 3months if your lucky. Over reving a engine past its power peak is pretty dumb in many situations.

If your power peak is 7500rpm, you will only exceed that in 1st and 2nd gear and then you'd likely not gain anything by going past that in higher gears except to ware down your apex seals to stubs quicker.

Now if you had at least a bridgeport, then your shifting would be more like 8500 in 1st depending on extent of porting. But normally bridgeport peak is 8000rpm so exceeding that very far is almost useless unless your drag racing and trying to stay with with in the upper power ban range...

 

Okay.. Let's leave him alone now. Everybody came in and kicked him while he was down. I feel like those Single Turbo thread guys - Viscious.

They act like a pack of dogs and attack anytime anybody says anything remotely different than the norm.

You gotta see it, it kinda funny sometimes. Not a good place for the Newbies.

 

Supercharger.

 

yea shut the hell up. And the tranny grinds mostly when I am downshifting at about 25 mph. Its not like I am even going to 10,000 rpms. I never said that. All of you need to read again what I wrote. the engine can go over 8,000 rpms, I NEVER said that I would take it that high.