sa22crotor

I was giving my 7 a nice go on an open bendy strech the other day and everything was cool, new oil and plugs type cruse. The car was in 4th doing about 3300rpm when i gave it some before 5th, going to 5200 i shifted and on letting the clutch out driving normaly the 5th gear rattled and shook and sounded like the rear bearings do when they are shot. It's like the bearings dropped off the shaft in the box, back to 4th and no noise......
So back to 5th for another listen and sure as its there, loud allmoast grinding noise. Question is- Do the 82 12a's have a weak box? ccan the problem be fixed?
What is the "box of choice with a high hp 12a" ?
It,s a real bad problem that i tried to look up in the faq's, the car shakes in 5th!
the motor is fresh, the diff is new, axles are new all bearings were done on the hunt for squeeks and rattles.
Thank you all for any help.
Ben

B3RX7

Dear sa22crotor,

yep, SII box 5th is a bush and prone to failure.

In the class that we run for Targa Tas, you have to maintain the original gearbox casing....so our box runs full syncro CR straight cut gears in a hybrid SII case with a S1 5th (because for some strange reason, the S1 5th was needle roller bearings).

I'm going up to a 13b and will build the same thing from a S5 box (i.e. syncro's, straight cut and CR where 5th becomes 1st and 4th (1:1) becomes the new 5th). John Needham in Melbourne (Australia) builds these for A$3000 he has mine right now for a freshen up post Classic Adelaide - it's yours for $2500 if you want it.

I have to tell you, once you've done the intake, porting and exhaust, nothing unleashes pace in a high hp rotary like a close-ratio box (with straight cut gears they sound fantastic as well!!). Cheers

sa22crotor

This is only my 1st rx7 and it's going to recieve the the treatment, should i just get a new box? What box should i use and what cars are they found in? e.g. 82 12a rx7.
Please help i want to fix this today.......tonight maby.

sa22crotor

Do you know if the 5th in the sI fits the sII? And how long does the bush last for if all i do is the bush, pitty i havn't got the $2500 for yours (would if i didn't have to do a rebuild with low comp rotors and install efi!) Thanks very muchB3RX7

B3RX7

The needle bearing s1 5th will bolt into the s2 but you basically need 2 gearboxes to build this combo....

For a useful/strong street/drags setup and if you are not competing in categories where you have to run an original box/casing - then a S5 box is the go. There's plenty of them and they are very strong.

sa22crotor

So the starter and from the s2 and the bellhousing will go onto a s5 box? or do i need a new starter? I have the factory guide on doing the box but it looks too much for a 1st try, lol, or does the s5 box and bell bolt up with no mods to the inputshaft/starter ?
Your an absolute book of handy info B3RX7 cheers! The 5th started after i put the new diff in, it was like the next day i serviced and here we go....it's straight line speed was very good (off the clock in 4th, 6800)the longer i hold it the faster it goes, love the new cars with speed cut out's the old rotor screams at them on the way past.When it's done i just want to use it as a club/drag/learner prior to getting a gen3-one of the first and one of the last will do me anyday, then i'll work out what to do with a quad rotor.