at high rpms when i shift into 3rd it grinds and won't go into gear... at first i thought i had misshifted into 5th... 5th grinds anyway... but it is 3rd... normal everyday driving is fine... but when i really get on it and shift from 2nd to 3rd it grinds... any ideas on what it might be? my clutch has started to slip, so its hard to even try and do it now... just to make sure it is 3rd thats grinding.... i want to put a new clutch and do the 5th gear... but i want to fix whatever other problem i might be having as well... what do you guys think it is?

thanks

harrison

ps is 3rd gear hard to get to in the tranny? i've fixed a friends 5th gear... with help from a write up on the board... but how far into the tranny is 3rd?

 

transmision is going out

 

yea.... so can i fix it before it does... that what i'm asking.... i've got a diff brace and a tranny brace on it now so it shouldn't be recieving any more damage.....

 

Could be a broken synchro.

 

thats what i was thinking... would that make it only grind at high rpms though? i was thinking it would just grind all the time......

 

Its a damaged syncro ring.

The teeth on the syncor ring are suposta have shart points, but do to missed shifts, grinding gears, and high rpm ingagments they start to round off. The first sign of a worn syncro ring will come during high loads to the transmissin, such as high rpm shifts.

Its not hard to replace the syncro ring in the tranny, but 5th is a piece of cake, 3rd you iwll have to remove 4 gears in total to get to it. (input and output 5th, input and output 4th gears) Then you wll be at 3rd gear, compair the new syncro ring to the old one and you will see that the new one has sharp peaks while the old one has rounded ones.

 

sweet, so i should just order a new 3rd gear synchro when i order the new 5th gear synchro and updated shift select spindle?

 

I supose, if you want to fix it. If i were you i would replace all the syncors, costs more but you do it all at one time and dont worrie about it again. Y would you get a new shift select spindle?

 

well... updated shift select spindle... that was mazda's way of fixing the 5th gear synchro... it makes it harder to get into 5th... there for making misshifts less likely to happen.....

 

Who did you talk to at mazda? Parts guy?

Also, making it harder to get into 5th also increases the liklyhood of grinding the new syncro down more. Causeing the same problem. You miss 5th?
How do you miss the 5th gear shift?

 

Your direct problem is a worn 3rd gear synchro. The synchros serve as mini-brakes on the gears, slowing the gears to enable smoother inter linking between gear hubs during a shift. Your third gear synchro has lost its ability to slow the third gear sufficiently at high loads for some reason (an inspection is the only way to tell) to prevent gear grind.

A rebuild on your own is going to require a great deal of patience and an ability to keep your parts in meticulous order. The 5th gear repair is very straight forward. The third gear repair is not. To swap-out the third gear synchro you will need to tear down the entire transmission. The disassembly/assembly instructions in your manuel are not adequate in a number of respects and you are likely to encounter problems on reassembly.

If you are going to do it, be particularly attentive to the clocking of the gear hub assemblies. The dogs need to be positioned in the same place as they are removed inorder for the transmission to work properly. If you do not know what the "dogs" are then maybe you better rethink this exercise.

I agree with 89Turbo944 that you should probably plan to redo all of the synchros and several of the bearings while you are in there to save you a return trip later.

By the way, you did not say how many miles are on your tranny.

 

I have a funny kinda off topic story,

Well when i was in highschool, im my Gr12 year i was in a BCIT ELTT program, its training for becoming an apprentice. Anyway, we had a project that was to dissasemble and re assemble a standard transmission. I enede up with a unit out of a 3rd gen honda prelude. When i tooke the end cover off i noticed that bothe 5th gears were chewed to ****. All bent, black from being overheated so bad, and melted in places.

The person who rebuilt this tranny before me was the high schools shop teacher. He figured that the BCIT kids are doing it and so can he. He has some knowledge of automotive repair but nothing that you cant lear out of a book. So he rebuilds the tranny, and he puts the 5th gear in upside down. Mounts it in a car, and car goes off.

Car comes back next day and guy complains that his 5th gear is funny ont he highway, its like it has no power, and bogs the engine real bad. So he removes the tranny and inspects it. He messes up bad. Mangled 5th gear, costly mistake. If you are not fimilar with how a transmission works i suggest you stay away from the rebuild. Take it to a shop and avoid those problems.

 

http://www.scuderiaciriani.com/rx7/s...t_spindle.html

 

89turbo944,
the 93 rx7 had a weaker shift select spindle and 5th gear synchro. some time during the 94 year run mazda updated the parts. if you call mazda and ask them about it the will only have the new updated parts. infact the 5th gear synchro is a slightly different color, and the select spindle is noticable stiffer. also the 5th gear misshift is not always from trying to shift into fitth but most commenlly from doing the 2-3 shift and missing 3rd and going to fifth

 

Thanks for that. Didnt knwo that one. So seeing as i have a 96 then i should have the updated part in the car already. I have yet to have any problem with shifting in the R2.

 

yea you shouldn't have any problems at all if you have a 96... it was just the 93s.... and like apexkw said... its not really harder to shift into fifth... just moving the shift **** over to the right (5th and reverse) is a bit stiffer because of the harder spring... shifting forward into 5th or back into reverse stays the same....

thanks for all the input... i guess what i might do is just take out the tranny when i do my clutch, order all the parts, and then take it to a tranny shop.... that way it shouldn't be to expensive as the tranny is already out of the car.... and maybe i'll just buy 1,2,3,4,and,5th synchros... and just replace them all....

thanks again

harrison