83 rx7 vibration during acceleration??? any help
 

Ok so I have a

so i'm bringing home my new toy tomarrow, i just bought an 1983 rx7 most likely the base model not too sure on what type, but it has the stock 12a in it but it seems to have a bit of a vibration while accelerating, but it doesn't feel to be losing any power or slipping so i've come up with a few ideas of what it could be,
such as a bearing of some sort, it does kinda feel like its coming from one side that being the rear passinger, so mabey the rear ends going out??? as soon as you let off the gas it stops and its a manual so it keeps rpm as long as the cluch is disengaged so mabey not. does the drive shaft have a cv joint in it??? could be a broken cv or mabey an axil?? somthing else. I fairly sure engines alright. it was just replaced it looks like a brand new block or someone when a bit overboard on painting the mazda white and the block blue and making it look pristine..... nice engine compartment. like seriously i was dry humping the car i think.... more than likely i was dry humping. car also has one other issue with overheating, it looks like the heater core is leaking onto the passanger side from under the dash looks to be fluid not just rain water, and I've never owned or worked on one but most/all of the cars i have worked on thats where the heater core is. doen't that affect engine temp since coolent runs through it. heater seems to work fine and stops the overheating so i'm good for a little while i really just need to figure out this vibration. I've fixed pleanty of overheating issues and always prevailed.

check the u-joint on the drive shaft, i hade the exact same problem before and thats what it was.

My 5th gear seems to vibrate pretty decently too, any suggestions?

thanks for the help, I'm pretty sure its the u joints, so a new drive shaft is needed right any idea how much a new or used one will cost me??? I've been searching but have found none. I live in oregon portland area. so if any one wants to get rid of one for a fair price hit me up.

or it might just be loses that wha happen when i 1st got mine but my drive shaft fell off right when i got home.

The early driveshafts had replaceable u-joints, by 83 they weren't. A good driveshaft shop can change them to replaceable and greaseable joints. You should also check the tranny and engine mounts, the rubber eventually tears and fails.

Overheating on a rotary is a serious issue. They will not tolerate overheating like a piston engine will and can very quickly fail, leading to a rebuild. If the heater core is leaking, check the hose connectiontions/clamps where they pass through the firewall. If those are good, take the hoses off and connect them together with a short length of copper pipe. Be careful removing the hoses, the brass tubes of the heater core are very thin and soft, they easily bend and distort. Double clamp each hose. If that stops the heater core leak, replace it.

Cause of overheating needs to determined and fixed immediately. Remove the radiator cap, inspect the passeges in core. If they have corrosion build up, have the radiator rebuilt or replaced. Also check the thermostat and water pump. Replace the thermostat with a Mazda OEM one only. When I have one that overheats, I go through the entire cooling system. Flush the system, replace the thermostat, belts, water pump and all of the radiator and heater hoses. Check the fan clutch. You may spend 3-400 in parts, but a decent rebuild is 2-2.5k and the cooling system would still need serviced.

The temp gauge needle normally never goes past 1/3, when it hits 1/2, I begin to worry, past that, the engine gets shut down. Often, by the time the needle hits hot, the damage is done.

In my sig line is a link to the online FSMs. Download it and the carb manual, they are now your new best friends.

Good luck and welcome to the forum.
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Thanks for all the info. I think i need to get to ten post before i can check your links so i guess heres one more.

I'm fairly sure its the heater core. I do know that u cant overheat a rotery because the roters will crumple due to them being aluminum right??? it doesn't overheat as long as the heaters on and it does blow warm air still but not super hot and it only fogs up my glass on defrost. so i'm fairly sure of the heatercore, but i do plan on going through the cooling system to see if anything else is about to go bad or is bad. Engine is very clean and was replaced/rebuilt due to overheating. I drove it home about an 45 minute drive on the freeway. and it stayed at the 1/2 mark.