Pedestrian X

for as long as i can remember theres been a nice sumwhat high pitch humming noise coming from teh rear end. its been like that for a long time and i dont THINK its causing any damage. performance seems fine but i was just wondering what the hell it might be? its only there when i let on the throttle, wenever there is power going to the wheels. the mroe i let on the louder it goes. its just more anoyying then anything. and its not the lack of gear oil or quality (royal purple). its just more anoyying than anythign else. it sounds like a crappy humming on a nicely paved wet road.. lemme know what you think.
p.s. its and 85 with the 13's and drum brakes :[

Defprun

It's the damn diff. Mine does that too. Maybe it's because there hasn't been a fluid change back there since 1984 >< I'm going to have that addressed along with the nasty rumbling car phenomenon that happens at 150kph....another lower control arm problem

Pedestrian X

k, sweet thnx. theres no rumbling over here tho :]

Defprun

Lucky. This problem just arised. My whole car shook when i was on the highway, and after i slowed down my mirror was still rattling! I had to stop it myself, it was funny, but i almost started to cry.

Keaponlaffen

The whining/freight train/whirring noise is most likely your wheel bearings. Diffs normally make an annoying "bus" whine (the noise buses make when accel/decelerating) or a grinding noise.

Jeff

VaSSagO

its not quite the same but i have a big backlash in my drive line, i am guessing its the diff. I took it to a rotary specialist and he said most rx7s are like that, (I doubt this, as he was the person who put the engine in my car and prob cause it). I have a 13B in a series 1, and this prevents me from going downt he gears when slowing down as the whole car shudders. Is there normally any backlash in series 1 rx7s with a 13B in them??

inittab

13b, 12a, v8..... backlash in the rear shouldn't have anything to do with what power-plant ya got. The two 1st Gen rears that I've messed with have had some backlash.

If the car shutters when you downshift, it could very well be your rear. How old and what kinda oil ya got back there? I'd try putting some quality synthetic oil in it to see if it cures the problem.

Good luck!

VaSSagO

Umm would not have a clue what oil is back there, i will have a look in the morning, is it easy to drain and top up?? I was told the 13B was a shorter block, causing the gearbox etc to be closer to the front of the car by a little bit (when i purchsed the car the gearstick hit the Cd player it was that far forward, had to get it bent).

I have had the car 6 months now and is my first Rx7, the guy i purchased it from showed me the receipt for $8000 aus for the 13B engine (Carbi, i dont know model) and gearbox (supposedly series 4 turbo) installed, a low km import engine, does this seem expensive?

Also the other day was having a look at the carbi and there was alot of mechanisms not connected, including the choke, i dont know what i did but i have lost heaps of straight after. Before when the car hit 3750rpm i would get heaps of power and in first tyres would lose traction. WHen i talked to Rotomotion (Rx7 specialist who put engine in) said that the emission controls on the carbi are not connected. Anyway is there something simple that i can do to fix it or should i take it in to get fixed?

Thanks for your help