240SX Troubles

[Brandoncb7]

Ok so this isn't about a CB or even a Honda but a friend of mine needs help and I don't know what to tell him so i'm comming to you guys with the question. I asked him to get a video of it that way it could be better diagnosed and he's going to but for the time being i'll explain what he's told me. The car is a 1993 240sx coupe. It has 173,000 miles on it, and he recently had a new clutch and tires put on it. He said the car will run fine in first, second, and third gear but when he shifts into fourth or fifth the car starts shaking and shit. That's about all I know right now because he left me an e-mail and has since went to bed so sorry for the lack of information but as far as I know that's all he could tell me. Everything is fine until fourth and fifth gear and then it's shaking. Any ideas anyone? Any help would be greatly appreciated. Thanks in advance, Brandon.

[cvc7chris]

make he's going to slow in those gears

or he's got a bent wheel of some sort or unbalanced. or some suspension/steering problem.

it probably wouldn't be the mounts or it would shake constantly

edit: i didn't read he had new wheels. so that probably rules out bent wheel problem probably or it would of been noticed while putting on the new tires

[Brandoncb7]

make he's going to slow in those gears

or he's got a bent wheel of some sort or unbalanced. or some suspension/steering problem.

it probably wouldn't be the mounts or it would shake constantly

edit: i didn't read he had new wheels. so that probably rules out bent wheel problem probably or it would of been noticed while putting on the new tires

Yeah he said that he made sure the tranny mounts were'nt loose. He's been driving a stick for a while too so the "too slow" isn't an option. I have no clue what it could be. I just told him to get a video of it that way maybe he could get some clearer answers from people. He lives in Alabama and i'm in Florida or I would just go over there and drive it myself. He said if nothing else he's just going to take it to a shop and see what's up with it but he wanted to see if anyone he knew could help out first. The reason i'm asking is because he's looking to get rid of it and I want it lol. But he's wanting to get it fixed first.

[93F22A6]

Fuel starvation? Not to sure seems like a very weird problem.

[Brandoncb7]

Yeah he was kind of vague in his description. He's not the best with words. I'll get more info from him but I figured I would at least post what I had so far and see if anyone could come up with anything. I was thinking fuel too but still not too sure.

[Brandoncb7]

Ok he got back online. He said it starts in 4th gear and then in 5th it gets worse. But once in fifth and up to about 65-75 mph it goes away lol.

[2.2litrebeater]

warped driveshaft?

[Brandoncb7]

The previous owner said something about the driveshaft missing a bolt but he already got underneath the car and solved all of that. Those were my first two guesses were the driveshaft/universals or the fuel. He said the fuel pump and the filter have been replaced.

[evil_demon_01]

Moved to other automotive.

Sounds like a wheel imbalance, get the wheels rebalanced.

[Blk EX Coupe]

Are you sure its a gear related issue or speed? If it only happens around a certain speed then it might be a wheel balance issue like evil demon said.

[Punkrampant]

Sounds like Driveshaft or yoke.

[Brandoncb7]

Moved to other automotive.

Sounds like a wheel imbalance, get the wheels rebalanced.

Are you sure its a gear related issue or speed? If it only happens around a certain speed then it might be a wheel balance issue like evil demon said.

I'm not really sure because he lives out of state and I haven't personally ridden in it. I've had one of my wheels get out of balance before and it did this exact same thing but he's saying he just got new tires put on and didn't think it was that. They could have messed up balancing them though and it would do it. He could just be hitting a certain speed if he's driving it the same way and that just happens to be the same time he goes into fourth. I wonder what it would do if he took it up to 65-70 mph in third.

Sounds like Driveshaft or yoke.

If that was the problem though wouldn't it be shaking all of the time?

[evil_demon_01]

One of the balance weights could have flicked off when he drove off down the road.
Tell him top get them rechecked, Its cheap enough to have done.

[Punkrampant]

Not exactly, I had a similar problem with my Nissan pickup. They are resonance dampened from the factory and after many years of driving and rust the frequency and balance changes causing vibration. Mine in particular vibrated at 40-45 kph, and again at 75-80 kph.

It is a possibility along with unbalanced tires, out of round tires, bad u-joints, hanger bearing, or rear wheel bearings.

It sounds like it is a drive line problem, but I cant say for sure.

Best bet is to get up in the air and see if there is any play.

[Brandoncb7]

I read up on this today and from what i've read so far it won't be too bad of a fix. So far it seems to be one of these: center bearing, dented or unbalanced driveshaft, bad u joints, companion flange, or something is loose. My cb isn't in that great of condition so either way it won't matter as far as I know so far. I think we are still going to go ahead with the trade. He's going to try and get it in the shop tomorrow and if not then, then sometime this week. I'm hoping it won't be too bad of problem because I want that car. It's the twin cam 93 coupe. It's no sr20 but I could care less. The motor that is in it with boost on it made more than the sr20 did anyways. Either way I want the car and hope it's an easy fix. Thanks for all of the help everyone. I still want to figure this out. Oh yeah it said that one of the weights could have come off also so you guys were right about that one too but without the car here I can't check all of this. This sucks lol.