Swapped gearbox and now car shudders.

[nile]

I had a C52 in my ae82 fxgt which started dropping 4th and 5th gears, so I got a 2nd hand box from trademe and put that in, I also took the clutch off to inspect the clutch disk.

Since putting the 2nd hand box in and the clutch back on the car has started to shudder, mostly noticeable around 700-1300RPM. Also this gearbox whined really loudly, so I put the old one gearbox back in.

The whine went away (so much for the box I got off TM being "mint"). The shudder is still there though. So I took the box off and checked the pressure plate was not orientated to be off balance or anything, and checked the disk was centred (used some PVC conduit, not a proper centring tool) and put the old box back on. It still shudders. Also when putting the cross-member on it is tilted down towards the passenger side slightly, but the bolts are fully done up, the movement is from the rubber mount thing where it bolts to the front of the chassis.

So I have come to the conclusion either something is wrong with my engine, clutch, or flywheel?

Any help would be greatly appreciated, this is driving me crazy!

[Mr Revhead]

Buggered mounts? Did you bend the crossmember somehow?
Did you change any of the bolts or studs on the mounts?
One I did once I used a bolt that was too long and under load it would hit the box causeing a vibration.
Or possibly an inner c/v

[nile]

Buggered mounts? Did you bend the crossmember somehow?
Did you change any of the bolts or studs on the mounts?
One I did once I used a bolt that was too long and under load it would hit the box causeing a vibration.
Or possibly an inner c/v

Thanks for the reply.

Mounts don't look worn or anything, the steel is pretty thick on the mounts so I doubt it's bent. I also don't think the crossmember would be bent cause it's pretty stiff? Would any of that stuff cause vibration, as the box is still bolted hard up to the box, all to the same torque.

I'm using all the original bolts (apart from on the lower bellhousing cover, which wouldn't cause any vibration.

Not a CV problem as the vibration is consistent, whether stopped/moving/gear/neutral/declutched.

[Mr Revhead]

Also when putting the cross-member on it is tilted down towards the passenger side slightly

Thats why i mentioned the crossmember....

[nile]

Also when putting the cross-member on it is tilted down towards the passenger side slightly

Thats why i mentioned the crossmember....

Do you know of any reason why that would cause vibration though? I can't, which is why I asked.

[Mr Revhead]

Well if it was bent and causing the mounts to be twisted maybe?
It may not be the cause, but there is definitely something amiss if its like you say it is

[crispy'86]

Or the mounts haven't been "centralised" after putting the replacement box in, what way did you tighten up the bolts, just put the mounts on and tighten with out anything supporting the weight of the box? I had that trouble once with putting a box into my race car, turned out the front mount was slightly twisted causing the front mount on the radiator side to rub on the bracket. I supported the box, loosened the bolts and re tightened. Noise went away

[nile]

Or the mounts haven't been "centralised" after putting the replacement box in, what way did you tighten up the bolts, just put the mounts on and tighten with out anything supporting the weight of the box? I had that trouble once with putting a box into my race car, turned out the front mount was slightly twisted causing the front mount on the radiator side to rub on the bracket. I supported the box, loosened the bolts and re tightened. Noise went away

The box was supported by the top/end mount up onto the chassis rail by the battery. Then I did the 2x mounts to the crossmember, then did the rear crossmember mount, then the front. The front one didn't line up (was about 40mm towards the passenger side) so I used a ratchet tie and pulled it into line then bolted it up.

Another thing my friend suggested was that while having the engine dipped to put the box in one of the pulleys could have touched the chassis rail and bent a bit. The P/S pulley looks to vibrate more and out of time to everything else so I am going to try taking the PS/AC belt off and seeing if the problem goes away. However it does seem like I've done something wrong with putting the mounts on the box/crossmember.

[ee80turbo]

It sounds like your gearbox mounts aren't installed correctly.

I have had problems where I got the front and back mounts mixed up before, they are stamped on them directional arrows (face forward I think).

Make sure you have the cross-member around the right way too, although I think it only can fit one way.

[crispy'86]

I always support the gearbox with a jack under it before tightening up the bolts part of the way, makes it easier to line up the bolts/mount better.

[Vertigo]

Do you mean the lurching at <1200rpm? Ive had that in every A engine car Ive had, most noticable in first and second gear.

[nile]

I always support the gearbox with a jack under it before tightening up the bolts part of the way, makes it easier to line up the bolts/mount better.

I jack the box up to get the mount on the left chassis rail done up but from then on I just leave the mounts to hold it up.

Vertigo, nah it's a constant shudder up until about 1300.

[whynot]

i found a similar problem when we bent the flex plate on an auto trying to put it together in a not so gentle manner, did you have any problems putting it back together? could you have bent the fly wheel (is that even possible??) it wouldn't take much to cause vibrations given the mass and the speed it is spinning.

[fangsport]

do the FWD boxws have a lower brace on each side??

i was lazy and never fitted to a RWD (even after being told one must do so), and made the flywheel bolts stretch due to bellhousing flex. it did shudder a wee bit................. before the flywheel came loose

[Dell'Orto]

i found a similar problem when we bent the flex plate on an auto trying to put it together in a not so gentle manner, did you have any problems putting it back together? could you have bent the fly wheel (is that even possible??) it wouldn't take much to cause vibrations given the mass and the speed it is spinning.

You'd have to be superman to bend a flywheel Clutch plate however...quite common, and will make for a juddery take off.

[nile]

You'd have to be superman to bend a flywheel Clutch plate however...quite common, and will make for a juddery take off.

Maybe I bent the flywheelt then

I'll try unhooking the ps belt and see if that fixes it, and check all the mounts (not too sure what to look for apart from visible damage?). After that I guess i'll try a different clutch.