Strange noise from my SC after box rebuild- please help!

[jph83]

Right, put my engine and box back in my '83 (euro) SC sat morning and now there's a noise that i can't identify. Here's the situation.

Dropped the eng + box for a box rebuild and LSD install, refitted them after the box work and everything was fine except can't get 2nd gear. Spoke to the box guy, tried all the usual things but ended up dropping the eng + box again and sent the box back.

Got the box back friday so refitted the eng + box sat morning. I can get all the gears now- great- but there's a strange noise which appears to be coming from the opening at the back of the 'tunnel' where the selector shaft meets the gear linkage.

It's a sort of a metallic rubbing / scraping sound but it isn't constant and there is no pattern to it. It seems to randomly get louder or quieter for no reason.
It only happens when you are moving (above about 10mph) but isn't affected by road speed or engine speed. It happens in any gear or coasting in neutral, it doesn't make any difference if you are braking or not, or if the clutch pedal is up or down. It becomes more pronounced when turning left and almost dissappears when turning right.

The car has only done about 2000 miles since a total rebuild with new brakes, wheel bearings, bushes etc.
All i did between no-noise and the noise appearing are the minimum jobs necessary to get the engine and box out, i haven't touched the exhaust or rear suspension at all (except the a/r bar).
So far i have checked driveshafts/cv joints, antiroll bar mounts, engine mounts, rubber seal in engine bay incase it was the tinware touching the body. Checked- gearbox oil level (swepco), clutch cable, gear linkage, throttle linkage.

I can't think of anything else to try short of dropping the eng & box out again. I've run the car up to triple figures and nothings dropped off, and the noise has remained the same.

Is there anything the gearbox guy could've done when fixing the 2nd gear selection problem which might cause this random noise?

I know it's almost impossible to diagnose without listening to it yourself but i would be gratefull for ANY suggestions as to what it might be.
Thanks in advance, Jon H.

Please help me.... it's driveng me mad and it's holding up my 3.6 conversion!

[jph83]

Come on guys, nobody got any ideas at all??

Jon H

[dean]

Wow that is quite the noise. It is very hard to diagnos a noise over the internet. Is there any way you can drive the car to the tranny guy and have them listen to the noise?

[fintstone]

I'd look at the LSD install.

[AZ1977911]

Just a stab in the dark... Are you sure your ground strap is connected. Could it be off and flapping around.

[TerryH]

"It becomes more pronounced when turning left and almost dissappears when turning right."

I'm a greenhorn here. Only had my Pcar a week, but this symptom can be indicative of binding cv joint on most cars.

[jph83]

Dean- unfortunately the tranny guy is 6 hours drive away so i'd like to try and find the cause myself.

Flintstone- thats a good idea but i put approx 500 miles on it when it was first built with the LSD (and i couldn't get 2nd gear) and there was no noise at all. As far as i know the diff hasn't been touched when the 2nd gear prob was fixed.

AZ1977911- another good one... but i already checked that.

TerryH- I inspected and repacked the inner joints on saturday when the noise first started, and the outers weren't disconnected during the eng & box drop.... but it could be them.

Thanks for the ideas guys, i've decided to get the car up on axle stands with the engine running and in gear and see if i can identify where the noise is coming from. If this doesn't work i'm gonna drop the eng & box again to see if i can find anything amiss.

Thanks again, and if any of you gearbox experts are reading this, is there anything they could've done when fixing 2nd gear that could cause this noise, yet allow the box to function perfectly in every gear?

Regards, Jon H.

[jph83]

RIGHT!
Just had the car up on stands, engine running, in all the gears.
The noise is definately coming from the gearbox, and from the input shaft end. No noise back in the diff area at all.
The noise is not directely related to engine or road speed but does alter in sound as the revs rise and fall.
This is the interesting bit.... Only happens in 1st 2nd 3rd & 4th. Doesn't seem to occur in 5th or reverse at all (i'm just about to go road test the car to double check this)

Is there an idler gear for 5th & reverse that is free to rotate when in gears 1,2,3 or 4?

If so would this have been touched while the 2nd gear prob was being fixed? Should it be shimmed to remove any free-play on the shaft? Could it have been assembled incorrectly and is now causing this noise while in the first 4 gears but stops when meshed with another gear in 5th or reverse??

Gearbox gurus please comment!

Regards, Jon H.

[jph83]

Just got back from the road test, the noise is clearly audible in the first 4 gears, but nothing in 5th or reverse. But the whine you get in reverse gear does seem to be much louder than i remember before this problem appeared.

Needless to say i will be ringing my gearbox man first thing in the morning, but if any of you have any comments regarding my diagnosis please post!

Thanks, Jon H.

[88911coupe]

This is of no help but your problem sounds similar to the issue I have on my 88 (yes, G50, I know but it sounds similar)
I get a whirring sound (almost siren like) when slowing down and being in or out of gear makes no difference and depressing the clutch makes no difference. I can't say turning has any sort of substantial effect but it does disappear around 20 mph. My next attempt at diagnosis will be to put in on jacks and then get the drive train up the 30-40 mph.
FYI, I have done no driveline work on the car.

[john walker's workshop]

the 5th and reverse shift sleeve (slider) is probably adjusted improperly so the outer teeth on the sleeve are ticking on the teeth of the reverse idler. the noise goes away when you shift the sleeve into 5th, which moves it away from the idler, and when reverse is engaged, which totally engages the idler. the cure is to remove the end cover and adjust the fork position to allow more space between sleeve and idler. there is also a flat thrust washer between the idler and end cover that is sometimes forgotten, allowing the idler to move in and out and cause the same symptom. either way, you'll see it when you're in there.

[Jim Sims]

"Ensure the the 5th/reverse speed selector shift fork rod is in neutral position (rearmost detent groove in rod under the detent in the gear housing). The idler gear should then be pushed rearward against the fixed 5th speed gear (the one on the input shaft). Then the 5th/reverse speed selector shift fork is pushed forward against the 5th/reverse sliding gear (operating sleeve) removing all play between them in the forward direction. Move the fork and sliding gear clamped (by hand) together to obtain .040" or 1 mm axial (front to rear) clearance between the straight gear teeth on the idler gear and the straight teeth on the sliding gear. Then while holding this position the 5th/reverse speed selector shift fork clamping bolt should be "snugged"; the .040" clearance should be rechecked and if correct the clamping bolt tightened to 18 ft-lbs." Jim

[jph83]

Buck good luck fixing your problem, i know how infuriating it is not knowing whats causing it!

John thanks for the advice, i will suggest this to the guy who rebuilt the box. If i were to undertake this repair myself would i need any special tools, the gearbox guy is a 6hr drive away so if it's a straighforward job i'll have a go myself.

Regards, Jon Hawkins

[jph83]

Thanks Jim, sorry i was replying while you were posting! By the sounds of it i should be able to tackle this job myself.

Regards, Jon H

[Jim Sims]

Spanners and sockets (13mm if I recall correctly), feeler (thickness) gage and a torque wrench (could likely do without). May need add'l gear oil and perhaps a new paper gasket for the joint between the front cover and gearhousing. I do believe you will need to drop the engine/transmission assembly to do this. The transmission may be left attached to the engine. Be aware of items (thrust washers) stuck in the oil on the inside bearing surfaces of the front cover. Jim

[jph83]

Thanks again Jim.

Jon H.