Bang/clonk noise, followed by no drive

[Rich135]

Hi All

I would appreciate any guidance before I get under the car and start taking things apart.

Just as I was pulling onto a roundabout, letting the clutch out in 1st gear (not a racing start or anything silly) I heard a bang/clonk noise underneath and I lost all drive. I let my 12 year old son steer while I pushed the car to the side of the road (he loved that!).

Luckily I was close to home so a couple of petrolhead neighbours came and pushed me home, and after checking, the clutch and gearbox are fine, as the propshaft is still spinning into the rear diff, but neither rear wheel has any drive. There aren't any strange noises coming from any parts (diff or rear drive shafts).

Where should I start? I am assuming the rear diff has a problem, but if a drive shaft had gone on one side would that cause me to lose power to both rear wheels? I believe I have CV joints, not donuts.

Many thanks for any help.

Rich

[rgh0]

Most likely a broken diff output shaft. if one breaks inside the diff which is common on pre 1970 cars then you loose drive to both wheels unless you have a LSD

cheers
Rohan

[gus]

yup diff output shaft, I see a diff removal in your future. You should replace both, clean the little shaft bits out, bearings, seals, off you go.

[Rich135]

Thanks both. After doing a bit of research on here, I tend to agree with you both. My garage is too small for me to jack it up in there, so I will do that outside when I next get a chance and check by spinning one wheel at a time first, then see if the other spins.

I will replace both if only one is broken. Good winter project

Thanks again.

[Coupe]

Same happened to me - replaced with TTR steel billet shafts.

[Rich135]

Thanks Coupe, I will look at them when I rebuild, even if that isn't the problem.

So far I have the CV joint off of the drivers side shaft and the shaft spins and sounds like it's moving cogs inside the diff casing. It won't pull out either, so I am guessing that one isn't broken (yet). i will try to do the passenger side next week days (won't get a chance over the weekend).

Rich

[gjz30075]

It won't come out until the big circlip is out. Even then, it may take a puller of sorts to pull it out, due to
bearing fit.

[Rich135]

Ah, ok thanks Greg, I will clean it up and see if I can find the circlip.

[RichardHawkins]

Rich,

Do make sure you clean the diff case and components thoroughly. You don't want bits of shrapnel left inside to ruin the gears and bearings. When I took my diff apart there were bits of debris left from a previous failure which may have accounted for the premature wear of my crown wheel and pinion.

Richard Hawkins

[gus]

Coupe that is an atypical break

usually they break where the splines leave the diff

that also appears to be a 'fat' shaft which usually do not break

[rgh0]

Coupe that is an atypical break

usually they break where the splines leave the diff

that also appears to be a 'fat' shaft which usually do not break

While the break at the radius of the shaft to the outer bearing is less common it does happen . The failure where the spline leaves the diff is most common and twisted splines at this point can be observed in most pre-1970 cars with the original early shafts even if they have not progressed to failure yet.

I have had one of each type of failure in my Elan until I got better quality billet shafts fitted back in the early 80's

cheers
Rohan

[Davidb]

How often do the outer 'spindles' break? On a road car?

[Famous Frank]

The outer axles break right after you say they never break.

Actually, I have seen the outers break only once on a road car that had skinny no grip original type of tires. Once you put sticky tires on or head to the track for a few hot laps, your percentages go way down.

Frank

[seniorchristo]

Gus
I don't think that is a "fatter" shaft. It looks like the splines taper down to the shaft. "Fatter" shafts ,as shown on the right, have shaft diameter the same as splines.

[alan.barker]

It seems with CVs it's a good idea to have the latter shafts. This could be a plus for running rotoflex
Alan