Jump to content
neilstockton

Series 2a Gearbox Rattle

Recommended Posts

Hi all, 

Some advise please on some interesting transmission noises if you don't mind.

Series 2a 88, 3.5 flapper, suffix D gearbox, 3.54 Range Rover axles

Initial problem - Rattle / classic marble noises / chattering present when accelerating in 2nd gear, all other gears had no noise present when selected. Noise present in 2wd and 4wd, low and high ranges. No issues with selection in any fwd / reverse gears, no slipping out of gear on overrun, No whines or other rumbles, oil condition good (no swarf, bad smell, discolouration) in both gearbox and transfer box. 

Noise not present in neutral, clutch depressed or up, or with high, low or neutral selected. Rpm change would not produce any noises either.

Upon investigation the main-shaft nut was loose by 1/2 turn, installed new nut and locking tab, torqued, noises still present. Decided to remove the transmission and strip / inspect. 

Results - First motion shaft bearing race had collapsed, thrust bearing was noisy when spun, 3rd/4th syncro hub had some slight wear present, everything else looked acceptable. Reassembled everything with new parts as listed above. Set the pre load on the output shaft bearing with new shims.

Test drive - Now rattling in every gear under acceleration, noises diminish with higher rpm / reduction in load. 1st gear whines more than I remember. From what I have now read in other posts Layshaft bearings can give trouble, should have replaced these I know but hind sight n all. Any chance this could be output shaft bearing related? ie. re adjust of pre-laod?

Next step prop-shaft removal for front axle for UJ inspection but any other advise would be appreciated.

 

Thanks

 

Share this post


Link to post
Share on other sites

A layshaft bearing issue should be present in 1st, 2nd and 3rd but would likely be absent in 4th if you don't get noises when running those gears with the transfer box in neutral (ie. no significant load on the lay shaft).  If 4th makes the same noises as the other gears, I'd suspect the main shaft more.  You are certain it's the gear box, not the clutch or transfer box, though?

The gear box has no thrust bearings as such, just the lip on the big bronze bush between 1st and 2nd and the steel bushes for 2nd and 3rd.  I can't see how they could be noisy when spun.  Can you describe which bearing you found noisy when spun?

The lay shaft rear bearing is pretty small and can cause trouble.  The front bearing is more substantial and less likely to cause trouble. It is possible for the bolt through the front bearing into the lay shaft that holds the shaft in place longitudinally has come loose, allowing the shaft to slip fore and aft.  That could make the noises you describe, including increased whine in 1st.  If you do reopen the unit, it is certainly worth replacing that rear bearing, though.

It'd be worth checking the main shaft end float and the end float of the gears through the top covers first, before you remove the transmission, and you may be able to check for end float on the lay shaft (there shouldn't be any) through the drain plug.

Prop shaft issues will tend to be road speed related, not engine rpm or gear specific, but can cause the knocking sounds or tinkling.

Share this post


Link to post
Share on other sites

Definitely could be transfer box related but I also didn't replace anything in the there, just stripped and inspected. Now the noise is worse it makes me think its not this.

Would your thinking for clutch be related to the pressure plate or something else in the assembly? The noisy bearing when spun was the clutch release bearing in the clutch withdrawl mechanism. 

The layshaft has a castlated nut with split pin instead of the bolt but definitely remember torquing this. 

There is some end float on the main shaft, the nut is tight and locktab in position but theres definitely some movement. Approx 1mm. With the top cover off (for a visual to the main shaft nut) I was able to get a feel for backlash with each of the gears engaged (transfer box in neutral). Whilst chattering the rear most main shaft gear back and forth by hand this certainly sounds like the noise I'm getting whilst on the road, only louder. The most movement with 2nd engaged, the least with 4th. 

I would now say the noise is present with the transfer box in neutral and gearbox in either neutral or with 1st through 4th engaged, not as previously stated. It's faint, but the same noise I believe, and can be heard when blipping the throttle from idle. Once warm I cant get this to happen. Prior to the first road test I had let everything warm though for a good 30 mins on the driveway (a lot of other things have been done).

May be a week or so before I can check the other end floats but thanks for the advise.

Share this post


Link to post
Share on other sites

1mm of end float on the main shaft is excessive, so it sounds like the rear bearing is worn out.  Whether that is the source of the noise is unsure, though - a rough clutch release bearing could make all sorts of horrible noises.

Did you lock the lay shaft nut with a split pin or thread lock compound?  It's unlikely to have come loose so fast even if you didn't, but it'd be worth doing next time you're in the bell housing.

Share this post


Link to post
Share on other sites

Not looking particularly healthy thats for sure, I'll try and do a proper measure up just out of curiosity. 

Thought I was onto the noise by the state of the pinion bearing, and with the thrust bearing in the mix this would have only added to things. Layshaft nut was torqued and split pin installed.

Looks like its coming out again at some point, will replace all the bearings this time and throw in a clutch for good measure.

 

Pinion Bearing.jpg

Share this post


Link to post
Share on other sites

Yep, that'd make some noise for certain!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy