gearbox rattle

[Pat]

Hi All,
I bought a 1977 TR7 FHC in June 2009. Apart from some water leaks to the drivers area, a fantastic car & pictured in the club mag last year thanks to Val who was invaluable before and after purchase.

Shortly after purchase, I noticed a rattle/vibration which disappeared when the clutch was pushed to the floor. I ignored it and garaged the car for that bitter winter we had and the duration of a neck injury I sustained. The car is back on the road since the end of April but the rattle has got a little worse. Took it to local mechanic (a stag owner) last week (unfortunately my expertise is still limited) as I thought it might be clutch release bearing. He says it's in gearbox - bearings or layshaft and says I should stay driving until noise gets worse or I have problems engaging gears. Gearbox rebuild and new clutch (seeing as gearbox will be out) will cost nearly half what I paid for car. Should I wait for gearbox to give trouble as he suggests or bite the bullet now ?

I would gratefully appreciate the opinions of the expert and experienced TR7 owners.

Regards,

Pat
(In Ireland - so all parts have to be imported - an additional factor when assessing costs)

[Hasbeen]

Pat, first of all, welcome to the mad house. There are a couple of things I would suggest you look at, before undertaking any large expenditure. Before you start go to jclay's sight, & download the relevant workshop manual info.

1/. Have a look at the gear change extension mounting bushes. There are a couple of good photos of this on here by Jclay. If these are shot, & they all are if they have not been replaced, the extension can drop enough to rub on the tail shaft.

Try lifting the gear stick, an inch or 2, & see if the noise goes away. Probably should replace them, unless you can see they are new ones.

2/. Check the gearbox/rear engine mount. These tend to get oil soaked, & turn from firm rubber to something like black jelly, & about as much use for supporting the gearbox.

While you are there at the gearbox mount, also check that there is a round steel spacer, about 2 inches diameter, & an inch thick between the rubber mount & the gearbox. These have often gone missing over the years, as they don't look like they are part of the mount.

If either soft mount, or missing spacer occur the bottom of the box can/will sit on the sub frame, rather than be suspended above it.

When this occurs the normal gearbox noise resonates right through the body. This sounds as if the box is about to suffer immediate failure. I know of one instance when a 7 owner shipped his car over 1000Km, by train, to a Triumph specialist to have the gearbox overhauled, when all it needed was this spacer.

When working in this area make sure the 12mm bolt that fastens the box to the mount is long enough. These bolts are often lost & replaced with something too short. The first few turns of thread in the box are often damaged by this, & easily stripped.

Good luck, & happy crawling.

Hasbeen.

[Marko]

4 speed or 5 speed gearbox?

[TR Tony]

Pat, if you have the five speed gearbox then your problem sounds exactly the same as I have on my 81 FHC.

I bought my car with with 4500 miles on the clock, it had been parked up for 22 years. Even with that low mileage, ever since I have had the car there is a rattle that is quite noticeable at idle and which disapears when the clutch is depressed (i.e. the drive is disengaged from the box). Otherwise the gearbox works perfectly, smooth changes, no whines or cruches.

I have had two opinions on this "problem", both from trusted & experienced mechanics who know TR7s (one is a transmission specialist). Both have said it is the layshaft bearings, but it is not worth stripping down the box unless & until the noise gets worse or there are problems with gear selection. Very much like the advice you have been given.

I have had the car 6 years, I have covered about 15K miles in that time, including 2000 miles in 48 hours on the Club Triumph Round Britian Run! The extension mounting bushes & the box mounting rubber have been changed (which did improve the smoothness of the shift), I have changed the gearbox oil twice (once when I got the car & once last year), & the noise is the same, so I am just living with it.

I do notice the rattle more when the gearbox is hot, I guess that is simply due to the transmission oil getting thinner when hot.

So, do the checks that Hasbben suggests as they are worthwhile anyway, otherwise just listen to your car & be prepared to take action if things get worse.

Tony

<font size="1">1981 2L FHC Cavalry Blue
1980 3.5L V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">

[bmcecosse]

Since no-one else seems to have suggested it - check there is oil in the gearbox - in fact - change it for new oil!

[jeffremj]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by TR Tony</i>

Pat, if you have the five speed gearbox then your problem sounds exactly the same as I have on my 81 FHC.

I bought my car with with 4500 miles on the clock, it had been parked up for 22 years. Even with that low mileage, ever since I have had the car there is a rattle that is quite noticeable at idle and which disapears when the clutch is depressed (i.e. the drive is disengaged from the box). Otherwise the gearbox works perfectly, smooth changes, no whines or cruches.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">Ditto on one of my TR7s. It (5 speed) has been like it for years. Only occurs at idle.

[kstrutt1]

You are describing gear rattle, this is a common issue mine always did it with the 4cyl engine especially when hot, basically the loose gears on the main shaft resonate and rattle when excited by the engine torsional vibration. It's a common problem even more so today with the very thin oils used to improve fuel economy and usually addressed by fitting dual mass flywheels and / or damped clutches.

If you only use the car in the summer you may find reverting to EP80 gear oil instead of the thinner oils commonly used today helps (without affecting shift quality to much,changing the idle speed may also help, otherwise treat it as part of the character of the car!

[Hasbeen]

On thing I failed to mention in my info on the gearbox mount causing
a bad noise is, one symptom of this noise is that it disappears
when the clutch pedal is fully depressed.

The action of the clutch moves the box off the subframe, & the noise
stops, only to return when the pedal is released.

Hasbeen

[Pat]

Thanks very much for all your replies. I should of course have pointed out that it is a 5 speed box and I have the standard 2L engine (which was replaced by 1st owner in 1990 and recon. replacement had only 4000 miles on when I got it).

Interesting that the rear mount was suggested as a possible cause - when I got the car it was losing a small amount of oil from the gearbox and the rear rubber mount was saturated. I got a new rear seal and mount and had a mechanic fit them (not the same garage I went to this time). The leak stopped and I presume that he fitted the new mount.

I guess that it's time to find a dry day, dust off the axle stands and go for a crawl underneath to check things out.

Many thanks for your advice and I will let you know how I get on.

Regards,
Pat