Gearbox information on S4

[tyasman]

I have a '68 S4, and have just developed a strange gearbox noise. It is a hissing sound, which disappears when I put the clutch in. I am advised it is a "thrust race". Not knowing much about gearboxes, can I please ask
1. Is the diagnosis correct?
2. Is it serious?
3. Will it break, causing damage, or just get worse?
4. What is involved it mending it? I assume the engine and gearbox have to come out. If this is so, I may change to a 5 speed box - which is the best to go for?
5. What other work should I consider while the gearbox is out? I am also considering changing to solid drive shafts and hear that Susan Millers are the ones to go for.
Lots of questions but I would be glad of members views as I am taking the car to the continent in July and want to come back in it, not in the passenger seat of a recovery vehicle!
Thanks in anticipation
Simon

[elans3]

Hi Simon, your answers in order :-

1. The diagnosis seems correct, it sounds like the clutch release bearing (thrust race). The only other possibility is the spigot bearing spinning in the end of the crankshaft. Without hearing it it is difficult to tell, but more likely the release bearing.
2. No it's not serious, but it's a very annoying noise....
3. It won't break if it is the thrust bearing.
4. Definitely eng and box out. Why would you want to go for a five speed box ? Are you going to be doing long, regular motorway journeys ?I know you're going to the Continent, but will it be a rare trip ? If so, you ought to think of fitting a 3.55 diff instead.
I say that because the Lotus (Austin Maxi) box is not good. You lose that rifle bolt precision of the 4 speed, (in fact unless you get a particularly good or rebuilt Lotus 5 speed, they can be awful). Other makes are not a straight fit, and unless you're good mechanically, then you'll struggle or pay someone a lot of money for them to take the pain.
5.Solid drive shafts definitely a good idea, either Sue Miller or Tony Thompson Racing, I've used both and they're very good.
Hope that helps
elans3
Steve

[tyasman]

Hi Steve,
Thanks for your reply, plenty of food for thought. I see in the handbook that the 2 diff. options are 3.55 and 3.77. I assume I have the lower geared of the two. What revs should I be doing in top gear so I can check, and if I change how much difference will it make to top gear when cruising? It's certainly a much cheaper option than changing the box, and I'll take your advice about leaving it alone. I think I'll also put up with the thrust race noise for a while as long as it's not going to disintegrate and leave me stranded. Last question - honest! Where would be a good place to get the modified diff.gears or can any Lotus Garage do it? I'm about to take the little car into Chris Foulds near Wakefield, who knows his stuff.
Thanks
Simon

[steveww]

The difference between a 3.55 and 3.77 diff is 6%

Thus if the engine is spinning at 4500rpm @ 80mph fitting the 3.55 diff would bring that down to 4230rpm or give 85mph for the same rpm. Not that much in it really.

[ianf]

Not much in it but having had a 3.55 and then having had a 3.77 fitted "mistakenly"when it broke, the difference is quite noticeable. Apart from the top gear cruising being a bit more frantic I found my car lost much of its 3 gear range and therefore a bit of the mid range fun. I will put a 3.55 back in when I have the time/ cash!

Ian

[elans3]

You can hunt for a pukka 3.55 from an Elan, or you could fit a 3.54 from an Escort RS2000 mk 2, the latter are far easier to find.
It really does make a difference, I've changed to this diff on two of my roadcars, and it does make for more relaxed cruising.
Look in Ebay at RS2000 differentials in the classic car section, and also under the Car Parts section. You're looking for an "English" diff, 3.54 RS2000 Mk 2.
Hope that helps
Steve
elans3

[tyasman]

Thanks for replies