View Full Version : RV8 Spigot bearing

01-06-03, 07:52 AM
Hi folks,

I have a RV8 and the engine number traces it back to a SD1 with manual box,

I have completed a re-build and it is ready to go. The gearbox I have is a late 'd' type LT77 acquired seperate to the engine.

On measuring the diameter of the primary input shaft of the box this measures 10mm, when measuring the innner diameter of the spigot bearing this measure 13mm. Does anyone know if this is ok or could it be that I have a spigot bearing for an auto in the engine, even though the engine was originally fitted to a 5 speed box.

Also just to complete my knowledge, could someone tell me what the spigot bearing is there for



' and it was going oh so well '

01-06-03, 12:49 PM

This has been covered before. Try a search on "spigot bearing" and you should find the info.

01-06-03, 12:56 PM

see attached pics.

Manual and Auto spigot bearings are very 'obviously' different.

Spigot bear supports the input shaft and holds it inline with the crankshaft. It also reduces wear on the intermediate bearing between the gearbox input and output shafts, which in an LT77 is a small taper roller bearing not designed to run 'out of alignment'.You must use a spigot bearing of the correct diameter in the crank.

If your input shaft really is 10mm dia, then it could have been ground because of previous wear (unlikely - not being rude but how did you measue it?). If it is, you'll have to get a bearing machined up from phosphor bronze to the correct dia for your shaft.


01-06-03, 04:35 PM
thanks russ

looking at the pictures I definately have a manual spigot bearing, so now I need to measure the input shaft acurately,

thanks fo rthe advise


01-06-03, 08:09 PM
Just measured bearing and shaft on my manual SD1 engine, both are coming out at 12.7mm according to my verynear.

03-06-03, 10:35 PM
Thanks all for the replies.

Checking the input shaft nose this measures to spec but measuring the part of the shaft that mates with the bearing this is nearer 10mm so off to the gearbox doctor I go - will report back soon,

bloody anoying given I paid a fellow fake snake charmer on this forum 300 for the 'box, talk about buyer beware !!!!!!!!

(Ian you know who you are !!!!)


'and it was going oh so well'

06-06-03, 07:33 AM
Now back from seeing Dr Gearbox and I now have a luverly LT77, the chap sorted the Input shaft problem and whilst he was at it replaced a worn selector fork, seals and a worn bearing.

If you are in yorkshire then this chap is in Leeds, contact me if you need detials of a gearbox doctor