Lotus Elan and Lotus Elan Plus 2 Forums

Hello all. I’m restoring my +2 and having taken the diff out the bolt holes in the case appear to have worn. Is this going to be an issue? Anything I can do? Many thanks.

dr_jayhart wrote:Hello all. I’m restoring my +2 and having taken the diff out the bolt holes in the case appear to have worn. Is this going to be an issue? Anything I can do? Many thanks.

Doesn't look too bad. Tidy up the bores, and make up and fit a pair of press-fit thin-wall brass bushings,

A word of warning - on the face of it that seems a good idea but I've seen that repair technique go horribly wrong. First you have to drill out the hole for the brass insert so you have less material left to carry the stress. The fit in old, probably crystalline aluminium is critical. Too tight when you press it in and tbe diff ear will split or break off. Too loose and the brass will fret the hole and you'll be in a worse position than you are now. You will need to heat the aluminium to get a tight fit but then you will need to check the gasket face for distortion. I would check the fit of the long bolts in the hole and get new spreader washers so that when you tighten the assembly through the frustacones the washers are supporting the bolts and assisting the aluminium. With old cast parts like these you need to take extra care.

If I remember correctly the long bolts are 3/8” diameter. In my case I used 10mm bolts to accommodate for the wear in the casting,

Hope this helps,

Richard Hawkins

If your +2 doesn't have a Diff Brace fit one. I have just fitted TTR heavy duty normal "frustacones" they do a nice job. When you fit the Bolts fit correctly from bottom or you will have problems with the Fuel Tank on a +2.
A little smear of Copperslip on Bolt shafts to stop corrosion/action with the alloy.
Alan

Don't put brass in aluminum. Electrolysis! will damage the aluminum.

Eric
64 S1

ecamiel wrote:Don't put brass in aluminum. Electrolysis! will damage the aluminum.

Eric

This would be good advice in a marine environment, where there is plenty of the necessary third partner, salt water electrolyte.

Galvanic compatibility had crossed my mind, but then I remembered that both the filler, drain, and breather plugs are all brass in an aluminium casting, and I have never seen any sign of corrosion in my 50 year old diff casing


I would very much second the fitting of a diff brace.

In the Diff Ears what's the clearance in the holes with new Bolts. They should be like fitted Bolts + a little more.
I would not want to enlarge the dia of the holes that's for sure.
They are already a design on the limit and fragile.
Alan

Forgive my ignorance how does the brace work?

dr_jayhart wrote:Forgive my ignorance how does the brace work?

A steel angle section ties together forces on the two 'ears' which are fragile extensions of the main casing, and also transfers some of the force to the iron casting of the diff nose.

The original brace has only one bolt connection to the nose, I have made up a brace which connects to three bolts.

Sounds like diff brace is the answer. I suspect they are not off the shelf?

Get a Diff Brace off the shelf from TTR
Alan

dr_jayhart wrote:Sounds like diff brace is the answer. I suspect they are not off the shelf?

Tony Thompson Racing :

https://www.tonythompsonracing.co.uk/pa ... brace-bar/

£25 ex. VAT. nothing wrong with that !

Col Croucher has a great video on a Diff brace on Elantrikbits.

jonesa62 wrote:Col Croucher has a great video on a Diff brace on Elantrikbits.

Found the site, but not the diff brace.

Do you have a link ?