Differential top bolt REMOVAL

[BlakeJ]

I'm removing the diff on my 2017 Duratec Caterham with the BMW diff/cage in order to install a new one (with a Tracsport LSD inside).

 

All went smoothly, but the top long bolt won't come out. The nut came right off, but the bolt only twists a few degrees, as if it's attached/seized to the rubber bushing. I've hammered on it, I've put an impact wrench on it, I've put PB-Blaster on it; it won't move or rotate (more than a few degrees).

The interwebs have suggestions for installation, but removal doesn't seem to give people issues.
I've put pressure from underneath with a floor jack, too. I can still see the copper slip used when installing it... 

 

Any suggestions?

[KnifeySpoony]

Apparently a common issue. There's a few threads on blatchat and this one just recently on pistonheads: https://www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=2032116

[BlakeJ]

Thanks, Knifey Spoony! I will try a home made pusher/puller, as suggested in your attached link.

[KnifeySpoony]

I'll be honest, I'm not sure how to rig such a thing up. Please post pics! 

[wemtd]

Apply a heat gun & time to warm things up & expand clearances ?

Edited April 30, 2023 by wemtd

[MV8]

If the heat gun is not enough, drill the rubber all around the bolt head until the rubber will tear when you torque the bolt. An impact is only effective over very few degrees of rotation (also why drive extensions don't work with an impact). Use a six point socket and 1/2 inch drive breaker bar and if you have room, a short piece of gas/black steel pipe with an id a 1/2 inch larger than the 1/2 inch breaker handle.

 

I always use anti-seize or wheel bearing grease on bolt shanks, especially extra long shanks like this one.

 

I have some suggestions if the bolt shank is actually seized to the cage.

[BlakeJ]

Got it broken loose with a 4 ft jack handle extension over a breaker bar. Oy. Thanks for the responses, all!

Now the measuring must ensue, as the new diff/cage presents as a few mm narrower than the original. 

I'll report on how the Tracsport diff feels after some use.

[IamScotticus]

Pics of the diff swap!

How long will your break-in be?

[BlakeJ]

Didn't take pics. Too busy cursing.

A few hundred miles to break in, from what I understand.

[BlakeJ]

Tracsport LSD is in!

Initial impressions are very good, but it must be noted that:

 

a) Steve Perks (the diff builder) recommended a few hundred miles before doing donuts (really), and

 

b) my old Titan LSD (actually not old... new in 2017/18 and only 20 or so track days on it) was not operating, so any LSD would feel like an improvement.

 

I was pleased with Steve's service, and look forward to putting many track miles on the new unit.  It defintely feels more flickable and controlled when sliding;)