11 replies to this topic

[Peter_NottinghamS]

I've spent some time underneath Marvin today and I have two issues.

The exhaust is blowing at the Y-joint (the pictures shows the leakage) and although the exhaust still seems stable there is no attachment/bracket securing the exhaust system.

I've identified a bracket - Exhaust to Gearbox (1985 on) Manual (part number GEX7526) but can't find an image of such a bracket is attached (to the gearbox) and to the exhaust.

I've spent 20-minutes searching the topic on the forum but I can't find a suitable answer.

Does anyone have an image or advice?

Also, while underneath, I identified the gear change rod has lots of play where the 'bayonet' style joint where it connects to the gearbox.

Gear changes seem okay but I suspect it has far too much play.

Should this joint be loose and sloppy? I suspect not.

Thanks in advance.

Peter

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Edited by Peter_NottinghamS, 20 April 2025 - 08:05 PM.

[nicklouse]

Pipes not pushed in far enough. Don’t bother with any bracket there are they are gearbox wreckers. But if you must replace the bolt with a longer stud as the bolts are not available at a suitable length.

 

gears. The roll pins connected sleve? Yes they can be loseish. Not much you can do.

[Steam]

With the gear linkage, given what a PITA it is to drive out the roll pins , I would suggest you leave it be for now and do some research on the better options for the pins. I make my own system but you can decide on your best fix so when the gearshifts become troublesome you have a plan ready to go.

[Chris1275gt]

I bought one of these and found it very good. Saves distorting the seal in the box when beating the roll pins in.

https://www.minispar...lector-coupling

Edited by Chris1275gt, 20 April 2025 - 09:39 PM.

[Spider]

Bolting the exhaust to the gearbox only pulls the threads out of the gearbox. Not a good idea at all.

[Peter_NottinghamS]

Thanks for all the replies.

Great advice. I appreciate it.

Peter

[coopertaz]

Bolting the exhaust to the gearbox only pulls the threads out of the gearbox. Not a good idea at all.

but running without it, i found, the y pieces of the lcb tended to split near the bulkhead, budget with triangular box section the worst but even more expensive ones failed. Renewed engine mounts, exhaust mounts and fitted many engine steadies but only fitting this bracket prevented it. Yes you do need bolts slightly longer or you will pull the threads

[Cooperman]

On my rally cars I find that unless I fix the exhaust pipe(s) to the gearbox the exhaust eventually cracks due to the silencers hitting the ground and putting a shock bending load at the exhaust bend, where the Y-piece sits. In fact, the first time it happened to me was in 1965 on my first 998 Cooper when the pipe fractured and the front of the exhaust pipe dropped onto the road!

In fact, the cars with the aluminium remote gear change had a tapped 5/16" thread in the remote housing, but it was difficult to access when using a modified system. On my cars I make up a plate which attaches to two of the output shaft cover plate bolts. then I Helicoil the threaded holes and use slightly longer bolts. I fit the bolts with Loctite and have not had any issues and I have never had any exhaust issues on a rally in many, many years.

In aircraft engines it's usually mandatory to fit 'thread wire inserts' in any threaded holes in aluminium castings.

[Gaz66]

I used to have lcb breakages until I fitted the auxillary thermostat housing steady.
Never had a breakage again and no gearbox exhaust bracket.

[Cooperman]

Yes, I also have an 'Ultimate Engine Steady' as well.

[Gaz66]

On my cars I make up a plate which attaches to two of the output shaft cover plate bolts

I always thought that's where the factory bracket fitted?
It's the only exhaust/gearbox bracket I've ever seen.
This one.
https://www.minispar...-larger-version
So which threads strip?
I take it a bracket is fitted to the diff cover studs and it's those that strip?

Edited by Gaz66, 22 April 2025 - 08:32 PM.

[Lplus]

 

On my cars I make up a plate which attaches to two of the output shaft cover plate bolts

I always thought that's where the factory bracket fitted?
It's the only exhaust/gearbox bracket I've ever seen.
This one.
https://www.minispar...-larger-version
So which threads strip?
I take it a bracket is fitted to the diff cover studs and it's those that strip?

 

It's the diff cover studs that strip.  The torque on them isn't that much and the stud length isn't really enough when the bracket is fitted.  I made up an extra "ear" for mine which goes under the lower right hand diff housing 3/8" bolt/nut and is welded to the bracket to give extra support.  The loads are push/pull on the big stud/nut instead of shear on the diff cover studs.  so far so good.  (Touches wood...)