Cat/downpipe to exhaust fixings

househead · October 19, 2019, 10:19

Anybody know what fixings I would need to swap out my cat/downpipe? Not the 3 amigos, got some of those in reserve, but the other end?

Petrus · October 19, 2019, 10:50

I am confused; I simply re-use the ´donut´ gasket and OEM bolts.
The important thing is that the decat pipe ´extends´ beyond the flange so the gasket gets compressed.
That donut gasket may be only thing you need?

Oh and do you have the O2 sensor extension?

wotugonado · October 19, 2019, 10:54

Cat to back box?

If so you can reuse those as long as the mesh conical gasket is OK.

househead · October 19, 2019, 10:55

It's actually a sports cat so I wouldn't need the sensor extension. It comes with a gasket for both ends, although it's a traditional flat gasket rather than a donut crush ring type one.

It's just the bolt spec I'm after ... afaik the current bolts are the same age as the car so firstly I'm expecting them to potentially be shot and considering I might need to drill one or both out, so be good to have stainless replacements on hand.

househead · October 19, 2019, 10:56

Quote from: wotugonado on October 19, 2019, 10:54Cat to back box?

If so you can reuse those as long as the mesh conical gasket is OK.

Yep, the cat to backbox ones.

wotugonado · October 19, 2019, 11:13

Well id bin off the flat gasket, the doughnut gasket are tried and tested.
They're pretty robust bolts to be fair, I've got some used ones I can look and see if the size is on them.

Edit:- nothing on the bolts but I had the bag with the reference on.

183819344770 put that into ebay

househead · October 19, 2019, 11:57

Quote from: wotugonado on October 19, 2019, 11:13Well id bin off the flat gasket, the doughnut gasket are tried and tested.
They're pretty robust bolts to be fair, I've got some used ones I can look and see if the size is on them.

Edit:- nothing on the bolts but I had the bag with the reference on.

183819344770 put that into ebay

Awesome thanks mate

househead · October 19, 2019, 21:58

It's the Malian sports cat I have, I'm not sure it will actually fit with that standard fitting kit. The pipe doesn't extend beyond the flange as @Petrus alluded to. It's just a flat finish. I'm I to use the flat gasket they provided? In their description they say

" Direct replacement and will still allow the car to pass a UK MOT, does not fit in exactly the same way as the OEM pipe.

The joint that has a ring gasket will be replaced with a solid joint. Will need an adapter if you want to keep the wire ring joint for fitting to aftermarket cat back systems"

Which is somewhat contradictory. I have the TTE exhaust although it might actually be the Remus (which I take to be basically the same thing?) it's stamped with Remus and has 06/06 on it, which if it's the manufacture date, is two years newer than the car and not fitted on purchase as I was led to believe by the last owner.

Gatouzze · October 20, 2019, 09:11

I also recently installed the Malian sport cat.

I used the OEM Toyota crush rings and donut gasket but it is not that easy to place them properly due to the flat flange.

And since I keep having a P0420 error code randomly but not sure what causes it... (Google says either exhaust leak, dead O2 sensor or dead cat...)

Regarding the installation you need the following item:
https://www.mr2-ben.co.uk/products/1175
https://www.mr2-ben.co.uk/products/1176

As the bolt is supposed to go directly in the back box you will need to buy a couple of nuts (not sure which one though as the kit I used was provided with the back box I bought...)

The 3 amigos (manifold to cat) should have been delivered with the cat but you can use the ones currently installed.

Piece of advise, use a lot of Plus Gas a couple of days before changing the cat as the bolts/nuts can be very rusty ^^"

Petrus · October 20, 2019, 10:01

Quote from: househead on October 19, 2019, 21:58It's the Malian sports cat I have, I'm not sure it will actually fit with that standard fitting kit. The pipe doesn't extend beyond the flange as @Petrus alluded to. It's just a flat finish. I'm I to use the flat gasket they provided?

Horses for courses.
The gauze donut ring is for the extended pipe flange.
The flat gasket is for flat surfaces.

The Malian supplied flat one is not a durable seal: That particular gasket is a sandwich and the gasses will blow out the middle layer, burning the outer. This type needs a metal ring pressed in on the inner side.

Another potential issue with the flat one is that the OEM type is somewhat ´flexible´; not once fitted, but to ensure a properly matching seal without tension on the joint.

househead · October 20, 2019, 10:45

Quote from: Gatouzze on October 20, 2019, 09:11Piece of advise, use a lot of Plus Gas a couple of days before changing the cat as the bolts/nuts can be very rusty ^^"

I'm still in that plusgassing stage and seeing if I can loosen them up for now. They sure are stubborn! Taking care not to round them off. Thanks for your help.

househead · October 20, 2019, 10:48

Quote from: Petrus on October 20, 2019, 10:01Horses for courses.
The gauze donut ring is for the extended pipe flange.
The flat gasket is for flat surfaces.

The Malian supplied flat one is not a durable seal: That particular gasket is a sandwich and the gasses will blow out the middle layer, burning the outer. This type needs a metal ring pressed in on the inner side.

Another potential issue with the flat one is that the OEM type is somewhat ´flexible´; not once fitted, but to ensure a properly matching seal without tension on the joint.

Yea I noticed that I'd be removing some flexibility that the oem fixing provides. Your other point is even more important, I think I'll hang fire until I understand more about how this should safely fit and get the relevant adapter.