exhaust system

Hi everyone, I havent posted for some time so with the risk of sounding redundant " happy new year and all that ".

Anyway my six is needing a new back box so any advice on suppliers would be much appreciated. I am thinking of either replacing the back box or possibly taking the plunge & going for a complete system i.e. stainless steel with new manifold depending on cost.

Mine is an 88 highline which has the original exhaust, which is fine apart from the back box. Financially I know it will make sense to buy the back box in the short term but I just want some info on the pros & cons of replacing the whole system at this stage?

Hello!

  I tried a lot of back boxes for my BMWs...I agree: BMWexhaust are the best for noise suppression and durability...

They cost a bit more than the other OEM brands, yep.It's not cheap, specially for late 635s...but if you look big and pay up, You will have no regrets for years...

Also I found (after a lot of rear boxes and money spent) some hint You should follow, as they are very effective(though they are a bit funny, for someone...anyway 1 example: my friend destroyed his first 1985 M635 back box after 6 months, after that time-end 1985-he bought only one box ...Now i'll tell you the tipps and tricks of this longlasting method.

1 after You fit the back box ,drill a hole (2-3 mm or 1/8 of an inch)at the bottom where the 2 pipes are getting in , You will notice that this is usually the lowest point of the rear box.Drill a hole ????On a brand-new-mega-dear box?Yes, the water condensation will drop from there,so there's no starvation inside...old trick but effective...

after You have drilled the hole I sprayed inside a "Liquid Zinc spray"(bought from BMW dealer) and I sprayed it into the hole...It's a strong spray product, and it avoids the rust to come on ...

Then , when I do not  use the car I always cover the two chromed pipe with 2 "plugs" made of wadding , that I previously drown in engine oil(not old oil, as the sulphur content in the old oil will destroy the chrome of pipes)....

huh, Do't forget : NEVER , during winter storage, turn on engine and warm up the car in your garage, or the moisture(right?my english is bad , as usual...) will never come out from the rear box totally , so after 6 months You'll find an other hole in your rear exhaust box(also in your wallet!!!)

My friend , since the end of 1985 , use this method to his M635 exhaust...I woudn't believe it, but it's the same box in 20 years( I read the production date stamped by Boysen those days)...And it's quiet as it was new, no rust , no other problems...the car is pampered and it's used rarely(46k kms since new)

Your wheather is not so friendly as our one  in Italy(despite we have now 60 cms of snow on the streets...)  and the we had no bog salt on the motorways, or small roads...but the salt will ruin the box from the outside, not from the inside...

Hoping that this helps

Francesco

 

 

 

Edited by siscobmw

siscobmw wrote: Drill a hole ????On a brand-new-mega-dear box?

You'd need some balls to do that at £500 a pop!!!

Cheers for that Francesco, if I replace the back box I would go for BMW part but I was thinking along the lines of an upgraded system with manifold, I have spoken to Fritz,s Bits & they are asking £1150 + vat.

I am looking for the pros & cons in fitting an upgrade apart from the obvious one of cost difference?

 

Edited by DAT 635

Everything I would have wrote to you, dear DAT635 , is been wrote by Sohlman....Very good and complete!

SiSco From Italy

 

PS: My friend tried to do the same system as original BMW parts, but made of stainless steel....A complete nightmare cause the strange shape of the boxes( he was able to get the same really shapes, it was really similar!!)....and the noise was however noticeably more than stock system,even if filled up with the same noise deadening material...What a fuss.....

Francesco

 

 

Edited by siscobmw

Agreed about the gen. system - My father had a 535i E28 for 13 years, we only ever replaced the back box - it was too late for the hole trick, which, incidentally I was told about by a master tech at L & C Tunbridge wells as common practice to get the most life out of the exhaust.  Surely 17 years life from a £500.00 system speaks volumes about a system's quality. Certain cars need a standard system IMHO , espcially a special car like a Highline. Agreed with James about a decent header on the early cars, the manifold restriction around the steering column is quite nasty!

Cheers for now

Phil