Mk 1 S7 Monocoque - Prevention Of Cracking

[Andy Spencer]

I'm starting to plan the winter engine & gearbox exchange on my Mk1 Sierra S7 monocoque. Whilst I've got the engine and box out, I'm going to tidy up the underbonnet wiring etc, but am also thinking about possible strengthening to stop the cracking that some people seem to suffer from. I can only find threads relating to S3a's or Exmo's.

 

Mine was on the road in 1996 and has done 6000 miles since, reasonably gently as its only a 1.6. I cannot see any evidence of cracks in the usual places (where Jim suffered with his) or indeed anywhere else but one of the Midlands members suggested I welded in some strengthening in the back of the engine bay from the floor upwards. Apparently it also improves handling, but I want to do something before I fit the 2 litre with DGAS, ported head and decent cam!

 

Have any other Mk1 Sierra S7 members (Alan Rowe / Peter Bell?) suffered from cracks or done any preventative work? Would a mobile welding company be able to come out and do something with it up on axle stands in the garage?

 

Any suggestions welcome.

 

Andy

[chris n]

My Cortina S7 is now 12 years old no evidence of cracks that I've found.

[niduncan]

My Series 3 has been on the road for 8 years and 11,500 miles with no signs of any cracks.

[Peter Bell]

Andy, I am pretty sure the series one is made from slightly heavier gauge material than the later cars. I have had some cracking at the back of the engine bay floor panels difficult to describe but it starts at the end of the vertical stiffening flange. Have had them welded (tig) been fine since. this is a common fault on the Mk1, look carefullyaround the area where the angle iron frame for the front suspension bolts to the monocoque, mine seems fine but I think some people have had problems around there.

Peter

[BigLee]

Andy, Is it a stainless monocoque or a steel one?

 

The stainless will have a higher chance of fatigue that a mild steel one. (wont rust though)

 

My s7 is steel and shows no sign of cracking. Been on road since 1994 and pushes out some torque with it's current powerplant.

 

I'm also having engine and bos out in the winter (needs a clutch) and will do some tidying but i'm not strengthening it (apart from to fill the big hole around the steering shaft that lets red hot air through. I also suffer from Bobsons problem of bl**dy hot pedals and feet.

 

Good luck with your winter refurb.

[geoff shep]

Mine's a '95 S7 zintec monocoque - it started to crack at the advertised place at the back of the engine bay floor panels, as Peter said, starting from the stiffening flange. I ran 2 lengths of 1" box section along the underside, hard up against the flange, all the way from the front crossmember back to below the footwell and I think it was also attached to some strengthening acroos the body around the gearbox support area.

 

I also added some strengthening at the back over the rear spring areas.

[Guest Peejay]

Dave Andrews website gives details lots of strengthening that can be done, mind you look at the engine he's using!!!

 

http://hometown.aol.com/dvandrews/