Nickel Bronze chassis welding near Stockport

[tompollock]

Hello,

The Caterham 1700 Supersprint I am refurbishing has some nasty but localised chassis corrosion on the joint immediately underneath the rhs engine mounting. The perforation in the 3/4 inch round tube is about 7cms in length. Can anyone recommend a garage nearby that can do a repair for me.

Thanks in advance,

Tom.

[Hampshire West AR]

Arch Motor & Manufacturing Company Ltd, Redwongs Way, Huntingdon, 160 miles from you.

[Tazio]

Seconded, Arch every time for me.

[tompollock]

Thanks for the replies.  I'll send some pics to Arch over the weekend.  Hopefully it won't be an engine out job.  Unfortunately the MOT has expired and I'm not sure how Mr. Plod would view the 160 mile journey across to them for the repair.  Fingers crossed.

 

[tompollock]

Refurbishing a 1990 Caterham 1700 Supersprint, 5 speed Sierra XR4i gearbox, with De Dion rear suspension. Numpty questions from a 7 novice.

In the limited crawl space underneath with the car on stands I have not been able to locate either the gearbox or diff filler plugs to change the oils.  Where are they?

Secondly, there is no fuel filter fitted on this particular car, which seems a strange omission.  I am considering fitting one of those clear nylon jobbies with the visible paper filter, immediately before the standard Ford pump. Any problems with this?

Finally this motor, though standard, has been dry-sumped, as much for ground clearance as anything else. The tank would probably hold about about 5 litres.  Information on the web about fill levels seems a bit vague.  Should I check the level with the engine running around 3000rpm and how much above the top baffle should it be?  Currently 3 litres in the system which seems not a lot and the fill level is about 3/4 inch above the top baffle at tickover.

Thanks in advance.

 

[SM25T]

Take the boot floor out to see the full/level plug on the rear face of the diff. It might be very tight. I use a long breaker bat with a hex bit to crack it.

Gearbox fill/level plug on passenger side. Needs a 10mm Allen key with short leg cut shorter

[Tazio]

If you have a Pace Easiclean Dry Sump Oil tank the level should be about 10 to 12 mm below the top baffle just after you have switched the engine off. On mine after it's been stood a while, quite a bit the oil syphons itself back into the sump, so I crank mine over with the fuel pumps off to scavenge some back into the tank before firing her up. Mine has about 5 litres in.

[7 wonders of the world]

oil level on DS must be checked with the oil up to full temp circa 90 degrees and with the engine running at idle, oil should be 15mm below top baffle plate.

you do get limited oil draining back in some applications via the pump this poses no problem simply fire it straight up and the scavenge will deal with it without issue, you will cause more damage clearing this by cranking.

Plastic fuel filter should be fitted after the OE mechanical fuel pump.

 

[John Vine]

Re #4:

...I'm not sure how Mr. Plod would view the 160 mile journey across to them for the repair.

My understanding is that, as your MOT has already expired, the only journey you can legally undertake is to a pre-arranged MOT, so you'll need to have the car MOT'd before taking it to Arch.  If it passes, you don't have a problem.  If it fails on the chassis fault, you're probably going to need a trailer for the trip. 

The rules seem vague to say the least, so perhaps others can shed more light?

JV

[Roger Ford]

You could presumably book an MOT in the vicinity of Arch. There's no stipulation on the maximum distance you're allowed to travel for a pre-arranged MOT. If it then fails, you could legally take it to a 'place of repair', e.g. Arch Motors, for repair.

[John Vine]

Re #10:

Yes, I think that would work.  But you'd need to check that you're insured for the trip to the MOT and, if your car fails, for the onward journey to Arch (IME, insurers generally don't cover the latter).  On top of that, if the car fails with a dangerous fault, it would need to be trailered to Arch. 

Of course, when travelling to the MOT appointment, your car will still need to be roadworthy.  Is your chassis problem likely to be serious enough to render the car unroadworthy?

JV

[tompollock]

Thanks for all the valuable info received so far. Just so you know the problem I have. Not pretty is it? (The bottom of the picture is the front of the car). 

Interesting that the failure going forwards is pencil straight, so it looks like the round tube manufacturing weld line itself failed initially, allowing moisture in to start the corrosion along that line. The bronze welding of the round to square tubes is sound.

Good thing is the square section longtitudinal (which I assume is the most important load bearing element for the engine mount?) is completely sound, as is all framework fore and aft. Will keep you posted when Arch get back to me.  I imagine other Caterham chassis may have failed at this point.

[John Vine]

But no pic?

JV

[tompollock]

Strange. Pic shows on my laptop. Will re-post pic.

TP.

[ECR]

I had a lower front wishbone bush tear out of the chassis. It left a gaping hole not unlike the one shown. I took it to arch assuming that tubes would need to be cut out and replaced but they very neatly bridged the gap with braze. A delight to watch them do it and a very neat and strong finished job

[John Vine]

Re #13:  Sorry about that.  My utterly useless Nokia/Android phone failed to show it.

I imagine that hole would trigger an instant MOT fail.  Excellent suggestion from Roger (ECR).

JV

[tompollock]

Spoke to the very helpful Phil at Arch Motors at lunchtime and sent him the picture.  Just waiting on the verdict now.  Said they may be able to repair without taking the engine out!  Fingers crossed.

[tompollock]

Phil at Arch Motors is hopeful that the tube can be replaced without taking the engine out. Wonderful! And he thinks my theory about how the corrosion started is very likely. Now to get the MOT done so I can take it there.

I found the diff, drain plug.  Trouble is that there's less than 25mm clearance between the drain plug and the de dion tube, not enough to get a socket with hex bit in there.  Difficult!

Thanks for all the your help and suggestions.  You're all stars and it's very encouraging for a new member.

[Jonathan Kay]

Diff filler plug:

Try an L shaped key or a piece of sawn-off key in a wrench. 

You can improve access by jacking the suspension and removing the boot floor. 

I'll add some links when I'm not on a bus. 

Jonathan

[Jonathan Kay]

Diff stuff from Alcester Racing Sevens: access,plug removal, filling.

(Now only on the Wayback Machine so links to images might not work.)

Jonathan

[John Vine]

Now to get the MOT done so I can take it there.

Here's hoping the tester isn't too concerned, but I have to admit that you could be facing a fail.  And if the VT30 describes the defect as "dangerous", you'll be needing that trailer.

JV

 

[tompollock]

MOT tomorrow!  Fingers crossed.

[john g]

Hope all goes well.

[Mcalvert]

Let us know how it all goes.

Part 3 of the most excellent "Get to know Your Seven" guides here  gives useful tips for things like changing the diff oil.

 

[tompollock]

I'm a very happy bunny. Passed first time, with the only comment being that the n/s headlight was a touch low!  Also did a compression test and was overjoyed to get readings of 161/161/158 and 166.  Happy days.

After Phil at Arch deemed the corrosion not bad enough to make the chassis structurally unsound I took the executive decision to employ a bit of cosmetic subterfuge. Looked perfect afterwards. I will be off to Arch to get it fixed properly as soon as we get a couple of guaranteed dry days for the drive, but meanwhile I've saved myself the possibility of some unnecessary and expensive trailering,

Thanks for all the advice from the forum.  Next job is a carb rebuild and setup. The usual spitting back between 1750-2250 rpm, particularly when cold, though it ticks over like a train. Seems there's plenty of archived material to get me pointing in the right direction.