View Full Version : Dax IRS build, SBC.

30-06-17, 09:25 PM
Hi fellow cobra and automotive enthusiasts. Thought I'd get the ball rolling on the new build section to the forum, creating a record of my efforts(!) over the course of the build.

I'm based just outside York and started my build three years ago having actually bought the chassis and chassis pack from Dax way back in about 2003! Career and other situations massively delayed the start of the project :)

I obtained donor jag axles and diff etc. as well as a rover sd1 in 2003 but then, following advice from this forum and an increase in knowledge, decided to change my engine choice to SBC in 2014.

I have a record of the chassis and suspension build up which I'll add in the future, but I'm gonna jump in first with the engine rebuild as I'm hoping for some pearls of wisdom as the rebuild progresses; it's my first ever! Obtained the SBC half engine from Realsteel, stripped her and had her pressure tested - all ok. I then followed the advice on block prep in Vizards max performance book and have, hopefully, attached some photos:
http://www.cobraclub.com/forum/attachment.php?attachmentid=34740&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=34741&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=34742&stc=1
The last shot arrows a slight crack in the starter motor mount and is a not uncommon fault apparently; a chunk of block can come off here! I wondered about a helicoil here to help spread the bolt load and would welcome some recs or thoughts......and I'd love a Ford sideoiler but I'm going Chebby this time!

Looking forward to seeing others get their blogs up on here. Tris

24-09-17, 07:17 AM
Here’s an update of work from quite a few moons ago. I’m hoping this build thread of someone putting together their first dax will show future builders some how to ideas and, as much, how not to! Insights will be included that I’ve been kindly informed of that could save some trouble, as well as any other options that could improve the quality of a build. These could be performance or safety related, or good old frugality.

So, being a Yorkshire lad, I opted for a penny saving option when reconditioning my suspension parts; following tear down of the early eighties Daimler V12 donor, the whole lot was zip wheeled excluding bearing surfaces etc. down to clean bare metal. Following this, kurust was applied, then blink 182, then two coats of chassis black. I would not do all this again! If finances allow, media blasting followed possibly by zinc plating and then powder coating would be a better and far quicker process. There’s a really good build thread in the Crendon section with more info on parts prep.

Following the dax manual on reconditioning, new bearings, oil seals, ujs etc. were purchased. Threads were cleaned with the correct taps and suspension parts were fitted out. Polyurethane bushes could be a performance option and it may be possible to track down aircraft grade bolts if you desire added peace of mind. I stuck with the Jag bolts that could be salvaged as they should be of sound quality and strength. Finding a PDF online called ‘XJS owners manual’ or similar, there’s a lot of advice and tips based on real owners experiences and could be worth a read before building up a rolling chassis if, based on XJ series I – III.

Here’s a couple of shots of the front end:
http://www.cobraclub.com/forum/attachment.php?attachmentid=35144&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35145&stc=1

If anyone can spare a moment, it would be great to know if these photos are visible to others. I can see them on my computer but who knows! The calipers were reconditioned on an exchange basis, although it is possible to totally rebuild these yourself.

The build manual is informative although some aspects are left a little to the imagination if you’re on your first build – certainly gets you thinking! Learning is one of the enjoyable parts of the build journey for myself and it’s always helpful to get advice from more seasoned travellers; thanks for your help thus far.

24-09-17, 07:53 AM
No problem seeing the pictures looking good so far. Incompletely up to you but I wouldn't re-use old bolts, I did this only to have one snap, (the long one holding the steering arm on. As it was lockwired on never noticed it untill the steering arm started to fatigue. Could of turned out really bad if I was traveling at speedbad enough I was in the middle of France at the time.
Keep us all upto date on your progress.

24-09-17, 02:16 PM
You might find the vin plate is not IVA compliant. I had to replace mine with a simple Ali rectangle with nothing but the vin number stamped on. Depends which IVA centre you use, apparently.
Not clear from your photos is the front, upper pivot shaft should have a minimum 2 threads beyond the nyloc to be compliant. Might just need tightening up a bit or loosening off at the other end. Locking word to follow I assume.

24-09-17, 02:18 PM
Not word - wire. (Fat thumbs & predictive text)

24-09-17, 02:19 PM
You might find the vin plate is not IVA compliant. I had to replace mine with a simple Ali rectangle with nothing but the vin number stamped on. Depends which IVA centre you use, apparently.
Not clear from your photos is the front, upper pivot shaft should have a minimum 2 threads beyond the nyloc to be compliant. Might just need tightening up a bit or loosening off at the other end. Locking word to follow I assume.

Good spot, looks like too many washers to me.

24-09-17, 03:02 PM
Hi chaps and thanks for having a good look at the photos, I'm glad that they are working properly.

I'll have to check up on the VIN plate issue as it only has the VIN stamped on, and on the chassis, but the axle weight listings are there too but the rating not. Also, the 'two thread' issue is a good spot and will hopefully be rectified once the full torque on the nuts is taken up when the engine and vehicle liquids are onboard; I've left these loose at the moment so as not to distort the bushes.

Tbh, the build is quite a way further on than this and I'm planning on adding updates periodically as I can. But I t's exactly these kind of things I'm hoping for others to add so do keep pointing stuff out I may have missed! :D

Richard Gibbs
25-09-17, 10:42 AM
Good luck on the build.

I see you're re building the Chevy 350 and have Vizards book on the process.
I bought a book on rebuilding the Chevy while in the US. It's called "rebuilding the small-block Chevy, step by step video book' by Larry Atherton and Larry Schreib. It's 150 pages, A4 ish, and has a 2 hr long DVD to go with it.
Certainly a good read/view.

I'm not rebuilding mine but bought the book for long term maintenance issues as and when they occur.

Hope that helps.

Might be worth adding to your reference sources.

25-09-17, 06:54 PM
Thanks Richard and also for the book rec. I'm building a bit of a collection. The max performance book by Vizard is from the SA Series and is a good read. He's also written one on standard small block rebuilding for HP Books, so that might be worth a look regarding maintenance.

My 1973 block has now been machined; decked, bored and then honed (+0.040"). Lots more to research before specific parts can be ordered. Hope your build is going well; if it's time for paint I suppose it must be going at least ok!?

Richard Gibbs
25-09-17, 07:43 PM
I will add to my engine books. Thanks.

I've got all the parts excluding the interior. Rolling chassis done. Luckily daughters boyfriend has an auto paint shop so he's going to paint it for me. Aiming to get it to him in November and out before Christmas so I can spend some time putting it all together beginning of the year. My build started in about 2002. Hence why I had a chuckle when I saw you were in the same position.

General life chaos, one redundancy, one house move, 2 young kids, I'm sure you can imagine how time and money was sucked out of the Cobra pot.

Still, onwards. One red cobra on the way!

27-09-17, 05:46 AM
Sounds like you'll be on the road next summer, all being well :) Have you attached the body to the chassis yet or are you getting it sprayed first and then affixing it? Mine is on before paint but I think it can and has been done the other way. Good luck with the build up; keep us posted of how it goes and feel free to add anything on this thread if you feel like it. Tris

27-09-17, 06:20 AM
Hi Tris,
The chassis plate will be wrong from 2003.
Dax supplied me with a new (IVA friendly) one FOC earlier this year.
That was the old DAX regime then.
Give them a call.

27-09-17, 02:34 PM
Thanks Kev for clarity on this and to Colin for the initial heads up. I've talked with Jon at Dax and he's just ordered a batch of IVA compliant VIN plates which should be with them in a fortnight or so.

Martin, I have set of Simon hubs sat in storage, so when it comes to fitting them and setting up end floats and caliper centralisation etc. I’m gonna swap some of the old bolts out at the same time. Thanks for the warning!

Richard Gibbs
27-09-17, 06:26 PM
I do hope to be on the road next year.
Body isn't on the chassis yet but should be soon, and before the paint process starts.
Once car is at the paint shop I'll be getting the engine out of the lock up, painted and the gearbox installed.
Aiming to get some shine to the power train before it settles into its new home when the car gets back.

Keep us posted. I'll do the same.

29-10-17, 08:43 AM
Following on from the front, it was time to start building up the rear end. The wishbones and drive shafts had been shortened on an exchange basis when I collected the chassis from Dax so they were ready to go. The diff’ was heaved on to the bench and drained of its foul smelling lubricant (possibly 33 years old), overnight. Pinion oil seal and the drive flange seals were replaced and, following some more tiresome zip wheeling, the unit was given a few licks of paint. It’s well worth considering a complete refurb of your diff’ and Russ Ram on the forum would be the expert to contact, having reconditioned many for builders over the years.

Rear toe was set using the Dax supplied tool and a number of shims purchased from SNG Barrett – I read recently that a forum member has made some from old beer cans cut to size and had success with this method :)Also, there was a real sense of satisfaction when refilling the diff’ with fresh, quality LS appropriate oil!

Hubs were vapour blasted to bring the aluminium up to a new look finish and they were then rebuilt with new bearings, seals etc. with pre-loads being carefully set. Local engineering co. kindly pressed the UJs into the drive shafts after my vice waved the white flag…now time to bring it all together:


To complete the rolling chassis I ran the battery cable (50 – 70mm~), fuel line and brake lines in, being careful to use conduit where the former two run through the chassis at the prop’ shaft hoop:


The importance of setting up the suspension geometry (as best I could using a laser level and plumblines etc.) at this point is worth noting, as it saves considerable faffing about later on, and is also paramount when it comes to body fitment – getting the alignment correct so that all four wheels are evenly spaced, from offside to near side, under each arch. The chassis must be level to undertake these adjustments. Dave Brookes loaned a tie bar to simulate ride height which allowed me to make four clones, greatly assisting with this job – thanks Dave!

Completed rolling chassis:


Year one simply flew by! :-P

29-10-17, 09:32 AM
All very nice. They look like Ford engine mounts? If they are and if you’re fitting a Chevy they’ll need changing. Better done as early as possible.
Of course I could be wrong.

29-10-17, 12:02 PM
Thanks and also for raising the engine mount issue. Originally had rover mounts and had them changed for a 350 at Dax when collecting the body - I’ll be gutted if they’re not suitable for SBC :confused: If any one can clarify this from the photo that would be great? I’d have gone the Ford route as love the engine tone/ sound but chose Chevy for various reasons.

29-10-17, 12:24 PM
I think Chevy mounts are asymmetrical. Yours are definitely Ford mounts.

29-10-17, 12:41 PM
Oh, now I’m not sure. Someone else might be able to help.

29-10-17, 09:38 PM
My Chevy is in on symmetrical mounts without any issues. I can't see too clearly in the photos but one of them looks in the same place as mine...?

30-10-17, 07:39 AM
They look my Chevy mounts as far as I can tell.

30-10-17, 08:09 AM
Regarding the asymetric comment/issue - Dax position the nearside SBC engine mount slightly further back so that, rather than being inline with the chassis rails, the engine is skewed anticlockwise, with the rear of the gearbox pointing towards the diff input shaft.

30-10-17, 10:28 AM
Thank you for the input guys, much appreciated. Some simple measuring reinforces what Alan has stated, that the n/s mount is fractionally closer to the cockpit - by approx 5mm. Communication was clear on the day of the welding and, as part of it, a section of rail was removed and rewelded to make space for the starter motor. Here’s some better shots of the mounts:

http://www.cobraclub.com/forum/attachment.php?attachmentid=35257&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35258&stc=1

30-10-17, 11:01 AM
Yes, sorry about that. I’ll get my coat.

30-10-17, 11:05 AM
Glad to be of help. I see you also have the (often absent) steering rack input shaft support bracket in place. Well worth it, as it takes a lot of strain off the shaft bearings!

30-10-17, 11:26 AM
Yes, sorry about that. I’ll get my coat.

No worries; I could well have missed the VIN plate issue if you hadn’t pointed it out ;)

30-10-17, 11:29 AM
Glad to be of help. I see you also have the (often absent) steering rack input shaft support bracket in place. Well worth it, as it takes a lot of strain off the shaft bearings!

Yeah, spherical bearing with two bolts welded to the top of it and a sleeve loctited to the shaft. Not my brain child but a brill local automotive engineer that builds rally cars! Thanks again.

21-01-18, 03:40 PM
Quick update with a few engine pics - possibly interesting for those building, probably a bit dull for the rest of the human race!

Following strip down of the Chevy 350 from realsteel, I did a quick degreasing and then had the block pressure tested - she checked out. Then some die grinding work to remove flashing and flow oil ways a bit, thread chasing and cutting 1/4” npt threads for the front three oil gallery plugs. Then professionally cleaned at some awesome place over in Birmingham - came back looking like new! Off to the machine shop next and David at performance unlimited has done a smashing job: mains checked for tolerance with new arp bolts, rebore and hone (w/ deck plates) to +0.040 and decked to 9.00”. Came back looking like this:


21-01-18, 03:42 PM
Hour or two with a needle file and deburring tool broke all the sharp edges from machining and then time to plan the big clean. Got all the gubbins together; jet washer, air compressor, loads of gunk, wd40 and brushes. Cold day for it:

http://www.cobraclub.com/forum/attachment.php?attachmentid=35433&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35434&stc=1

Plan was to paint with por15 engine enamel, so following blasting with the air compressor I setup a fan to gently dry out the block - it was back in the garage at this point! Applied metal prep to convert surface rust that started to form immediately. Here’s a bit of before and after:

http://www.cobraclub.com/forum/attachment.php?attachmentid=35435&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35436&stc=1

21-01-18, 03:51 PM
Washed off the excess zinc phosphate and following drying applied por15 engine enamel, this being the first of three coats to get a deep black colour:


Masking off was a rather long-winded affair, hope it’s worth it once rebuild completed.

Would appreciate some advice on the next bit - will be fitting a stroker crank from Scat, so need to check and then possibly die grind 0.060” clearances near the pan rails in the block. I guess it makes sense to check and do this work before having the cam bearings installed? Otherwise this grinding debris could get behind these bearings and ruin everything in short order - does this sound right?

15-02-18, 11:10 AM
Ok, completed block painting. She’s cleaned and ready for pre-assembly checks. Feeling a bit more sense of urgency to get things moving following the recent potential changes in emissions law.
http://www.cobraclub.com/forum/attachment.php?attachmentid=35505&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35506&stc=1
Will check clearances of rotating assembly first, and then have cam bearings installed. Also sectioned off the far end of the garage to create a “clean area” ready for the slow and steady buildup. Apologies if this is just another engine build for some, being my first it’s as scary as it is fun; I could be building up to some pretty hefty disappointment! :shock: Cheers, Tris

21-02-18, 07:34 PM
Looks like you’re doing a cracking job! Enjoying following your progress. Good luck with the next stage.

22-02-18, 03:35 PM
Thanks Boxoftricks, I've had lots of help to get to this point. Re. luck; with the Chevy rebuild I think I'm gonna need some! Cheers.

22-02-18, 08:13 PM
Looking very good

25-02-18, 07:55 PM
After the rolling chassis was finally completed, and following a good clear out again in the garage, it was time to turn attention to body fitment. “Guardsman Blue”, or one of the shades of, will be the chosen paint job eventually, so blue gel coat made sense from Dax. I’m building in stages, so saving, then purchasing – this was a big one! Opted for the stainless-steel bulkhead kit too, though if I undertake another build, I would probably go with aluminium sheeting and make simple templates to manufacture my own, this being quite a saving. Probably quite satisfying work I’d imagine too. See pic for footwell mods that need to be performed if going with the s/s lining kit:
Scouring the ever-helpful forum threads from the past/present, I found that the goof I could make is not centralising the body between the hub faces. This would result in a visible difference from side to side, particularly on the rear arch to tyre. Plumblines and a ruler are helpful here:
http://www.cobraclub.com/forum/attachment.php?attachmentid=35539&stc=1 http://www.cobraclub.com/forum/attachment.php?attachmentid=35540&stc=1

25-02-18, 08:07 PM
Although I had stored the body for a period of only a couple of months before fitment, and supported the boot area as recommended, the o/s tub section was sitting proud of the chassis rail by about 15mm. Oh dear :-( But following a chat with a pro, I used some fan heaters on the rear arch area and put some sand bags in the driver’s seat to help “reshape” that section of the body. It worked, and by chasing using the rivet gun, from footwell to rear bulkhead, I managed to get that problem sorted. Turns out that the best possible place for a fibreglass body to be stored whilst awaiting fitment, is on the chassis itself! Suppose you could rig up some sort of pulley system to enable this.

I put together an info/ tick list to help on the day of fitment, so if anyone doing their first fit thinks it may help them out, just ask.

Lastly, some spreader plates were made up for the front arches and, with the bonnet in place, the wings were manipulated so that they followed the bonnet line. Clamped in place, wurthed and riveted. I was advised to use six rivets to help add strength at this point because at higher vehicle speeds there can be a lot of air trying to pull/ push the body away from the chassis there; sage advice!
Suddenly started to look like a car which was really motivating :)

25-02-18, 08:19 PM
I like those front shocks :D

That looks like a tight garage for space either side. Are you going to use some wheel dollies?

25-02-18, 08:44 PM
:p Yeah, really cheap too.

Garage is tight, but not quite as bad as it looks like from the perspective of the shot of the full car. Wheel dollies on the long list of automotive gadgets I’d like to own, but not high on the priority list at the mo. It’s not ideal but hey, it’s a hobby, so I’ll muddle through...

30-04-18, 08:03 AM
Looks great. Can't wait to see the final outcome.

30-04-18, 07:35 PM
Looks great. Can't wait to see the final outcome.

Thanks. Hopefully something like this, but with Avons not Goodyears, and made out of plastic :D

01-07-18, 04:21 PM
Seems like an age since I have managed to get anything proper carried out on the Dax, but recently it has felt like Christmas again and then again...

Following some discussion with Bob at Vintage Wheels, I opted for some 15” HA02 wheels to marry up to my Simon hubs and, after much deliberating, chose the bead blasted finish. Bob also had the operator lightly take the sheen off the gray paint centres and when they arrived, I was pleased with the result. First to fit the hubs.

Front Simon Hubs, preliminary fit:

Using the mantra “nearside normal, offside odd”, referring to the threads, I ensured the hubs are are on the correct side. Hopefully I won’t experience seeing one of my own wheels overtake me....

01-07-18, 04:32 PM
Following Bob’s rec’, drive pins were torqued to 60 lbf.ft using medium strength thread locker (blue), following a clean out of threads with solvent etc.

Wheels and spinners on, preliminary fit:
Encouraging to see some progress on her again, albeit for little actual work.

01-07-18, 04:40 PM
Finally, following an agonising postal process, I took delivery of the rotating assembly from Scat for my Chevy lump.

Here’s a picture of some boxes :)
And some of the items out of the boxes:
I was reminded of being a kid opening up the Lego “Car Chassis” one amazing Christmas. Thanks for looking, cheers.

22-09-18, 10:45 AM
Summer sun made it hot work in the garage....damn these wonderful prolonged hot spells we may start to experience on a regular basis.

Managed to make some progress with the Chevy rebuild. Dropped the crank in and measured up using plastigauge on the mains: read a little on the tight side of spec, but was assured from various camps that this will not be a cause for concern. There is even polar advice from the racing fraternity that they are looking for tighter tolerances, but there’s lots of conflicting experiences and theories...certainly beyond my fledgling build and its application.

Crank sitting proud in the block:

Bench assembled the rods on the crank to do a simple bearing check there - all good. Next fitted the crank, rods and pistons to the block, ready for clearancing the 3.75” stroke crank - minus rings. Spent some time slowly rotating the crank and checking clearances. No problems on the pan rails but the bottom of the bores were too close on six of the cylinders:
What seemed like a lifetime later (checking, dismantling, grinding a little here n there, cleaning, reassembling etc.) I came out of the other end with comfortable clearances and I hadn’t hit water...phew:
Lastly, I whizzed a ball hone through the lifter bores to eliminate any potential burrs:
She’s ready for a good clean up and then some more detailed preassembly.

Richard Gibbs
22-09-18, 04:11 PM
Looking good. Progress.

You'll have that ready for start up soon.

I've almost got the diff back in. Centring the discs in the callipers to allow the handbrake callipers to fit right. Should have it sorted in the morning.

Keep up the good work.

23-09-18, 08:00 AM
Thanks Richard. Waiting on an order of parts to build the short block (fasteners, oil pump & pan, starter motor etc.) then on to the top end....start up may be some time yet, but thanks for your vote of optimism!

Sounds like yours is coming together well too. Good luck with those handbrake calipers; they can be a pain, particularly getting adjustment that is satisfactory. Keep moving it forward :wink:

23-09-18, 09:33 AM
Hi string,
Where did you go for the lifter bore ball honer? As will probably need to give mine a once over when starting to build it up.


23-09-18, 10:52 AM
Hi Greg. Try here:


7/8” flex hone for Chevy small block lifter bores. I went 180grit silicon carbide but you might consider a 240grit.

When you get to your engine build, I’d be interested to hear your parts choices and motivations for; there’s a lot to choose from!

Richard Gibbs
24-09-18, 09:47 PM
Hi String

Yup. I got the calipers sorted yesterday. All wire locked. Diff is now mounted to the car. As you know, the diff mounting plate I've found to be out of true both in angle down towards the front and in alignment the front. It points towards the drivers side rather than straight down the centreline of th car. I've shimmed the back of the diff under the mounting plate by 28 thou. That gives me the correct vertical alignment for the fulcrum shafts. Then there is the fulcrum shaft alignment left to right. I've got the near side shaft perfect. Goes into the chassis slot without any binding. The offside shaft goes in with a twist and a push. Good enough. But the shimming to counter the diff mounting plate offset to the drivers side means no shims at the front drivers side and no shims at the back near side. A few shims on the rear drivers side and a few at the front near side and the shafts go into the chassis slots and the diff spreader plate fits over the shafts at the back. If the diff mounting plate were any further offset from the car's centreline then there would be no chance of fitting the diff without re-welding the mounting plate.

It remains to be seen if the toe in/out at the rear wheels is correct. Whatever the case, I cannot shim the fulcrum shafts any other way and still get them to fit into the chassis slots and install the diff spreader plate at the back at the same time.

I'm in London tomorrow but will be fitting the wishbones and drive shafts on Wednesday. Then it's back to engine installation.
More to follow.

Keep us all posted on the engine build. Loving the pictures.

26-09-18, 06:41 PM
Richard, this sounds like a complicated and frustrating issue that you have battled with. Apart from the potential affect on rear toe, I wonder if these adjustments will also affect the thrust line of your car. Have you spoken to Dax about this to see if they’ve had past experiences like this? Might be worth a try and/or some photos on your build blog so the chaps on here can cast an observant eye over the issue.

Will be a milestone getting the engine in; hope that goes in without too many niggles!

Richard Gibbs
27-09-18, 06:48 PM
Hi String

I'll be going over to Dax in a month or so and I'll talk this through with them.
I take your point about the thrust line.
I'll post some pics and annotate the issue and what I've done to solve it. The offset to the drivers side is very slight but enough to change the even shim arrangement at the front and back of the fulcrum shaft bracket. All this assumes that the diff has been machined perfectly and hasn't been re-machined by someone that owned the car it came from. It certainly doesn't look like its been tampered with.

I got the driveshafts and hubs on today. When I get the engine in and the car back on its wheels I'll see if I can take any alignment measurements to see what I'm dealing with.

If it all turns out badly then I'll get the car over to Dax for them to cut / re-weld the diff mounting plate and re-fit the axle. Lets hope its not needed.
Pics tomorrow.