Marlin Roadster (Re)Build - Page 2

Lucky@LeMans · #1 23rd January 2021, 16:55

I've used Davids 182 primer on GRP and had no issues. For ali you really need an etch primer, they are cheap enough and readily available in aerosol form.

MartinClan · #2 1st February 2021, 19:39

The front suspension is now entirely off revealing some fairly horrible construction in places. Odd bolts, holes in the wrong place etc.

without_front by Robin Martin, on Flickr
And aso plenty of evidence of the use of a large hammer when the suspension was removed from the donor, plus the torsion bars are well and truly rusted into the suspension arms at one end and the adjuster at the other. Amazing it ever passed an MOT but then things were rather different 30 years ago! Good job I bought a spare set of front suspension components off Ebay - between the two lots should be able to make one decent set. And the chassis itself hasn't been butchered at all.

Just the rear to dismantle now. The rear axle case is very rusty, particularly arround the spring saddles one of which has a hole rusted right through it. It looks like some serious repairs may be needed. I am also currently trying to get some prices for new rear springs. The plan is to:
A. Have then slightly shorter at the rear to avoid the spring sticking out look that the Marlin suffers from.
B. Have them made flatter than standard to avoid using the 'orrible lowering blocks that the car currently has.

rusty_axle by Robin Martin, on Flickr

And I learnt something today. I was suprised to find that the springs are assymetric in that the axle is positioned further forward than centre of the spring by some 4 inches. Curious as to why that was I did some Googling and it seems it's to reduce axle wind up (tramping) under heavy acceleration. And I always thought leaf springs were simple!

Cheers, Robin

MartinClan · #3 4th February 2021, 16:31

The chassis is pretty now pretty much dismantled and ready to be moved up to the man shed for restoration and a couple of planned modifications. I'm surprised how heavy it is - I guess the box sections must be quite a heavy gauge.

bare_chassis by Robin Martin, on Flickr

The rear axle, although being generally good, has rusted through spring plates and so I will have to do something about those. I think the only solution is to cut them off and fabricate some new ones and have them welded on. The position is fairly critical though. Apparently the diff flange needs to be 3 degrees off vertical otherwise the UJ's in the propshaft suffer.

spring_plate1 by Robin Martin, on Flickr

The rest of the spring mounting hardware seems to be OK other than the U-Bolts which I had to take the Dremel to. Even the rubber pads look servicable, although you can get new ones from SuperPro at a price that's not nice.
The large lump of rusty steel is a lowering block. It's 'orrible and doesn't feature in my rebuild plans!

spring_mounting by Robin Martin, on Flickr

MartinClan · #4 16th February 2021, 18:52

In my drive for a slightly more modern and safe car, and after some searching, I managed to find a rare Marina pedal box with servo and dual master cylinder (wow). Both were options would you believe...

pedal_box by Robin Martin, on Flickr

The servo looks pretty grotty and new ones are non existant. It's possible to get them rebuilt but apparently with this type (crimped construction) they have to saw them in half and then weld the two halves back together! I suspect that may be outside of my budget. But a bit of Googling has revealed that the Landrover Seies 3 servo has the same mounting points and looks very similar, and importantly is freely available. So I may take a punt and buy a new one of those. Can always sell it again on Ebay if it doesn't work out.

I am hoping to be able to rebuild the master cylinder. next job is to strip it to see what the bores are like. Can anyone idenity the model number? It's (obviously) Girling but do the long string of numbers mean anything? Unfortunately the Marina, even with the rare servo and dual master combo, used 4 different models so I can't identify it that way.

master_cylinder by Robin Martin, on Flickr

Cheers, Robin

AlanHogg · #5 16th February 2021, 19:50

I worked in the distant past for AP products {Lockheed, Borg and Beck] so not overly familiar with Girling . From what I remember the master cylinder number is only relevant for the first 8 digits ie 64678912. The Lockheed servo you could dismantle in that the two halfs locked together with a quarter turn, easy with the correct tools but possible with some ingenuity. I'm sure someone on the Owners club forum when looking for an alternative [similair problem] found a more modern set up that required little work to fit. Maybe off a Renault. Will see if I can find the details.

AlanHogg · #6 16th February 2021, 19:59

Seems Peugot 205 with an adaptor works well according to Marlin owners club post

Mitchelkitman · #7 16th February 2021, 20:13

When I wanted a servo to replace one on my Rickman Ranger (Escort mk2), a Land Rover one was ideal. £60 brand new (Britpart) compared with the £300 a specialist wanted to try (not definite) to fix the escort one. just needed a small mod to the pushrod and in under 3 hrs (taken at leisure) I'd removed and replaced. If it ever needs replacing I'm confident it will be available in the future.
ETA, the master cylinder (from Land Rover) looks like it would also have been suitable (with a union change on one brake pipe), but I was able to use the Escort one, as it fitted perfectly.

MartinClan · #8 20th February 2021, 18:35

Good and bad today.
First the bad news....
I attempted to dissasemble the master cylinder and it's just one mass of rust. I don't think it's worth saving.

master_cylinder_us by Robin Martin, on Flickr
So the hunt is on for an alternative. After a lot of Googling I found the GMC234 which is used on the TR6. It is designed to be mounted at an angle, and the bore is 20.3. A bit larger than the cylinder used on the Marina but probably not disastrously so.

gmc234 by Robin Martin, on Flickr
It also has the advantage that the servo it is used with (still available new) looks pretty much identical to that used on the Marina.

And the good news is, after much fretting, I decided to go for drilling out the old studs on the exhaust manifold and re-tapping it to fit new ones. All my other efforts at removing the old ones had failed miserably. But in the end it proved to be much easier than I thought.

manifold by Robin Martin, on Flickr
The observant might notice one of them is a bit on the p!ss. Well 5 out of 6 isn't bad and I don't suppose anyone will notice!

And this arrived in the post. The Alfa 8C was what the Marlin was loosely based on. You can see the family resemblance.

alfa_model by Robin Martin, on Flickr

Cheers, Robin

MartinClan · #9 25th February 2021, 20:14

The TR6 servo and master cylinder arrived today. Pretty much a perfect fit other than the servo needed packing out about 6mm. Temporarily done with washers but I willl make a proper spacer. The angle of the reservoir on the master cylinder is identical to that of the standard Marina one so fluid levels should be good. I do like it when a plan comes together.

new_pedal_box by Robin Martin, on Flickr

I should mention that the Marina pedals are shortened for use in the Marlin and someone has drilled go-faster holes in them...

Cheers, Robin

peterux · #10 25th February 2021, 22:22

Looks like an excellent solution. It may be the camera angle but it looks like an unusually shallow reservoir, presumably to clear the tr6 bonnet?

MartinClan · #11 26th February 2021, 07:53

Yes the reservoir is shallow but quite wide. I never thought about it before but you are probably right in that it is to clear the bonnet on the TR6.
It's interesting how all the bits from different marques fit one another. I guess there was a lot of plagiarism going on in those days. The servo also looks almost identical to the Metro one that the Sportster used - except the mounting studs are at different centres.
Cheers Robin

Lucky@LeMans · #12 26th February 2021, 07:59

Quote:

Originally Posted by MartinClan

Yes the reservoir is shallow but quite wide. I never thought about it before but you are probably right in that it is to clear the bonnet on the TR6.
It's interesting how all the bits from different marques fit one another. I guess there was a lot of plagiarism going on in those days. The servo also looks almost identical to the Metro one that the Sportster used - except the mounting studs are at different centres.
Cheers Robin

The car designers had a massive parts bin to chose from. Think how many marques fell under the "Leyland" banner in the end.

MartinClan · #13 5th March 2021, 08:51

The chassis is now in the man-shed ready for the start of refurbishment and re-assembly! It fiited lengthways with only a few inches to spare but fortunately plenty of space widthwise. I had measured it up beforehand but you never know if there is going to be any unforseen issues.
The downside is that I promissed my wife the kitcen refurbishment would start once the chassis was in its new home so progress may slow down for a while....

The chassis is very sound but covered in a mixture of old paint and surface rust. Any suggestions how best to remove it greatfully received. I am trying to avoid mechanical (wire brush in drill) means as it makes such a mess.

in_man-shed1 by Robin Martin, on Flickr

Cheers, Robin

Mitchelkitman · #14 5th March 2021, 09:22

There are 'rust removers' and 'rust converters', and in my experience both do a 'good job'. Maybe just a case of research and 'choose your poison'?

oxford1360 · #15 5th March 2021, 11:39

You could take it back outside and give it a thorough jetwash (meanest setting) on a sunny day. Then back inside for some of the above.

I used this stuff on mine and found it very good -

https://www.ebay.co.uk/itm/AQUASTEEL...r/264680865517

Mitchelkitman · #16 5th March 2021, 14:19

The rust converters work by using dilute phosphoric acid (sometimes tannin as well as/instead of?) to give a protectived iron phosphate coating - In my experience, they work well and are easy to use (wear eye protection).
The rust removers do exactly that - if it's a rough, pitted surface it will end up rough & pitted (minus rust) which can be good for paint adhesion. I used some 10 years ago on the outside of brake drums and with red oxide, undercoat, and satin paint there has been no return of rust (FLW's). Takes a lot of time/brushing and mess though (a jelly version is suitable for chassis or similar.). For small parts the fluid version is great, as you just leave the parts submerged for a day or more (which is very easy of course).

MartinClan · #17 18th March 2021, 10:10

Quote:

Originally Posted by oxford1360

You could take it back outside and give it a thorough jetwash (meanest setting) on a sunny day. Then back inside for some of the above.

I used this stuff on mine and found it very good -

https://www.ebay.co.uk/itm/AQUASTEEL...r/264680865517

That's a good idea. In fact many years ago I used a sand blast attachment on my Karcher to good (if messy!) effect so I might do that. My lawn could do with some sand treatment anyway ;-)

Cheers, Robin

jonkoxe · #18 18th March 2021, 12:06

You could also consider these from Car Builder Solutions. Probably the smallest available. Think about the fixing method of the PIN. It will need some strengthening as the GRP rear tub will not give enough strength and will fracture over time.
https://www.carbuilder.com/uk/mini-b...ches-pair-75mm

Lucky@LeMans · #19 5th March 2021, 17:30

Quote:

Originally Posted by MartinClan

The chassis is now in the man-shed ready for the start of refurbishment and re-assembly! It fiited lengthways with only a few inches to spare but fortunately plenty of space widthwise. I had measured it up beforehand but you never know if there is going to be any unforseen issues.
The downside is that I promissed my wife the kitcen refurbishment would start once the chassis was in its new home so progress may slow down for a while....

The chassis is very sound but covered in a mixture of old paint and surface rust. Any suggestions how best to remove it greatfully received. I am trying to avoid mechanical (wire brush in drill) means as it makes such a mess.

in_man-shed1 by Robin Martin, on Flickr

Cheers, Robin

Have you considered powder coating the chassis ? Very cost effective and the finish will be like new. I recently had my Scimitar chassis done which is bigger and more complex, it only cost £250 including collection and delivery.

peterux · #20 5th March 2021, 18:53

Quote:

Originally Posted by MartinClan

The chassis is very sound but covered in a mixture of old paint and surface rust. Any suggestions how best to remove it greatfully received. I am trying to avoid mechanical (wire brush in drill) means as it makes such a mess.
Cheers, Robin

Well done getting that in your shed!!
I find Hammerite Rust Remover Gel works very well and you can get it in Halfords. Sometimes it needs a couple of goes and it may not get into every small corrosion pit so a rust converter is useful to kill what's left.
I think you may have recommended the Hammerite stuff to me some years ago