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Mad Ax

TA02 Celica GT4 Rally Rebuild

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This is a light restoration thread of a vintage TA02 chassis into a rally / rallycross runner.  Probably a fairly short build as I have most of what I need and I know what direction I'm heading.

The History

This chassis came to me many, many moons ago from a local ex-TC member.  I think his name may have been GazWilts, or something like that.  He posted a For Sale ad here for a hardbody Robbe Jeep sitting on a TA02 chassis.  As he was fairly local, I made the journey to his place by car, talked nonsense for a couple of hours and eventually gave him some cash.

The Jeep only ever got one run in stock form, at a TC bash at a sandy site in South Wales.  Even with locked diffs the stock Hummer tyres couldn't cope with the soft sand and, although it looked brilliant, the Jeep spent most of its runtime stuck chassis-deep in the gold stuff.  After trying various options the Jeep body ended up going over a Losi MRC chassis (an old project that was shelved years ago and might be pulled out again before lockdown ends), and the TA02 chassis went into a box of bits, never to see the light of day again.

Until Sunday.

The Trigger

Lockdown has meant I'm running exclusively in my own garden.  I've made a rough track that incorporates a short lawn section and some rustic patio slabs.  It's a little too tight for modern 1:10 buggies, but perfect for trophy trucks and rallycross.  Although I already have a TB01 (in need of a little care and a new body), and have just recently purchased a DF03Ra, I felt the need to fit up something different for rally duties.  I had a Celica GT4 ST165 bodyset NIP that I bought a few years ago when I had planned to do some local rally events.  So when I finished my XV01T S10 build on Sunday morning and I had the rest of the day to myself, I figured I might as well grab down this old chassis and dust-covered bodyset and see if I could mate the two together.

The Plan

Keep It Simple, Stupid.  A partial stripdown and once-over, replace anything broken, rebuild with a semi-hot brushed motor and some rally block tyres.  Fit an old set of CVAs adjusted for long travel, and go rallying.

The Build

It started with the chassis.  As you can see, it's exactly what it claims to be.  A vintage TA02.  Front arms were missing but I later found them (or something very much like them) while digging through a zippy bag marked "CC01 Misc".  Shocks were missing but I had a set rattling around the bottom of a spares bag in the box that my vintage touring race cars were sat in (a TL01LA and a modded TB01).

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First thing I noticed was that the rear diff was locked.  The previous owner (in building a scaler) had done the old trick of putting the stock ball diff up front and locking the gear diff with putty for a high traction rear end.  I hammered apart the diff housing to find this.

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It looks (and smells) a bit like paint but I imagine it's some kind of putty, maybe a body filler.  It flaked off the plastic housing well enough but wasn't easy to get off the metal parts.

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Fortunately I had a couple of sets of diff internals sitting in 99% IPA for a few weeks now, one set were almost clean, so I dropped the puttied diff into the juice and pulled out the older ones.  An hour with a craft knife, small flat bladed screwdriver and a compressed air nozzle and they were clean enough to use.

 

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Next I turned my attention to the transmission.  Bearings were installed in the wheel hubs but not in the internals, so everything was pulled apart and replaced with bearings from a random packet of misc bearings that I keep just for this situation.  I've pretty much exhausted all the common bearings now so will have to order a few more sets when next month's budget comes into play.

Looks like the last person to touch the transmission had used some kind of heavy general purpose grease.  Most of it came off when I was handling the gears.

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This also turned out to be one of those cars built by someone who pulls parts off sprues with their bare (bear) hands.  Most of the plastic parts had nasty jagged spikes on them, including the gears, which were catching on the housing as they span.  This amount of gear--bear-hand-handling robbed the gears of their grease, so I used a generic GP grease before reassembly.

Next I pulled apart the rear end.  As I mentioned above, this chassis was only driven once by me, in deep sand.  A lot of it is still attached.

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It took me a while to give everything a light clean (not a soap-and-water job - just a quick attack with a small common or garden paintbrush).

I then hunted around until I found some front hubs.  I think these are TA02 - they fit well and the track width is correct.  One was damaged (pictured) so I fitted nut-type ball ends on a machine screw with a washer, so it clamps up the damage and will hopefully survive a few runs around my garden.

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Next I turned my attention to the shocks.  I had some old CVAs that were running on another car, which were assembled to give a little more travel than stock (I think).  They are just right for the rally build.  I'll worry about springs later, I just wanted to get them installed.  The front end went on easily enough using screw-in ball-ends but the back end is more complicated on the TA02.  The upper mounts need a spacer so a ball type doesn't really work as well (I could make it work but figured the stock installation was good enough for a home runner), and the lower mounts pass through the wishbone, so it's not possible to fit a ball stud.

A closer look at the bottom arm revealed a problem.  The previous owner had hacked out part of the arm, probably to get a non-standard shock end in there.  The problem was, he had hacked into the area where the screw thread goes.  I tried to get a machine screw with a not on the end in there, but there wasn't enough space without hacking it out further and besides, I'd have needed to file down a collar to take up the play in the shock end and I was too lazy.

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What I was not too lazy to do was get out the trusty electric screwdriver and a selection of hex-ended drill bits and progressively drill out the recess to 3mm.  Then I could use one of those trusty hinge pins with the thread up by the head to secure the shock in place.  I also had some conventional shock bolt collars that had O-rings on them, to reduce any slop in the installation.

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While sitting back and marvelling at my own genius, I took another look at my diff parts.  The putty was already dissolving and with a little help from a small screwdriver I managed to lever the gears apart.  They are now soaking for another week, or until I need them next.

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Next - final assembly.  I found an NIP Pargustore motor mount in a box of bits, a Super Stock RZ motor in a box with some touring cars, and I ripped the ESC out of my King Blackfoot since it's unlikely I'll be running it any time soon.  Hopefully I'll have saved up enough cash for a huge haul of cheap LiPo-safe speedos before lockdown ends and I can run my bigger stuff again.

I also found some NIP OZ Racing style wheels in my Big Box of Touring Car Wheels, and I pulled the (still unglued) tyres off my TB01 rally car, which has never had its tyres glued in all the years I've own it (at least 12) or in the years of its previous ownership.  To be fair they're hard as fossilised rock now and probably about as grippy, but they'll do until I can order some new rally tyres.

This took a fair bit longer than I thought it would, but I'm more excited about this project than I thought I would be.  If I get a good run of body trimming on Weds I can probably have this painted by the weekend.

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It seems that the wheelbase isn't exactly perfect for this body.  Not sure why - I thought TA01 and TA02 wheelbase was the same.  This is using stock TA02 body posts and the holes pre-marked in the body.  The front looks perfect but the rear is a little off.  I might be able to trim-n-shim the rear wishbones to get it a bit better but the dogbone angle on the TA02 is already fairly extreme.  Anyway, it might look better when it's all trimmed and painted.

I had planned to go with a yellow-and-black-stripes paint theme.  The plan was not to make a full liveried rally replica, but more to make the kind of car you might see at a clubman rally or rallycross event.  Basically a road car that someone has converted for racing in the workshop that they usually use for doing MOTs and oil services or changing tyres.  Having looked at some online photos, the yellow isn't really working for me, so I'll probably stick with all red, then add some basic sponsor decals.  Not international company names, just little local business types.  I'll design them and get a mate to print them for me.

More to follow when the body is painted - probably next weekend.

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I want to see some pics of your garden raceway!  I love hearing about all these back garden tracks people are setting up during the lockdown! 

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It'll sit different when it's sat down on the posts😉👍

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8 hours ago, 78Triumph said:

I want to see some pics of your garden raceway!  I love hearing about all these back garden tracks people are setting up during the lockdown! 

I keep meaning to make a video.  One day I'll get around to it.  I tried to film it myself but it's too technical a track to drive without full attention.  Once it's filmed I'll probably spend the next two weekends figuring out how to dub my own commentary over it.

 

7 hours ago, svenb said:

It'll sit different when it's sat down on the posts😉👍

In the final shot the body is set at what will probably be final height.  I've left it quite high because there's a lot of suspension travel, although I might be able to drop it a little more if the chassis bottoms out before the wheels are fully compressed.  It is level front-to-back, so in theory it should line up properly - but I'll see, it might look better when trimmed or lowered :

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The wheelbase discrepancy between shell and chassis is a puzzle to be sure. I have compared your photos with those of my own recent TA-02 rally build which fitted a Tamiya Subaru shell very nicely, and I can't see any differences that would account for a shorter chassis on your car. Due to the front kick-up, increasing ride height causes the wheelbase to grow longer rather than shorter, so I don't think it is because the car is raised at all. All I can think is that the shell itself is designed for a chassis longer than the standard 257mm, such as would result from combining TA-02 rear arms with a TA-01 chassis tub?

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It is a curious one and no mistake, @TurnipJF.  This bodyset was re-released on the TT01E some while ago, which has a wheelbase of 257mm.  The TA01 and TA02 are both listed as 260mm, although this may be a 'max' given the change in wheelbase due to the kick-up.  I can't see any reason why my chassis would be shorter than anyone else's.

I had to check my chassis against's @Bluefoot's old TA01 / TA02 comparison entry from 2006 to confirm it was actually a TA02, as I didn't know what it was for sure.  I thought it was some kind of hybrid.  I can't see any obvious adjustments to the wheelbase, but it's possible the previous owner did a bit of trickery to correct the wheelbase for the Robbe Jeep body.

https://www.tamiyaclub.com/showroom_model.asp?cid=48983

As @svenb says, it may well work out fine once I've trimmed and settled it properly on the chassis.

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20 hours ago, Mad Ax said:

It seems that the wheelbase isn't exactly perfect for this body.  Not sure why - I thought TA01 and TA02 wheelbase was the same.  This is using stock TA02 body posts and the holes pre-marked in the body.  The front looks perfect but the rear is a little off.  I might be able to trim-n-shim the rear wishbones to get it a bit better but the dogbone angle on the TA02 is already fairly extreme.  Anyway, it might look better when it's all trimmed and painted.

I've run into this myself and never actually took the time to figure it out (I have a nice used ST165 shell that I'd planned on running on a TA02 chassis). The two chassis start off as the same wheelbase, but I know that the damper setup is particular to each. The ST165 only came on the very first iteration of the TA01 chassis that employed the blue dampers rather than the black ones that appeared on the TA02's. There is definitely something about the way the dampers are built that seems to have a pronounced effect on the wheelbase of these cars. If you take a look at the TA02T trucks, sometimes they are listed at a slightly much shorter 251mm rather than the 257 that is a fit for the touring/rally models. I haven't spent anytime comparing the build manuals but suspect there's something happening with the setups that give you the funky wheelbase. Oh, and another thing I've considered is maybe the possibility of different amounts of toe-in moulded into the TA02 and TA01 arms? Like I said, this has been on my list of things I wanted to investigate but never got around to it. Interested to see how your project addresses it 👍

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Here's the thread that discusses this a bit:

 

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1 hour ago, OCD said:

I've run into this myself and never actually took the time to figure it out (I have a nice used ST165 shell that I'd planned on running on a TA02 chassis). The two chassis start off as the same wheelbase, but I know that the damper setup is particular to each. The ST165 only came on the very first iteration of the TA01 chassis that employed the blue dampers rather than the black ones that appeared on the TA02's. There is definitely something about the way the dampers are built that seems to have a pronounced effect on the wheelbase of these cars. If you take a look at the TA02T trucks, sometimes they are listed at a slightly much shorter 251mm rather than the 257 that is a fit for the touring/rally models. I haven't spent anytime comparing the build manuals but suspect there's something happening with the setups that give you the funky wheelbase. Oh, and another thing I've considered is maybe the possibility of different amounts of toe-in moulded into the TA02 and TA01 arms? Like I said, this has been on my list of things I wanted to investigate but never got around to it. Interested to see how your project addresses it 👍

The TA02T is a bizarre beast because it uses a TA02 chassis tub with TA01 arms.  This should give a very short wheelbase, except the rear arms are flipped.

I probably have enough iterations of 01 and 02 lying around that I can make and measure every possible combination.  It would be interesting to know what's possible, although since these days almost all bodies are 257mm there's not a lot of point.  It does annoy me somewhat that a Honda Civic and a BMW 5 series are made on the same wheelbase.  Actually I think that annoys me more than cars having the wrong motor location / drivetrain / suspension setup.

I digress.  I have just been to check the chassis and I realised the rear body pins were a little high.  Dropping them down a level has evened out the wheelbase a bit.  It will be more clear if it's fixed it when it's cut and painted.

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I was supposed to have this body painted a week ago, but my spare time didn't quite work out.  I try to do a little bit of "easier" RC stuff (like sanding and masking bodies) while I'm watching over my toddler, but just recently she's wanted to be outside in the sunshine a lot so we've been out in the countryside having fun.  Which is great, but means I don't get on with my lockdown projects so much.

Anyway, I don't really like to do boring things like sanding and masking on my Big Sunday Workshop Day, but this week I pretty much ran out of stuff I could do due to parts having not arrived or new things needing to be ordered.  So I decided I would feel better if I got a few things done, and I took the Celica body up into the workshop to finish sanding, cleaning and masking.  The weather was still warm and dry, with a nice breeze flowing through the workshop to take away any fumes, so I got some paint out.

I painted up three swatches using PS-2 Red.  One was backed with PS-1 White, one with PS-12 Silver, and one with PS-13 Gold.  I was looking for a nice vivid red for this car, and the white-backed swatch looked way better than the other two.  It surprised me as I usually back my colours with silver.

This was taken outside in the sunlight.  Silver-backed on the left, white-backed in the middle, gold-backed on the right.  This was shot using a "vivid" colour balance (as opposed to 'natural' or 'muted' which are the other options on my camera).

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If I'm honest, the photo isn't really doing it justice.  The silver-backed swatch looks better in the photo but to my eye it's a bit dark.  It's lost some of its lustre.  The white-backed swatch actually looks a tiny bit pastel here but in real life it really pops, it's got so much energy.  I expected the gold-backed swatch to feel warmer, but it's not so much different to the silver.  You can make out a tiny bit of metallic in the finish, though.

This was taken under the garage roof.  There's some natural light plus some old striplights.  Here the difference is clearer (and looks more like my eye sees).  The middle (white-backed) swatch really bangs.  The silver (left) is muted and darker, but a little richer.  The gold-backed (right) is warmer and in this photo looks fab but isn't quite that good in real life.

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Anyway, I went with white backing.  I painted the grille detail on the outside using a tough automotive satin black which gives a lovely natural plastic finish.  I cut the overspray film with a craft knife and peeled it away to form a nice sharp mask.  I usually do my black areas on the outside to get that natural satin effect.

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Car / detail decals will be added when I have time, it's not a job I relish so it will wait until I have a peaceful afternoon in front of Disney+ with my daughter, then I have to decide if I'll get some sponsor decals made or find something suitable on the many millions of decal sheets I have lying around.

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