Tamiya vintage Mad Cap rebuild?

[911hillclimber]

I don’t want to do a silent thread on the rebuild of my new to me Tamiya car.
Is there any interest in such a thread?

[911hillclimber]

Maybe like this:

[911hillclimber]

As I suspected, no interest!
Saved me some time at least.

[Bootsy]

Do it. Plenty of interest in James’ thread

[hot66]

Always interested Graham

[911hillclimber]

Ok, let's kick off.

How did this all come about?
35 years ago I bought a Tamiya Madcap second hand for my 5 year old daughter as a Xmas pressie. Car was in really nice condition, all there, all working and not very old. The Madcap was very much a Tamiya entry-level car, very popular and now a collector's piece.
Many were butchered and modified with many 'hop-up' parts as the USA slang was back then and still is.

She loved it and we spent many a happy hour outside on the ice and snow scooting around the cul-de-sac race track. I was about to get the hillclimb bug.
We went to watch lots of r/c car racing at the local track at Himley Hall, all nitro super-fantastics.

Life happened and the Madcap was carefully stored away in the dark until about 2 years ago when I got it going again after a new NiCad battery pack was bought off ebay.

Our grandson arrived just 7 months ago which stirrers things into the mind and seeing an opportunity to re-live those far gone days, he is bound to love this Madcap in a few years time, right?

Found the car again, then James on here breaks ground with his Tamiya Buggy build and the idea was born; why not build or rather re-build a Madcap as a winter pastime and all that ready for him to have TWO race cars!

The search was on. A few hours on ebay found a suitable example, bit naff, bit bruised, bit incomplete and reasonably cheap at £65. Good runners were going for £160 to £300.

It arrived last week.

Comparing it to my original Madcap show I was in for a fight (good) to get this one to run and work correctly.

Biggest issues (so far) are:
No receiver (Rx), no Transmitter (Tx) now sourced.
Wrong rear wheels and bald tyres
Why is there so much WD40 all over the place?
No body shell

Set to finding some of those parts while working out what I really wanted from this build and joined the Tamiyaclub forum, could be useful as the world of r/c cars is big!

Originally I was going to build the car as a stock original, but I have one of those, so why not modify one? ("drag him to the noose")



The perfect car is in the blue example above, and that is the target. This now frees the mind...

More ebay buying and i have a Tx with 27 MHX crystal, a Rx without crystal (should have looked harder at the pics).
A matching crystal set found for £8 and awaited, and have found new shells are available though a bit expensive.

Front tyres are unavailable generally, so that led to the Blue Car with available bigger wheels and very spikey tyres for around £30. These will not fit the suspension but can be modified (good!)

So far I have been changing r/c connectors to fit the Rx and have managed to get some moments of activity from the very Old Skool electrics, more head scratching to be done while the crystals arrive.

I love the engineering of these cars, such robust plastics and suspension, all a bit mini hillclimb car stuff without freezing in the garage!

A few pics to set the scene:

My original Madcap;



The 'new' one:





'New Tx and Rx;



Side by side for a while:

[911hillclimber]

Started the full strip-down this afternoon and some simple testing.

Servo's first. Using my original Madcap electrics substituted the old car's servos for engine control and steering and validated they work, are silent and smooth. Big Tick.
Stripped the electric loom which seems ok if a bit brittle and the proportional speed control seems ok too, no burnt parts etc, so just a good clean and polish for that lot.

Unscrewed 8 screws to release the power motor and gearbox and LSD (!!!) these cars have, all very very oily and greasy, so will delve closer when all washed and de-greased. The motor is
non standard so someone has been here before me....

Rear suspension off and kept as a unit. will clean strip and re fit as a unit, similarly the front suspension.

A 'hop-up' trick on these is to fit a ball race kit, wheel bearings etc, gearbox brgs and much more. This will take a lot of the slop out of things and quite cheap, all rubber sealed to.

[911hillclimber]

Gave everything a good wash down to remove grease and WD40, much better.

Stripped a lot more down focusing on the motor/gearbox/drive.

The motor it seems is a hot option from the day, a good increase in performance and further proof that this car has been got at.

The motor was held in by just one screw, and only just with that one. The drive gears all look great, so removed the old grease and gave a reasonable re-fill with fresh after a good cleaning.

The gearbox base plate has been mauled in the past with all 3 screw holes broken in the cover which is very lightly designed imho, no wonder the lugs broke.
All super glued together now.

The motor is a Kyosho Stock 34 Competition Super Series, and originals now rare (I've read) so a good boost to the car.

All back together now so a sealed unit again.

Glued the rear chassis tab too, a common failure again started by over tightening the screws in the plastic.

This is a theme across this car, too much force used. My original has none of this.

[911hillclimber]

Started to look harder at the suspension, starting with the rear damper/coil-overs.

Found out that there were 2 options for the Madcap, 'ordinary' and advanced designs for the dampers.

My original had the ordinary units but no parts for the advanced, but the car being rebuilt has the yellow option units, the advanced design.

Advanced means oil filled dampers as opposed to friction.

Thus the oil all over the rear of the car was infact damper oil leaking from one damper, the other is oil tight, not liberally applied WD40.

The failed unit has a split O ring around the piston rod. Need to find one in my box in the garage.

For damper oil replacement ill use some fork oil from a previous bike rebuild. The original Tamiya oil is surprisingly thick.

The quick look at the Yellow fronts shows some bodging on the lower spring platform carrier, so some small machined parts required on the old lathe.

This will keep me quiet for a while.

[911hillclimber]

Going to a big motorsport do tonight, so getting an hour or so in on the car this morning.

Lots of screwing together, rear suspension arms and uprights on, drive shafts in (great CV joint design used complete with end float cushions), speed control servo already checked for function in and the top plate with speed regulator all cleaned contacts and screwed down but missing it's weather proof cover , so need to make one.

Ordered a set of new damper oil seals for under £4 for 6 as I don't have 3mm O rings anywhere.

[hot66]

Looks good. Out of interest how’s the steering servo attached to the chassis ?

[911hillclimber]

Thank you James.
I wish I could buy a screw set so all fasteners are bright zinc, but non available.

The steering servo is located with just two self cutting screws, the motor assembly has just 3!

The Madcap was an entry level car, designed very simply, but many love them.

[911hillclimber]

Time for the front clip to get some TLC.

Removed the two dampers, oil still in both but the damping effect was very different.

Previous owners had lost the lower spring mounts and used a cup washer instead which lead to the spring binding on the body of the damper.
Not good. The one lower wishbone pivot pin was rusted solid in the mounting block, so that needed a bit of a blunt approach to remove, polish the rust off and re-install, all corners not free as a bird to move.

Thus 2 new spring lower mounts needed, but £26 for 2 CNC machined parts was too much so made my own on my trusty Drummond lathe, 100 years old this year.

Found some acetal in black and made the pair in 40 mins, zero cost, max satisfaction!

The front clip has a top brace to stiffen-up the mounting and the front bumper/skid plate which was missing on the car.

One on ebay for £23, again too much so made one from quality aluminium.

It was missing because the car had one too many front crashes and snapped the mounting on the chassis pan. Had to make one on the lathe and glue now setting.

My 27 MHz crystals have failed to arrive after a week in the Post office second class, so £9 lost. I've been offered a free matched set from elsewhere.

Hope the damper oil seals (O rings) arrive soon so I can get the car up.

Wheels and tyres next, bit of a challenge...

For this pic:
Silver cup washers as the car had, blue lower spring mounts off the rear units, and in black the home made fronts with smaller diameters for the smaller springs.





New wheels and tyres I want are Tamiya Egress with big spikes like these!

[HenrikL]

What year is this car? I was playing with Kyosho RC cars from 1985-1990.

[hot66]

Reason I ask about the steering servo is that on my sand scorcher, it’s located solely using 3m sticky pad …. This the next step in my build when I get round to 8t