SRB Cage Racer - aka. Mjolnir (the heavy metal Hammer)

[njmlondon 570]

I could not believe a cage nut like you did not know the 400!

I am going to go and check out what decals the Hornet has that are so interesting?!

[JennyMo 3526]

16 hours ago, njmlondon said:

I am going to go and check out what decals the Hornet has that are so interesting?!

Hee hee - it's just I thought the Hornet set seem to have a nice selection of coloured logo/brand stickers that are a good size.

Jx

[JennyMo 3526]

Just got home...

Yep, that works.

Jx

[JennyMo 3526]

And this looks like it will work too!

More soon - a busy weekend ahead I fear!

Jx

[JennyMo 3526]

Ok then, I've been busy with drills and files and paint... Spoiler Alert: it's not finished yet, but it's getting close now!

 

Rear Suspension tower

First of all, the rear suspension... after two failed (clumsy) attempts to drill and tap 2mm holes though 5mm thick aluminium (not impossible, but 2mm taps are tiny, and easy to snap!), I decided to look at an alternative way to mount the top of the rear shocks - especially since I wasn't happy with the way the rod-ends could potentially twist with the twin shocks attached (although nothing a dab of superglue on the threads wouldn't stop I'm sure):

photo. The solution was a Tamiya Hop-up M-06 rear damper stay - there is way too much carbon fibre for my liking on this build now ;o)

 

photo. Test fitting on the 2nd generation 'tombstone' - the shocks are spaced about 78mm apart, giving a good angle to support the rear end, while clearing the cage framework.

 

photo. Mk 3 tombstone, and I took the opportunity to drill and tap the base so that there were no ny-loc nuts above the bracket now - providing a flat surface to mount the electronics... note. the top of this tombstone will ultimately be shaped to follow the profile of the damper mount, once the final height/preload has been dialled in.

 

photo. With the shocks reattached, the car was standing back on all for wheels and six shocks again... note. the modified U joints from the spare steering column parts attached to the end of the suspension bolts - as upper mounts for the seat-belts.

cont.

 

[JennyMo 3526]

cont.

So with that done, it was time to reassemble the chassis/interior, and remove the engine covers for paint [matching]:

 

photo. I LOVE these scale seat-belts! They are fiddly to assemble, and take a bit of time to adjust, but they actually hold Kelly in the seat without having to glue her, while still allowing her to move slightly as the steering turns - it's very realistic!

 

Engine

photo. Primed and ready! I decided to remove the two [clear] engine/gearbox side covers, and also paint those in metallic silver to more closely match the metal centre gearbox...

photo. I'd say that worked out pretty well!

 

photo. the engine was painted in a metallic silver, then washed over with black dry-brushing to bring out the details. note. self-adheasive aluminium foil used for the top (and bottom) of the air-filter pods, and also the engine valve covers.

 

photo. it looks quite grainy here, but the overall effect is a rough-cast alloy engine block. The pod air-filters were painted dirty red inside (like a K&N) and a mesh cover made from wrapping a length of aluminium mesh around a rod to give it a radius/curve.

 

photo. engine ancillaries fitted. HT leads still to come...

 

photo. Exhaust test fitting... note. originally I planned to wrap the headers in cream ribbon to replicate heat-wrap tape, but unfortunately the effect was not as authentic as I'd have liked... Instead I've decided to paint the headers and silencers in 'high temperature' black, and have sanded them back a little to replicate the paint wearing off - they are not finished yet (in the photo above), but you can see the effect I'm after...

 

photo. I found it was necessary to slightly modify the left hand exhaust, so that it would sit properly square to the engine.

 

And finally... although it was really late last night when I'd finished, I just had to screw the body back on and see how it all looked...

photo. note. Kelly's helmet is currently getting a 70's silver metallic make-over.

The only other things to re-fit are the head and tail lights, plus I've had [what I hope is] an inspired idea with regard to the rear load-bay cover and hiding the electrics...

 

It ought to be running by the end of this week!

More soon!

Jenny x

[Re-Bugged 10159]

Fantastic job, well worth all the effort you have but in. Cracking wheels for it 

[Only4Fun 169]

A-W-E-S-O-M-E 

[wildwillhappy 15]

wow 

 

[wildwillhappy 15]

hi jenny 

are you still using the torsion bar the rear arms?

wild

[JennyMo 3526]

Some late night engine modifications...

photo. more simple/neater air-filter mesh, and added HT leads...

More soon!

Jx

[JennyMo 3526]

On 2/15/2018 at 10:06 AM, wildwillhappy said:

hi jenny 

are you still using the torsion bar the rear arms?

wild

Hi Wild' - no, I cut the torsion bars out (noted much earlier on in this thread), and just used the brass bushes - and the rear end is now supported by the twin OEM shocks with internal springs...

On a rear-suspension related note: I notice the spring return/rebound on the rear end is not the same as it is at the front (although maybe this is an SRB trait in general?) - in that if you push down on the rear it tends to squat with the wishbones/axles horizontal, rather than fully extend again? and it's particularly noticeable once the battery is mounted behind the seats...

I suppose I could try some stiffer internal shock springs, and/or adding a little preload to the rear shocks (by moving the mounting location down a few mm), although I did wonder if it was just a case of the rear tyres gripping/dragging a bit, as when it rolls over a bump the suspension seems to return ok - any SBR aficionados care to chime in?

Jx

[Country Mike 120]

Id surmise a slow rebound with plenty of travel for the rear for grip where has fast rebound at the front for sharp steering. 

[Country Mike 120]

Id surmise a slow rebound with plenty of travel for the rear for grip where has fast rebound at the front for sharp steering. 

[Biz73 603]

Wouldn't the heavier gearbox keep the rear from rebounding as much as the front?

[Grastens 2795]

Agreed with Biz73, I think; this behaviour was more prevalent on the stock SRBs, which used the same dampers front and rear. And as Country Mike suggests, this might be best for handling, though it could also make rough-terrain driving interesting...

I am most impressed with the way you finished the engine! It almost looks like the same material as the gearbox.

[TurnipJF 9192]

2 hours ago, JennyMo said:

On a rear-suspension related note: I notice the spring return/rebound on the rear end is not the same as it is at the front (although maybe this is an SRB trait in general?) - in that if you push down on the rear it tends to squat with the wishbones/axles horizontal, rather than fully extend again? and it's particularly noticeable once the battery is mounted behind the seats...

I suppose could try some stiffer internal shock springs, and/or adding a little preload to the rear shocks (by moving the mounting location down a few mm), although I did wonder if it was just a case of the rear tyres gripping/dragging a bit, as when it rolls over a bump the suspension seems to return ok - any SBR aficionados care to chime in?

Jx

I don't claim to know a great deal about SRBs, but I have been told by a few experienced racers that one should never rely on static testing when it comes to setting ride height with springs.

 

The point to which the suspension returns when the car is squished and left to rebound on the spot is hardly ever the same as the point to which it returns when the suspension is compressed while the car is in motion.

 

I was always told to squish the suspension, then roll the car backwards and forwards a few times before checking to what height the suspension has returned. 

[JennyMo 3526]

1 hour ago, Biz73 said:

Wouldn't the heavier gearbox keep the rear from rebounding as much as the front?

 

Hi Biz' - yes, as you say that would be the case (certainly there is a lot more weight at the rear, especially once the spare wheel and battery is in place too), but I thought having double shocks would support it better - the problem is it doesn't return all the way to full extension [regardless of how quickly] unless the rear end is unladen/tyres off the ground?

I might experiment with a little more preload on the shocks, by moving the the mounts down a few mm on the tombstone...

Jx

 

 

[JennyMo 3526]

On 2/15/2018 at 1:12 PM, TurnipJF said:

I don't claim to know a great deal about SRBs, but I have been told by a few experienced racers that one should never rely on static testing when it comes to setting ride height with springs.

 

The point to which the suspension returns when the car is squished and left to rebound on the spot is hardly ever the same as the point to which it returns when the suspension is compressed while the car is in motion.

 

I was always told to squish the suspension, then roll the car backwards and forwards a few times before checking to what height the suspension has returned. 

This is a very good point Turnip... certainly when I roll the car over my hand for example, the wheels go up and down individually in the way they would be expected to, while the chassis remains level - so perhaps I'm just over thinking it while it's static on the bench*

*I say 'bench', I mean kitchen table of course ;o)

So that's all the more incentive to get it up and running eh?!

Jx

[JennyMo 3526]

On 15 February 2018 at 8:50 PM, Grastens said:

I am most impressed with the way you finished the engine! It almost looks like the same material as the gearbox.

Yes, ultimately I would have liked the engine 3D printed in actual metal, but the cost would have been too high; so I used the same [silver] paint that I used on the gearbox covers, and then distressed the engine parts with fine sandpaper a little, plus some black-wash...

I've also finished gluing the revised air-filter mesh and exhausts in place this evening!

Jx

 

[JennyMo 3526]

...and put some stickers on the seats and belts:

Epic nerdage!

Jx

[SRB Bloke 237]

Wooooooooooooooooooooo!!!!!!!!!!   she's coming along nicely, very nicely.  J, can I ask how you got those wheels to fit, can we see whats behind them. I've lost track of the hubs etc that you have behind them.  Do these hubs make the stance much wider than the original SRB's Rough Rider/Sand scorcher etc which is approx. 222mm from outer tyre face - outer tyre face. ?

Loving those seatbelts, might have to get a set, they sound fiddly but look awesome

[JennyMo 3526]

On 16 February 2018 at 4:25 PM, SRB Bloke said:

Wooooooooooooooooooooo!!!!!!!!!!   she's coming along nicely, very nicely.  J, can I ask how you got those wheels to fit, can we see whats behind them. I've lost track of the hubs etc that you have behind them.  Do these hubs make the stance much wider than the original SRB's Rough Rider/Sand scorcher etc which is approx. 222mm from outer tyre face - outer tyre face. ?

Loving those seatbelts, might have to get a set, they sound fiddly but look awesome

Hi SRB' - I'll do a spec/summary post once everything is finished, but for the time being - they are the Locked-Up RC .185 rear SLW 6-bolt hubs, together with their front bearing adaptor SLW 6-bolt hubs::

http://www.lockeduprc.com/SLW-Hex-Hubs--185_p_246.html

http://www.lockeduprc.com/SLW-Hex-Hubs--Bearing-Adapter_p_864.html

 

I also bought a set of their 4-40 x .25" Acorn wheel-studs (to fit the thread in the SLW pattern hubs):

http://www.lockeduprc.com/4-40-x-25-Acorn-Wheel-Studs-28_p_228.html

 

...and ultimately bought a set of 1.9 Vanquish Method Roost alloy wheels (again that feature the SLW 6-bolt pattern than Vanquish use).

http://www.vanquishproducts.com/method-roost-1-9-wheel-clear-anodized/

 

...and I have to say, everything fits together perfectly - the way the LURC hubs interface with the Vanquish wheels is spot on.

 

for info. The rear SLW hubs fit onto a set of SRB Hex adaptors (again a perfect fit) - and I've just measured the width of my 1.9 BF Goodrich tyres on the Vanquish wheels - would you believe, bang on 222mm outside edge to outside edge - so I'd say exactly what you're after!

note. At the front I've widened the track of the front suspension by approx 15mm, so the outside edge to edge of those tyres is 215mm - but essentially the freewheeling front hubs have the same offset as the rears, so ought to remain in proportion on a regular SRB chassis.

Hope that helps!

Jenny x

[SRB Bloke 237]

Thanks Jenny, that helps, but I can’t seem to find any hex adapters for the SRB’s.  Obviously I’m just putting the wrong words in to the search...

 

[JennyMo 3526]

36 minutes ago, SRB Bloke said:

Thanks Jenny, that helps, but I can’t seem to find any hex adapters for the SRB’s.  Obviously I’m just putting the wrong words in to the search...

 

Radshape make some simple ones: https://www.radshaperc.com/product/12mm-2wd-hex-adapter-for-vintage-tamiyas

The ones I have on the Cage Racer are slightly more refined/machined - I think they were from a Far East seller originally, and possibly for the Frog? - but they are basically the same width/offset as the Radshape ones above.

Jx

 

edit. Looking at the Radshape listing, they say they will fit the Hornet and FAV too - as do the Tamiya Frog ones: #53913 - so I guess they are interchangeable... the Tamiya ones are more like the shape I have (see photos on page 4: here).