Schumacher Mi5 Build Review
I think a most people will agree with me when I say that a lot of touring cars are pretty much the same with slight feature differences that differentiate them on the track… there is the very odd exception to this rule (the Awesomatix A700 being a good example of something ‘different’). The reason that I am starting this review with that sentence is that I believe that Schumacher, with their new Mi5, have definitely tried to bring something a bit different to the touring car market.
I have built and raced a number of Schumacher cars over the past few years and have published build reviews on the Mi3.5, Mi4CX and Mi4CXL which you can read here;
The Mi4 platform was definitely an evolution and Schumacher squeezed every ounce of performance out of it and it was still performing at the sharp end of finals in the BRCA, in the hands of the likes Chris Grainger and Matt White, and also in Europe at the RedRC ETS events driven by Martin Hofer.
But with other manufacturers introducing new kits Schumacher has gone back to the design board and started pretty much from scratch looking at all parts of the car and also what impacts the performance of modern high speed touring cars. This has allowed them to look at areas such as tweak, chassis flex and power delivery through modern gear diffs etc.
And the Mi5 is what they have come up with;
Before getting into the build review I want to look at some of the features that made this a car that I just had to build and run;
One of the key design features the Schumacher R&D team wanted to incorporate was the longest uninterrupted flex possible.
They achieved this aim with a top deck that goes from centre of of the rear diff to centre of the front diff. And, of course it is hard not to notice that the top deck is mounted vertically which aims to provide side to side flex but not front to back – this should give more side to side grip.
One of the nightmares of modern touring cars is tweak (on the most basic level, tweak can be thought of as an uneven weight distribution on a car’s suspension, and can lead to odd behaviour and inconsistent performance) – tweak can be caused by a variety of things, including a twisted chassis, poor electronics placement, uneven tires, and mismatched shock springs. Schumacher have looked to address tweak by mounting the motor mount directly to the centreline of the chassis.
Underneath the mount there is a small gap so as to not affect the symmetrical nature of the chassis flex. Being connected to the chassis in as few places as possible and also in a symmetrical arrangement should help… they have also done this with the steering and servo mount as well but more on this later.
To make the car very smooth in the steering department Schumacher have mounted the steering rack on bearings and then have gone a stage further with a new micro caster block that is lighter than traditional designs and allows the hub to run on bearings for a super smooth and precise steering action with no binding.
Schumacher have, in the past, outsourced their gear diff by including a SpecR diff in their Mi4 kits – they have now applied the Schumacher touch to the Mi5 gear diff and the kit now includes, for the first time in a Schumacher kit, an all new Schumacher gear diff.
This is a very high quality gear diff that is small and also incorporates double o-ring sealed casing for less oil leakage.
One of the most exciting features, for me, with the Mi5 is the fact that you get the option of two cars in one… with the addition of the U4290 Speed Secret mid-motor conversion pack the Mi5 can be turned into a mid motored touring car!
In theory using a mid motor could give more rear end traction and better rotation on tight hairpins and this is something that I aim to try indoors on our carpet track.
You can see the full Schumacher Mi5 introduction page here; http://www.racing-cars.com/pp/Car_Showroom/Mi5.html
The feature list for the Mi5 features the word NEW a lot;
- New vertically mounted, ultra long top deck offers super linear flex characteristics.
- New lightweight carbon fibre wishbones for optimum stiffness.
- New simple pivot ball system for wishbone mounting and easy roll centre adjustment.
- New single piece motor/layshaft mount, centrally mounted to the chassis for perfect flex control.
- New simple 3 point mounted ball raced steering rack for super smooth linear steering.
- New single piece, centrally mounted, alloy/cf CNC servo and steering mount, for maximum stiffness in the steering system, and minimal impact on chassis flex.
- New micro 4 deg caster pivot gives super low centre of gravity and super smooth ball raced steering action with optional 6? available.
- New below arm shock mounting gives a low centre of gravity shock whilst keeping the same shock travel.
- New chassis mounted droop screws for decreased unsprung weight.
- New Schumacher lightweight gear diff.
- New ultra lightweight front spool.
- New shape lightweight foam bumper and chassis mounted mouldings.
- New anti roll bars in 0.1mm increments.
- New optional servo saver.
- New LiPo retention mouldings.
- New ball joint design for 2.0mm hex drivers.
- New ball cup design with adjustment hole.
- New 2 piece shock cap, for easier shock build.
- New precision matched shock springs.
- Optional Mid Motor conversion available, for extra high agility handling.
- Aerospace carbon fibre 2.5mm soft weave chassis and components throughout.
- Extreme lightweight alloy transmission housings.
- CNC alloy, 20 tooth layshaft pulley.
- Single sided layshaft mounting with quick release layshaft design for ease of maintenance.
- Stiff 3mm shock towers with optimised shock positions.
- Carbon fibre upper link design with options to adjust roll centres.
- Anti-roll bar mounts with precise vernier adjustment to minimise play.
- ìOî ring retained alloy wheel hexes.
- Fully adjustable, suspension geometry, wheelbase, caster, camber, roll centre, ackerman, droop, anti-dive, anti-squat, front toe in/out, ride height and much more.
- Efficient transmission with twin bando belts and precision CNC pulleys.
- Alloy eccentric adjusters for optimum belt tension.
- Quick release front and rear entry diffs to leave chassis structure intact when removing diffs for maintenance.
- Ultra smooth nickel-teflon plated threaded alloy shock absorbers for extreme smoothness and durability.
- Dedicated front & rear, reverse cup, high tensile steel, CVD driveshafts.
- Differential and spool plastic insert ìslidersî. Offer a lightweight, efficient driveshaft interface.
- Speed secret parts available to fine tune to all track conditions.
- Adjustable front steering hubs with optional carbon fibre parts.
- Adjustable rear hub carriers with optional carbon fibre parts.
- Black alloy M3 nuts.
- Lightweight black alloy washers throughout.
- Alloy front kingpins.
- Front to rear, 3 position, cell LiPo adjustment for fine tuning weight distribution.
- Quick release alloy layshaft fence for quick release diff and belt removal.
- Top adjustable lightweight roll bar sockets and links.
Schumacher have also published a video of Chris Grainger introducing the new car at the Gran Canaria round of the RedRC ETS; http://youtu.be/s5MsRy18-EM
On of the Irish drivers, Derek McCloskey had one of the pre-production cars at a recent race before the actual production cars came out and after getting a look at Derek’s car I new I just had to get one to build and run.
On with the build
Enough of the introduction on with the build review… that’s why you are here after all…
When I opened the plain brown carton that the kit box arrived in I was in no doubt that I was in possession of the new Mi5 with the new black/blue logo and the picture of the Mi5 on a carbon fibre background;
And here are the complete contents of the box;
There had been a bit of a delay between the initial cars being available to the team drivers and the release of the second batch of cars and the amendment sheet that makes an appearance alongside the manual give some insight into what may have been updated/changed during the delay;
When I had first read the online manual when it became available there were parts of the instructions that showed the build requiring inserts to be glued into the chassis and into the carbon fibre arms… Schumacher have taken the decision to do this for you which is probably a relief for some people worried about gluing thing on the wrong way round or getting it wrong. There are a few subtle changes so well worth reading through the amendment sheet alongside the manual.
The manual, as is expected from Schumacher, is very clear and concise and I really like the section at the back of the manual that takes you through some of the setup changes that you can make and what effect they have on the cars handling. The manual also includes two setup sheets, one from the team test session on carpet and another which is from Cotswolds, here in the UK, home of one of the rounds of the BRCA championship.
The Mi5 comes with a lot more carbon fibre parts than most cars due to the arms being carbon as well as the servo plate;
Schumacher also supply a couple of tools in carbon fibre including the interesting one at the top of the photo below which is used to hold some parts in place as you are screwing them onto the chassis and also for pre-threading the plastic roll bar parts but more on this later;
The picture above also shows the carbon fibre steering parts that have to be separated.
I did this with a Dremel and smoothed it off when I cut the piece joining the two parts;
After sanding down the edges of the chassis and applying a thin coat of glue on the edges the first step in the manual is to screw the small blocks onto the chassis that stop your Lipo battery hitting the belt.
Note that I did not ‘prep’ any of the other carbon parts especially the arms as I did not know if gluing the edges of the arms would have any effect on flex or handling so elected to leave them.
You can see in the picture below how the special carbon fibre tool is used to hold the small parts in a straight line while you screw it to the chassis.
You can also see the plastic inserts in the picture above that the droop screws are screwed into (yes the droop screws are in the chassis, not the arms like a ‘normal’ touring car).
Next up is attaching the arms to the car… this is a step in a normal car build that comes after the bulkheads etc are attached but this is a different build. You can see in the picture below that Schumacher supply some alloy screws and some steel ones and you need to make sure you use the alloy ones in the front and steel to the rear. The amendment sheet explains that the alloy are used in the front to save the chassis in the event of an impact.
Schumacher also supply a nice spanner to hold the pivot balls as you screw the screws in. Probably worth looking at whether you are building for carpet or tarmac at this stage as the carpet setup calls for 0.5mm spacers and tarmac 1mm.
The arms in place;
Next up are the bulkheads and motor mount which all all made out of black 7075-T6 alloy. The front and rear bulkheads are marked clearly as A and B and this indicates which side of the car they are for;
Bulkheads and motor mount in place;
The motor mount which is very different from the previous Mi4 versions;
The rear bulkheads… you can see how close the arms are to the bulkheads but they do not touch;
Two screws attach the rear shock tower with the fine adjustment holes for shock position;
The same with the rear;
Next we come to the very long vertical top decks that everyone has been talking about and is a feature you will either love or hate looks wise. But there is no denying the amount off side to side flex it allows the car while restricting front/rear flex;
You can also see in the picture above two holes for the cross brace and this allows an additional brace to be bought and added later to stiffen the car a bit more.
The top deck in place… note you have to put the front belt in place at this stage as the brace for the top deck goes through it;
It really is a long top deck!
We now build the centre layshaft and pulley. At this stage I swapped out the kit supplied 48dp spur gear for a 64dp one. Just personal preference and I have a full collection of 64dp pinions. Schumacher also supply the alloy version of the 20T pulley on the layshaft – this used to be an option part;
All ready to go into the car;
And in place;
Note that you later have to remove the pulley guard to get the belts on;
Next up is one of my favourite parts of the car – the steering and servo mount;
The steering uses a centre track rod system that is like a modern version of the steering that was used on the old TC3. But in this case it is made of very nice alloy and runs on three bearings making one of the smoothest steering systems I have ever seen. Take your time building it as the rear bearing can be moved forward/backward to hold the track rod in place;
And then fitting the system into the car is just two screws on the chassis and what makes this even more amazing is the fact that the servo is also attached to this arrangement which you will see later;
A top view;
In the past Schumacher have used Spec-R gear diffs but for the Mi5 they have supplied their own take on the gear diff and it is very well executed as you would expect;
The actual diff housing is quite narrow when joined together and there are two large o-rings used as part of the seal which gives confidence that it will not leak. Schumacher also use their additions to the alloy outdrives which are plastic inserts with a 7075-T6 alloy sleeve over them. This means that it is the plastic parts that wear and are cheap replacement parts compared to replacing alloy outdrives.
When building the gear diff I followed the recommendation in the manual and only added one shim on one side and seemed to give the perfect gear mesh.
The completed gear diff;
You can see the rear belt and the eccentrics used to set the belt tension in the picture below. Because of the long top deck Schumacher had to rethink access to the diff and how the belt tension could be set and came up up a very simple solution.
Hopefully you can see in the picture below, at the very back of the car, the diff clamp in place with two screws and this connects with the eccentrics. To adjust you simply remove the two screws from the diff clamp, rotate the eccentrics, and them reattach the diff clamp making sure it’s in the same place on both eccentrics;
A top view;
And here you can see the diff clamp in the default position shown by the dot on the eccentric;
More very nice alloy in the front spool which is all one piece;
And builds up using the same plastic outdrive inserts as the rear;
The front spool in place;
Everything in place with the diffs, centre layshaft and front spool;
Schumacher have, for the past few cars, used these carbon inboard suspension link parts which come in two different widths (the kit is 4 dink with an optional narrower 3 dink version available). This allows the width to be adjusted. Then the height of the bull stud can be adjusted by adding/removing washers;
The plate in place;
You can see in the rear view below the strange looking cut out at the rear which is were we will fit a roll bar collar to stop the roll bars moving from side to side;
By this stage we are up to page 18 of the manual and start to work on the arms again;
The ball studs are attached to the plastic parts to allow the roll bar and shocks to be attached. These are then screwed onto the carbon arms;
Next are the rear hubs which also get the carbon fibre treatment with the carbon parts being screwed onto the plastic hubs. This has allowed Schumacher to be able to supply different carbon parts for tuning;
The complete hub in place;
You can also see in the picture above that the shock ball stud sits low on the plastic part and this has allowed Schumacher to continue to use long shocks but keep everything as low as possible on the car.
The Mi5 kit comes with steel drive shafts front and rear and the only purple parts appear at this point in the form of the wheel hex. This is hidden by the wheel so doesn’t ruin the black stealth look that the rest of the kit has;
Built up and in place;
The front of the car also makes use of the plastic parts for the outside of the arms;
The insert in place, again with the bull studs for the shock and the roll bar;
The front hubs and 4 degree ‘carriers’ are another great innovation on the car… The 4 degree micro caster block is lighter than traditional designs and allows the hub to run on bearings making them very smooth.
There are two bearing in the caster block and a king pin type arrangement is screwed up into the hub. In the amendment sheet it is recommended that the included M4 grub screw is used to start the threading process but do not do too far in. This means that when you screw in the king pin it also threads part of the hub and therefore holds better.
The assembly along with the carbon parts;
Schumacher supply their steel driveshafts with the car but I have been using DCJ’s on previous cars for a while now so I decided to add them to the Mi5 as well;
These are part number G884 and are here on the site; http://www.racing-cars.com/pp/New_Cars_and_Parts/Mi4CXL/G884.html
All fitted to the car;
Turnbuckles in place;
I skipped over the shocks and roll bar build at this stage and moved on to build up the bumper;
Complete with Schumacher’s adjustable body posts front and rear;
The bumper in place;
Another picture of the rear body post in place (obviously before I cut it!);
Most modern cars either come with a floating servo mount or have it as an option… Schumacher supply it with the Mi5 as it is an integral part of the steering assembly as I mentioned above;
It consists of a carbon fibre plate and two plastic mounts that the servo screws into;
A picture of the completed holder in place;
And a picture showing the gap between the chassis and the servo once in place;
You can see in the picture below the number of positions that the battery can be put in with tape slots to hold a normal long lipo in three different positions and the Mi5 also allows for the use of newer shorty lipos again with three location positions.
Schumacher supply nice moulded battery holders and there are optional carbon versions available;
Now back to the shocks…
All the parts that make up the shocks;
The shocks, as with Schumacher’s previous versions, go together very easily indeed and the only things that I did differently was use some 0.1mm shims to try and get the pistons to have as little play as possible. I also used CoreRC 350cst oil as per the Cotswolds setup sheet although Schumacher do supply a bottle of 35wt oil and it would probably be a good starting point.
It is also worth noting that there is a minor mistake in the manual with the way the o-ring and the spacer goes into the bottom of the shock but this is corrected in the amendment sheet (Pg 26, Step 37).
The completed shocks… along with everything else on the car the shocks have had the black stealth mode makeover as well;
Schumacher have a new spring set for the Mi5 as well with the following five colours/rates;
- White = 13.9 lb/in
- Blue = 14.9 lb/in
- Green = 15.9 lb/in
- Red = 16.9 lb/in
- Yellow = 17.9 lb/in
Here is a direct link to the set which is part no. U4309
The kit comes with Green springs (15.9 lb/in) front and rear.
A lot has been said in the past (mostly bad) about the roll bars – I never really had an issue with them but some people complained because they could not be adjusted up and down at the mount points on the arms to allow for tweak etc. Schumacher started addressing this in the roll bars and mounts that came with the Mi4cxl with the arm mount points made up of two ball ends and a long grub screw that could be adjusted. But with the new versions they have come up with a very good system that stops the roll bars moving from side to side as well as providing an easy way to change them to fix roll bar tweak.
The parts that make up the roll bars;
And the bars ready to go onto the car;
The roll bar system from the rear and you can see the collar in the middle of the link mount carbon fibre plate that stops the roll bars moving from side to side.
You can also see the red marking on the roll bar above and you can buy complete sets of roll bars;
The roll bar sets range from 1.1mm to 1.6mm;
- 1.1mm = Yellow
- 1.2mm = Red
- 1.3mm = Green
- 1.4mm = Blue
- 1.5mm = Grey
- 1.6mm = Orange
I went with Red/Red (1.2mm) front/rear as per the Cotswold setup.
The picture below shows the linkage that can be adjusted with a 2mm hex driver to sort out any roll bar tweak… simple but effective;
We have pretty much come to the end of the build and I thought I would post some pictures of my completed car with the electrics etc. installed.
With the servo orientation it is very easy to fit you electrics;
A view from the rear complete with the massive fan that seems to be mandatory these days with the gearing that is put on 13.5 motors;
I currently have an LRP Flow Works speedo and Reedy 13.5 motor installed but I think over the summer I will possibly be looking at a change to something different maybe in the Speed Passion or GM camp that Schumacher UK distribute so watch this space;
So in conclusion the Mi5 is a car that you will either love or hate looks wise and personally I really like the new stealth black looks. The different ideas in the top deck, arms, micro caster blocks and the mid motor conversion all make sense to me so I am looking forward to trying the car on the track.
And finally my thanks again to Chris Ashton at Schumacher UK for sorting me out with the kit and taking me back into the Schumacher team fold and to all the team at Schumacher for not only a car that looks a bit different but one that seems to be starting to produce good results here in the UK and further afield. Chris Grainer and the rest of the top Schumacher Team drivers have been going well at the BTCC and BRCA so far this year and Martin Hofer has been putting in a good show at the RedRC ETS competition.
I will let you all know how I get on via my blog here and I will also be trying the mid motor conversion at some stage so check back to see how I get on.