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Mar 25, 2019, 07:27 PM
Did I make the A Main?
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Mini-Review

REVIEW: PR Racing SB401-TypeR


This will be an evolving thread as I build and review a PR Racing SB401-TypeR. Look for regular updates to this post as I plan to race this buggy in the 13.5T 4WD Buggy class at Thornhill Racing Circuit (Turf Track). Full disclosure, I recently picked up a sponsorship through PR Racing so be prepared to expect some bias, but I will do my best to identify potential areas to consider making upgrades to improve the quality of this kit where applicable.



A quick background on me: I started club racing around 2010 and have slowly improved my skills to where I'm one of the slowest of the fast guys at the club in my area, ha! I typically average between 96% -98% consistency and will occasionally pick up a win for club racing and often make the A Main for regional events in 13.5 stock. My first wheeler was an InTech ER-14 (clay), then I switched to a Schumacher CAT-K2 (clay+turf) and spent the last 16+ months running a TEKNO EB410 mostly on turf. Expect to see me try different things, I'm sure some ideas will fail, but that's where I always try to learn from my mistakes and I welcome you to share these experiences with me here on this thread.




Hits:
  • Loaded with upgrades in the kit for exceptional value!
  • Global Team Driver Support with setups posted on Facebook and PetitRC
  • One of the lowest LCG designs I've seen on the market!
  • Thin 2mm aluminum chassis with carbon reinforced spline offers one of the most flexible chassis's I've seen to date!
  • Aluminum: hangers, caster blocks, rear hubs, gear box support
  • Carbon: towers, center brace, battery strap, ackermann, steering support
  • Easy access diffs for super quick tuning changes between rounds
  • Slide lock aluminum motor mount with Center slipper which is perfect for stock racing on medium to high traction surfaces
  • Aluminum shafts and shock standoffs are available as upgrade options for stock racing
  • Floating servo to increase chassis flex
  • Wire management channels under center braces for super clean wiring jobs
  • Aftermarket support from RideLow Racing (center gear cover) and Ardntcraft fan shroud

Misses:

  • Only 5 labeled bags A - E, will need to spend some extra time organizing parts during build
  • E clips used in gear diffs, probably worth it because they don't leak
  • Currently only 2 distributors in the US, but there is promise of a large distributor picking up PR soon!
  • If you will be running 13.5T motors for stock racing, some high torque motors (i.e. Trinity Punisher) may require larger pinions which you need to decide if you want to cut the motor mount to fit a larger pinion or purchase the smaller 73T spur to accommodate a wider range of stock gearing options


Summary:
If you want a car that offers tons of corner speed and as low as 14mm ride height out of the box then look no further than the 401R. I am still in the middle of the tuning window for most options and the car just wants to throw itself into tight corners. I'm able to make inside passes with confidence... not sure how they managed to make the car feel both smooth and aggressive, it's like you get the best of both worlds! On a high traction turf track, it's common to see many folks struggle with traction rolls, but the 401R just demands more throttle than I ever though would be possible in the tightest of corners. The shocks are butter smooth too, with very graceful landings, the car just plants itself on flat areas without down ramps... it just sticks the landing with no bounce giving full/even traction immediately. On occasion I have been tangled up with lap traffic and more often than not, the low profile towers allow the front wheels to get a pinch more bite allowing me to blip the throttle and get the car back on all fours again which makes it far less likely to require marshaling as a huge bonus. I have already picked up a full lap after switching to PR by my second race day, the car keeps getting faster with each run... my only regret is not getting the 401R sooner!

Tips:

Check out more stuff on My Bookmarks page!
Last edited by bill_delong; Apr 03, 2019 at 09:41 AM.
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Mar 25, 2019, 07:47 PM
Did I make the A Main?
bill_delong's Avatar
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Box measures 5"x9"x18":


White wheels are included along with a clear lexan body, wing and wing reinforcement, there are 4 large sealed bags with bag steps C+D combined into 1 bag:


24 page instruction manual, window masks, decals, velcro for body mount, antenna tube, double sided tape, zip ties and foam battery spacer included:


Kit includes box wrench and black grease, no thread lock is included but I will be using gel based vibra-tite brand and green grease brand for all the rubber seals and metal to metal gear mesh:
Mar 25, 2019, 09:33 PM
Did I make the A Main?
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A Bag

Parts are separated by dozens of other small bags without any additional labels, you will need to carefully organize your parts if you accidentally open a bag that is intended for a sub-step listed on a different page. Instructions for Bag A span out from pages 3-7 and sub-steps are labeled A1-A5 in the manual.


Probably a good idea to sort all the hardware grouped by size so you don't accidentally use the wrong length screw in certain parts of the build:


Although no mention is made in the manual, I would highly recommend sealing the edges of the shock towers with CA glue to prevent the carbon from splintering in a hard crash:



Step A1 - Chassis Brace

*** it can be a little tricky lining up the chassis bracing because the holes use the same spacing on the carbon deck as the holes on the chassis, just be sure each brace lines up so that the center gear diff cutout looks like this:



*** Before applying the battery foam I was careful to degrease the surface with an alcohol swab:


Test fit of the shorty LiPo that I plan to race with:


Step A2 - Gear Diff Assembly

No diff fluid is included in the kit. I like to use the out drives as a skewer and reverse the order of the seals to be placed inside the diff case and will apply grease first then slide the seals into place without any mess:


I like to use my multi-tool to hold my diff in place, and I use Ryan Lutz's method to fill the diffs to the top to get a consistent build every time:



I am going to start with Kev Lee's setup which calls for 10K in both front+rear diffs, I also use a silver sharpie to mark the fluid and can use an alcohol swab later to remove the marking if necessary to fill/mark with different weight fluids:


*** I will not be using the kit bearings and have ordered AVID Ceramic Single Metal Aura bearings, do not go by the sizes in this pic, I had ordered the bearings based on the 401LW and didn't realize that they changed sizes with the Type-R, here are the correct bearings to order:

(6) 5x10x4
(4) 5x13x4
(8) 10x15x4



Step A3 - Slipper Assembly

*** I made sure to crimp the spring flat a few times with some channel locks to help break in the spring and make it easier to tune. Although the manual calls for minimum of 1.1mm gap, I am using 0mm gap to have the softest setting to start out with... as the slipper breaks in, I will go back and tighten as necessary.


Step A4 - Front Gear Box Assembly

*** Be sure to note the orientation of the gear to be placed and number of shims, this is critical to ensure a butter smooth mesh, also note the direction of the shock tower with the beveled edge facing the center drive shaft


Step A5 - Rear Gear Box Assembly
Mar 25, 2019, 09:51 PM
Did I make the A Main?
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B Bag

Step B1 - Suspension Mount

Look at all these fancy aluminum bits!


Organizing all my new B Bag hardware mixed in with some left over hardware from the A Bag


Fit and finish is nothing but top notch!



Step B2 - Front Hub Assembly

I really like these captured CVD's which use steel rings to prevent the pins from popping out and no set screws to mess with either, anyway I like to lubricate all metal linkages with dry teflon based bike chain lube and this ensures the longest possible wear life of these parts which can be expected to last many years with proper care and maintenance:


Both sides finished:


Step B3 - Suspension Mount Installation

I spent the better part of 15 minutes trying to figure out how to get this 3x4.6x0.1mm shim installed and before I started turning more of my hair gray, I decided to toss these shims into my pit box and decided I was okay with having 0.1mm of slop in these links... shrug


Starting to look like a car!


Step B4 - Front Upper Turnbuckle Assembly
I took a little more time by using Ryan Lutz's method to assemble camber links, this is VERY IMPORTANT to ensure you can adjust your links later without risk of popping off the ball ends


Step B5 - Front Gearbox Reinforcement

After having several bulkhead/gearbox failures with my TEKNO EB410, this is the single most important feature that has drawn me to run PR!
Mar 25, 2019, 10:04 PM
Did I make the A Main?
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C Bag

Step C1 - RF Suspension Mount

The rear shock tower can be a little confusing because you have 2 different options for the wing mounts which can be narrow/high or wide/low on the tower, I chose the high mount because I didn't want to risk any tire rub on the wing, but I think I will try the low mount option on my next wing because the high mount is no where close to touching the low profile Schumacher wheels after I finished the installation.


Step C2 - Rear Hubs



Step C3 - Rear Hub Assembly


Step C4-C5 - Rear Upper Rod Assembly + Sway Bars

The manual calls for 1mm spacing between the ball ends of the sway bar links, so I decided it would be easier to add my own 1mm spacers to make it easier to get proper length and give a more appealing look at the same time:


I also used a drop of shock oil to lube each ball cup when popping them into place on the arms:
Mar 25, 2019, 10:21 PM
Did I make the A Main?
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D Bag
It doesn't matter what kit I build, the D Bag is always my favorite step, ha!

Step D1-D2 - Bell Crank + Steering Installation

Getting everything organized, look at those shiny carbon bits


***Before installing the servo saver I am crushing the spring to break it in... I have heard that many drivers prefer to glue (lock) the saver but I want to give it a try and see how it works, if I run into centering issues then I will put the locker in later.


Very nice fit with almost no slop!


D3-D6 - Turnbuckle + Steering Servo + Center Mount + Battery installation
I've got a lot going on in this pic, I couldn't find any aluminum servo horns from RC Pro Shop and I couldn't use the flat face arms from TEKNO, but I did find that the Losi 22 arms also use a long neck design and are shallow enough to fit under the ultra low profile body. I used one of the floating servo mount screws to mount my MRT transponder on top of the floating servo. Wire management is superb with the center channel slot to route my ESC and motor cooling fan wiring under the center drive shaft. I recycled my ESC from the EB410 that I was running before and I had to extend some of my wires so that's why you see some splice joints.
Last edited by bill_delong; Mar 26, 2019 at 10:38 AM.
Mar 25, 2019, 10:31 PM
Did I make the A Main?
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E Bag

Steps E1-E5 - Shocks, Motor, Body, Tires

The remaining steps are fairly straightforward, however I decided to make some minor modifications.

The kit comes with an 81T spur which is limited to a 26T pinion max, however I am running a 13.5 Trinity Punisher motor which requires a 31T pinion to be competitive. There is an optional 73T spur but I didn't realize the gearing limitation until after I got this far into the build so I decided to cut the slot on the upper motor mount to easily fit my 31T pinion with the stock 81T spur:


There is an optional 25mm fan mount available but the part was on back order and a little farther away from the motor than I would like so I decided to make my own custom fan mount using some 90 angle aluminum and placed the mount as close as it could fit next to the nipple on the side pod:


I drilled and countersunk new holes:


This is a 30mm fan and gives me a lot more air flow than any 25mm fan could:


I discovered that the Lunsford titanium (lifetime warranty) EB410 shock standoffs are compatible:


I also found that I could stretch the 12.75mm springs over the 13mm captured perches from TEKNO, this is the single most important feature that I have loved about the TEKNO design is not having to worry about losing spring cup during a race!


Also note that the TEKNO hex head screws are also compatible, this makes it a lot quicker to perform shock maintenance without having to swap driver bits


Here is how I trimmed the front PR wing to fit flush on the front shock tower behind the shocks:


Here is my Ride Low Center Diff Cover just to have as insurance not to risk tearing up my wiring in the event of a nasty crash, I replaced the 3x6mm button head screws with 3x8mm screws to account for the added thickness of the cover:


Final race weight is 1735g... I am considering to upgrade with some lightened aluminum shafts later on... I did upgrade to some aluminum wing mount caps
Last edited by bill_delong; Mar 26, 2019 at 10:43 AM.
Mar 29, 2019, 08:05 AM
Did I make the A Main?
bill_delong's Avatar
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Recent thoughts shared on RC Tech about new car recommendation
Apr 02, 2019, 03:00 PM
Did I make the A Main?
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My first race day with the 401R was last Wed night (Mar 27), I took 1st place at our club on the Wed night "Triple Threat" program which is not a typical race program. They do best 2 of 3 heads up races with results combined between multiple heats with no resorts, drivers are randomly mixed together with all skill levels spread out and 3 rows of cars on the grid so everyone gets a chance to start on the front row once per race night, and then start row position changes each following round. I shattered my personal record by 9.8 seconds (almost half lap) with a 28/10:03 last night after switching from a TEKNO EB410!





If you notice in the 3rd round, my race ended after lap #6 because I broke... I knew I had already won the series for the night, but the RD was egging me on to run the car faster and I was really pushing the envelope beyond my skill level, I was trying to stay harder on power and went full throttle into the wall and broke a shock cap, arm and slightly bent the suspension arm pin... you know it had to be a hard enough crash to bend the pin, and it was a VERY loud hit... not really sure any brand of car would've made this crash without breaking... anyway, this gave me a good opportunity to see which parts I need to stock up on

Last edited by bill_delong; Apr 02, 2019 at 03:08 PM.
Apr 02, 2019, 03:31 PM
Did I make the A Main?
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My next race day was Sat Mar 30 and things were progressing very well for me during the quals, the car was getting faster each round and I would beat my PR qualifier by 4 seconds in R2, then I would shave another second off my PR in R3 with an overal Q2 spot on the grid... normally I get somewhere around Q5-Q7 with this group of drivers
http://trc.liverc.com/results/?p=view_points&id=1251033

Things were going very well for me in the main... I maintained #2 position throughout the race and was spread out evenly with about 7 seconds on either side between the #1 and #3 cars respectively, then with 1 min left on the clock my battery dumped... I pulled a rookie mistake and took about 5-6 laps of practice before the main started when I should've only taken 1-2 warmup laps.... argh!

http://trc.liverc.com/results/?p=vie...lt&id=1845533#


Anyway, I was on pace for a 23/8:04 finish which would've been more than 1 full lap off my previous PR of 22/8:06... oh well there's always next time to try and beat my PR with my PR, ha!
Apr 15, 2019, 02:27 PM
Car Bashing
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Nice to read a new review from you Bill Very interesting and detailed. Nice to see you at the first place Name: Cool.gif
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I saw some PR Racing chassis, 4WD and 2WD in good used condition on ebay and at a good prices, mainly sold from UK. But as i don't have short pack and don't race, i passed my way on them.
Apr 15, 2019, 02:36 PM
Did I make the A Main?
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Thanks Jym

The quality of PR cars is pretty good, especially because they include so many upgrades in the kit making it very cost effective... I would definitely reconsider one later on, even if it would require you to get a shorty pack


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