darrenjlobb's Rolling Road Chassis Dyno Project

[darrenjlobb]

Seen as though I haven't had any any interesting projects to blog on here in a while (other than a stupid, broken, pointless petrol!!) I thought I'd add another on going project of the last month or so of mine on here given some people may be interested in this sort of thing.

So as many know (but maybe alot of newbies dont) I spend most (if not all) of my time when im not farming, messing with cars, in particular tuning dervs. One of the biggest problems I have in general, when working on ANY car, is some form of benchmark / ability to monitor the small gains. Obviously when I get a car that im putting a big pump, or big turbo, or both, or even more extreme sometimes in my workshop, its night and day, obvious the difference you have made, but then all the small things, that make all the difference, get very hard to monitor. Constant "road runs" are required to get mixture / tuning / everything right, which is not only a total pain in the arse / waste of time, but frankly, not accurate at all, as we all know, the arse dyno only works on power + noise!

So a few months ago I embarked on constructing a rolling road, with the aim to be able to "load up" cars, in the workshop, and be able to tune, while monitoring exhaust / temps / output etc, without having to worry about driving, and without going anywhere. Buying a complete fully working Dyno, was obviously totally out the question, given the price these fetch. So the original ideal was to construct my own, the plan was to use an old leyland fluid flywheel:



I was planning to convert this to a water brake, by mounting bearings externalls / adding water in / out and welding a load arm etc to it.

However, while this was all going on, out of no where, a decommissioned (knackered) Dyno came up for sale in Oxford...an old Clayton unit, now i picked this up for near enough nothing, and initially, was planning on using it purely for the rollers, as my own homemade project had already come to the conclsion that the most major investment in the project was to be the rollers themself, given the need to be strong, balanced, and perfectly round, this was obviously something I would have had to have made up, and would be very expensive...So I was really only looking at this dyno for the rollers, anything else would be a bonus.

So spoke to matey, who sent me some photos of it where it used to be installed:
(ignore red lines, that was us figuring out how to get it home!)



After deciding that given the price, I simply couldnt ignore this, so spoke to Ruan, (lives that way) and decided best way was to rent a van, and drive the thing back to Cornwall....so thats what we did, well I say we, acaully Ruan did, so many thanks again to Ruan for taking the time to bring the thing home, as it would have been a real job for me to get up there and get it myself!

So after getting it home, set about stripping it down / figuring out what was good, and what was bad:

The roller frames:



One of the water brake retarders:



The epic retro electronic readout!:



So as you can see, what we have ended up with, is a twin brake rolling road, with analog readout, and even managed to score the water pump, and tank with the deal...remember at the time I was buying this purely for the rollers and / or frames!

Its a water brake unit (same as I planned, ideal for prolonged loading / ability to remove the heat), one brake per rollers, although have a link shaft to convert to single brake, but then its only able to read 250hp, but with both its 500hp, or 400whp as the oem readout system uses whp. Obviously the accuracy of this is likely out, and would need calibrating, but my eventual plan would be to convert the unit to computer data logging, and obviously new digital load cells, so really for now the readout side of it dosnt matter, that said, if it works, then great, as thats at least something to go by...

Obviously, the thing has issues, hence the sale, and as with all of these units, its always in the brakes that the problem lies, normally wear to the stator and rotor. So I started to tear into them, so see if they are shot, or if they may be repairable, as the way I saw it is at the end of the day, if we could re use those instead of building my own, things will be much simpler, worst case, they would get sacked off, link shaft fitted, and use the leyland unit as originally planned.

First step was to get the rotor housing off, and inspect the stator:



Here you can see me removing the rotor from the shaft, but already you can see the corrosion on the edge of the stator, this is the main problem with the units, as this metal wears away, the brake looses its braking effect, therefore massively reducing the hp load capability of the dyno.

However, to my suprise, unlike most of these units ive seen apart, the rotors were infact in very good condition, totally useable, and very little corrosion:



Less could be said about the stator though.....:



I decided at this point, that weather the brakes were fixable or not, the rest of the unit was exactly what I needed, so went ahead and totally stripped it down, so that I could get it shot blasted, and then I will re paint it, to try and tidy it up some what, as well as rebuild / repair the mechanical brakes to allow cars to load / unload the dyno.

All stripped down ready to shotblast: