[Jaggu]

Is this the test? How is it important from a CJ perspective?

SAE J2452 is a standard defined by the Society of Automotive Engineers to define the rolling resistance of tires.
The rolling resistance coefficient (RRC) indicates the amount of force required to overcome the hysteresis of the material as the tire rolls. Tire pressure, vehicle weight and velocity all play a role in how much force is lost to rolling resistance.
The basic model equation for SAE J2452 is:
Rolling Resistance ( N / Lbs) = Pα x Zβ x (a + bxV + cxVxV)
where:
P is the tire inflation pressure ( kPa / psi)
Z is the applied load for vehicle weight ( N /Lbs)
V is the vehicle speed ( km/h / mph)
alpha, beta, a, b, c are the coefficients for the model.
The units of the coefficients are matched to the units used in the model, i.e. ( metric / Imperial)

Source: SAE J2452 - Wikipedia, the free encyclopedia

Originally Posted by DHABHAR.BEHRAM

Dear Sharath - if you feel that this communication is deviating from your CJ340 issues, please feel free to delete the posts without any hesitation. After correcting the steering, please also carry out a coefficient of rolling resistance test on your CJ340. Let's see how effective the tyres are. I am sending you the procedure by a PM.

Best regards,

Behram Dhabhar

[SPIKE ARRESTOR]

OT- ^^ That is TOO complicated, there are simpler ways to determine the rolling resistances, that is by "feel". I will keep quiet for time being.

Spike

[Jaggu]

Ok forget calculation, what is the relevance wrt to steering? Apart from the obvious harder steer and more load on the system? less FE eh??

[ex670c]

Originally Posted by Jaggu

Is this the test? How is it important from a CJ perspective?

Hi Jaggu,

You can try this

Background Information

Rolling resistance - Wikipedia, the free encyclopedia

Regards,

Arka

[SPIKE ARRESTOR]

Yes, FE is one thing, why do you think steering effort reduces when the vehicle starts to roll a bit (as compared to being stationary). There is a graph for the same which I will post if I happen to find.

Spike

PS- Power steering systems are designed on the basis of this graph.

[trammway]

Originally Posted by ex670c

If you don't get a proper L-Bolt, you can fabricate a bracket to bolt the steering box-brace and weld it to the Chassis, IIRC, the Classic and MM550XD have this instead of the L-Bolt.

Arka,

The L bolt or the stabilizer bolt for the steering box is seen on my Mahindra Classic. See the picture here, you will notice the L bolt similar to CJ340

http://www.team-bhp.com/forum/attach...12011-006-.jpg

I'm sure you are right on the MM550 part as I haven't spotted one when I was working on Shibu's MM550.

[DHABHAR.BEHRAM]

Dear Trammway - in your CJ340, you have provided additional clips to hold the spring leaves in place. If more than the designed number of these clips are used, the spring rate will go out of specification. Please revert to OE specification. Also, this clip will damage the axle articulation stopper. Please take care. Also, fender support on chassis seems to be broken. Please fix it. If I remember correctly, this is a 5/16 inch size fastener but you can use M8*1.25. Please see CL550MDI Major vehicle design. We had completely changed the body mount orientation in this area. I kinow that you will appreciate it, hence this information.

Dear Jaggu - measuring coefficient of rolling resistance is not rocket science, neither is Wikipedia required. Think about it. Tomorrow, I'll try to log on in the afternoon and provide details.

Best regards,

Behram Dhabhar

[SPIKE ARRESTOR]

Originally Posted by DHABHAR.BEHRAM

Dear Trammway - in your CJ340, you have provided additional clips to hold the spring leaves in place. If more than the designed number of these clips are used, the spring rate will go out of specification. Please revert to OE specification.

Sir,

Your observation is correct. However, there are two things which need mentioning here:-

1. The spring clips have a rivet at the bottom, the clips then close in with the spring pack at the top portion. That means those cross bolts are not as per OE specification.

2. The first clip when seen in the pic must come at the 3rd leaf beginning (including primary and secondary leaf), the second clip comes at the 6th leaf (including primary and secondary leaf).

Spike

[DHABHAR.BEHRAM]

Dear Pratheesh - you are correct. If an OE design uses a bolt, there is a spacer incorporated with a rubber insert designed for the purpose. The CJ340 spring pack has snap on clip, only 2 per spring. The one in the photograph is after market, not designed for this application, it will not work properly. People have started understanding right from wrong now, so it is a good sign. We must help them.

Dear all - just to get your analytical abilities into overdrive, "how does a silent block bush work?". Let's see.

Best regards,

Behram Dhabhar

[trammway]

Originally Posted by DHABHAR.BEHRAM

Dear Trammway - in your CJ340, you have provided additional clips to hold the spring leaves in place. If more than the designed number of these clips are used, the spring rate will go out of specification. Please revert to OE specification. Also, this clip will damage the axle articulation stopper. Please take care. Also, fender support on chassis seems to be broken. Please fix it. If I remember correctly, this is a 5/16 inch size fastener but you can use M8*1.25. Please see CL550MDI Major vehicle design. We had completely changed the body mount orientation in this area. I kinow that you will appreciate it, hence this information.


Best regards,

Behram Dhabhar

Hello BD Sir,

Thanks for the information. You are right the spring configuration is completely out of OE specification as I was trying out helper plate setup and I have already decided to revert it back to OE even though few advantages were observed. I'm completely agree with you on the articulation ability with OE configuration.

Another reason for thinking of reverting to OE is about the missing inner side hanger bush(is that what you mentioned as silent block bush?) setup for the newly introduced shackle and eye bolts, which turns out to be an issue.

About the fender support, I really missed to notice the same. Thanks for the hint. Will work on it along with my near future body work planned.

[Samurai]

Here is something I forgot to mention about Sunday. I usually fill up diesel after 250kms of travelling since the fuel gauge nowhere near accurate. It only gives me a very approximate indication.

After driving mostly around 50kmph all the way to Chikmagalur, I decided to top up the diesel tank as usual.

The petrol bunk kid fills up 14 litres of diesel and then stops.

Me: Why did you stop?
He: It is full.
Me: What do you mean? It can't be full so fast...
He: No, it is full.

I am stunned, I just pay and continue. After a while I jump out and check, he is right, it is full.

The distance covered since the last fill-up in Bangalore is almost 250Kms. And I am not going by the Jeep speedometer. I do know the physical distance.

That means I got 17.85kmpl for this drive!!!

I know it is outrageous. I usually get 11-12kmpl, when I mostly drive between 70-80kmph gunning the engine most of the time.

However, the first time I drove this Jeep, that is when I drove it from Bangalore to Manipal, I got something similar. At that time, I occasionally touched 70-80kmph, but mostly drove at 50-60kmph. At that I used the Jeep speedometer, which is at least 10% inflated.

Originally Posted by Samurai

The FE report is out, it is unbelievable, at least for me.

Anand told me he gave me a filled up tank, the reading was 8232 during fillup, and 8248 when he delivered it to me. On the way I filled up for 500 bucks or 13.8L (not 10L as I mentioned before), and today I filled up at 8712, an additional 15.8L only.

In other words, the Jeep drank 29.6L for covering 480Kms of mixed road conditions, about 80Kms of city traffic, about 200Kms of straight highways, and about 200kms of twisting roads including ghat sections. Don't forget the congestion in ghat section.

That's 16.2kmpl!!!

My total fuel bill for the trip is Rs.1034 only. (I deducted 16kms (1L) used by before delivery)

But, I am not able explain the FE this time. All I can say is I couldn't gun the engine thanks to the wandering wheels. So, what does this mean? If one drives the XDP engined Jeep at 40-50kmph in 4th gear most of the time, one can get phenomenal mileage? I can tell you it is absolutely no fun...

[svsantosh]

Originally Posted by Samurai

So, what does this mean? If one drives the XDP engined Jeep at 40-50kmph in 4th gear most of the time, one can get phenomenal mileage?

In engineers terms, the 'sweet' spot - top of the torque curve in a XDP4.90 - with the 4Spd KMT90 and '5.38' axle ratio is around is around 50Kmph, beyond that the curve falls steeply. Engine revs, speed does go up, but at the price of F.E.

Exactly why Trammways classic (like many others), gives 16+ even under heavy foot conditions - its got a 4.88!!!

I am going for the 4.88 in near future.

[Sudarshan]

My 540 is a long chassis , 5 door steel body , weighs 1775 kg .

I never drove above 80, normally drive at 65 to 70 . This provided me with best figures of 11 & worst of 9 ( on out of city driving )


Try keeping the max speed at or bellow 70 , you will get at least 13/14 per litre. Yours is a 80" wb it wont be weighing above 1400 kgs so achieving 15 km mark regularly is quite possible.



I use lot of engine braking , I keep my eye on obstacles & take right foot off the accelerator much before ,this also helps


Sudarshan

[star_aqua]

Originally Posted by Samurai

If one drives the XDP engined Jeep at 40-50kmph in 4th gear most of the time, one can get phenomenal mileage?

I did Bangalore - ooty - Bangalore 3 times which included 50kms of 4wd track for each trip. on highways i maintained constant 70kmph. with 4 people onboard plus luggage i got F.E of 14kmpl.

[Samurai]

Let me update the status of repair work regarding the steering system.

The mechanic opened up the steering system, and discovered that the bearing of the bell crank had gone bad. So he replaced the bearings, and welded it back. Now the Jeep steering is back to normal. I have attached the detailed bill.