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This is a read-only archive of the old Madabout Kitcars forum. New posts and replies are no longer possible, but every thread is still here to browse and read.

Dual 7" Servo

23 Dec 2011, 8:34am
Hi Peter

Yes, it was a little surprising to see the minor variations, though not totally unexpected, as the MBM samples were slightly different from the Duksville unit. I am glad I held back on having the adaptor plates produced solely on the basis of the first two sample Powder coated servos. I have to say, my heart sank when the planned adaptor did not fit all variations............I felt a bit like the marathon runner hitting the 20 mile wall. But having got that far, you don't give up.............
I'd like to thank Mashtun for coming to my rescue. He has drawn and re-drawn the plates we require at very short notice, and made sourcing the plates so much easier. As has been said before, just another example of how well this site, and the group who use it, works for the benefit of all.
I also hope to draw Oaktree 11 in to help as well - with machining the recess to the back of the plates to clear the post rivets. And with Jason finding the Dual servo, and doing the testing it has been a true collective effort.

You have certainly been very observant of the photos!

The Chrome and Zinc servos are actually the same design, only varying by finish. The rubber bung you can see in the Chrome unit is only the transport dust cover. The push rod ends are slightly different from the Powder coated servo, but are adjustable on a thread just the same.

"Why there are small differences?" I can not be certain, but I suspect MBM may be marketing generic products along with their own units?
But which is which, and does it matter? They are all sold as "Universal" and they all appear to be good quality: much more substantial and a definite step up from the Metro unit I have, even though it was new.

I trust everyone will be happy with their their choice of finish,(Chrome guys get your dusters out!) and that the improvement in performance matches our own expectations.
Jason and David have both been very positive, but I'll only truly relax when there are more positive reports! So those of you with drivable cars, please let us all know what you think!!


I feel like I'm on the final mile now, and the end is in sight ........

Mike


peterux wrote:
Probably like you, it's a surprise to see the different designs as we had all assumed it was just the coating. They seem to have different types of push rod ends and the chrome ones seem to have a kind of rubber boot just inside the m/c opening?
Any clues from MBM why they are so different?


Thanks again to you, Mike, for your diligence and commitment now you have umpteen different combinations to design, order and deliver.
I hope you (and Mrs. Mike) do have a good Christmas and you are not dreaming of servos too much.
I'm sure most of us can wait another week or so, so don't spoil your Christmas break trying to get them all shipped out. (I certainly won't need mine for at least a few weeks... :lol:)
23 Dec 2011, 9:27am
Thanks, Mike, all clear now!
Great team effort, well done!!
23 Dec 2011, 9:46am
Money now transferred Mike.
Thanks very much and like Peter, no hurry for me.
23 Dec 2011, 10:53am
Mike

PM sent

Cheers

John
23 Dec 2011, 11:06am
Mike

PM sent

Robin
23 Dec 2011, 2:20pm
sent you a pm, will get $$ over to you this evening :)

Patrick
23 Dec 2011, 3:23pm
Adaptors Not Made Yet

Hi all

The guy cutting the adaptors has not been able to fit them in pre - Christmas, so they will now be made in the New Year - sorry.
I'll let you all know as soon they are available.

regards to all

Mike
31 Dec 2011, 11:48am
Adaptor Plate - Finish

Mike wrote:
Hi all

The guy cutting the adaptors has not been able to fit them in pre - Christmas, so they will now be made in the New Year - sorry.
I'll let you all know as soon they are available.

regards to all

Mike


Adaptor Plates (those who had a preference for stainless)

I have spoken to a couple of people, including fabricator/welders, who have advised against making the adaptor plates from stainless plate/thread, as it does not have the same tensile qualities as mild steel. Given that these are going to be highly safety critical items subjected to tensile load, I would not like to be responsible for supplying something which might fail (however small the risk), and would prefer to supply mild steel only.

I am quite happy to order and supply substitute mild steel plates instead of stainless, or refund those who prefer to get their own stainless ones made at their own volition. (I can forward a drawing if anyone would like one).

Please let me know if you are happy to go with the mild steel, and PM me your bank details for the £3 refund: or the full £12.50, if you prefer to source your own.

I apologise for any disappointment this may cause, but I am sure you can understand my concern/reasoning.

Very best wishes to all for the New Year

Mike
31 Dec 2011, 1:17pm
Hi Mike

As we discussed, from a safety perspective, I will go with mild steel. Don't worry about the price difference, its not worth the effort for the sake of £3.00.

John
31 Dec 2011, 1:30pm
That's fine don't worry about the £3
31 Dec 2011, 5:28pm
Mild steel ok with me, call it quits on the £3. :)
31 Dec 2011, 7:56pm
Mild steel is fine with me also. Don,t want the £3 back, but thanks for offering it.
6 Jan 2012, 8:33pm
The Adaptors are made!

Hi Guys - Happy New Year to you all

The adaptor plates have been made and are now with me, ready for dispatching. Many of you have said "Don't rush to send mine - the car is in bits!". So, are there any of you who would like to be in the early batch to be sent out? - particularly anyone who has their car on the road over winter, who can give us some more feedback on their findings?
GOO will be included in the first complete kit batch, for all his sterling efforts in testing the prototype, and Mashtun who helped greatly with his drawings. I'm also putting Nigel at the front of the queue for his fantastic help on my engine wiring - I'm easily bought!

Seriously, if anyone would like to PM me for a quick dispatch, please do as most are happy to wait a couple of days extra.

Regards to all
Mike
9 Jan 2012, 5:45pm
Hi Mike.
Have just sent you a PM.
Peter.
9 Jan 2012, 6:13pm
This is interesting as I had earmarked my local Screwfix as a source of Stainless Steel C'sk screws for the master cylinder. They list them as High Tensile Stainless but now I am thinking of reverting to Mild Steel.

Metal tensile strength differences aside, my understanding is that a high tensile screw is formed by rolling in the thread form so the grain pattern of the metal flows up and down the thread form, which makes the thread much stronger than a machine cut thread. In a machine cut thread the grain pattern of the original bar runs parallel to the axis and so will run across the thread form producing lines of potential weakness in the thread.

It would be interesting to know comparative UTS figures for Mild Steel and Stainless and if so what the material specs are?

Peter.

Mike wrote:
Adaptor Plates (those who had a preference for stainless)

I have spoken to a couple of people, including fabricator/welders, who have advised against making the adaptor plates from stainless plate/thread, as it does not have the same tensile qualities as mild steel. Given that these are going to be highly safety critical items subjected to tensile load, I would not like to be responsible for supplying something which might fail (however small the risk), and would prefer to supply mild steel only.

I am quite happy to order and supply substitute mild steel plates instead of stainless, or refund those who prefer to get their own stainless ones made at their own volition. (I can forward a drawing if anyone would like one).

Please let me know if you are happy to go with the mild steel, and PM me your bank details for the £3 refund: or the full £12.50, if you prefer to source your own.

I apologise for any disappointment this may cause, but I am sure you can understand my concern/reasoning.

Very best wishes to all for the New Year

Mike
9 Jan 2012, 8:44pm
I need to service my tin top this weekend so not in a massive rush :)
9 Jan 2012, 8:53pm
Contact

Stuart

I have sent a PM - can you contact me, please?

Regards
Mike
10 Jan 2012, 5:29pm
All servos dispatched

Hi Guys

All servos have now been dispatched for delivery
(bar Cabrioman, as requested).

I would appreciate a quick PM acknowledging safe receipt, please.

...........and of course any feedback from anyone who can test theirs, as I am sure we will all have a slightly different experience, due to variances with master cylinder bores, pedal ratios, brake pots, pads, discs, drums etc.

I hope they all meet with your expectations.

Have fun!

Regards to all
Mike
10 Jan 2012, 6:20pm
Thanks very much Mike :)
10 Jan 2012, 6:24pm
Stainless stress

I think stainless would have been ok!!!!!!!!!!!!!!!!!

Based on these figures an M8 bolt, which has a cross section width conservatively of 7mm, has a radius of 3.5mm, and therefore a cross sectional area of 36.75mm2. So, at 700N/mm2 = 25.7kN = 4,250lbs per bolt, it would take in excess of 3.5 TONS of force for the bolts to fail.

Anyone got a right foot that heavy!

May be this is a little flippant, as the failure is likely to be stripping the threads, rather than on the cross section failing?
Anyone any ideas how to calculate that?

Mike



Grey V8 Pete wrote:
Have found the following website giving some insight into the Stainless Steel vs Mild Steel strength issue.

http://www.volksbolts.com/faq/basics.htm

Peter.
10 Jan 2012, 8:48pm
great news mike, will turn up in perfect time for me to finish all me pedal box building
10 Jan 2012, 8:56pm
Mike wrote:

Anyone got a right foot that heavy!



Only on the right pedal.......................!!
10 Jan 2012, 8:59pm
Mike wrote:
So, at 700N/mm2 = 25.7kN = 4,250lbs per bolt, it would take in excess of 3.5 TONS of force for the bolts to fail.

Anyone got a right foot that heavy!

Mike



Only on the right hand pedal...........................!!
10 Jan 2012, 10:20pm
NigelB wrote:
Only on the right pedal.......................!!


:lol: this should hopefully sort that 0.5 seconds when someone in a tin top with ABS and a servo bigger than their engine slows down quickly in front of you and you just put your foot through the floor :biggrin1: