This may seem a silly question but it is one i need answering.
We are getting there with this Marlin trials build took a lot longer than anticipated i can tell you,several u turns in power plant choice did not help mind.
i will post pictures when it is completed i am at the stage of sorting out wheels, i will be using MGB rostyles they are plentiful and i have lots anyway. NOW????
Wheel bolts or locking lugs rim locks Tyre clamps. not sure what others call them, but basically they hold lyres run on low pressure on to the beed to stop instant deflation.
My questions !
1 .. Obviously they are legal to use !! -- Are they ?
2.. How many to fit.
3 Advice on construction and fitting
4 I Would rather make my own if at all possible but can you buy them and where from.
One last question as an after thought, i am ready to drill the 575 van drum brake hubs to take the disks, i fitted a old BMC ex riley 1100 remote brake servo with the std front disks, it works fine. But not sure how many are out there now. This got me thinking with the twin leading shoe drums being kind of self sevoing and taking into account i wont use this car on the road much. should i fit the drums rether than convert to disks.?
Instinct tells me the disks will clear better in mud etc, but what are others thoughts based on experience of drums on marlins or other cars in trials situations. ?
Liam
ReplyDeleteSecurity bolts - suggest you go to the start of a trial with your camera and take pictures & ask the competitors there. There are lots of different ideas, some simple some complicated. As to legal - who knows?
So what power unit have you decided to use?
ER..HEM! Get ready for it.. Are you sat down,.! this could be controversial 1300 well +60 hepolites probably 1320cc Ford kent cross flow. twin 40 dhlas Big valve self flowed head and a aftermarket cam four branch lots of bits lightened and balanced. Before anyone says i tried the 1600 yes it had more grunt, but it weighed more. being a chapman fan i just added lightness and went for the 1300, and i drew strong money only last week on ebay for my 711m 1600 that payed for all my 1300 mods to date, admitted i did a lot myself.
ReplyDeleteI would try running tubeless without bolts. I used to run tubes and had lots of problems with the valve tearing out due to the rim moving in the tyre. Once I went to tubeless I had no problems with deflation or tyres spinning on the rim, even at very low pressures.
ReplyDeleteFrom what I have heard bolts tend to damage the sealing bead on the tyre. No problem the first time you fit the tyre but if you have to take it off for any reason it may not seal properly afterwards.
I think you will get as many opinions as people you ask on the wheel question Liam. I run tubes on my Beetle front and back. Used to run tubeless on the front but found I got leaks with mud getting forced between bead and wheel.
ReplyDeleteDon't use bolts myself but people that do weld nuts to the rim and use pointed bolts to bite into the bead and stop the tyre spinning on the rim. You will see people run very low pressures without bolts. Keep an eye on the valve stem and when its gets to much of an angle swap the wheels round.
I run bolts on the rear of my beetle the idea is not only to stop the tyre spinning but als to stop it dropping into the well if you do get a punture on a section (you will still get grip and drive this way then hopefully not fail the section). i run 8 bolts each side (6 will pos do),
ReplyDeleteI have welded 8 M10 nuts & use M10 Cap headed bolts aprox 20mm long turned down to 7mm & domed on the bit thats protudes into the tyre/tube as not to punture... i have them placed so they just pinch the tyre (think about 9mm from the edge.
Hope this helps...
ps i dont run tubes on the front and the day after a trial both fronts are usualy flat!!!!
It all depends on the rim design most modern rims have a really good bead retaining ridge, I've no idea what mgb rims are like.
ReplyDeleteAs for bead locks, I've done it with 8 m6 nuts welded to the rim and if I remember correctly 12mm long bolts they worked fine, legal wise I expect not but soon getting out of bed will be considered a risk...
As for a 1600cc xflow being heavier than a 1300 it is but not by much at all for the torque increase
I understand your point about going tubeless, i was actually referring more to tubeless tyres and something inside the rim like on motorcycles to hold the Tyre up against the shoulder and keep it in the bead. I did think three would be enough on a 14 inch Tyre but perhaps not, they would not need to press into the Tyre inner wall as such just be a contact fit and stop it slipping off and letting air out. A softer walled Tyre will obviously be a better candidate for staying seated at low pressures than a stiff commercial spec Tyre. I get the general idea not sure if i have it totally correct that 12 psi is the lowest pressure you can run and Tyre checks are carried out as a matter of course. Now 12 psi seems enough to hold a Tyre on a rim bead in most situations but add the rough terrain and all the other factors of classic trials and surly they must deflate don't they. as far as i can tell from Google 4x4s use a weld on rim cleat ring of sorts that is available in 15 and 16 inches Devon 4x4 sell them by all accounts.
ReplyDeleteSo far lee as my thoughts covered quite well, that is how i imagined things would be. i have to say i did not recon on the soil ingress, that sounds a problem.
Do you think it is caused by Tyre bead movement trapping soil for want of a better word betwixt the Tyre and rim and like walking it in to the Tyre, and if so one would think keeping the Tyre in contact with the shoulder and thus the seal band square on the bead this would not only keep a larger bearing surface to help prevent Tyre in rim spin, but slow the ingress of debris
My main reason for originally enquiring about locking lugs or whatever you want to call them, was my thoughts that perhaps many punctures are not really punctures at all but deflation due to tyres being forced off rims. Ok i suppose they are technically one and the same but perhaps by good location partially avoidable .
OK, here goes ...
ReplyDeleteRemember that in Class 7 you'll be running with tyre pressure restrictions (probably at 10/12 psi) more often than not. My view is that any form of tyre bolt is more trouble than it's worth at these pressures - just think about the effort of changng a tube mid-trial. I know some Marlins on Rostyle wheels have been using tubeless for some years quite satisfactorily whilst others sticks to tubes. If you notice the valves moving you can always swop tyres side-to-side mid-trial. I know, I've done it!
Are you suggesting disc brakes on the back? (All Marlins that I know already have them on the front). That sounds like a very bad idea to me. Discs on the back always give problems with handbrakes and you'll need a 110% handbrake for the number of restarts you'll be doing. And has anyone made a hydraulic handbrake work with rear discs, or is it better with the greater leverage?
1300 Crossflow in preference to 1600 Crossflow?? Good luck, you'll need it!
Andrew
1) Run tubeless and glue the tyres to the rims with Sikaflex.
ReplyDeleteA very popular solution in both the VSCC and sporting trials world.
2) Self tapping screws: drill holes in the rim, 8 per side, not very big, the just screw the self tapper into the bead after the tyre has been inflated to something above road pressure.
3) Forget bolting the tyre to the rim, but fit tractor valves to your tubes, These bolt the tube valve to the rim. Then use lots of french chalk when fitting the tube, and the tyre can slip to its hearts content without the tube moving.
If you have a tube, the tyre will not come off the rim even with pressures as low as 4-5psi. Its only when its completely deflated and you are still pushing hard that this happens.
The legality of retaining bolts? Anything that goes into the tyre bead would arguably compromise its structural integrity and therefore give the health & safety boys kittens. Its one of those questions you really shouldn't ask!
As for all that engine tuning stuff - why didn't you apply all those 1300 mods to a 1600? and then you might be getting somewhere close!
Great replies thank you, I was skeptical regarding the legality for on road use any way of any form of locking lugs etc. I like the sikoflex idea a lot, The replies on this post have given us some insight we simply did not have. The engine choice. Well i did suggest it would be controversial didn't i now. It is undoubtedly less suitable than an equivalent 1600 or 1700, but selling the used 1600 got me the funds i needed to build what is in effect a new engine. I can always metaphorically suck it and see. And the 1600 kent is always still an option if it fails miserably.
ReplyDeletePersonaly i think i am the weak link in this chain not this engine.
Well after suffering a run of 'snake bite' punctures on my Pug, where the tube gets pinched in the cover's sidewall when thumping over rocks, I tried a few events running tubeless instead, with the bead sealed flexibly to the rim with the Sikaflex that Simon refers to. No more punctures, but in a FWD car the tyre gets pushed sideways more than in a RWD, so pretty soon I was getting little stones lodged in the gap (much as Mike observes) which worked into the sealant and caused slow leaks. Impossible to get out again without tyre removal.
ReplyDeleteSo I figured the puncture culprit was too stiff a wheel rim, which I'd reinforced with a 10mm rod welded around the circumference...no 'give' for the poor old tyre over rocks. So a full day of weld cutting had 'em all out, and this restored compliance seemed to stop the pinch punctures.
To retain the tyre bead, I weld about a dozen 12mm long and 2mm high ridges round the seat which gives the bead a bit of rotational key and some extra tension to stop him popping inwards past the retention lip. Personally, I'm another who's not keen on screwing directly into the tyre's bead, though the domed bolts behind it do seem tidy.
Another good response thank you, The feedback on the sikoflex idea was most welcome, I see the idea of screws as a potential if the Tyre deflates and you try and make it out as a ripe recipe for a nice tidy hole in your side wall every time.
ReplyDeleteThe bead of weld sounds another good idea, Getting a fair few ideas now, and it is maybe time to start implementing a couple myself see first hand the pros and cons.
I have still not drilled my front hubs for the std marina disk brakes, i still have all the drum brake 575 components as standard, should i simply fit the front drums or is the disk install a must. I have all the std disks so i have both options for no financial outlay. Fit the disks or just use the drums your thoughts gentlemen please.
Hi which sikaflex is the best to use as i want to try to run tubless?? Me and my dad had 6 punctures between us in the lands end. All look like pinched tubes with no tyre damage. Is 12 psi to low to run?? Thanks in advanced steven.
ReplyDelete