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PollyMobiles Rebuild

just researching into beville springs and some manufacturers say they can be prone to failure from excessive cycles, corrosion, high temps beyond material rating, mechanical damage and overloaded.
http://www.solonmfg.com/springs/faq.cfm

another suggests the preload should be at 15% of available deflection and should never exceed 75% of available deflection.
http://www.bellevillesprings.com/disc-springs-din-2093-fatigue-life.html

I'm starting to think that the beville spring rate was too soft and couldn't handle either the sustained 160ftlb or a sudden shock of torque during up-change so it was squished beyond it's safe 75% deflection repeatedly till it cracks in half each time
 
pollyp said:
description on opieoils.co.uk says not suitable for synchromesh boxes
Click to expand...

Best to read Millers blurb rather than Opie.

Quote from Millers:
Designed for the lubrication of competition gearboxes and axles which require limited slip high performance oils. Hypoid differentials with limited slip, gearboxes with combined limited slip differential, synchromesh and non-synchromesh manual gearboxes and transfer boxes. Hewland, Xtrac, Glebe Transmissions, ZF, Tran X.
 
I'll stick with the same oil for now, does a good job & no noise.
this broken disc spring is more of a material spec issue
 
Your not having much luck paul, you would expect a free replacement! By the way im not very clued up on gearboxes but while i was under the car refitting my exhaust you know the gear selector arm (gearbox side) where theres a rubber boot protecting the rod. Mines has popped off and the oil seal which i think holds it in place wont push right back. Is that a big job to replace? Aswell as the input shaft bearing?

Cheers
 
I agree Stani & Ed that it should be fixed free of charge cos Gripper stated that all their LSD from 2011 comes with lifetime warranty but I have a cloud of doubt cos I've been stung with paying the full price to fix it back in 2012 when I thought john said it'd be free.

Think the excuse was cos my diff and the original failed disc spring was technically an older pre-2011 design and I also requested changing ramps, it wasn't covered.
Charged me £65 to rebuild, £25 change ramps, £10 postage and £20 vat.

But then after supposedly fixing n upgrading the disc spring to a newer type in 2012, surely it should really be under the lifetime warranty now?

If they say yeah they'll fix/replace it for free and I get surprise stung again then that breaks the T&C, my trust and will prob have to abandon the diff cos it'd simply be unreliable and uneconomically sustainable.
 
Stani1029 said:
By the way im not very clued up on gearboxes but while i was under the car refitting my exhaust you know the gear selector arm (gearbox side) where theres a rubber boot protecting the rod. Mines has popped off and the oil seal which i think holds it in place wont push right back. Is that a big job to replace? Aswell as the input shaft bearing?

Cheers
Click to expand...

Yeah the selector boot on mine pops off too. U just stretch the flat rubber edge over the lip of the gearbox selectors hole. Bit fiddly.
I think the rods seal is press fitted onto the gearbox casing? Vague memory.

Taking the rod out involves removing the casing, and punching out the two dual split pins locking the rod to the selector head (used some square cut nails as drift punches)
 
pollyp said:
I agree Stani & Ed that it should be fixed free of charge cos Gripper stated that all their LSD from 2011 comes with lifetime warranty but I have a cloud of doubt cos I've been stung with paying the full price to fix it back in 2012 when I thought john said it'd be free.

Think the excuse was cos my diff and the original failed disc spring was technically an older pre-2011 design and I also requested changing ramps, it wasn't covered.
Charged me £65 to rebuild, £25 change ramps, £10 postage and £20 vat.

But then after supposedly fixing n upgrading the disc spring to a newer type in 2012, surely it should really be under the lifetime warranty now?

If they say yeah they'll fix/replace it for free and I get surprise stung again then that breaks the T&C, my trust and will prob have to abandon the diff cos it'd simply be unreliable and uneconomically sustainable.
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It's not about warranty, it's about the item that was supplied being 'fit for purpose' which it is clearly not. Check your rights as a customer and don't take any **** excuses. You could always drop the 'trading standards' bomb if they don't play ball. You are in the right Paul, no doubt about it
 
Noddie said:
It's not about warranty, it's about the item that was supplied being 'fit for purpose' which it is clearly not. Check your rights as a customer and don't take any #### excuses. You could always drop the 'trading standards' bomb if they don't play ball. You are in the right Paul, no doubt about it
Click to expand...

have loadsa Q's and all this legal stuff is a minefield but indeed the original and the replacement disc spring were clearly not fit for purpose.

if the old spring had defective material spec and i was told the newer versions were improved, well imo it seemed as though they just replaced my old broken one with the same older defective design

here's a quote in Grippers T&C
http://www.davemacprops.com/gripper_tc.html

14. DEFECTIVE GOODS: Subject as mentioned below the Company guarantees that all reasonable care will be taken to ensure good quality of both material and workmanship and that in the event of any defect arising within 12 months from the date of invoice (or as agreed in writing) will repair or replace goods free of charge provided that:-
(i) That goods are returned "Carriage Paid" to the Company's works and
(ii) It is proved to the Company's satisfaction that the defect is due to faulty material or workmanship.
This obligation to repair or replace defective goods shall be the full extent of the Company's liability under the above guarantee and the Company shall not be liable for any further or other claim in respect of loss, damage, injury or expense of whatever nature arising in any way from or out of any goods sold by the Company.
Click to expand...
the "guaranty within 12mth of invoice" means bollucks that just cos I'm not able to disassemble my daily gearbox every month like a racing team and spot the issue on time they just slap a big fine on me for being too late.

does disassembling the unit invalidate the warranty? cos how am I suppose to know if the products damaged if I don't inspect the parts other than thinking Oh there's no preload?

plus what is technically the date "of invoice?" is it the date from when the product was ordered from Gripper or when the end customer purchased it from a distributor?
cos i ordered it via humphris and guessing either:
  • he may have brought it years ago pre-2011 & put into his storage till i brought it off him in Feb 2011
  • he ordered mine directly from gripper
so the goods have a 12mth guarantee from invoicing and a lifetime warranty? whats the difference?

it says i have to pay postage to send the "goods" back to them (the whole LSD product or just the failed ring?),
to be checked that its faulty (they'd probably need the whole LSD sent back to be assessed),
before they only repair or replace the goods (if they had the whole LSD it'd cover the condition that their repair & quality checks ensure the product is suitable for use before sending back to customer)
and free post back,
all free of charge (well that condition didn't happen last time did it eh)

i get the feeling I may have to send the whole diff out to be repaired/replaced at the risk of rogue charges

but spoke to dad bout it and he advises that word of mouth like last time on the phone doesn't mean/prove anything, I must get the agreement (that they'll fix the goods free) in writing or email as evidence to cover my ass before committing to the action. so if they invoice me, they've broken terms condition.
 
pollyp said:
Yeah the selector boot on mine pops off too. U just stretch the flat rubber edge over the lip of the gearbox selectors hole. Bit fiddly.
I think the rods seal is press fitted onto the gearbox casing? Vague memory.

Taking the rod out involves removing the casing, and punching out the two dual split pins locking the rod to the selector head (used some square cut nails as drift punches)
Click to expand...

Ok thanks for that :)
 
frank said:
it looks to me like there is just too much preload paul, cant you run with a more open diff ? (less ramp)
Click to expand...

try different ramp angles?, made no difference to the reliability issue.
they offer 45/45 (original 2-way ramp I first had and was very on/off) 40/65 and 30/65 (the current 1.5-way I'm using, which is progressive) but both had shattered the preload ring.

too much preload, possibly.
the disc spring has to withstand the initial deflection of the preload to press the clutch & ramp driver against the planet pins PLUS the max force produced by the ramp action at peak torque whenever I floor it over its service life and if the preload + ramp force has exceeded 75% of the available deflection repeatedly then it could explain the premature failure.

the preload of the rebuilt diff wasn't very high tbh (gripper actually set it lower than when I had the 2-way ramp cos I mentioned I use it daily and john said a high preload would be a nightmare on street).

even though I specified that she produces 160ftlb and used daily with occasional trackdays, it's as though the preload ring was under-specced.
either it's spring rate wasn't high/stiff enough to contain the combined preload + max torque within its safe 75% limit on only 2 trackdays
and/or it wasn't tough/durable enough to handle the repeated cycle.
 
frank said:
no, softer ramps/less preload paul, so that that diaphragm spring is,nt being stressed so much
Click to expand...

Can't soften the ramps cos thats all they offer but i'll see if they can reduce the preload with less packing or stiffen the disc spring rating

Seems abit backwards for a manufacturer to be told to reduce preload due to overloading?

I mean they're the one who's suppose to design n test & verify their products limitations, not me the customer.

They state its been extensively tested n used in several motorsports. My setup is quite tame in comparison to motorsport and we both verified my torque is within their diffs limit and yet it fails frequently.

If they'd tested & known such amount of preload will eventually wreck it, or even if it wasn't tested, why offer it?

This is all a lot of assumptions, so lets just make a phone call and find the facts
 
i meant shave some off the top of the ramps mate, or like you say, set a lower preload :)
we have a similar problem with our kart multiplate wet clutches, where the baskets are now very worn, and i have to fit an extra friction plate into the basket to take up the slack
 
frank said:
i meant shave some off the top of the ramps mate, or like you say, set a lower preload :)
we have a similar problem with our kart multiplate wet clutches, where the baskets are now very worn, and i have to fit an extra friction plate into the basket to take up the slack
Click to expand...

Hmm that's a point bout the stacking. I've read on someones thread bout replacing the beville ring with more clutch discs to mainly increase Lsd braking but it also eliminates the weak spring.

But the preload would now be even more sensitive to plate thickness and the value may deteriorate at a faster rate as the plates wear thin by mm's so requires constant disassembly & shimming compared with a spring that'll provide consistent load over a larger distance & service intervals, provided it stays intact.

So really there's not a win win design.
 
Resorting to changing the ramp angles is robbing Peter to pay Paul surely? (excuse the reference Paul ;))

The failure mode needs to be understood and appropriate corrective action taken by Gripper to resolve the issue.

If I wasn't selling my gearbox, I'd be tempted to open mine up for an inspection to see the condition.
 
Low Rider said:
Resorting to changing the ramp angles is robbing Peter to pay Paul surely? (excuse the reference Paul ;))

The failure mode needs to be understood and appropriate corrective action taken by Gripper to resolve the issue.

If I wasn't selling my gearbox, I'd be tempted to open mine up for an inspection to see the condition.
Click to expand...

agree. similar to software bugs, this is Grippers responsibility to assess the failure and update/upgrade the product/goods to meet their original requirement claims. I'm just the customer who purchased their goods in agreement that their spec claims are suitable for my needs (ie checking it could handle 160ftlb) yet I have a sorta Beta version of the item.

trying to modify the internal parts would prob invalidate the warranty (tis like attempting to fix a hard drive urself with a sledge hammer and telling the manufacturer their products faulty) and is really a bandaid without finding the actual source of the problem.

also, to reduce the force of the ramp action, you actually need a Steeper ramp angle. filing the ramp would make it shallower and increase ramp force against the disc spring.
 
pollyp said:
, you need a Steeper ramp angle.
Click to expand...
get that dremel out paul ;) they,re only gonna fit another diaphragm spring (probably foc) and you,ll be back to square one in 6 months time.
you will end up with a slightly more open (and reliable) diff imo :)
 
frank said:
get that dremel out paul ;) they,re only gonna fit another diaphragm spring (probably foc) and you,ll be back to square one in 6 months time.
you will end up with a slightly more open (and reliable) diff imo :)
Click to expand...

Taking a Dremel to an £800 LSD? That's golden signature material right there Frank :p
 
frank said:
get that dremel out paul ;) they,re only gonna fit another diaphragm spring (probably foc) and you,ll be back to square one in 6 months time.
you will end up with a slightly more open (and reliable) diff imo :)
Click to expand...

um no frank, making the ramp steeper requires adding material (which requires replacing or making a new ramp driver) so the pin exerts less "wedge" action towards the preload disc spring, but as I mentioned before I did use a steeper 45deg ramp with less wedge effect but still the same problem.

manually dremeling the ramp to a shallower angle by removing material will:
increase the wedge action = force against spring = likely to break,
invalidate lifetime warranty = permanent expensive paperweight
create uneven engagement - The ramps are precision made so a rough inconsistent ramp will cause unpredictable behavior & likely failure of the cross pins.

this diff product is an expensive valuable investment to me with a lifetime warranty cover and I'd rather let the specialists spend their time n money fixing it properly for me free (like a new car warranty) than to treat it like a disposable pound shop item.

its not a £800 paperweight yet, the ramp action still operates fine, it's just lost a portion of its preload (only 1/4 of the rings broken).
so once the spring is replaced hopefully with a stronger rating but shimmed to the same original preload, it'll be back to normal with a more reliable unit.

better to fix a problem immediately at its source than to fudge a bandaid and end up costing you more in the long run.
 
pollyp said:
um no frank, making the ramp steeper requires adding material (which requires replacing or making a new ramp driver) so the pin exerts less "wedge" action towards the preload disc spring, but as I mentioned before I did use a steeper 45deg ramp with less wedge effect but still the same problem.

manually dremeling the ramp to a shallower angle by removing material will:
increase the wedge action = force against spring = likely to break,
invalidate lifetime warranty = permanent expensive paperweight
create uneven engagement - The ramps are precision made so a rough inconsistent ramp will cause unpredictable behavior & likely failure of the cross pins.

this diff product is an expensive valuable investment to me with a lifetime warranty cover and I'd rather let the specialists spend their time n money fixing it properly for me free (like a new car warranty) than to treat it like a disposable pound shop item.

its not a £800 paperweight yet, the ramp action still operates fine, it's just lost a portion of its preload (only 1/4 of the rings broken).
so once the spring is replaced hopefully with a stronger rating but shimmed to the same original preload, it'll be back to normal with a more reliable unit.

better to fix a problem immediately at its source than to fudge a bandaid and end up costing you more in the long run.
Click to expand...

Too easy.

Better to resolve it with hands-on cunning rather than writing out another cheque Paul ;)

Joke to all those not in the immediate loop....
 
ok I called john at Gripper bout the failure.
the batch of preload springs from 2011 are the same ones used throughout their product range from low power rally coopers to 500bhp monsters and non of them had ever had this sorta failure so he'll be interested in what the cause was.

He needs the whole diff unit sent back so they can investigate exactly what part of the diff has caused the failure, fix it and then send it back. he's sending the postman to pick it up tomorrow so I don't have to sort out postage.

we clarified that it'll be free of charge and I requested that he emails me the estimate as proof.
 
Good to see John on side with you Paul. Will be interesting to see if they can find the root of the issue.

Depending on the situation, I may very well open up this LSD to see if anything is afoot too. There's nothing performance wise to suggest that there is, but given your unfortunate situation it maybe pertinent to do so.
 
pollyp said:
ok I called john at Gripper bout the failure.
the batch of preload springs from 2011 are the same ones used throughout their product range from low power rally coopers to 500bhp monsters and non of them had ever had this sorta failure so he'll be interested in what the cause was.

He needs the whole diff unit sent back so they can investigate exactly what part of the diff has caused the failure, fix it and then send it back. he's sending the postman to pick it up tomorrow so I don't have to sort out postage.

we clarified that it'll be free of charge and I requested that he emails me the estimate as proof.
Click to expand...
Ah very good result :) Good stuff, was worried about my purchase of a gripper.
 
Low Rider said:
Good to see John on side with you Paul. Will be interesting to see if they can find the root of the issue.

Depending on the situation, I may very well open up this LSD to see if anything is afoot too. There's nothing performance wise to suggest that there is, but given your unfortunate situation it maybe pertinent to do so.
Click to expand...

try jack up one of the front wheels at a time and spin it my hand.
if its a 2-way, u should feel it lock up n resist turning both ways.
if its a 1.5-way, it should lockup/resist turning one direction more than the other.

the lockup action on mine will be more sensitive on one side than the other wheel due to the asymmetric clutch pack setup to fit the speedo gear.

if the lockup/resistance feels very low or zero like mine currently, then the preload ring might be worth checking.
 
pollyp said:
try jack up one of the front wheels at a time and spin it my hand.
if its a 2-way, u should feel it lock up n resist turning both ways.
if its a 1.5-way, it should lockup/resist turning one direction more than the other.

the lockup action on mine will be more sensitive on one side than the other wheel due to the asymmetric clutch pack setup to fit the speedo gear.

if the lockup/resistance feels very low or zero like mine currently, then the preload ring might be worth checking.
Click to expand...

It's the standard 45/45 setup with integral speedo ring Paul, it works very well and there is plenty of pre-load there. It's curiosity more than anything and also due to some mild apprehension from the buyer. It would also be easier for me to see something through with Gripper, should there be any issues, since I am the original purchaser.

I must admit, Gripper have pretty poor literature on their site in general. In one instance they state 'current ramp angles available are 30/65, 40/65 and 45/45'. However within their 2013 price list they state 'the most popular ramp angle is 30/65, 40/65 and 45/45, others if required.' So, technically, there are infinite possibilities when it comes to setups.
 
thx frank.
after the call, i thought "does john have my email? how's he gonna email me the estimate if he doesn't have it?"
so I emailed em to remind him :p
 
Low Rider said:
It's the standard 45/45 setup with integral speedo ring Paul, it works very well and there is plenty of pre-load there. It's curiosity more than anything and also due to some mild apprehension from the buyer. It would also be easier for me to see something through with Gripper, should there be any issues, since I am the original purchaser.

I must admit, Gripper have pretty poor literature on their site in general. In one instance they state 'current ramp angles available are 30/65, 40/65 and 45/45'. However within their 2013 price list they state 'the most popular ramp angle is 30/65, 40/65 and 45/45, others if required.' So, technically, there are infinite possibilities when it comes to setups.
Click to expand...

yeah their website is very prehistoric with no spec info at best.
 
postman collected the diff tday

new oil gallery copper washer fitted

DSC08071.JPG
DSC08072.JPG
DSC08073.JPG
 
Last edited:
sky renewal letter quoted £572 (last year was £597) but their price guarantee says they'll refund the difference if anyone's cheaper.
rang around and adrian flux did £520 and could also offer breakdown extra £54, injury £15 and key cover £15 (won't need any of that)
rang back Sky and Clive could match that price, sorted. couldn't do breakdown cos it's above 15yrs but meh.
 
pollyp said:
sky renewal letter quoted £572 (last year was £597) but their price guarantee says they'll refund the difference if anyone's cheaper.
rang around and adrian flux did £520 and could also offer breakdown extra £54, injury £15 and key cover £15 (won't need any of that)
rang back Sky and Clive could match that price, sorted. couldn't do breakdown cos it's above 15yrs but meh.
Click to expand...

You must be in a good postal code Paul. My quote was a tad more and on less power. Still a long way from the £245 I pay now though through Chauser.
 
prob cos I also changed the job from design engineer to software engineer (less driving risk?) but then added business use cos I go to meetings #dunno#
long as its cheaper
pays to shop around
 
Gripper replied back that I didn't include any paperwork with the diff to ID it, but he didn't mention it did he. anyway its passed their IN box and gonna be seen to nxt week
 
Been over a week now and not heard back. Emailed john yesterday and still nothing.

Very poor customer service Gripper, not informing me what's going on, broken promises, dunno if they've just nicked me diff & ran.
 
pollyp said:
Been over a week now and not heard back. Emailed john yesterday and still nothing.

Very poor customer service Gripper, not informing me what's going on, broken promises, dunno if they've just nicked me diff & ran.
Click to expand...
If it don't exist then you can't complain about it lol

signature...please ignore anything I say...when using my phone it is either bad grammar or rubbish spelling.
 
just rang john at gripper.
the diff was rebuilt since friday. tech had no idea what caused the failure but the preload ring showed signs of alot of polishing wear for some reason, even though it wasn't used much of last yr.

asked could it have begun cracking on the 1st track day since it was last rebuilt and got worn down over the brief period I used it, said nope this mostly appears on high mileage units where the ring flexes each time under load and polishes the touching edges.

anyway he only has my mobile and email but requires my addr to post it out, which I've just emailed over.
 
indeed.
not sure all the lsd faults are fixed if their tech can't even find the cause. I'm hoping the replacement preload ring is of a modern batch that might be better quality.

if this one also fails again soon, then this LSD won't turn out to be reliable. Can't see myself having to rebuild the LSD every few months/per year.
worse case last resort would prob be to tell em to replace the weak preload ring with additional clutches.
What do you do as a customer if you've been sold a product that's not reliable or fit for purpose? other than getting it rebuilt every year under warranty or selling it at a loss?
 

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