The Ed Gault improved timing belt upgrade: any long term users?

From what I've read and been told by such unfortunate owners the teeth on the belt are stripped off because the tensioner bearing fails and seizes up.

 

Well, he only made a few sets AFAIK, and he used one himself. Some guy just posted on a car he has overseas that appears to have that system on it, so they are still around. He cant seem to find a belt for it so its probably the original.

All I know is that the stock 308 belt was designed to transfer a maximum of some 12 HP or thereabouts, and the new style HTD belt is rated at about 10 times that figure IIRC. At any rate, its not just going to strip teeth off, jump time and bend all your valves with the frequency these POS ones we have on the cars now do.

 

I gotta agree with this. Besides, the number of actual belt failures is probably 5% of the number that are reported to have failed. The real number of failures is unknown. There have been threads in the past where requests were made for first hand sightings, preferably with pics, but the response is usually underwhelming or the thread gets hijacked

Quite frankly, unless someone can say "A belt has failed on MY car" I won't believe it. Even then, pictures or a repair bill would help me believe. The exceptions would be Brian Crall and Dave Helms, perhaps a few others, whose experience and honesty is unquestionable.

This is not to say the design cannot be improved. Scott's setup clearly shows that it CAN be improved. Where money is a limiting factor (that's most of us) then I find it hard to justify changing from the original setup.

Dave

 

I've got one of Ed's kits sitting on the shelf and will probably install after the end of this driving season. I ordered it shortly after I replaced the OEM belts. My initial inspection of the pieces indicated a well thought out system.

Bill

 

Any comments on the idler pulley? I have Scotts sprockets but would like a tensioner like Ed's. With new drive sprocket bearings the system would be good for a long long time.

 

I'd really like to see close up pix of Ed's tensioner, including pix of the numbers on the bearing.

Any measurements would be appreciated.

WHY:
I'd like to evaluate reproducing them to go with the cam gears I got from smg2.

 

I hope you're going to get those lower gears machined soon from Scott's stock... one set is mine!

 

I'm scheduled to start on them the 1st week in June. A bunch of work arrived just before I got the stock.

 

All this 3x8 info is cool but where it is desperatly needed is in the engine out cars. 512s and TRs come to mind.
I did a square tooth to rounded tooth mod to my 84 Lotus Turbo esprit. The later ( 88+ ? ) cam gears and belts were the Superior rounded tooth kind. Tensioners normally ride on the back side of the belt; No mod required.
There are "Super" belt manufacturers out there for the NSX and other cars which exceed Mfgs specs.
What is needed is to have gears made ( or taken from other existing engines ), and a "super" belt Mfg make or possibly use an existing one, upgrade the tensioner bearing and PRESTO! 60k+ belt changes.
Now who volunteers to do the testing ?

 

You give me the upgraded parts, tensioner bearings, drive gears, belt, and I'm crazy enough to do it with my 348.

 

Verell,

Ed's system is boxed up in my basement somewhere, but I'll pull it out and see what's there later this week. I;ll get you the information you need.

Bill

 

Looking at pictures of his setup, and I admit I cant see the tensioner in any pics, it appears he may simply have slipped a sleeve over the OEM tensioner bearing? Anyone have any better pics of his system? Just increasing the outer diameter a small amount with an aluminum or steel sleeve pressed over it would slow the stock bearing down considerably and allow it to survive much longer.

 

How much available room is there to increase the diameter (without interfering with something else)? It seems like improved tensioner "wheels" would be the easiest part of the project.

 

The tensioner is a double raced ball bearing, just off the top of my head I would guess its about 3 inch in diameter. I would have to look to see for sure, but I believe we could easily press a sleeve over it to make it an inch larger in diameter. Obviously I am guessing at dimensions, but there is some room. If the wheel were increased in size 33% (3-4) there would be a speed reduction of 25%.

 

Nick has a tensioner already like this, and would save you the trouble of re-engineering the thing. It's simple enough, but machining and material costs just don't make it worth while to me. just a heads up.

 

Is it possible we could run a roller bearing instead of this ball bearing thing? I realise a roller has no real thrust capability, but there really shouldnt be any on this should there be? Is a ball bearing really better in this situation??

Nick, how is your tensioner different from OEM and how much larger in diameter is it?

Scott, if we increase the diameter of the tensioner, we will need a longer belt, no?

Maybe its time to go play with my lathe for once, lol.

 

Shouldn't be any real thrust load and considering that the tension is applied to the "slack" side of the belt, pretty low radial load. Seems to me like there's no reason a good bearing should ever wear out (yet they seem to).

 

high rpm on double row ball bearing, a roller would be best and slowing it down even better.

yes you'll need a longer belt if you go larger, however the stock length can accommodate some increase, I have calcs that specify belt length based on pulley dia.

 

The limit is likely to be the cam belt cover, doubt that you could go as large as is being suggested.

I know that Nick has an alternative bearing, but I like to try things myself. Expect to do this after salt season begins, which is when I'll be doing a major on my QV & installing the supercharger.

Even holding almost the same OD, a roller bearing might hold up better.

I think the fundamental reliability problem boils down to the combinatin of heat buildup due to fairly high rotational speeds + engine heat trapped inside the belt covers cooking the bearing's lubricant.

Whenever I change belts, there's always a substantial amount of grease that's leaked out of the tensioner bearing's seals. Saw it again a couple of weekends ago while changing 2 year old belts with only about 3,000 miles on them!

 

Waste of time and money unless the inferior cam drive bearings and seals are redesigned as well since the 308 will start spewing oil from the drive seals long before the new type of belts need to be replaced. Doesnt make sense unless the rest of the engine is updated to reduce maintianence such as cam seals and valve adjustments.

 

I disagree. I'd much rather have a more modern and robust belt on my car DESIGNED for 100,000 miles than one that is a 25+year-old design that Ferrari says needs to be changed every 3 years.

That doesn't mean I'd actually wait 100K miles to change it, because of the other components, but I like the idea of less probability of a failure due to the belt itself.

 

A more robust belt could be worse... if the tensioner bearing seizes but the belt does not break or slip a tooth, what then will happen to the engine...does any one have an educated guess? My point was that you should be changing the tensioner bearings every 30k miles or 5 to 7 years anyway, so why not change the belts at that time too?

 

Can't one just use one of the newer ceramic bearings, advertised to last "forever" in high tech applications....

 

Its a waste of money but feel free since its coming out of your wallet. As a mechanic myself I know you're spending in the wrong area.

 

Absolutely!