gilmor belt drive.

[Robert May Eng.]

Is anybody running one of these gilmor belt drives? I was wondering about the quality vs the price.

SBF FORD GILMER KIT PERFORMANCE RACING CRANK WATER PUMP ALTERNATOR | eBay

Bob

 

[Keith]

I have done - get the measurements right and they are bullet proof, although they would need to be changed every season if you were racing hard to be safe. No belt = no engine. For regular street use probably overkill. I got mine "pre-owned" and saved a bunch of money, but if I were racing today - I wouldn't hesitate.

Correct tension is key.

Note: I think I would want a hands on inspection before I parted with money. That Ebay version looks a little, er, Chinese for want of a better word, and although some very fine products come out of China - not all of it is. The Gilmer belts and pulleys I used were very lightweight and finely machined - certainly not polished up as in the advert photograph. Blingtastic - caveat emptor.

Edit 2: Here's a picture of mine:

 

[Jac Mac]

If the cogs run true & pitch matchs the belt & the ratios /speeds are what you want they 'should' be OK, but I have removed more than fitted for any one of the above reasons..... bling bling boy racer crap in my view..... prefer a bit of 'slip' factor on the pump & alternator.... take for example if an alternator bearing goes bad & seizes, belt is an instant fail with gilmer, wheras vee belt will slip/squeal & give a warning.Wear rate of alloy teeth is very high on some examples.

 

[Keith]

take for example if an alternator bearing goes bad & seizes, belt is an instant fail with gilmer, wheras vee belt will slip/squeal & give a warning.Wear rate of alloy teeth is very high on some examples.

Good points. I believe mine was alloy but a very hard one - no appreciable wear in a couple of seasons. I had concerns about the alternator failing as above, and I ditched the whole shebang and ran on gel batteries, but, that was racing only obviously. It also might be apparent that I ran one-to-one on the water pump as that was the size pulley I got. Should have been running at half speed with a bigger pulley but never got around to it. Although this was a 1/4 mile car, I ran the same system on my road race Penske Camaro without issues (also, no alternator)

Like I say, mine was a very expensive example, only cheaper because it was pre-owned. I think I paid at least the EBAY advert price 28 years ago 2nd hand.

 

[Jim Craik]

I know the depth of the belt may well be a problem, I doubt they would fit in the narrow area available in an SPF 40.

 

[Rich E.]

Personally I think the depth of the pulley wouldn't fit our applications unless you cut a deeper relief into the panel. I've got gilmor style pulleys on my RX-7 and believe in them however, without a shoulder on the drive or water pump pulley you run the risk of the belt walking off under high RPM decel and flex especially when the belt starts to stretch.

 

[Robert May Eng.]

The only way to find out if its any good and if it fits then is to buy it Some valid points on the alternator seizing so if it all goes in there its probably best to fit new. I will also have it checked to find out if the ali has a chocolate content and report back. On the last 40 we had trouble getting enough belt contact on the alternator pulley and ended up with the belt running a lot tighter than was good for it. On one occasion the belt flipped over and shredded hence the interest in the gilmer system, it also has a spare v off the lower which could run ac pump if it ever needed it. If it works out to be garbage or wont fit I will let you know.

Bob

 

[BruceA]

Ummm .. Id be interested to know what the benefits are of fitting a gilmer type drive to an engine?

 

[Jac Mac]

Should have mentioned in my earlier post, The tooth belt drives Ive used in recent times for dry sump pumps have all been hard anodized and tooth wear on those items is virtually non existant after several seasons, whereas older systems non coated have so much wear that a good belt will not seat correctly when wrapped around that worn gear. Only 'good' reason to fit is if you need a positive / timed drive, other than that a flat poly vee belt is a best option if you must change from an old style vee belt. A smaller crankshaft pulley dia to reduce effective belt speed will cure most problems & 'DO NOT' chrome your steel pulleys, been a fair few alternator 'problems' eliminated here on the forum after ditching the bling/chrome. Deep enough vee in the pulleys to prevent 'bottom' riding is another must, vee belts drive on the flanks.[/B

 

[Mike Drew]

Some additional considerations:

1) Gilmer belt drives are INCREDIBLY noisy in a mid-engined car. Hall Pantera used to sell a setup for Pantera use, and it was popular among people who drove just a few miles to the car show and wanted to impress their friends with the sound as they pulled into the lot. But almost every one I know of has since been removed because they are just too aggravating to live with in the long term.

2) They offer zero advantages over conventional V-belts for simple water pump/alternator applications, and lots of disadvantages, not the least of which is their much greater size. You won't fit one in a GT40 without extensive modifications to the engine access panel, and now you've got this protrusion into the cabin and the belt is screaming in your ear.

3) Because the belts are toothed, they don't need an enormous amount of tension, certainly less than conventional V-belts do. A friend was driving his Gilmer-equipped Pantera from Las Vegas to the San Francisco area, alone, at night, when one of his machined aluminum pulleys simply disintegrated, because he had too much tension on the system. In the course of falling apart, it also demolished the belt, and he was way, WAY stranded. I think he had to get a new pulley and belt overnight-shipped from Hall Pantera, but I wouldn't count on the ability to get replacement parts that quickly today.

Bottom line--just say no! There are plenty of other places where you can waste money more effectively on a GT40. :laugh:

 

[flatchat(Chris)]

Bling factor only, they're POS and a waste of money -- totally agree with Jac and Mike

 

[Robert May Eng.]

The reason I am looking at these is to try and get away from the v belt. I will have a look at the gilmer but if that does not work out I will have a look at serpentine. Its not about bling because the thing is buried ,its just to get a reliable belt system in there that works with very little belt contact. Gates recommend a max v belt speed of 6500 feet per minute, belt speed at 6500 rpm with a stock lower pulley is nearly 10000 feet per minute. Even with the underdrive march pulleys you are pushing 8000fpm. Take the revs to 7500rpm and even with the march pulleys you are back up to 10000fpm. Just some food for thought.

Bob

 

[Rick Muck- Mark IV]

Much of the concerns with alternator failure can be rectified with decent bearings. Most alternators, in particular rebuilts, have cheap bearings from over the pond. With quality bearings and a well balanced armature, failures should be rare. Beware, many new "performance" alternators are built with cheap bearings. Worth the time to take it apart and install decent bearings.

As an aside, when Ford was designing and testing the 1988 Taurus SHO they ran the DOHC Yamaha V6s at wide open throttle for 24 hours. The engines lasted fine....the alternators and power steering pumps failed! Thus a lower redline than was really required by the engine was applied.

 

[Jac Mac]

The reason I am looking at these is to try and get away from the v belt. I will have a look at the gilmer but if that does not work out I will have a look at serpentine. Its not about bling because the thing is buried ,its just to get a reliable belt system in there that works with very little belt contact. Gates recommend a max v belt speed of 6500 feet per minute, belt speed at 6500 rpm with a stock lower pulley is nearly 10000 feet per minute. Even with the underdrive march pulleys you are pushing 8000fpm. Take the revs to 7500rpm and even with the march pulleys you are back up to 10000fpm. Just some food for thought.

Bob

Was just browsing thru my gates tooth belt handbook, they also use that 6500 feet per minute max belt speed for the tooth belt range, now I am not suggesting you ignore the data, but you will find most motorsport applications exceed the design data, & being an american company the handbook is full of legal stuff about not using the product in any application that might cause injury etc. Not sure about the set you were looking at, but at a guess I would put that crank pulley/gear at around 4" plus in dia which would put it at about one foot per Rev so 6500 would be about its lot also, then its a Gilmer ( square tooth ) belt, not a curvilinear or HTD profile which are supposedly better & quieter. The TVR I did the work on has a 4" dia crank vee belt pulley & runs to 7800 with a vee belt that has a 'tooth' profile at the belt ID to allow for tight belt wrap around the pulley- absolutely no problems in what must be coming up to ten years of racing now- IMHO opinion your overthinking the issue- number of belt teeth in contact with the crank/drive gear can be an issue, have a look at the cam belt drive on a subaru or nissan V6 & note that the belt wraps around the crank pulley by at least 180°, that system your looking at will only get around 120°.

 

[Rick Muck- Mark IV]

BTW the cause of most of the noise of a Gilmer type drive belt is the air being "squeezed" out of the cogs as the belt advances. A couple of small holes in the valley of the tooth on the pulley will reduce the sound greatly. I have seen this demonstrated on a blower drive with a 4" wide drive belt.

 

[John Fitzpatrick]

Jac-
Given all the caveats on Gilmer and toothed belt drives, why do they find such wide use on dry sump systems?

 

[Jac Mac]

Jac-
Given all the caveats on Gilmer and toothed belt drives, why do they find such wide use on dry sump systems?

The oil pump 'needs' to have a positive drive in order to match its flow rate to the engine bearing/lubrication requirements, so it has to be either direct coupled to crank or camshaft speed- that could be chain, gear, toothed belt or direct off end of cam/crank or auxilary shaft, ( it just happens that the belt is one of the easiest setups, doesnt require lube or ultra accurate mount position compared to the others). Im sure the caveats implied by the manufacturers are at the behest of company lawyers etc who will have asked for a 'number' from the engineers that will have a fair amount of padding in it. If anyone cares to 'do the math' you will probably find that most belt driven DOHC engines exceed the belt limits when pushed up past the factory red-line.
Also in the handbook is an absolute disclaimer if anyone is foolish enough to use a belt as prop speed reduction unit ( or for that matter in any critical application ) in an aircraft, yet talk to any homebuilt chapter & its likely you will find someone using a belt for such purpose, but they probably asked for it as a drive for a rotary hoe when purchaseing
Bottom line, I dont think the belts are likely to fail directly as a result of being used for a dry sump pump, more likely to be from misalignment, poor mounting etc.

 

[John Fitzpatrick]

I knew a rotary hoe in high school, and her belt kept slipping off too. Probably the result of a bent shaft in a misaligned coupling.

"A bun is the lowest form of wheat."
Oscar Wilde.

 

[Jac Mac]

I knew a rotary hoe in high school, and her belt kept slipping off too. Probably the result of a bent shaft in a misaligned coupling.

"A bun is the lowest form of wheat."
Oscar Wilde.

I dont know whether to offer commiserations or congratulations with regard to that statement, s'pose it depends on whether your gardening endeavours were successful and if the seeds sown actually germinated.........