1934 Jowett Van Braking System

[Mike Allfrey]

I'm Back!!!

Friends have a 1934 Jowett van-based special. The chassis and most of the running gear is 1934 van. As far as I can determine the brakes are rod operated Girling brakes. Despite a comprehensive overhaul, and several attempts at brake adjustment, brake performance is practically non-existent. It appears that the system does not have any means of compensation. Surely a rod system would have compensation front and rear? I believe that the Bradford models featured front and rear compensation.

My 1937 10 hp Four is fully compensated.

Can anyone out there throw a spot of light on how the system works and is adjusted?

Help with this will be greatly appreciated.

Kind regards to all,

Mike Allfrey.

Mike Allfrey.

[george garside]

the sevens were all ( from 29/30 )fitted with Jowetts own system which is completely different to girling and essentially non compensated. Adjustment by wing nut on each wheel anad master adjustment by wingnut uner bonnet .

to set up ( and assuming drums not worn outside limit and caams in good nick with no ploay in opperating shaft etc.)

Jack up all 4 wheels, apply handbrake 3 notches and then adjust wingnuts so that each wheel is moveable by the same effort.Release handbrake lever and check all wheels free to rotate i.e. brake shoes clear of drums. Can also be checked by tapping drims with hammer which should produce clear ring or by driving a short distance without using brakes & testing each drum with hand for undue heat.

Once that has been set up routine adjustment is by the wingut under the bonnet.

Handbrake adjustment by wingnut at end of pull rod under the floor - again adjusts all 4 brakes.

the large diameter tunbe on the main brake cross shaft is a safety device being rivetted to the brake cross shaft in the centre giving a slight compensating effect from side to side. This tube should be a loose fit in support brackets mounted on crossmeber .

george

[george garside]

Mike should have added for clarification that tee \Jowett system was used on all the Jason 4 cyl and all * & 10 from oct 1936 - '37' model year used bendix cowdrey self servo system ( a bit like the girling system) but The 1937 8hp van based on 34 ish car parts probably retained the Jowett system. A few very ealy Ca Bradfords had the bendix brakes but then in I think 1946 went over to girling, initially 8" and later 10"drums

[Mike Allfrey]

Dear George,

Thank you for that useful information. I am hoping that careful adjustment, under your guidance, will effect a fix for this little Jowett. The car is located in Brisbane and I am down in Melbourne, so I can only help from a distance.

I had always thought the 1930s Jowetts used Girling braking systems. That probably stems from my involvement with Jupiters and their Girling brakes.

I will be sending an article on this special to Alan, so it can be placed in the Jowetteer at some point in the future.

Kind regards and thanks,

Mike Allfrey.

[Tony Fearn]

Hello Mike.

Yesterday I typed up a reply to your query about brake adjustment on the Pre-war sevens in Microsoft Word. But before I copied it into JowettTalk and posted it, I thought that, even though it wasn't definitive, and only observational from sorting my two pre-wars out, I would send the copy to two pre-war 'experts' to vet it, as once posted it would be world-wide.

I've had the ok from one of my long-time friends, but as yet haven't had the ok from my other (almost as long-time) friend. When he telephones me (not being computer savvy!), and if he concurs, I will post my deliberations.

Regards,

Tony. (Member of the Sydney Branch of the JCCA as well as the JCC of the U.K.)

[Tony Fearn]

Hello Mike and George.

I’m going to add my ‘penneth’ for what it’s worth. These are observations only, and need to be thought through again by anyone using them to help set-up their pre-war 7 brakes, in case I’ve omitted anything.

scan0007.jpg

1. Are the brake rods the original length? This will affect the angle of the cross-tube levers and the midship hanger.

2. Make sure the rods are in the correct holes on the cross-tube and the hanger, and that there’s no wear in the rod ends or the holes they go through? (See pic above)

3. Are the springs on the brake rod ends able to take-up slack and not closed up?

4. Brake levers are most efficient when they pull up towards 90 degrees.

5. Are the brake linings ok and not too worn?

6. Make sure that at the rear brake levers, and the front slave levers, the special locking washer is in-situ on the bolt. This special washer makes sure that the levers don’t slip around the bar. The bar has a groove machined into it into which the flat end of the washer fits. If this is not present, and the brakes are applied vigorously, the lever may just spin around the bar if the bolts are not tight enough, with disastrous results!

7. Support the vehicle on stands under the axles, not the chassis so that all four wheels are off the ground.

8. Remove the road wheels.

9. Loosen the wing nuts at each rod end and wind them back some way. This will allow the brake shoes to find their ‘resting place’ being pulled together by the brake shoe springs.

10. Loosen and wind back the wing nut at the bottom of the brake pedal (under the bonnet)

11. Crack the lock nut on the handbrake adjusting bolt and wind back the bolt. This will free the system from interference by the handbrake at this time.

12. Drum by drum, by hand, pull the brake actuating lever and determine whether the brakes are coming on before or after 90 degrees. There shouldn’t be much lever movement if the shoes are almost, but not quite touching the drum when at rest. If there’s excessive movement perhaps experimenting with shims under one or both ends of the brake shoes might help. Using thicker linings used to be another option. A
chalk mark around the linings whilst sorting out the clearance will show how much of the lining is bearing on the inner surface of the drum when the lever is pulled on whilst the drum is turned by hand. I’m informed that if half the lining is touching the inner surface of the drum when turned by hand, then this should be ok.

13. At the front hubs, there is a stout rod (??silver steel) through each kingpin which transmits leverage from the rod-end-lever to the little slave lever at the top of the backplate. There should be no loss of motion here. I have in my collection, rods of differing lengths! Lengthening the rod will alter the angle of the rod-end-lever and vice versa.

14. Turn the cross-tube towards the rear of the car so that the ends of the rods at the wheels push out a little more from their levers. This makes sure that the cross-tube levers will come up to 90 degrees when the footbrake is applied at the end of the adjustment sequence.

15. With someone holding the cross-tube, screw in all 5 thumbscrews until they just touch the levers without compressing the rod springs.

16. Put a 1” (or so) square piece of wood between the foot board and the foot brake lever (under the bonnet) to simulate just applying the brakes.

17. Re-fit the road wheels and starting at the rear, turn the thumbscrews at each wheel until the same force is needed at each wheel to turn it. Do not over tighten at this stage.

18. The brake pedal thumbscrew under the bonnet will need monitoring as it may need adjusting as the others are tightened.

19. When the brakes are finally setup correctly, the pedal thumbscrew, if turned clockwise, should take up all brakes equally when adjustments are necessary. Of course when new linings are needed it will have to be backed off so that the process can be gone through again.

20. Remove the wood from behind the brake pedal and check that all wheels revolve easily.

21. Screw in the handbrake adjusting bolt until it just touches the boss on the cross- tube and tighten the lock nut. George describes a thumbscrew on the hand brake rod for adjustment, but my 1934 saloon doesn’t have one. On reflection, and by email, he says perhaps he’s wrong about this thumb screw.

22. I feel that this is the basic setup. The handbook instructions, to which George has alluded, should now be gone through to get a more definitive result.

Regards,

Tony.

[Mike Allfrey]

Dear Tony,

Thanks for that well-researched set of instructions. I have relayed it all to our club members in Brisbane and I hope to hear from them soon with a positive result.

Reading your piece, it all comes back to me about my apprenticeship days on Ferguson tractors. We were told that the lever angles were all-important with respect to achieving good results.

Your mention of placement of shims under brake shoes takes me back many years!

Kind regards,

Mike A.

[george garside]

Tony's very thorough blow by blow description of setting up the Jowett rod system should be gallery and/or legacy project stuff for future reference

Can somebody copy it to one or both?
george

[AlanBartlett]

Thanks for the reccommended link Tony. Ive gone through this, your guide this afternoon. Have found various problems, such as 3 out 4 levers are pulling excessively until point of contact with the drum. Ive fitted a selection of good shoes out of my spares, but I'd like to know what are the varying thicknesses of the shoes. I know that JCS have started to sell newly produced shoes so this might be a good start. Also what size of shims to fit, I'd imagine what ever sizes fit in between the shoe and bring the shoe closer to the drum. On the drums what are the wear rates and information?

[george garside]

Alan,
if its of any use the brake drums should be between 10.003'' and 10.997'' efficient and smooth braking also depends on them being absolutely round. checked with internal micrometer, digital calipers on mounted on lathe faceplate


george

[Tony Fearn]

....the brake drums should be between 10.003'' and 10.997''

There's a difference of almost an inch between these two measurements George. Are they internal diameter? What's the source of the info? Seems a bit odd to me, although there were two thicknesses of brake lining available.

IP has gone into the problems of brake shoes and linings on the pre-wars on members' behalf Alan, so perhaps a telephone call might be of use. In one of the more recent Jowetteer mags I think he explained part of it, perhaps in a JCS advert.

Tony.

[Forumadmin]

Must be a typo.
Suspect it should be 9.997 and 10.003 i.e. +/- 3 thou

[george garside]

Spot on Keith 10.003 - 9.997- sorry about the typo chaps.

Its stated in the ''Jowett owners Maintenance Hanadbook'' for models 1935 -39 that was publihed by JCL in 1952 presumably because they were still being asked for pre war handbooks and had none.

george

[AlanBartlett]

I've spent today setting up the brake system. And I am now happier with the overall set up. One of the main problems which was pointed out by your detailed setup instructions was that the cross tube was not moving towards the 90 degree angle, so it wasn't pulling quite as it should be. Have yet to road test but it already feels like a better pedal motion. Have just got to set up the screw adjustment on the handbrake to finish off.

[AlanBartlett]

Ive taken it out for a few test runs up and down the road. The brakes now slow the car down, and at slower speeds brings the car to a halt. (That movement you get when you slam on a modern cars brakes and wheels are stationary and the body as it were moves) Now I know ive got a while to go before the linings are bedded in, but what should the pedal be like?.

Before I made any adjustments it seemed to go down a fair amount and be soft, and spongey? is the way I can describe it. Now that Ive made all the adjustments the pedal travels the inch and stops at that point, and is hard to move any further than that point, but does slow the car down. Is this how its meant to have been the whole time? As I have no carpet in, I can prop up the floor board and see the workings of the cross shaft coming up to 90 degrees when the brakes are on, and is at the position when the brake is full pressed.