1300 fwd wheels and other problems

[oli-triumph]

Last year i bought myself a 1300fwd. I have been paying all year to keep it on the road many months and no i have replaced nearly everything. one thing i am looking for is a set of alloy wheels but i have been told that you can not put any wheels other than standard on these cars. Is this true or just people trying to make everyone stay original? the other problem i am having is when i get into fourth gear at higher speeds 55 mph+ the car starts to back out and no longer rev. When this happens it feels like either the clutch is slipping or the breaks are been pressed on and off. So i changed the brake pads (the disks seemed fine, so did all the rear brakes) and adjusted the clutch. Unfortunately the problem still exists, iv even tried many different tuning setups but all this does is increase or decrease the speed this happens at. Does anyone know what the problem could be?

[james_r_lucas]

Once you get to 55, try pulling the choke out. Mine needs this assistance to hit 70...

As for wheels, I know people who run non standard wheels with no problems (other than flaring the arches). However you'll be opening a massive can of worms if you mention too much about it on here - have a search to see what I mean!

[1300_2door]

The only alloy wheels you could fit without any fouling problems would be ones intended for the Rover Metro/100, I know of at least one club member with these fitted and he doesn't report any problems.

As for your running problems, if the clutch was slipping you would get an increase in revs but with no increase in speed to show for it, Are you getting full throttle ? if the linkages and bushes from the peddle to the carburetor are worn you won't get full travel, the two bushes you can look at are is one on the bulkhead and the one on the transmission tunnel under the dash.

Gordon

[Spunkymonkey]

Also check your fuel pump - the diaphragms can go porous which means they can't pump enough for high speed, high throttle conditions.

So the carbs start to empty, the revs drop, fuel demand reduces, the carb refills, revs increase, pump can't keep up...... and so on.

[soe8m]

:-"

[sprint95m]

Can we please avoid a repeat of the below.....
viewtopic.php?f=4&t=21176&st=0&sk=t&sd= ... 300+wheels






Thanks,
Ian.

[soe8m]

Ok, here we go.

I have 4 books of chassis and suspension designs/designing and they all tell the same. I did bought these books how to understand why a dolomite does handle as it does and how to improve. There can be a lot of improvement but that's not on here. The 1300fwd question is.

There's something like the scrub distance. This is the distance between the kpi line and the wheel centre line. When the scrub is zero, the wheel turns exact at it's centre point and this gives the lightest steering. Also the forces on the bushes and steeringrack are at their lowest. When the scrub is high, the wheel turns and scrapes more so more forces on the suspension and steering and the steering will be more heavy.

Drivingwise, the more scrub will cause unstable driving at high speeds. The wheels tend to go toe out. It can also cause under or oversteer when entering corners or suddenly have to go round a pedestrian.

A 1300 has about the same suspension setup as a dolomite but the hubs are more out because of the cv joint. To have the centre of the wheel more to scrub zero there is a very much offset to have the centre line of the rim towards the hub. A dolomite has hubs that are closer to the ball joints and do not have to use a big offset. These 1300 wheels have a unique offset and a normal dolomite wheel will cause a very different scrub. You can fit wider wheels on any car as long they are enlarged the same on the inside and outside to have the centreline at the same place, or more ideal, wheels with an ofsett that creates less scrub than original. In the case of an 1300fwd you have to fit wheels that have the nuts outside the wheel, like Ben Hur. Phisically every wheel with the same pdc will fit but does have a big influence in handling.

For an 1300fwd the instability at high speed will be less because it's fwd and the traction forces will move the wheels to toe in a bit but the overall handling does not benefit other ofsett wheels.

Jeroen

scannen0005.jpg (204.73 KiB) Viewed 2030 times

For some Dolomite facebook people, i do have two 1300fwd's

[oli-triumph]

Hi. Thanks for all the advice. i have just been confused to why the car has been doing this and only doing it in fourth gear. And also thankyou for the advice on wheels the only reason i need a set is because one of mine is bent so i no longer have a full set and i was just wondering if alloys was an option.
Thanks oli

[ed1993]

I have 2 fwd wheels sitting on my spare subframe at home. I'm not sure what condition they are in but they weren't bad when I last looked, just in need of a lick of paint. I'll be at home this weekend, if you are interested just drop me a PM

[DavePoth]

Hi. Thanks for all the advice. i have just been confused to why the car has been doing this and only doing it in fourth gear. And also thankyou for the advice on wheels the only reason i need a set is because one of mine is bent so i no longer have a full set and i was just wondering if alloys was an option.
Thanks oli

It's a steel wheel - get it hammered back!

Unless it's really out of shape a decent tyre fitting place should be able to sort it.

[Jordan T]

Ok, here we go.

I have 4 books of chassis and suspension designs/designing and they all tell the same. I did bought these books how to understand why a dolomite does handle as it does and how to improve. There can be a lot of improvement but that's not on here. The 1300fwd question is.

There's something like the scrub distance. This is the distance between the kpi line and the wheel centre line. When the scrub is zero, the wheel turns exact at it's centre point and this gives the lightest steering. Also the forces on the bushes and steeringrack are at their lowest. When the scrub is high, the wheel turns and scrapes more so more forces on the suspension and steering and the steering will be more heavy.

Drivingwise, the more scrub will cause unstable driving at high speeds. The wheels tend to go toe out. It can also cause under or oversteer when entering corners or suddenly have to go round a pedestrian.

A 1300 has about the same suspension setup as a dolomite but the hubs are more out because of the cv joint. To have the centre of the wheel more to scrub zero there is a very much offset to have the centre line of the rim towards the hub. A dolomite has hubs that are closer to the ball joints and do not have to use a big offset. These 1300 wheels have a unique offset and a normal dolomite wheel will cause a very different scrub. You can fit wider wheels on any car as long they are enlarged the same on the inside and outside to have the centreline at the same place, or more ideal, wheels with an ofsett that creates less scrub than original. In the case of an 1300fwd you have to fit wheels that have the nuts outside the wheel, like Ben Hur. Phisically every wheel with the same pdc will fit but does have a big influence in handling.

For an 1300fwd the instability at high speed will be less because it's fwd and the traction forces will move the wheels to toe in a bit but the overall handling does not benefit other ofsett wheels.

Jeroen

That was an interesting read Jeroen, I would love to hear more about suspension geometry. Could you tell me the names of the books?

Similarly, I had Triumph Herald 3.5J wheels on my Toledo and it understeered quite a bit more than when it was running on its standard wheels. Having read your theory, it must have been the greater offset the herald wheels had causing the poorer handling.

I've always liked the weird look of the 1300 FWD wheels.

[1300_2door]

Ok, here we go.

I have 4 books of chassis and suspension designs/designing and they all tell the same. I did bought these books how to understand why a dolomite does handle as it does and how to improve. There can be a lot of improvement but that's not on here. The 1300fwd question is.

There's something like the scrub distance. This is the distance between the kpi line and the wheel centre line. When the scrub is zero, the wheel turns exact at it's centre point and this gives the lightest steering. Also the forces on the bushes and steeringrack are at their lowest. When the scrub is high, the wheel turns and scrapes more so more forces on the suspension and steering and the steering will be more heavy.

Drivingwise, the more scrub will cause unstable driving at high speeds. The wheels tend to go toe out. It can also cause under or oversteer when entering corners or suddenly have to go round a pedestrian.

A 1300 has about the same suspension setup as a dolomite but the hubs are more out because of the cv joint. To have the centre of the wheel more to scrub zero there is a very much offset to have the centre line of the rim towards the hub. A dolomite has hubs that are closer to the ball joints and do not have to use a big offset. These 1300 wheels have a unique offset and a normal dolomite wheel will cause a very different scrub. You can fit wider wheels on any car as long they are enlarged the same on the inside and outside to have the centreline at the same place, or more ideal, wheels with an ofsett that creates less scrub than original. In the case of an 1300fwd you have to fit wheels that have the nuts outside the wheel, like Ben Hur. Phisically every wheel with the same pdc will fit but does have a big influence in handling.

For an 1300fwd the instability at high speed will be less because it's fwd and the traction forces will move the wheels to toe in a bit but the overall handling does not benefit other ofsett wheels.

Jeroen

The attachment scannen0005.jpg is no longer available

For some Dolomite facebook people, i do have two 1300fwd's

Yes and no, that's to say I agree with some of what Jeroen says.

Your theories on scrub radii I agree with, the 1300fwd has virtually no scrub radius, I think this is why the steering can (to some people) feel a bit dead. Thus adding some (reducing the ET) scrub would help in my opinion, the ET of the original wheels is about 62mm and the Metro wheels i mentioned earlier i believe to be about 50mm ( the wheels we're not mentioning are 35MM) so that's an extra 12mm of scrub. One of the down sides to adding to the scrub radius is and increase of torque steer but there isn't really enough power for this to be a problem

The bit i don't agree with is the difference between the Dolomite and Fwd steering geometry, I don't believe the distance from the mounting face for the wheel to the suspension ball joints is that different if any at all, the reason the wheels sit farther out is because the suspension is mounted farther outboard, it's all in the fulcrum brackets. I have Dolomite suspension on my two 1300's with fwd uprights and with my RFX Revolution wheels (Specific front wheel drive wheels) sit well inside the arches and these wheels have a ET of 29mm

I didn't get involved in the discussion last time as it did get a bit messy, but these are just my opinions gained through 26 years of modifying 1300's, if some people don't agree I'm willing to listen to any constructive critique.

Jordan, I'd recommend this book, http://www.amazon.co.uk/Competition-Car ... 613&sr=8-1



Gordon

[soe8m]

More scrub is alway's bad. It gives more feel because the wheels want to move outwards, toe out and that gives you that feel/ more feeling. But it's a bad feeling. The dead feel is most of the time worn lower trackrod bushings and moving the lower baljoint backwards due to wear. At my dolomites and my fwd also i shorten the front lower trackrods and on my daily i did a rally gp2 mod and that's the 2500 bushings where it is connected in the subframe hole. When you shorten the front trackrod the lower baljoint moves forward, more castor and gives a better centrating effect, thus more stability. After varoius adjustable ones i do shorten them 15mm and make them solid as this is the most ideal compromise between steering effort and better roadholding. When this centrating effect is more the wheels want to go in line with the car more and that will also get rid off the dead feel. You can compare it to a supermarket trolly. These have this in the extreme. The little wheel does alway's want to follow the trolly in line. With a car you must use more strenght to move the wheels offline, called steering, and that gives a better feel or even a feel.

The less scrub, the lighter the steerring because the wheels have less drag and less stresses at all joints. Having more scrub just to have more feel is the wrong way round.

Jeroen