General Category > General Discussion
Early Tonti Fork Springs?
wirespokes:
My G5 project has really stiff front suspension, so I took a look. Dampers are fine, springs are pretty stiff. They're Wirth, and I tried looking for data on them. Good luck! I found the german site, and MG Cycle has no data - only sells them, but not currently in stock.
The springs are about an inch longer than the damper rods, and that's all the pre-load they have.
So what are they? What rating are they? Stiff, medium or light weight? MG Cycle appears to sell only one version for the T3, G5 etcetera, but don't list the Wirth part number.
The number painted on the spring is KBA ABE 91079-401.
Any data on them would sure be appreciated.
Littlefield:
Not an answer to your question but if you can’t find the data it’s pretty easy to calculate the stiffness. Google the formula which uses spring diameter, number of coils, wire size and modulus of elasticity (30E6 psi for steel).
moto:
--- Quote from: wirespokes on July 08, 2026, 08:52:41 PM ---
So what are they? What rating are they? Stiff, medium or light weight? MG Cycle appears to sell only one version for the T3, G5 etcetera, but don't list the Wirth part number.
The number painted on the spring is KBA ABE 91079-401.
Any data on them would sure be appreciated.
--- End quote ---
They are progressive-wound springs, so they don't have a single spring rate. The way this works is that part of the spring has a closer space in between the coils and it binds up after the initial compression, leaving the wider wound part of the spring to take over. With fewer coils then left in action, the spring rate becomes stiffer.
MG Cycle in fact sells two different Wirth spring sets with overlapping suggestions for the applicable bikes. I'm too tired to try to figure out which set is stiffer. Maybe the staff can help. Or maybe Stein Dense lists the same parts, with more guidance.
Aldo:
--- Quote from: wirespokes on July 08, 2026, 08:52:41 PM ---My G5 project has really stiff front suspension, so I took a look. Dampers are fine, springs are pretty stiff. They're Wirth, and I tried looking for data on them. Good luck! I found the german site, and MG Cycle has no data - only sells them, but not currently in stock.
The springs are about an inch longer than the damper rods, and that's all the pre-load they have.
So what are they? What rating are they? Stiff, medium or light weight? MG Cycle appears to sell only one version for the T3, G5 etcetera, but don't list the Wirth part number.
The number painted on the spring is KBA ABE 91079-401.
Any data on them would sure be appreciated.
--- End quote ---
On a separate note, are you sure you have the correct dampers? They made slightly shorter dampers for the T3, T, V7 Sport, Lemans, and Eldorado 850 with disk front end which look pretty close to the later ones. With that, the springs length changes; these used shorter springs. Is it possible you have the shorter dampers with the longer wirth springs? Maybe that is why you have excessive preload?
PeteS:
I would suspect the dampers rather than the springs. Are the dampers stock?
Pete
Navigation
[0] Message Index
[#] Next page
Go to full version